:root{
  --bg:#f5f6f4; --surface:#ffffff; --surface-2:#eceeea; --line:#d7dbd4;
  --ink:#1c2321; --muted:#566160; --brand:#6b2f22; --brand-ink:#ffffff;
  --bead:#c8891c; --bead-ink:#3a2506; --rod:#8a8f8a; --frame:#5a2a1f;
  --good:#1f7a4d; --bad:#b3261e; --focus:#2458c6; --img-dim:1;
  --f-display:"Bricolage Grotesque", "Noto Sans Devanagari", "Segoe UI", system-ui, sans-serif;
  --f-body:"Source Sans 3", "Noto Sans Devanagari", "Segoe UI", system-ui, -apple-system, sans-serif;
  --f-mono:"JetBrains Mono", ui-monospace, "SFMono-Regular", Consolas, monospace;
  --s1:.25rem; --s2:.5rem; --s3:.75rem; --s4:1rem; --s5:1.5rem; --s6:2rem; --s7:3rem; --s8:4.5rem;
  --r:12px; --r-lg:22px; --shadow:0 18px 40px -20px rgba(70,35,15,.45); color-scheme:light;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#141817; --surface:#1c2120; --surface-2:#232a28; --line:#343c3a;
  --ink:#e8ece9; --muted:#a3adaa; --brand:#e0937c; --brand-ink:#1a0f0b;
  --bead:#e2a63a; --bead-ink:#2a1a03; --rod:#6c7370; --frame:#8a4a3a;
  --good:#5fc58f; --bad:#f08a80; --focus:#8fb0ff; --img-dim:.8; --shadow:0 18px 40px -20px rgba(0,0,0,.8); color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#141817; --surface:#1c2120; --surface-2:#232a28; --line:#343c3a;
  --ink:#e8ece9; --muted:#a3adaa; --brand:#e0937c; --brand-ink:#1a0f0b;
  --bead:#e2a63a; --bead-ink:#2a1a03; --rod:#6c7370; --frame:#8a4a3a;
  --good:#5fc58f; --bad:#f08a80; --focus:#8fb0ff; --img-dim:.8; --shadow:0 18px 40px -20px rgba(0,0,0,.8); color-scheme:dark}
:root[data-style="classic"]{
  --f-display:"Source Serif 4", "Noto Serif Devanagari", Georgia, "Times New Roman", serif;
  --r:4px; --r-lg:6px; --shadow:none}

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;overflow-x:clip}
body{margin:0;background:var(--bg);color:var(--ink);font:400 1.0625rem/1.65 var(--f-body);overflow-x:clip}
img,svg{max-width:100%}
a{color:var(--brand);text-underline-offset:.18em;text-decoration-thickness:1px}
a:hover{text-decoration-thickness:2px}
:focus-visible{outline:3px solid var(--focus);outline-offset:2px;border-radius:4px}
h1,h2,h3{font-family:var(--f-display);line-height:1.15;text-wrap:balance;letter-spacing:-.01em;margin:0}
h1{font-size:clamp(2rem,4.2vw,2.9rem);font-weight:700}
h2{font-size:clamp(1.45rem,2.6vw,1.85rem);font-weight:650;margin-top:var(--s7)}
h3{font-size:1.2rem;font-weight:650;margin-top:var(--s5)}
p,ul,ol,table,figure,details{margin:var(--s4) 0 0}
li+li{margin-top:.3rem}
:lang(hi) body,body:lang(hi){line-height:1.8}
:lang(hi) h1,:lang(hi) h2,:lang(hi) h3{line-height:1.35;letter-spacing:0}
.skip{position:absolute;left:-999px;top:0;background:var(--surface);padding:var(--s2) var(--s4);z-index:50}
.skip:focus{left:var(--s4)}
.wrap{max-width:1120px;margin:0 auto;padding-inline:max(16px,4vw)}
.prose{max-width:68ch}
.num,.mono{font-family:var(--f-mono);font-variant-numeric:tabular-nums}
.eyebrow{font:600 .85rem var(--f-mono);letter-spacing:.06em;text-transform:uppercase;color:var(--brand);margin:0 0 var(--s3)}
:lang(hi) .eyebrow{font-family:var(--f-body);letter-spacing:0;font-size:.95rem}
.center{text-align:center;justify-content:center}
[id]{scroll-margin-top:84px}

/* ---------- header ---------- */
.site-head{position:sticky;top:env(safe-area-inset-top,0px);z-index:30;background:color-mix(in srgb,var(--bg) 86%,transparent);backdrop-filter:blur(10px) saturate(1.2);-webkit-backdrop-filter:blur(10px) saturate(1.2);border-bottom:1px solid var(--line)}
.head-row{display:flex;align-items:center;gap:var(--s3);min-height:64px}
.logo{display:flex;align-items:center;gap:.55rem;font:700 1.2rem var(--f-display);color:var(--ink);text-decoration:none;flex-shrink:0}
.logo svg{width:30px;height:30px}
.nav{margin-left:auto}
.nav>ul{list-style:none;display:flex;align-items:center;gap:.15rem;margin:0;padding:0}
.nav li{margin:0}
.nav-a,.sub-btn{display:flex;align-items:center;gap:.3rem;padding:.5rem .75rem;border-radius:9px;color:var(--ink);text-decoration:none;font:600 .97rem var(--f-body);white-space:nowrap;background:none;border:0;cursor:pointer}
.nav-a:hover,.sub-btn:hover{background:var(--surface-2)}
.nav-a[aria-current="page"],.has-sub.current>.sub-btn{color:var(--brand);background:color-mix(in srgb,var(--brand) 10%,transparent)}
.sub-btn svg{width:14px;height:14px;transition:transform .15s}
.has-sub{position:relative}
.has-sub.open>.sub-btn svg{transform:rotate(180deg)}
.sub{list-style:none;position:absolute;left:0;top:100%;min-width:250px;margin:6px 0 0;padding:.4rem;background:var(--surface);border:1px solid var(--line);border-radius:14px;box-shadow:0 18px 40px -16px rgba(0,0,0,.35);display:none;z-index:40}
.has-sub.open>.sub{display:block}
.sub li+li{margin-top:2px}
.sub a{display:block;padding:.55rem .75rem;border-radius:9px;color:var(--ink);text-decoration:none;font-weight:600}
.sub a:hover{background:var(--surface-2)}
.sub a[aria-current="page"]{color:var(--brand);background:color-mix(in srgb,var(--brand) 10%,transparent)}
.nav-game{margin-left:.25rem;background:linear-gradient(180deg,color-mix(in srgb,var(--bead) 22%,var(--surface)),color-mix(in srgb,var(--bead) 10%,var(--surface)))!important;border:1px solid color-mix(in srgb,var(--bead) 55%,var(--line))!important}
.nav-game[aria-current="page"]{color:var(--ink)!important}
.head-tools{display:flex;align-items:center;gap:.35rem;flex-shrink:0;margin-left:var(--s2)}
.menu-pop{position:relative;margin:0}
.head-row{flex-wrap:nowrap}
.nav>ul{flex-wrap:nowrap}
.nav>ul>li{flex-shrink:0}
@media (min-width:901px) and (max-width:1080px){
  .head-row{gap:.5rem}
  .nav-a,.sub-btn{padding:.5rem .55rem;font-size:.94rem}
  .nav-game{margin-left:.15rem}
  .head-tools{gap:.3rem;margin-left:.25rem}
  .logo{font-size:1.12rem}
}
.menu-pop>summary{list-style:none;display:inline-flex;align-items:center;gap:.35rem;height:40px;min-width:40px;justify-content:center;padding:0 .6rem;border-radius:10px;border:1px solid var(--line);background:var(--surface);color:var(--ink);cursor:pointer;font:700 .88rem var(--f-body)}
.menu-pop>summary::-webkit-details-marker{display:none}
.menu-pop>summary:hover,.menu-pop[open]>summary{border-color:var(--brand);color:var(--brand)}
.menu-pop>summary svg{width:19px;height:19px}
.pop{position:absolute;right:0;top:calc(100% + 8px);min-width:220px;background:var(--surface);border:1px solid var(--line);border-radius:14px;box-shadow:0 18px 40px -16px rgba(0,0,0,.35);padding:.5rem;z-index:45}
.pop ul{list-style:none;margin:0;padding:0}
.pop li+li{margin-top:2px}
.pop a{display:flex;justify-content:space-between;gap:1rem;padding:.55rem .75rem;border-radius:9px;color:var(--ink);text-decoration:none;font-weight:600}
.pop a:hover{background:var(--surface-2)}
.pop a[aria-current="true"]{color:var(--brand);background:color-mix(in srgb,var(--brand) 10%,transparent)}
.pop a small{color:var(--muted);font-weight:500}
.pop-h{font:700 .78rem var(--f-body);text-transform:uppercase;letter-spacing:.08em;color:var(--muted);margin:.35rem .3rem .35rem}
.pop-h+.seg{margin-bottom:.6rem}
.seg{display:flex;gap:3px;padding:3px;border:1px solid var(--line);border-radius:11px;background:var(--bg)}
.seg button{flex:1;border:0;background:transparent;color:var(--ink);padding:.45rem .55rem;border-radius:8px;font:600 .9rem var(--f-body);cursor:pointer;white-space:nowrap}
.seg button[aria-pressed="true"]{background:var(--brand);color:var(--brand-ink)}
.menu-btn{display:none;font:600 .95rem var(--f-body);background:var(--surface);color:var(--ink);border:1px solid var(--line);border-radius:10px;padding:.5rem .85rem;cursor:pointer}
@media (max-width:900px){
  .menu-btn{display:block}
  .head-tools{margin-left:auto}
  .nav{display:none;position:absolute;left:0;right:0;top:100%;background:var(--bg);border-bottom:1px solid var(--line);padding:var(--s3) max(16px,4vw) var(--s5);max-height:calc(100svh - 64px);overflow:auto;box-shadow:0 20px 30px -20px rgba(0,0,0,.3)}
  .nav.open{display:block}
  .nav>ul{flex-direction:column;align-items:stretch;gap:2px}
  .sub-btn{pointer-events:none;font:700 .78rem var(--f-body);text-transform:uppercase;letter-spacing:.08em;color:var(--muted);padding:.8rem .75rem .3rem}
  .sub-btn svg{display:none}
  .sub{display:block;position:static;box-shadow:none;border:0;padding:0;margin:0;min-width:0;background:none}
  .nav-game{margin:.5rem 0 0;justify-content:center}
  .sub-game{display:none}
}
@media (max-width:400px){.logo span{font-size:1.02rem}.menu-pop>summary{padding:0 .45rem}.head-row{gap:.4rem}}

/* ---------- page chrome ---------- */
main{padding-block:var(--s6) var(--s8)}
.crumbs{font-size:.9rem;color:var(--muted);margin:0 0 var(--s4)}
.crumbs ol{list-style:none;display:flex;flex-wrap:wrap;gap:.35rem;margin:0;padding:0}
.crumbs li+li{margin:0}
.crumbs li+li::before{content:"/";margin-right:.35rem;color:var(--line)}
.crumbs a{color:var(--muted)}
.lead{font-size:1.2rem;color:var(--muted);max-width:62ch;margin-top:var(--s4)}
.meta{font-size:.9rem;color:var(--muted);margin-top:var(--s3)}
.page-head{padding-bottom:var(--s5);border-bottom:1px solid var(--line);margin-bottom:var(--s5)}
.meta-row{display:flex;flex-wrap:wrap;align-items:center;gap:var(--s2) var(--s4);margin-top:var(--s3)}
.meta-row .meta{margin:0}
.inshort{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:var(--s4) var(--s5);max-width:68ch}
.inshort h2{font-size:1rem;text-transform:uppercase;letter-spacing:.08em;margin:0;color:var(--brand)}
:lang(hi) .inshort h2{letter-spacing:0}
.inshort ul{margin-top:var(--s2);padding-left:1.1rem}
.note{border-left:4px solid var(--bead);background:var(--surface);padding:var(--s3) var(--s4);border-radius:0 var(--r) var(--r) 0;max-width:68ch}
.note strong:first-child{display:block;font-family:var(--f-display)}
.table-wrap{overflow-x:auto;max-width:100%;margin-top:var(--s4)}
table{border-collapse:collapse;width:100%;min-width:520px;font-size:.98rem;background:var(--surface)}
.table-wrap table{margin:0}
th,td{text-align:left;padding:.6rem .75rem;border:1px solid var(--line);vertical-align:top}
th{background:var(--surface-2);font-weight:650}
td.num,th.num{text-align:right}
caption{text-align:left;font-weight:650;padding-bottom:.4rem;color:var(--muted);font-size:.92rem}
.grid{display:grid;gap:var(--s4);grid-template-columns:repeat(auto-fit,minmax(min(100%,240px),1fr));margin-top:var(--s5)}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:var(--s4) var(--s5);min-width:0;display:flex;flex-direction:column}
.card h3{margin:0;font-size:1.1rem}
.card p{margin-top:var(--s2);color:var(--muted);font-size:.98rem;flex:1}
.card a.more,.card .more{margin-top:var(--s3);font-weight:600;color:var(--brand)}
.step{font:600 .78rem var(--f-mono);color:var(--brand);letter-spacing:.05em;margin-bottom:.3rem}
:lang(hi) .step{font-family:var(--f-body);letter-spacing:0;font-size:.88rem}
.pill{display:inline-block;font:600 .78rem var(--f-body);padding:.15rem .55rem;border-radius:99px;background:var(--surface-2);color:var(--ink);border:1px solid var(--line);white-space:nowrap}
.pill.trains{background:color-mix(in srgb,var(--good) 16%,var(--surface));border-color:color-mix(in srgb,var(--good) 40%,var(--line))}
.pill.reported{background:color-mix(in srgb,var(--bead) 18%,var(--surface));border-color:color-mix(in srgb,var(--bead) 45%,var(--line))}
.pill.unproven{background:color-mix(in srgb,var(--bad) 12%,var(--surface));border-color:color-mix(in srgb,var(--bad) 35%,var(--line))}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:.4rem;font:650 .98rem var(--f-body);padding:.62rem 1.05rem;border-radius:10px;border:1px solid var(--brand);background:var(--brand);color:var(--brand-ink);cursor:pointer;text-decoration:none}
.btn:hover{filter:brightness(1.08)}
.btn.ghost{background:transparent;color:var(--brand)}
.btn.small{padding:.35rem .7rem;font-size:.88rem}
.btn.big{padding:.85rem 1.7rem;font-size:1.1rem;border-radius:14px}
.btn svg{width:16px;height:16px}
.btn-row{display:flex;flex-wrap:wrap;gap:var(--s3);margin-top:var(--s4)}
input[type=text],input[type=number],input[type=search],select{font:500 1rem var(--f-body);padding:.55rem .7rem;border:1px solid var(--line);border-radius:9px;background:var(--surface);color:var(--ink);min-width:0}
label{font-weight:600}
.field{display:flex;flex-direction:column;gap:.25rem}
.field label{font-size:.92rem}
.tool-head .field{flex-direction:row;align-items:center;gap:.5rem}
.check{display:flex;gap:.45rem;align-items:center;font-weight:500}

/* ---------- full-bleed sections (Modern) ---------- */
.bleed{margin-inline:calc(50% - 50vw)}
.hero-full{position:relative;isolation:isolate;margin-top:calc(-1 * var(--s6));min-height:min(calc(100svh - 64px),800px);display:flex;align-items:center;overflow:hidden;
  background:linear-gradient(100deg,var(--bg) 0%,var(--bg) 34%,color-mix(in srgb,var(--bead) 7%,var(--bg)) 100%)}
.hero-full::before{content:"";position:absolute;inset:0;z-index:-2;background:radial-gradient(60% 70% at 12% 30%,color-mix(in srgb,var(--bead) 16%,transparent),transparent 70%)}
.hero-full::after{content:"";position:absolute;left:0;right:0;bottom:0;height:110px;background:linear-gradient(transparent,var(--bg));pointer-events:none}
.hero-bg{position:absolute;top:0;right:0;width:62%;height:100%;object-fit:cover;object-position:50% 58%;z-index:-1;filter:brightness(var(--img-dim));
  -webkit-mask-image:linear-gradient(90deg,transparent 0%,rgba(0,0,0,.5) 24%,#000 48%);mask-image:linear-gradient(90deg,transparent 0%,rgba(0,0,0,.5) 24%,#000 48%)}
.hero-inner{position:relative;width:100%;max-width:1120px;margin:0 auto;padding:clamp(2.5rem,8vh,5.5rem) max(16px,4vw) clamp(3rem,9vh,6rem)}
.hero-copy{max-width:min(560px,46%)}
.hero-copy h1{font-size:clamp(2.3rem,4.7vw,3.55rem);line-height:1.07}
:lang(hi) .hero-copy h1{font-size:clamp(2rem,4vw,2.9rem);line-height:1.3}
.hero-copy .lead{color:color-mix(in srgb,var(--ink) 80%,var(--bg));font-size:1.15rem;max-width:46ch;text-shadow:0 0 18px var(--bg),0 0 2px var(--bg)}
.hl{background:linear-gradient(transparent 60%,color-mix(in srgb,var(--bead) 42%,transparent) 60%,color-mix(in srgb,var(--bead) 42%,transparent) 92%,transparent 92%);-webkit-box-decoration-break:clone;box-decoration-break:clone;padding:0 .06em}
.chip-eyebrow{display:inline-flex;align-items:center;gap:.5rem;padding:.38rem .8rem;border-radius:99px;background:color-mix(in srgb,var(--surface) 72%,transparent);border:1px solid var(--line);backdrop-filter:blur(6px);-webkit-backdrop-filter:blur(6px)}
.chip-eyebrow::before{content:"";width:16px;height:9px;background:var(--bead);clip-path:polygon(22% 0,78% 0,100% 50%,78% 100%,22% 100%,0 50%)}
.hero-copy .btn-row{margin-top:var(--s5)}
.hero-copy .btn{padding:.78rem 1.25rem;font-size:1.02rem}
.hero-facts{list-style:none;display:flex;flex-wrap:wrap;gap:.5rem;padding:0;margin:var(--s5) 0 0}
.hero-facts li{margin:0;font:600 .86rem var(--f-body);padding:.32rem .75rem;border-radius:99px;background:color-mix(in srgb,var(--surface) 70%,transparent);border:1px solid var(--line);backdrop-filter:blur(6px);-webkit-backdrop-filter:blur(6px)}
@media (max-width:860px){
  .hero-full{display:block;min-height:0;background:var(--bg)}
  .hero-full::after{display:none}
  .hero-bg{position:relative;display:block;width:100%;height:auto;aspect-ratio:1059/997;max-height:60svh;object-position:50% 45%;
    -webkit-mask-image:linear-gradient(180deg,#000 55%,transparent 100%);mask-image:linear-gradient(180deg,#000 55%,transparent 100%)}
  .hero-inner{margin-top:-4.5rem;padding-top:0;padding-bottom:var(--s5)}
  .hero-copy{max-width:none}
}
.kid-band{position:relative;isolation:isolate;margin-top:var(--s8);min-height:540px;display:flex;align-items:center;overflow:hidden;border-block:1px solid var(--line);
  background:linear-gradient(90deg,var(--surface-2) 0%,var(--surface) 60%)}
.kid-bg{position:absolute;left:0;top:0;width:52%;height:100%;object-fit:cover;object-position:50% 30%;z-index:-1;filter:brightness(var(--img-dim));
  -webkit-mask-image:linear-gradient(270deg,transparent 0%,rgba(0,0,0,.6) 18%,#000 40%);mask-image:linear-gradient(270deg,transparent 0%,rgba(0,0,0,.6) 18%,#000 40%)}
.kid-inner{width:100%;max-width:1120px;margin:0 auto;padding:clamp(2.5rem,7vh,4.5rem) max(16px,4vw);display:flex;justify-content:flex-end}
.kid-text{max-width:min(540px,50%)}
.kid-text h2{margin-top:0}
.kid-text ul{padding-left:1.1rem}
@media (max-width:860px){
  .kid-band{display:block;min-height:0;background:var(--surface)}
  .kid-bg{position:relative;display:block;width:100%;height:auto;aspect-ratio:846/969;max-height:56svh;object-position:50% 25%;
    -webkit-mask-image:linear-gradient(180deg,#000 60%,transparent 100%);mask-image:linear-gradient(180deg,#000 60%,transparent 100%)}
  .kid-inner{margin-top:-3.5rem;padding-top:0;display:block}
  .kid-text{max-width:none}
}
.tool-strip h2{margin-top:var(--s6)}
.link-card{text-decoration:none;color:var(--ink);transition:transform .15s ease,border-color .15s ease,box-shadow .15s ease}
.link-card:hover{transform:translateY(-3px);border-color:var(--brand);box-shadow:var(--shadow)}
.link-card.feature{border-color:color-mix(in srgb,var(--bead) 60%,var(--line));background:linear-gradient(160deg,color-mix(in srgb,var(--bead) 16%,var(--surface)),var(--surface))}
@media (prefers-reduced-motion:reduce){.link-card{transition:none}.link-card:hover{transform:none}}

/* ---------- soroban ---------- */
.soroban-box{background:var(--surface);border:1px solid var(--line);border-radius:16px;padding:var(--s4);min-width:0}
.soroban-readout{display:flex;justify-content:space-between;align-items:baseline;gap:var(--s3);flex-wrap:wrap;margin-bottom:var(--s3)}
.soroban-readout .val{font:700 2rem var(--f-mono);font-variant-numeric:tabular-nums;color:var(--ink)}
.soroban-readout .words{color:var(--muted);font-size:.92rem}
.hide-readout .soroban-readout{display:none}
.soroban{--rods:5;display:grid;grid-template-columns:repeat(var(--rods),minmax(0,1fr));border:10px solid var(--frame);border-radius:12px;position:relative;padding:0 .2rem;user-select:none;-webkit-user-select:none;touch-action:manipulation;
  background:linear-gradient(180deg,color-mix(in srgb,var(--frame) 5%,var(--surface)),color-mix(in srgb,var(--frame) 12%,var(--surface)));box-shadow:0 16px 26px -16px rgba(40,15,5,.55),inset 0 2px 6px rgba(0,0,0,.08)}
.rod{position:relative;display:grid;grid-template-rows:auto 10px auto;justify-items:center}
.rod::before{content:"";position:absolute;top:0;bottom:0;left:50%;width:4px;margin-left:-2px;border-radius:2px;
  background:linear-gradient(90deg,color-mix(in srgb,var(--rod) 70%,#000),color-mix(in srgb,var(--rod) 45%,#fff),color-mix(in srgb,var(--rod) 70%,#000))}
.heaven,.earth{position:relative;display:flex;flex-direction:column;align-items:center;width:100%}
.heaven{height:64px;justify-content:flex-start;padding-top:6px}
.earth{height:150px;justify-content:flex-end;padding-bottom:6px}
.beam{width:calc(100% + .4rem);height:10px;position:relative;z-index:1;background:linear-gradient(180deg,color-mix(in srgb,var(--frame) 70%,#fff 10%),var(--frame) 45%,color-mix(in srgb,var(--frame) 70%,#000))}
.beam .dot{position:absolute;left:50%;top:50%;width:5px;height:5px;margin:-2.5px;border-radius:50%;background:var(--bg)}
.bead{--b:var(--bead);position:relative;z-index:2;width:min(52px,88%);height:26px;border:0;padding:0;cursor:pointer;background:transparent;transition:transform .16s ease;filter:drop-shadow(0 2px 1.5px rgba(0,0,0,.32))}
.bead::after{content:"";position:absolute;inset:0;clip-path:polygon(22% 0,78% 0,100% 50%,78% 100%,22% 100%,0 50%);
  background:radial-gradient(55% 48% at 48% 24%,rgba(255,255,255,.6),rgba(255,255,255,0) 72%),linear-gradient(180deg,color-mix(in srgb,var(--b) 62%,#fff) 0%,var(--b) 42%,color-mix(in srgb,var(--b) 58%,#000) 100%)}
.bead:hover::after{filter:brightness(1.1)}
.bead:disabled{cursor:default}
.bead:disabled:hover::after{filter:none}
.bead.on{--b:color-mix(in srgb,var(--bead) 72%,var(--frame))}
.heaven .bead.on{transform:translateY(30px)}
.earth .bead{margin-top:2px}
.earth .bead.on{transform:translateY(calc(-1 * var(--lift,0px)))}
.rod-label{font:600 .7rem var(--f-mono);color:var(--muted);text-align:center;padding-top:.35rem}
:lang(hi) .rod-label{font-family:var(--f-body);font-size:.75rem}
.labels{display:grid;grid-template-columns:repeat(var(--rods),minmax(0,1fr));padding:0 calc(10px + .2rem)}
.soroban-controls{display:flex;flex-wrap:wrap;gap:var(--s2);margin-top:var(--s3);align-items:center}
.soroban-controls input{width:9rem}
.calc-log{list-style:none;padding:0;margin:var(--s3) 0 0;font:500 .95rem var(--f-mono);color:var(--muted);display:flex;flex-direction:column-reverse;gap:.15rem}
.calc-log li{margin:0}
.calc-log li:last-child{color:var(--ink);font-weight:700}
.calc-log li.err{color:var(--bad);font-family:var(--f-body)}
@media (prefers-reduced-motion:reduce){.bead{transition:none}}
.home-try{max-width:560px;margin:0 auto}
.home-tool{margin-top:var(--s6)}

/* ---------- tools ---------- */
.tool{background:var(--surface);border:1px solid var(--line);border-radius:18px;padding:var(--s5);margin-top:var(--s5);min-width:0}
.tool-head{display:flex;flex-wrap:wrap;gap:var(--s3);align-items:center;justify-content:space-between}
.target{font:700 2.2rem var(--f-mono);color:var(--brand);margin:var(--s3) 0 0}
.status{font-weight:650;min-height:1.6em;margin-top:var(--s3)}
.status.good{color:var(--good)} .status.bad{color:var(--bad)}
.qs-list{list-style:none;padding:0;display:grid;gap:var(--s2);grid-template-columns:repeat(auto-fill,minmax(min(100%,220px),1fr))}
.qs-list li{margin:0;display:flex;align-items:center;gap:var(--s2);background:var(--surface-2);border-radius:9px;padding:.5rem .7rem;border:2px solid transparent;min-width:0}
.qs-list li.right{border-color:var(--good)} .qs-list li.wrong{border-color:var(--bad)}
.qs-list .q{font:600 1rem var(--f-mono);white-space:nowrap}
.qs-list input{width:5.5rem}
.qs-list .fix{font:600 .85rem var(--f-mono);color:var(--bad)}

/* ---------- game scene ("arena") ---------- */
.arena{--a-ink:#fbf1e3;--a-muted:#e3c9ab;--a-glow:#f3c46a;position:relative;isolation:isolate;overflow:hidden;border-radius:26px;margin-top:var(--s5);padding:clamp(1.25rem,3.6vw,2.6rem);color:var(--a-ink);
  background:radial-gradient(ellipse 60% 48% at 50% -6%,rgba(255,206,132,.42),transparent 72%),radial-gradient(ellipse 40% 40% at 100% 100%,rgba(226,166,58,.12),transparent 70%),linear-gradient(180deg,#2a120c 0%,#3b1c13 52%,#4a2417 100%);
  box-shadow:0 34px 60px -32px rgba(30,10,4,.75),inset 0 1px 0 rgba(255,255,255,.07)}
.arena-deco{position:absolute;inset:0;z-index:-1;pointer-events:none;overflow:hidden}
.arena .lamp{position:absolute;left:50%;top:-180px;width:620px;height:520px;margin-left:-310px;background:radial-gradient(closest-side,rgba(255,222,165,.28),transparent);filter:blur(6px)}
.arena .table{position:absolute;left:-20%;right:-20%;bottom:-4%;height:56%;transform:perspective(760px) rotateX(56deg);transform-origin:50% 100%;opacity:.95;
  background:repeating-linear-gradient(91deg,rgba(255,255,255,.035) 0 2px,transparent 2px 10px),repeating-linear-gradient(89deg,rgba(0,0,0,.09) 0 1px,transparent 1px 26px),linear-gradient(180deg,#8d522d 0%,#6a3a20 55%,#4d2814 100%);
  box-shadow:inset 0 60px 70px rgba(20,6,2,.55)}
.orb{position:absolute;width:var(--s,46px);height:calc(var(--s,46px) * .55);clip-path:polygon(22% 0,78% 0,100% 50%,78% 100%,22% 100%,0 50%);
  background:radial-gradient(58% 52% at 46% 24%,rgba(255,255,255,.75),transparent 62%),linear-gradient(180deg,#f6cf7a 0%,#c8891c 52%,#6e420a 100%);animation:floaty 9s ease-in-out infinite}
.o1{--s:66px;left:3%;top:10%;filter:blur(1.5px);opacity:.75}
.o2{--s:36px;left:9%;top:56%;opacity:.6;animation-delay:-2s}
.o3{--s:96px;right:-2%;top:5%;filter:blur(3px);opacity:.5;animation-delay:-4s}
.o4{--s:30px;right:8%;top:42%;opacity:.75;animation-delay:-1s}
.o5{--s:54px;left:44%;top:-4%;filter:blur(4px);opacity:.3;animation-delay:-6s}
.o6{--s:24px;left:26%;top:28%;opacity:.4;filter:blur(1px);animation-delay:-3s}
.o7{--s:44px;right:22%;bottom:10%;filter:blur(2.5px);opacity:.45;animation-delay:-5s}
.o8{--s:74px;left:-3%;bottom:7%;filter:blur(3.5px);opacity:.4;animation-delay:-7s}
@keyframes floaty{0%,100%{transform:translateY(0) rotate(-7deg)}50%{transform:translateY(-14px) rotate(7deg)}}
@media (max-width:640px){.o5,.o6,.o7{display:none}.arena{border-radius:20px;margin-inline:calc(-1 * min(12px,2vw))}}
@media (prefers-reduced-motion:reduce){.orb{animation:none}}
.arena-in{position:relative;max-width:760px;margin:0 auto}
.arena h2{color:#fff;margin:0;font-size:clamp(1.5rem,3vw,2rem)}
.arena-top{display:flex;justify-content:space-between;align-items:center;gap:var(--s3);flex-wrap:wrap}
.arena-top .field{flex-direction:row;align-items:center;gap:.5rem}
.arena-sub{color:var(--a-muted);margin-top:.4rem}
.arena label{color:var(--a-muted)}
.arena select,.arena input{background:rgba(18,7,3,.5);color:#fff;border:1px solid rgba(255,228,196,.3)}
.arena select option{color:#1c2321;background:#fff}
.hud{display:flex;flex-wrap:wrap;gap:.5rem;margin-top:var(--s4)}
.chip{display:inline-flex;align-items:center;gap:.4rem;padding:.38rem .8rem;border-radius:99px;background:rgba(255,240,220,.09);border:1px solid rgba(255,228,196,.22);backdrop-filter:blur(6px);-webkit-backdrop-filter:blur(6px);font-size:.92rem;color:var(--a-muted)}
.chip svg{width:18px;height:18px;color:var(--a-glow)}
.chip strong{color:#fff;font-size:1.05rem}
.chip-of{color:var(--a-muted)}
.pips{list-style:none;display:flex;gap:6px;padding:0;margin:var(--s3) 0 0;position:relative}
.pips::before{content:"";position:absolute;left:0;right:0;top:50%;height:3px;margin-top:-1.5px;border-radius:2px;background:rgba(255,228,196,.22)}
.pips li{flex:1;height:14px;margin:0;position:relative;clip-path:polygon(22% 0,78% 0,100% 50%,78% 100%,22% 100%,0 50%);background:rgba(255,240,220,.2);transition:background .25s}
.pips li.now{background:linear-gradient(180deg,#fbe0a3,#d79a2b);animation:pulse 1.4s ease-in-out infinite}
.pips li.ok{background:linear-gradient(180deg,#9df0bf,#2e9a62)}
.pips li.bad{background:linear-gradient(180deg,#ffb0a4,#c2453a)}
@keyframes pulse{50%{opacity:.55}}
@media (prefers-reduced-motion:reduce){.pips li.now{animation:none}}
.prompt-card{position:relative;margin:var(--s4) auto 0;max-width:440px;text-align:center;padding:.85rem 1.2rem 1rem;border-radius:18px;
  background:linear-gradient(180deg,rgba(255,240,220,.13),rgba(255,240,220,.04));border:1px solid rgba(255,228,196,.24);box-shadow:inset 0 1px 0 rgba(255,255,255,.12),0 18px 30px -18px rgba(0,0,0,.6)}
.prompt-label{display:block;font:600 .78rem var(--f-mono);letter-spacing:.09em;text-transform:uppercase;color:var(--a-glow)}
:lang(hi) .prompt-label{font-family:var(--f-body);letter-spacing:0;font-size:.95rem}
.arena .target{color:#fff;font-size:clamp(2.4rem,7vw,3.4rem);margin:.1rem 0 0;text-shadow:0 2px 20px rgba(243,196,106,.5)}
.arena .g-prompt.q-sum{font-size:clamp(1.8rem,5.4vw,2.6rem);white-space:nowrap}
.arena .g-prompt.q-text{font:650 1.3rem/1.45 var(--f-body);color:#fff;text-shadow:none;margin-top:.3rem}
.arena .soroban-box{position:relative;background:transparent;border:0;padding:var(--s4) 0 0;max-width:560px;margin:0 auto}
.arena .soroban-box::after{content:"";position:absolute;left:6%;right:6%;bottom:2px;height:30px;background:radial-gradient(closest-side,rgba(0,0,0,.6),transparent);filter:blur(5px);z-index:-1}
.arena .soroban{border-color:#2b110a;background:linear-gradient(180deg,#f7e9d5 0%,#ead3b4 100%);box-shadow:0 0 0 1px rgba(255,255,255,.07),0 24px 34px -18px rgba(0,0,0,.75),inset 0 3px 9px rgba(60,25,10,.22)}
.arena .rod::before{background:linear-gradient(90deg,#7c6a58,#efe2cf,#7c6a58)}
.arena .beam{background:linear-gradient(180deg,#5d2c1c,#3a170e 60%,#24100a)}
.arena .beam .dot{background:#f7e9d5}
.arena .bead{--b:#c8891c}
.arena .bead.on{--b:#9e5a19}
.arena .rod-label{color:var(--a-muted)}
.arena .soroban-readout .val{color:#fff}.arena .soroban-readout .words{color:var(--a-muted)}
.arena .labels{margin-top:.2rem}
.game-answer{display:flex;justify-content:center;align-items:center;gap:.6rem;flex-wrap:wrap;margin-top:var(--s4)}
.game-answer input{width:10rem;font:600 1.25rem var(--f-mono);text-align:center}
.arena .btn{border-radius:12px}
.arena .btn.glow{background:linear-gradient(180deg,#f8d585,#d7992a);color:#2a1503;border-color:#f3c46a;box-shadow:0 10px 24px -10px rgba(243,196,106,.75),inset 0 1px 0 rgba(255,255,255,.55);font-weight:700}
.arena .btn.ghost{color:var(--a-ink);border-color:rgba(255,228,196,.4);background:rgba(255,240,220,.06)}
.arena .status{text-align:center;color:#fff;margin-top:var(--s3)}
.arena .status.good{color:#8ff0b6} .arena .status.bad{color:#ffb8ad}
.arena :focus-visible{outline-color:#a9c3ff}
.arena .meta{color:var(--a-muted)}
.game-start h2{text-align:center}
.levels{border:0;padding:0;margin:var(--s5) 0 0;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:.75rem}
@media (max-width:640px){.levels{grid-template-columns:1fr}}
.lvl{position:relative;display:flex;flex-direction:column;align-items:center;text-align:center;gap:.35rem;padding:1.15rem .8rem;border-radius:18px;background:rgba(255,240,220,.07);border:1px solid rgba(255,228,196,.22);cursor:pointer;transition:background .15s,border-color .15s,transform .15s}
.lvl:hover{transform:translateY(-2px)}
.lvl input{position:absolute;inset:0;opacity:0;margin:0;cursor:pointer}
.lvl:has(input:checked){background:linear-gradient(180deg,rgba(243,196,106,.3),rgba(243,196,106,.08));border-color:var(--a-glow);box-shadow:0 0 0 1px var(--a-glow),0 14px 28px -14px rgba(243,196,106,.65)}
.lvl:has(input:focus-visible){outline:3px solid #a9c3ff;outline-offset:2px}
.lvl-beads{display:flex;gap:4px;height:18px;align-items:center}
.lvl-beads i{width:30px;height:16px;clip-path:polygon(22% 0,78% 0,100% 50%,78% 100%,22% 100%,0 50%);background:radial-gradient(58% 52% at 46% 24%,rgba(255,255,255,.75),transparent 62%),linear-gradient(180deg,#f6cf7a,#c8891c 52%,#6e420a)}
.lvl-t{font:700 1.15rem var(--f-display);color:#fff}
.lvl-d{font-size:.88rem;color:var(--a-muted)}
.result-card{margin:var(--s4) auto 0;max-width:560px;text-align:center;padding:var(--s5);border-radius:22px;background:rgba(255,240,220,.07);border:1px solid rgba(255,228,196,.22)}
.result-card h2{margin-bottom:.2rem}
.ring{--p:0;position:relative;width:150px;height:150px;margin:var(--s3) auto 0;border-radius:50%;display:grid;place-items:center;
  background:conic-gradient(var(--a-glow) calc(var(--p) * 1%),rgba(255,240,220,.12) 0);box-shadow:0 0 44px -10px rgba(243,196,106,.65)}
.ring::before{content:"";position:absolute;inset:12px;border-radius:50%;background:radial-gradient(circle at 50% 35%,#55291a,#2a120c)}
.ring span{position:relative;font:700 2.3rem var(--f-mono);color:#fff}
.stars{display:flex;justify-content:center;gap:.4rem;margin-top:var(--s3)}
.stars svg{width:30px;height:30px;color:rgba(255,240,220,.2);transition:color .3s}
.stars svg.on{color:#f8d585;filter:drop-shadow(0 0 8px rgba(243,196,106,.75))}
.review{margin-top:var(--s5);text-align:left;background:rgba(0,0,0,.2);border-radius:14px;padding:.65rem 1rem}
.review summary{cursor:pointer;font-weight:650;color:#fff}
.g-review{padding-left:1.3rem;font-size:.95rem;color:#f2e3d0}
.g-review li.wrong{color:#ffb8ad}
.burst{position:absolute;left:50%;top:50%;width:0;height:0;pointer-events:none}
.burst i{position:absolute;left:-8px;top:-5px;width:16px;height:9px;clip-path:polygon(22% 0,78% 0,100% 50%,78% 100%,22% 100%,0 50%);background:linear-gradient(180deg,#fbe0a3,#d79a2b);animation:burst .85s ease-out forwards}
@keyframes burst{from{transform:translate(0,0) scale(.5);opacity:1}to{transform:translate(var(--dx),var(--dy)) rotate(var(--r)) scale(1.1);opacity:0}}

/* ---------- worksheets ---------- */
.ws-controls{display:flex;flex-wrap:wrap;gap:var(--s3) var(--s5);align-items:flex-end;margin-top:var(--s4)}
.sheet-paper{margin-top:var(--s4);background:#fff;color:#1c2321;border:1px solid var(--line);border-radius:10px;padding:1.25rem 1.5rem 1.5rem;box-shadow:var(--shadow)}
.sheet-head{display:flex;flex-wrap:wrap;gap:.5rem 1.5rem;justify-content:space-between;align-items:baseline;border-bottom:2px solid #1c2321;padding-bottom:.6rem;font-size:.95rem}
.sheet-head strong{font-family:var(--f-display);font-size:1.05rem}
.sheet{columns:3 170px;column-gap:1.6rem;font:500 1rem var(--f-mono);margin-top:.6rem}
.sheet div{break-inside:avoid;padding:.5rem 0;border-bottom:1px dotted #c9cdc6}
.sheet .ans{color:#1f7a4d;font-weight:700}
.sheet-key{display:none}
.sheet-key h3{margin:0 0 .5rem}
.sheet-key ol{columns:4 120px;font:500 .95rem var(--f-mono);margin:0;padding-left:1.4rem}

/* ---------- faq ---------- */
.faq-tools{display:flex;flex-wrap:wrap;gap:var(--s3);align-items:center;margin-top:var(--s5)}
.faq-tools input{flex:1 1 260px}
.faq-group h2{margin-top:var(--s6)}
details.qa{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:0;max-width:78ch;margin-top:var(--s2)}
details.qa summary{cursor:pointer;padding:.8rem 1rem;font-weight:650;list-style:none;display:flex;gap:.6rem;align-items:flex-start}
details.qa summary::-webkit-details-marker{display:none}
details.qa summary::before{content:"+";font:700 1.1rem var(--f-mono);color:var(--brand);line-height:1.4}
details.qa[open] summary::before{content:"−"}
details.qa .a{padding:0 1rem 1rem 2.1rem}
details.qa .a p:first-child{margin-top:0}
.faq-empty{color:var(--muted)}

/* ---------- figures ---------- */
figure.diagram{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:var(--s4);max-width:720px}
figcaption{font-size:.9rem;color:var(--muted);margin-top:var(--s2)}
.pic{display:block;width:100%;height:auto;border-radius:var(--r);border:1px solid var(--line);background:#fff}
figure.illus{margin:var(--s4) 0 0;max-width:var(--w,460px)}
.media{display:grid;gap:var(--s5);align-items:center;margin-top:var(--s4)}
.media>*{min-width:0;margin-top:0}
.media>.prose>:first-child,.media>div>:first-child{margin-top:0}
.media>figure.illus{margin:0;width:100%;justify-self:center}
@media (min-width:761px){.media{grid-template-columns:minmax(0,62ch) minmax(0,var(--w,340px));justify-content:start;column-gap:var(--s6)}}
figure.illus.home-art{margin:var(--s5) auto 0;max-width:340px}

/* ---------- pager / footer ---------- */
.pager{display:flex;justify-content:space-between;gap:var(--s4);flex-wrap:wrap;margin-top:var(--s7);padding-top:var(--s5);border-top:1px solid var(--line)}
.pager a{display:flex;flex-direction:column;text-decoration:none;font-weight:650;max-width:48%}
.pager a span{font:500 .8rem var(--f-mono);color:var(--muted);text-transform:uppercase;letter-spacing:.06em}
:lang(hi) .pager a span{font-family:var(--f-body);letter-spacing:0}
.pager a.next{text-align:right;margin-left:auto}
.site-foot{border-top:1px solid var(--line);background:var(--surface);padding-block:var(--s6);font-size:.95rem}
.foot-grid{display:grid;gap:var(--s5);grid-template-columns:1.6fr repeat(3,1fr)}
@media (max-width:760px){.foot-grid{grid-template-columns:1fr 1fr}.foot-grid>:first-child{grid-column:1/-1}}
.footer-h{font:700 .85rem var(--f-body);text-transform:uppercase;letter-spacing:.08em;color:var(--muted);margin:0 0 var(--s2)}
.site-foot ul{list-style:none;padding:0;margin:0}
.site-foot li+li{margin-top:.25rem}
.site-foot a{color:var(--ink)}
.site-foot .btn{color:var(--brand)}
.foot-langs{display:flex;flex-wrap:wrap;gap:.4rem 1rem;margin-top:var(--s4);font-size:.92rem}
.fine{color:var(--muted);font-size:.88rem;margin-top:var(--s5)}
.toast{position:fixed;left:50%;bottom:calc(20px + env(safe-area-inset-bottom,0px));transform:translateX(-50%);background:var(--ink);color:var(--bg);padding:.6rem 1rem;border-radius:10px;font-weight:600;z-index:60;max-width:calc(100% - 32px);box-shadow:var(--shadow)}

/* ---------- sharing ---------- */
.link-btn{display:inline-flex;align-items:center;gap:.35rem;background:none;border:0;padding:.3rem .55rem;margin:0;border-radius:8px;color:var(--muted);font:600 .88rem var(--f-body);cursor:pointer;white-space:nowrap}
.link-btn:hover{color:var(--brand);background:var(--surface-2)}
.link-btn svg,.share-btn svg{width:15px;height:15px;flex-shrink:0}
.sec-head{display:flex;align-items:baseline;justify-content:space-between;flex-wrap:wrap;gap:.25rem 1rem;margin-top:var(--s7);max-width:820px}
.sec-head h2{margin-top:0}
.hero-share{margin:var(--s3) 0 0}
.hero-share .link-btn{padding-left:0}
.qa-links{display:flex;flex-wrap:wrap;align-items:center;gap:.4rem 1rem}
.share-card{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:var(--s3) var(--s5);margin-top:var(--s7);padding:var(--s4) var(--s5);border-radius:var(--r-lg);border:1px solid color-mix(in srgb,var(--bead) 45%,var(--line));background:linear-gradient(135deg,color-mix(in srgb,var(--bead) 10%,var(--surface)),var(--surface))}
.share-card p{margin:0;color:var(--muted)}
.share-card .share-card-h{font:650 1.12rem var(--f-display);color:var(--ink);margin-bottom:.15rem}
dialog.share-dlg{border:0;padding:0;margin:auto;background:transparent;color:var(--ink);width:min(480px,calc(100vw - 24px));max-width:none;max-height:calc(100svh - 24px);overflow:visible}
dialog.share-dlg::backdrop{background:rgba(20,10,5,.5);backdrop-filter:blur(2px);-webkit-backdrop-filter:blur(2px)}
.sd-card{background:var(--surface);border:1px solid var(--line);border-radius:22px;padding:1.2rem 1.25rem 1.1rem;box-shadow:0 30px 70px -20px rgba(0,0,0,.55);max-height:calc(100svh - 24px);overflow:auto}
@media (prefers-reduced-motion:no-preference){dialog.share-dlg[open] .sd-card{animation:sdIn .16s ease-out}}
@keyframes sdIn{from{opacity:0;transform:translateY(8px)}}
.sd-top{display:flex;align-items:center;justify-content:space-between;gap:1rem}
.sd-top h2{margin:0;font-size:1.3rem}
.sd-x{display:grid;place-items:center;width:38px;height:38px;border-radius:50%;border:1px solid var(--line);background:var(--surface);color:var(--ink);cursor:pointer;flex-shrink:0}
.sd-x:hover{border-color:var(--brand);color:var(--brand)}
.sd-x svg{width:18px;height:18px}
.sd-what{display:flex;gap:.75rem;align-items:center;margin-top:.9rem;padding:.7rem .85rem;border-radius:14px;background:var(--surface-2)}
.sd-what::before{content:"";flex-shrink:0;width:26px;height:15px;background:var(--bead);clip-path:polygon(22% 0,78% 0,100% 50%,78% 100%,22% 100%,0 50%)}
.sd-what div{min-width:0}
.sd-what strong{display:block;line-height:1.35}
.sd-url{display:block;font:500 .8rem var(--f-mono);color:var(--muted);overflow-wrap:anywhere;margin-top:.15rem}
.sd-fields{display:grid;grid-template-columns:1fr 1fr;gap:.7rem;margin-top:1rem}
@media (max-width:440px){.sd-fields{grid-template-columns:1fr}}
.sd-fields label{display:flex;flex-direction:column;gap:.3rem;font-size:.9rem}
.sd-fields label span{font-weight:500;color:var(--muted)}
.sd-fields input{width:100%}
.sd-label{font:700 .76rem var(--f-body);text-transform:uppercase;letter-spacing:.08em;color:var(--muted);margin:1rem 0 0}
:lang(hi) .sd-label{letter-spacing:0;font-size:.85rem}
.sd-msg{white-space:pre-wrap;overflow-wrap:anywhere;font:500 .92rem/1.5 var(--f-body);background:var(--bg);border:1px dashed var(--line);border-radius:12px;padding:.7rem .85rem;margin:.35rem 0 0;max-height:9.5rem;overflow:auto}
.sd-actions{display:grid;grid-template-columns:1fr 1fr;gap:.6rem;margin-top:1rem}
.sd-btn{display:flex;align-items:center;justify-content:center;gap:.5rem;min-height:46px;padding:.6rem .8rem;border-radius:12px;border:1px solid var(--line);background:var(--surface);color:var(--ink);font:650 .95rem var(--f-body);text-decoration:none;cursor:pointer;text-align:center}
.sd-btn:hover{border-color:var(--brand);color:var(--brand)}
.sd-btn svg{width:20px;height:20px;flex-shrink:0}
.sd-btn.wa{background:#128c4b;border-color:#128c4b;color:#fff}
.sd-btn.wa:hover{filter:brightness(1.08);color:#fff}
.sd-actions.no-native .sd-copymsg{grid-column:1/-1}
.sd-btn.done{border-color:var(--good);color:var(--good)}
.sd-status{min-height:1.4em;margin:.6rem 0 0;font-weight:650;font-size:.92rem;color:var(--good)}
.sd-status.warn{color:var(--muted);font-weight:500}
.sd-fallback{margin-top:.4rem}
.sd-fallback input{width:100%;font:500 .9rem var(--f-mono)}
.sd-note{font-size:.8rem;color:var(--muted);margin:.5rem 0 0}
:root[data-style="classic"] .sd-card,:root[data-style="classic"] .share-card{border-radius:6px}
.svg-fig svg{display:block;width:100%;height:auto}
.svg-fig{max-width:720px}
.abacus-svg .svg-num{font:700 17px var(--f-mono);fill:var(--ink)}
.abacus-svg .svg-lab{font:600 12px var(--f-body);fill:var(--muted)}
.fig-pair{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,230px),1fr));gap:var(--s4);max-width:620px;margin-top:var(--s4)}
.fig-pair figure{margin:0}

/* ---------- Classic style ---------- */
:root[data-style="classic"] h1,:root[data-style="classic"] h2,:root[data-style="classic"] h3{font-weight:600;letter-spacing:0}
:root[data-style="classic"] .site-head{background:var(--bg);backdrop-filter:none;-webkit-backdrop-filter:none;border-bottom:3px double var(--line)}
:root[data-style="classic"] .btn,:root[data-style="classic"] .card,:root[data-style="classic"] .tool,:root[data-style="classic"] .soroban-box,:root[data-style="classic"] .sub,:root[data-style="classic"] .pop{border-radius:4px}
:root[data-style="classic"] .link-card:hover{transform:none;box-shadow:none}
:root[data-style="classic"] .link-card.feature{background:color-mix(in srgb,var(--bead) 9%,var(--surface))}
:root[data-style="classic"] .bead{filter:none}
:root[data-style="classic"] .bead::after{background:var(--b);box-shadow:inset 0 -6px 0 rgba(0,0,0,.18)}
:root[data-style="classic"] .soroban{background:color-mix(in srgb,var(--frame) 8%,var(--surface));box-shadow:none;border-radius:6px}
:root[data-style="classic"] .rod::before{background:var(--rod)}
:root[data-style="classic"] .beam{background:var(--frame)}
:root[data-style="classic"] .arena .bead{filter:drop-shadow(0 2px 1.5px rgba(0,0,0,.32))}
:root[data-style="classic"] .arena .bead::after{box-shadow:none;background:radial-gradient(55% 48% at 48% 24%,rgba(255,255,255,.6),rgba(255,255,255,0) 72%),linear-gradient(180deg,color-mix(in srgb,var(--b) 62%,#fff) 0%,var(--b) 42%,color-mix(in srgb,var(--b) 58%,#000) 100%)}
:root[data-style="classic"] .arena .beam{background:linear-gradient(180deg,#5d2c1c,#3a170e 60%,#24100a)}
:root[data-style="classic"] .arena .rod::before{background:linear-gradient(90deg,#7c6a58,#efe2cf,#7c6a58)}
:root[data-style="classic"] .bleed{margin-inline:0}
:root[data-style="classic"] .hero-full{margin-top:0;min-height:0;display:grid;grid-template-columns:minmax(0,1.05fr) minmax(0,1fr);gap:var(--s6);align-items:center;background:none;overflow:visible;padding-block:var(--s3) var(--s6);border-bottom:3px double var(--line)}
:root[data-style="classic"] .hero-full::before,:root[data-style="classic"] .hero-full::after{display:none}
:root[data-style="classic"] .hero-bg{position:static;grid-column:2;grid-row:1;width:100%;height:auto;max-height:none;aspect-ratio:auto;-webkit-mask-image:none;mask-image:none;border:1px solid var(--line);border-radius:4px;padding:6px;background:var(--surface)}
:root[data-style="classic"] .hero-inner{grid-column:1;grid-row:1;padding:0;margin:0;max-width:none}
:root[data-style="classic"] .hero-copy{max-width:none}
:root[data-style="classic"] .hero-copy h1{font-size:clamp(2.1rem,4.2vw,3.1rem);line-height:1.12}
:root[data-style="classic"] .hl{background:none;padding:0;font-style:italic;color:var(--brand)}
:root[data-style="classic"] .chip-eyebrow,:root[data-style="classic"] .hero-facts li{background:none;backdrop-filter:none;-webkit-backdrop-filter:none;border-radius:4px}
:root[data-style="classic"] .kid-band{display:grid;grid-template-columns:minmax(0,.9fr) minmax(0,1.1fr);gap:var(--s6);align-items:center;min-height:0;background:var(--surface);border:1px solid var(--line);border-radius:4px;padding:var(--s5)}
:root[data-style="classic"] .kid-bg{position:static;width:100%;height:auto;max-height:none;aspect-ratio:auto;-webkit-mask-image:none;mask-image:none;border-radius:4px}
:root[data-style="classic"] .kid-inner{padding:0;margin:0;display:block;max-width:none}
:root[data-style="classic"] .kid-text{max-width:none}
:root[data-style="classic"] .arena{border-radius:6px}
@media (max-width:860px){
  :root[data-style="classic"] .hero-full,:root[data-style="classic"] .kid-band{grid-template-columns:1fr}
  :root[data-style="classic"] .hero-bg{grid-row:2;grid-column:1}
  :root[data-style="classic"] .hero-inner{grid-column:1}
}

/* ---------- beginner tutorial ---------- */
.tut-intro{background:var(--surface);border:1px solid var(--line);border-radius:var(--r-lg);padding:var(--s5);margin-top:var(--s5);display:grid;gap:var(--s4) var(--s6);grid-template-columns:minmax(0,1.2fr) minmax(0,1fr)}
.tut-intro h2{margin:0;grid-column:1/-1;font-size:1.3rem}
.tut-intro ul{margin:0;padding-left:1.1rem}.tut-intro li+li{margin-top:.35rem}
.tut-toc{list-style:none;margin:0;padding:0;display:grid;gap:.35rem;align-content:start;counter-reset:none}
.tut-toc a{display:flex;gap:.6rem;align-items:center;padding:.4rem .6rem;border-radius:10px;text-decoration:none;color:var(--ink);background:var(--surface-2)}
.tut-toc a:hover{background:color-mix(in srgb,var(--bead) 16%,var(--surface-2))}
.tut-toc .num,.tl-n{flex:none}
.tut-toc .num{display:inline-grid;place-items:center;width:1.7rem;height:1.7rem;border-radius:99px;background:var(--brand);color:var(--brand-ink);font-weight:700;font-size:.85rem}
.tut-tags{margin:var(--s2) 0 0;display:flex;gap:.4rem;flex-wrap:wrap}
.tut-svg{display:block;width:100%;height:auto;margin-inline:auto}
.abacus-svg .svg-call{font:600 15px var(--f-body);fill:var(--muted)}.abacus-svg .svg-call.strong{fill:var(--ink);font-weight:700}
figure.tut-anat{max-width:520px;margin-top:var(--s5)}
figure.tut-anat figcaption,.tut-big figcaption{margin-top:var(--s3);font-size:.95rem;color:var(--muted)}
.tut-rule{margin-top:var(--s4)}.tut-rule strong,.note>strong:first-child{display:block;margin-bottom:.15rem}
.rod-grid{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:var(--s3);margin-top:var(--s4);max-width:680px}
@media (max-width:560px){.rod-grid{gap:.35rem}.rod-card{padding:.4rem .2rem}.rod-card figcaption{font-size:.68rem}.rod-card figcaption .num{font-size:1.2rem}}
.rod-card{margin:0;background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:.6rem .5rem;text-align:center}
.rod-card svg{max-width:96px}
.rod-card figcaption{font-size:.82rem;line-height:1.3;color:var(--muted);margin-top:.35rem}
.rod-card figcaption .num{display:block;font:700 1.5rem var(--f-display);color:var(--ink);line-height:1.1}
.place-strip{display:flex;flex-wrap:wrap;align-items:center;gap:.4rem;margin-top:var(--s4)}
.ps-chip{padding:.45rem .9rem;border-radius:99px;background:var(--brand);color:var(--brand-ink);font-weight:700}
.ps-arrow{font:600 .85rem var(--f-mono);color:var(--muted)}
.pv-grid,.ex-list{display:grid;gap:var(--s4);margin-top:var(--s4)}
.pv-grid{grid-template-columns:repeat(auto-fit,minmax(min(100%,190px),1fr));max-width:880px}
.pv-card{margin:0;background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:var(--s4);display:flex;flex-direction:column}
.pv-card svg{margin-top:auto;max-height:230px}
.pv-n{font:700 2rem var(--f-display);margin:0;line-height:1}.pv-eq{margin:.2rem 0 var(--s3);color:var(--muted);font-size:.95rem}
.ex-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:var(--s4) var(--s5);display:grid;grid-template-columns:minmax(0,1.3fr) minmax(0,1fr);gap:var(--s5);align-items:center;max-width:880px}
.ex-h{font:650 1.15rem var(--f-display);margin:0}
.ex-chain{margin:var(--s3) 0 0;display:grid;gap:.5rem}
.ex-chain>div{display:grid;grid-template-columns:7.5rem minmax(0,1fr);gap:.6rem;align-items:baseline;padding-bottom:.5rem;border-bottom:1px dashed var(--line)}
.ex-chain dt{font-size:.78rem;font-weight:700;text-transform:uppercase;letter-spacing:.04em;color:var(--muted)}
.ex-chain dd{margin:0}.ex-chain dd.num{font:700 1.3rem var(--f-display)}
.ex-chain ul{margin:0;padding-left:1.1rem}
.ex-pic svg{max-height:250px}
.concept{display:flex;align-items:stretch;gap:.6rem;flex-wrap:wrap;margin-top:var(--s4)}
.c-box{flex:1 1 120px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:var(--s3) var(--s4);display:flex;flex-direction:column;gap:.15rem;max-width:220px}
.c-box span,.flow-panel figcaption span,.flow-act-h{font-size:.75rem;font-weight:700;text-transform:uppercase;letter-spacing:.06em;color:var(--muted)}
.c-box strong{font:700 1.6rem var(--f-display)}
.c-box.act{border-color:var(--bead);background:color-mix(in srgb,var(--bead) 10%,var(--surface))}.c-box.act strong{font-size:1.15rem}
.c-box.res{border-color:var(--good)}.c-box.res strong{color:var(--good)}
.c-arrow{align-self:center;font-size:1.4rem;color:var(--muted)}
.flow{display:grid;grid-template-columns:minmax(0,1fr) minmax(150px,.9fr) minmax(0,1fr);gap:var(--s3);align-items:center;margin-top:var(--s4);max-width:880px}
.flow-panel{margin:0;background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:var(--s3)}
.flow-panel.after{border-color:var(--good);box-shadow:0 0 0 1px var(--good) inset}
.flow-panel figcaption{display:flex;justify-content:space-between;align-items:baseline;margin-bottom:.3rem}
.flow-panel figcaption strong{font:700 1.4rem var(--f-display)}
.flow-panel svg{max-height:240px}
.flow-act{position:relative;background:color-mix(in srgb,var(--bead) 12%,var(--surface));border:1px dashed var(--bead);border-radius:var(--r);padding:var(--s3)}
.flow-act p{margin:.2rem 0 0;font-size:.95rem}.flow-act strong{font-size:1.05rem}
.flow-act .flow-act-h{margin:0}
.flow-arrow{position:absolute;right:-.95rem;top:50%;width:.9rem;height:.9rem;border-top:3px solid var(--bead);border-right:3px solid var(--bead);transform:translateY(-50%) rotate(45deg)}
.flow-key{font-size:.85rem;color:var(--muted);margin-top:var(--s2)}
.cols-sum{display:inline-grid;grid-template-columns:auto 6rem 6rem;margin-top:var(--s4);background:var(--surface);border:1px solid var(--line);border-radius:var(--r);overflow:hidden}
.cols-sum>div{display:contents}
.cols-sum span{padding:.45rem .9rem;text-align:center;border-bottom:1px solid var(--line)}
.cols-sum span[role=rowheader]{text-align:left;font-size:.8rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;color:var(--muted)}
.cols-sum .cs-head span{background:var(--surface-2);font-weight:700}
.cols-sum span.num{font:700 1.35rem var(--f-display)}
.cols-sum .cs-add span.num{color:var(--bead-ink);background:color-mix(in srgb,var(--bead) 18%,var(--surface))}
.cols-sum .cs-res span{border-bottom:0;border-top:2px solid var(--ink)}.cols-sum .cs-res span.num{color:var(--good)}
.carry-steps{counter-reset:cs;list-style:none;padding:0;margin:var(--s4) 0 0;display:grid;gap:.5rem;max-width:68ch}
.carry-steps li{counter-increment:cs;position:relative;padding:.6rem .9rem .6rem 3rem;background:var(--surface);border:1px solid var(--line);border-radius:var(--r)}
.carry-steps li::before{content:counter(cs);position:absolute;left:.75rem;top:.6rem;width:1.6rem;height:1.6rem;border-radius:99px;display:grid;place-items:center;background:var(--bead);color:var(--bead-ink);font-weight:700;font-size:.85rem}
.tut-big svg{max-height:270px}
.tut-levels{margin-top:var(--s4)}
.tl-progress{position:sticky;top:4.2rem;z-index:2;background:var(--bg);padding:.5rem 0;display:flex;align-items:center;gap:var(--s4);flex-wrap:wrap}
.tl-count{margin:0;font-weight:700}
.tl-progress .bar{flex:1 1 160px;max-width:320px;height:.6rem;border-radius:99px;background:var(--surface-2);border:1px solid var(--line);overflow:hidden}
.tl-progress .bar span{display:block;height:100%;width:0;background:var(--good);transition:width .3s}
.tl-list{list-style:none;padding:0;margin:var(--s3) 0 0;display:grid;gap:var(--s3);grid-template-columns:repeat(auto-fill,minmax(min(100%,250px),1fr))}
.tl-card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:var(--s4);display:flex;flex-direction:column;justify-content:space-between;gap:var(--s3)}
.tl-card h3{font-size:1.1rem;margin:.1rem 0 .3rem}.tl-card p{margin:0;font-size:.95rem}.tl-card a{font-size:.92rem;display:inline-block;margin-top:.4rem}
.tl-n{font-size:.75rem!important;font-weight:700;text-transform:uppercase;letter-spacing:.06em;color:var(--bead-ink);background:color-mix(in srgb,var(--bead) 25%,transparent);display:inline-block;padding:.1rem .5rem;border-radius:99px}
.tl-check{padding-top:var(--s3);border-top:1px dashed var(--line);cursor:pointer}.tl-check input{width:1.15rem;height:1.15rem;accent-color:var(--good)}
.tl-card.done{border-color:var(--good);background:color-mix(in srgb,var(--good) 7%,var(--surface))}
.tl-ready{margin-top:var(--s5)}
.try-btn{gap:.45rem}.try-btn svg{width:1.1em;height:1.1em;flex:none}
.tut-banner{display:flex;align-items:center;gap:var(--s4);margin-top:var(--s5);padding:var(--s4) var(--s5);background:linear-gradient(120deg,color-mix(in srgb,var(--bead) 16%,var(--surface)),var(--surface));border:1px solid color-mix(in srgb,var(--bead) 45%,var(--line));border-radius:var(--r-lg);text-decoration:none;color:var(--ink);max-width:880px}
.tut-banner:hover{border-color:var(--bead)}.tut-banner:hover .tb-go{transform:translateX(3px)}
.tb-badge{flex:none;font-size:.75rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;padding:.25rem .6rem;border-radius:99px;background:var(--brand);color:var(--brand-ink)}
.tb-text{display:flex;flex-direction:column;min-width:0}.tb-text strong{font:650 1.1rem var(--f-display)}.tb-text span{color:var(--muted);font-size:.95rem}
.tb-go{margin-left:auto;font-size:1.4rem;color:var(--brand);transition:transform .2s}
.try-task{position:relative;margin:var(--s4) 0;padding:var(--s4) var(--s5);border:2px solid var(--bead);border-radius:var(--r);background:color-mix(in srgb,var(--bead) 10%,var(--surface));max-width:720px}
.try-task.done{border-color:var(--good);background:color-mix(in srgb,var(--good) 9%,var(--surface))}
.tt-top{display:flex;justify-content:space-between;align-items:center}
.tt-from{font-size:.75rem;font-weight:700;text-transform:uppercase;letter-spacing:.06em;color:var(--muted)}
.tt-x{border:0;background:transparent;color:var(--muted);font-size:1.5rem;line-height:1;width:2.25rem;height:2.25rem;border-radius:99px;cursor:pointer}.tt-x:hover{background:var(--surface-2);color:var(--ink)}
.tt-goal{font:650 1.2rem var(--f-display);margin:.2rem 0 0}.tt-hint{margin:.3rem 0 0;color:var(--muted);font-size:.95rem}
.tt-status{margin:.5rem 0 0;font-weight:700}.tt-status.good{color:var(--good)}.tt-status:empty{display:none}
.tt-back{display:inline-block;margin-top:.5rem;font-weight:600}
@media (max-width:720px){
  .tut-intro{grid-template-columns:1fr;padding:var(--s4)}
  .ex-card{grid-template-columns:1fr;padding:var(--s4)}.ex-pic{order:-1}.ex-pic svg{max-height:200px}
  .ex-chain>div{grid-template-columns:1fr;gap:.15rem}
  .flow{grid-template-columns:1fr}.flow-arrow{right:auto;left:50%;top:auto;bottom:-.95rem;transform:translateX(-50%) rotate(135deg)}
  .flow-panel svg{max-height:150px}.flow-panel{padding:.5rem .75rem}.flow{gap:.6rem}
  .c-arrow{transform:rotate(90deg)}.concept{flex-direction:column}.c-box{max-width:none}
  .tut-banner{flex-wrap:wrap;padding:var(--s4)}.tb-go{display:none}
  .tl-progress{top:3.6rem}
}

@media print{
  .share-card,.sec-head .link-btn,.try-btn,.tut-banner,.tl-check,.site-head,.site-foot,.no-print,.pager,.crumbs,.share-btn,.preview-bar{display:none!important} body{background:#fff;color:#000} .arena{box-shadow:none}
  html.print-ws body *{visibility:hidden}
  html.print-ws .sheet-out,html.print-ws .sheet-out *{visibility:visible}
  html.print-ws .sheet-out{position:absolute;left:0;top:0;width:100%}
  html.print-ws .sheet-paper{border:0;box-shadow:none;padding:0}
  html.print-ws .sheet-out.with-key .sheet-key{display:block;break-before:page;page-break-before:always}
}
[hidden]{display:none!important}.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}