*,*::before,*::after{box-sizing:border-box}
:root{padding-top:env(safe-area-inset-top,0px);padding-bottom:env(safe-area-inset-bottom,0px)}
body{margin:0} img{max-width:100%} [hidden]{display:none!important}

/* Layout: a sea-blue board game — chunky "sticker" cards with ink outlines float on the water; one island per topic. Single deliberate daytime look. */
:root{
  --sea:#1B8CA3; --sea-deep:#0F5E70; --foam:#CFF1F5;
  --sand:#FFF3D6; --sand-2:#FFE2A1;
  --ink:#1C2A39; --ink-soft:#4A5868;
  --coral:#FF6B4F; --leaf:#26A85E; --sun:#FFC52E; --plum:#8C5BD6;
  --ok-bg:#DDF6E6; --bad-bg:#FFE3DC;
  --f-display:"ZCOOL KuaiLe","Noto Sans SC","PingFang SC","Microsoft YaHei",sans-serif;
  --f-body:"Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,sans-serif;
  --f-num:"Baloo 2","Noto Sans SC",ui-rounded,system-ui,sans-serif;
  color-scheme:light;
}
html,body{min-height:100%}
body{
  background-color:var(--sea);
  background-image:
    radial-gradient(ellipse 28px 6px at 30px 40px, rgba(255,255,255,.13) 60%, transparent 62%),
    radial-gradient(ellipse 20px 5px at 110px 95px, rgba(255,255,255,.10) 60%, transparent 62%);
  background-size:150px 130px;
  color:var(--ink); font-family:var(--f-body); font-size:16px; line-height:1.6;
}
.wrap{max-width:880px;margin:0 auto;padding-left:max(16px,env(safe-area-inset-left,0px));padding-right:max(16px,env(safe-area-inset-right,0px));padding-block:14px 48px}
button{font:inherit;color:inherit;cursor:pointer}
button:focus-visible{outline:4px solid var(--sun);outline-offset:3px}
.n,.num{font-family:var(--f-num);font-weight:800}

/* top bar */
.top{display:flex;align-items:center;justify-content:space-between;gap:10px;flex-wrap:wrap;margin-bottom:14px}
.brand{display:flex;align-items:center;gap:10px;background:none;border:0;padding:0;color:var(--sand)}
.brand-logo{width:44px;height:44px;border-radius:50%;background:var(--sun);border:3px solid var(--ink);display:grid;place-items:center;font-size:24px;box-shadow:0 3px 0 var(--ink)}
.brand-name{font-family:var(--f-display);font-size:22px;letter-spacing:.04em;color:var(--sand);text-shadow:0 2px 0 var(--sea-deep)}
.pills{display:flex;gap:8px;align-items:center}
.pill{display:inline-flex;align-items:center;gap:6px;background:var(--sand);border:3px solid var(--ink);border-radius:999px;padding:2px 12px;font-family:var(--f-num);font-weight:800;font-size:17px;box-shadow:0 3px 0 var(--ink)}
.coin-dot{width:18px;height:18px;border-radius:50%;background:var(--sun);border:2px solid var(--ink);display:inline-block}
.icon-btn{background:var(--sand);border:3px solid var(--ink);border-radius:999px;width:42px;height:38px;box-shadow:0 3px 0 var(--ink);font-size:18px}
.icon-btn:active{transform:translateY(2px);box-shadow:0 1px 0 var(--ink)}

/* hero */
.hero{display:grid;grid-template-columns:auto 1fr;gap:16px;align-items:center;margin:8px 0 22px}
.mascot{width:96px;height:96px;border-radius:50%;background:var(--leaf);border:4px solid var(--ink);display:grid;place-items:center;font-size:56px;box-shadow:0 5px 0 var(--ink)}
.hero h1{font-family:var(--f-display);font-weight:400;font-size:clamp(34px,7vw,54px);line-height:1.1;margin:0;color:var(--sand);text-shadow:0 4px 0 var(--ink);text-wrap:balance;letter-spacing:.03em}
.bubble{position:relative;display:inline-block;margin-top:10px;background:var(--sand);border:3px solid var(--ink);border-radius:16px;padding:8px 14px;font-weight:700;box-shadow:0 3px 0 var(--ink);max-width:52ch}
@media (max-width:520px){.hero{grid-template-columns:1fr;text-align:left}.mascot{width:72px;height:72px;font-size:42px}}

.section-label{font-family:var(--f-display);color:var(--sand);font-size:20px;margin:6px 0 10px;letter-spacing:.06em}
.islands{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:14px}
@media (max-width:700px){.islands{grid-template-columns:repeat(2,minmax(0,1fr))}}
.tile{display:flex;flex-direction:column;align-items:center;gap:4px;text-align:center;background:var(--sand);border:3px solid var(--ink);border-radius:22px;padding:14px 10px 12px;box-shadow:0 6px 0 var(--ink);transition:transform .12s}
.tile:hover{transform:translateY(-3px)}
.tile:active{transform:translateY(3px);box-shadow:0 3px 0 var(--ink)}
.blob{width:76px;height:64px;display:grid;place-items:center;font-size:36px;border:3px solid var(--ink);border-radius:58% 42% 52% 48% / 55% 48% 52% 45%;margin-bottom:4px}
.tile-name{font-family:var(--f-display);font-size:21px;line-height:1.2}
.tile-en{font-size:12px;color:var(--ink-soft);letter-spacing:.04em;font-weight:500}
.stars{font-size:18px;letter-spacing:2px;color:#C9B98F}
.stars .on{color:var(--sun);-webkit-text-stroke:1px var(--ink)}
.specials{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:22px}
@media (max-width:560px){.specials{grid-template-columns:1fr}}
.special{display:flex;align-items:center;gap:14px;text-align:left;border:3px solid var(--ink);border-radius:22px;padding:14px 16px;box-shadow:0 6px 0 var(--ink)}
.special:active{transform:translateY(3px);box-shadow:0 3px 0 var(--ink)}
.special .blob{flex:none;margin:0}
.special h3{font-family:var(--f-display);font-weight:400;font-size:23px;margin:0;line-height:1.2}
.special p{margin:2px 0 0;font-size:14px;font-weight:500}
.sp-riddle{background:#EBDDFF}
.sp-sprint{background:#FFE08A}
.foot{margin-top:26px;color:var(--foam);font-size:13px;line-height:1.7}
.foot b{color:var(--sand)}

/* play */
.playbar{display:flex;align-items:center;gap:10px;margin-bottom:12px;flex-wrap:wrap}
.back{background:var(--sand);border:3px solid var(--ink);border-radius:14px;padding:4px 12px;font-weight:700;box-shadow:0 3px 0 var(--ink)}
.play-title{font-family:var(--f-display);font-size:22px;color:var(--sand);text-shadow:0 2px 0 var(--ink);flex:1;min-width:0}
.dots{display:flex;gap:6px;margin-bottom:12px}
.dot{flex:1;height:10px;border-radius:6px;background:rgba(255,255,255,.3);border:2px solid var(--ink)}
.dot.ok{background:var(--leaf)} .dot.bad{background:var(--coral)} .dot.cur{background:var(--sun)}
.card{background:var(--sand);border:3px solid var(--ink);border-radius:24px;padding:20px;box-shadow:0 7px 0 var(--ink)}
.qno{font-family:var(--f-num);font-weight:800;color:var(--ink-soft);font-size:14px;letter-spacing:.08em;text-transform:uppercase;display:flex;justify-content:space-between;gap:8px}
.streak{color:var(--coral)}
.qtext{font-size:clamp(19px,4.2vw,24px);font-weight:700;line-height:1.55;margin:6px 0 12px;text-wrap:pretty}
.qtext .eq{font-family:var(--f-num);font-weight:800;font-size:1.5em;letter-spacing:.02em}
.visual{display:flex;justify-content:center;margin:6px 0 16px;overflow-x:auto}
.visual svg{max-width:100%;height:auto}
.opts{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.opt{position:relative;background:#fff;border:3px solid var(--ink);border-radius:18px;padding:12px 10px;min-height:64px;font-size:22px;font-weight:700;box-shadow:0 5px 0 var(--ink);display:flex;align-items:center;justify-content:center;gap:6px;text-align:center;font-family:var(--f-num)}
.opt:hover:not([disabled]){background:#FFFBEF}
.opt:active:not([disabled]){transform:translateY(3px);box-shadow:0 2px 0 var(--ink)}
.opt[disabled]{cursor:default}
.opt .key{position:absolute;top:6px;left:9px;font-size:12px;color:var(--ink-soft);font-weight:600}
.opt.right{background:var(--ok-bg);border-color:var(--leaf);box-shadow:0 5px 0 var(--leaf)}
.opt.wrong{background:var(--bad-bg);border-color:var(--coral);box-shadow:0 5px 0 var(--coral);animation:shake .35s}
.opt.dim{opacity:.55}
@keyframes shake{0%,100%{transform:translateX(0)}25%{transform:translateX(-6px)}75%{transform:translateX(6px)}}
.tools{display:flex;justify-content:flex-end;margin-top:12px}
.hint-btn{background:none;border:2px dashed var(--ink-soft);border-radius:12px;padding:3px 12px;font-size:14px;font-weight:700;color:var(--ink-soft)}
.hint{margin-top:10px;background:#FFF9E6;border:2px dashed var(--sun);border-radius:12px;padding:8px 12px;font-weight:500}
.fb{margin-top:16px;border:3px solid var(--ink);border-radius:18px;padding:12px 14px;display:grid;grid-template-columns:auto 1fr;gap:12px;align-items:start}
.fb.ok{background:var(--ok-bg)} .fb.bad{background:var(--bad-bg)}
.fb .face{font-size:34px;line-height:1}
.fb strong{font-family:var(--f-display);font-weight:400;font-size:21px;display:block}
.fb p{margin:4px 0 0;font-weight:500}
.next{margin-top:14px;width:100%;background:var(--coral);color:#fff;border:3px solid var(--ink);border-radius:18px;padding:12px;font-family:var(--f-display);font-size:22px;letter-spacing:.06em;box-shadow:0 5px 0 var(--ink)}
.next:active{transform:translateY(3px);box-shadow:0 2px 0 var(--ink)}

/* visuals */
.frac{display:inline-flex;flex-direction:column;align-items:center;vertical-align:middle;line-height:1.05;font-family:var(--f-num);font-weight:800;margin:0 .12em}
.frac>span:first-child{border-bottom:3px solid currentColor;padding:0 .2em .05em}
.frac>span:last-child{padding-top:.05em}
.seq{display:flex;gap:8px;flex-wrap:wrap;justify-content:center}
.seq span{min-width:62px;padding:6px 8px;border:3px solid var(--ink);border-radius:12px;background:#fff;text-align:center;font-family:var(--f-num);font-weight:800;font-size:22px}
.seq span.q{background:var(--sun)}
.groups{display:flex;flex-wrap:wrap;gap:10px;justify-content:center}
.grp{border:3px dashed var(--ink-soft);border-radius:50%;padding:10px 12px;display:flex;flex-wrap:wrap;gap:2px;max-width:110px;justify-content:center;font-size:24px;background:#fff}
.money{display:flex;flex-wrap:wrap;gap:10px;justify-content:center;align-items:center}
.coin{width:58px;height:58px;border-radius:50%;border:3px solid var(--ink);display:grid;place-items:center;font-family:var(--f-num);font-weight:800;font-size:16px;background:#E9E4D8}
.coin.gold{background:#F4CF5D}
.coin.big{width:66px;height:66px}
.note{min-width:92px;height:52px;border-radius:8px;border:3px solid var(--ink);display:grid;place-items:center;font-family:var(--f-num);font-weight:800;font-size:20px}
.note.n2{background:#C9A3E6}.note.n5{background:#A7DDB0}.note.n10{background:#F2A3A3}
.bal{display:flex;flex-direction:column;align-items:center;gap:0;width:min(100%,360px)}
.pans{display:grid;grid-template-columns:1fr 1fr;gap:20px;width:100%}
.pan{min-height:74px;border-bottom:6px solid var(--ink);border-radius:0 0 60px 60px;display:flex;flex-wrap:wrap;align-items:flex-end;justify-content:center;gap:4px;padding:6px 6px 8px;font-size:44px;line-height:1}
.wt{font-size:13px;font-family:var(--f-num);font-weight:800;background:var(--ink);color:var(--sand);border-radius:6px 6px 2px 2px;padding:6px 6px 3px}
.beam{width:100%;height:8px;background:var(--ink);border-radius:4px}
.post{width:10px;height:44px;background:var(--ink)}
.base{width:120px;height:10px;background:var(--ink);border-radius:5px}
.graph{border-collapse:collapse;background:#fff;border:3px solid var(--ink);border-radius:12px;overflow:hidden;font-size:16px}
.graph td{border-top:2px solid #E6DCC4;padding:6px 10px;vertical-align:middle}
.graph tr:first-child td{border-top:0}
.graph td:first-child{font-weight:700;white-space:nowrap;border-right:2px solid #E6DCC4}
.graph td:last-child{font-size:24px;letter-spacing:2px;white-space:nowrap}
.graph caption{caption-side:bottom;padding-top:8px;font-weight:700;font-size:15px}
.graph-title{font-weight:900;text-align:center;margin-bottom:6px}
.big-emoji{font-size:64px;line-height:1}
.shape-row{display:flex;gap:6px;flex-wrap:wrap;justify-content:center;align-items:center}
.shape-row .qbox{width:58px;height:58px;border:3px dashed var(--ink);border-radius:12px;display:grid;place-items:center;font-family:var(--f-num);font-weight:800;font-size:28px;background:var(--sun)}

/* result */
.result{text-align:center}
.result h2{font-family:var(--f-display);font-weight:400;font-size:clamp(30px,7vw,44px);margin:4px 0 6px;line-height:1.2}
.big-stars{font-size:56px;letter-spacing:6px;color:#D8C9A2}
.big-stars .on{color:var(--sun);-webkit-text-stroke:2px var(--ink)}
.score-line{font-size:20px;font-weight:700}
.btn-row{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-top:18px}
.btn{border:3px solid var(--ink);border-radius:18px;padding:12px;font-family:var(--f-display);font-size:20px;box-shadow:0 5px 0 var(--ink);background:#fff}
.btn.primary{background:var(--leaf);color:#fff}
.btn:active{transform:translateY(3px);box-shadow:0 2px 0 var(--ink)}
.review{text-align:left;margin-top:20px;border-top:3px dashed #D9C99F;padding-top:12px}
.review h3{font-family:var(--f-display);font-weight:400;font-size:20px;margin:0 0 8px}
.review li{margin-bottom:10px;font-weight:500}
.review .ans{color:var(--leaf);font-weight:900}

/* sprint */
.timer{height:16px;border:3px solid var(--ink);border-radius:10px;background:#fff;overflow:hidden;margin-bottom:12px}
.timer>div{height:100%;background:var(--sun);transition:width .2s linear}
.sprint-q{font-family:var(--f-num);font-weight:800;font-size:clamp(44px,12vw,72px);text-align:center;margin:8px 0 18px;line-height:1.1}
.flash-ok{animation:fok .3s}.flash-bad{animation:fbad .3s}
@keyframes fok{50%{background:var(--ok-bg)}}@keyframes fbad{50%{background:var(--bad-bg)}}

/* lessons */
.sp-learn{width:100%;background:#DDF4F8}
.l-title{font-family:var(--f-display);font-weight:400;font-size:clamp(26px,6vw,34px);margin:6px 0 10px;line-height:1.2;text-wrap:balance}
.l-body{font-size:18px;font-weight:500;line-height:1.75;margin:0 0 12px;max-width:62ch}
.l-body b{color:var(--coral)}
.c-hour{color:var(--coral)!important}.c-min{color:var(--sea)!important}
.remember{background:#FFF9E6;border:3px solid var(--sun);border-radius:14px;padding:8px 12px;font-weight:700}
.btn.wide{grid-column:1/-1}
.btn.go{background:var(--coral);color:#fff}
.pv{border-collapse:collapse;background:#fff;border:3px solid var(--ink);border-radius:12px;overflow:hidden;text-align:center}
.pv th{background:var(--sand-2);padding:6px 16px;border-left:2px solid var(--ink);font-size:16px;line-height:1.3}
.pv th small{display:block;font-size:11px;color:var(--ink-soft);font-weight:500}
.pv td{font-family:var(--f-num);font-weight:800;font-size:44px;padding:4px 16px;border-left:2px solid var(--ink);border-top:2px solid var(--ink)}
.pv th:first-child,.pv td:first-child{border-left:0}
.col{display:grid;grid-template-columns:repeat(4,1.2em);font-family:var(--f-num);font-weight:800;font-size:40px;text-align:center;line-height:1.15;background:#fff;border:3px solid var(--ink);border-radius:14px;padding:6px 16px}
.col .mk{font-size:18px;color:var(--coral);line-height:1;align-self:end}
.col .ln{grid-column:1/-1;border-top:4px solid var(--ink);margin:4px 0}
.col .r{color:var(--leaf)}
.bm{width:min(100%,420px);display:flex;flex-direction:column;gap:6px}
.bm-row{display:flex;width:100%;min-height:42px}
.bm-seg{border:3px solid var(--ink);margin-left:-3px;background:#fff;display:grid;place-items:center;font-weight:700;font-size:15px;padding:0 4px;min-width:0}
.bm-seg:first-child{margin-left:0}
.bm-seg.alt{background:var(--sand-2)}
.bm-seg.dash{border-style:dashed;background:var(--ok-bg)}
.bm-brace{height:12px;border:3px solid var(--ink);border-top:0;border-radius:0 0 12px 12px}
.bm-total{text-align:center;font-weight:900}
.bm-line{display:grid;grid-template-columns:3.2em 1fr;align-items:center;gap:8px}
.bm-lab{font-weight:700}
.tt-wrap{overflow-x:auto;max-width:100%}
.tt{border-collapse:collapse;background:#fff;border:3px solid var(--ink);font-family:var(--f-num);font-weight:700;text-align:center}
.tt th,.tt td{border:1px solid #E6DCC4;padding:3px 7px;font-size:16px}
.tt thead th{background:var(--sand-2);font-size:13px}
.tt tbody th{background:var(--sun);font-size:18px}
.fam{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.fam span{background:#fff;border:3px solid var(--ink);border-radius:12px;padding:8px 14px;font-family:var(--f-num);font-weight:800;font-size:22px;text-align:center}
.pair{display:flex;flex-wrap:wrap;gap:18px;justify-content:center}
.pair figure,.shape-grid figure{margin:0;display:flex;flex-direction:column;align-items:center;gap:4px;font-weight:700}
.pair figure svg{max-width:100%}
.shape-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px 18px}
.seq span.sym{border:0;background:none;min-width:0;padding:6px 0}
.ov-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}
@media (max-width:620px){.ov-grid{grid-template-columns:1fr}}
.ov-card{background:var(--sand);border:3px solid var(--ink);border-radius:22px;padding:14px 16px;box-shadow:0 6px 0 var(--ink);display:flex;flex-direction:column}
.ov-head{display:flex;gap:12px;align-items:center}
.ov-head .blob{width:60px;height:52px;font-size:28px;margin:0;flex:none}
.ov-card ul{margin:10px 0 12px;padding-left:1.2em;font-weight:500;flex:1}
.ov-btns{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.ov-btns .btn{font-size:17px;padding:8px}

.set section{padding:12px 0 14px;border-bottom:2px dashed #E3D3A8}
.set h3{font-family:var(--f-display);font-weight:400;font-size:21px;margin:0 0 8px}
.seg{display:flex;flex-wrap:wrap;gap:8px;margin:6px 0}
.seg-b{border:3px solid var(--ink);border-radius:12px;padding:6px 14px;background:#fff;font-weight:700;box-shadow:0 3px 0 var(--ink)}
.seg-b.on{background:var(--sun)}
.seg-b:active{transform:translateY(2px);box-shadow:0 1px 0 var(--ink)}
.chips{display:flex;flex-wrap:wrap;gap:8px;margin-top:6px}
.chip{display:inline-flex;gap:6px;align-items:center;background:#fff;border:2px solid var(--ink);border-radius:999px;padding:4px 12px;font-weight:600;cursor:pointer}
.chip input,.sw input{width:18px;height:18px;accent-color:var(--leaf);margin:0}
.sw{display:flex;gap:8px;align-items:center;font-weight:700;cursor:pointer}
.snote{font-size:14px;color:var(--ink-soft);margin:8px 0 0;font-weight:500;max-width:60ch}
.isl-set{border:2px solid #E3D3A8;border-radius:14px;padding:4px 12px;margin-bottom:8px;background:#FFFBEF}
.isl-set summary{cursor:pointer;font-weight:700;padding:6px 0;display:flex;gap:8px;align-items:center}
.isl-set .chips{padding-bottom:10px}
.cnt{margin-left:auto;color:var(--ink-soft);font-size:14px;font-weight:600}
.btn.danger{background:var(--bad-bg);font-size:17px}
.cheer{position:fixed;left:50%;top:36%;z-index:11;pointer-events:none;display:flex;flex-direction:column;align-items:center;gap:6px;transform:translate(-50%,-50%);animation:cheer 1.15s ease-out forwards}
.cheer.big{animation-duration:1.8s}
.cheer .thumb{font-size:96px;line-height:1;filter:drop-shadow(0 5px 0 rgba(28,42,57,.35))}
.cheer.big .thumb{font-size:120px}
.cheer-t{font-family:var(--f-display);font-size:30px;color:#fff;background:var(--coral);border:4px solid var(--ink);border-radius:999px;padding:2px 22px;box-shadow:0 5px 0 var(--ink);white-space:nowrap}
.cheer.big .cheer-t{background:var(--leaf);font-size:36px}
@keyframes cheer{0%{opacity:0;transform:translate(-50%,-50%) scale(.3) rotate(-12deg)}18%{opacity:1;transform:translate(-50%,-50%) scale(1.15) rotate(4deg)}32%{transform:translate(-50%,-50%) scale(1) rotate(0)}78%{opacity:1;transform:translate(-50%,-50%) scale(1)}100%{opacity:0;transform:translate(-50%,-75%) scale(.9)}}
.pill.bump{animation:bump .45s}
@keyframes bump{40%{transform:scale(1.25)}}
@media (max-width:440px){.brand-name{font-size:18px}.brand-logo{width:36px;height:36px;font-size:20px}.icon-btn{width:36px}.pills{gap:6px}.pill{padding:2px 9px}}
canvas#fx{position:fixed;inset:0;pointer-events:none;z-index:10;width:100%;height:100%}
@media (prefers-reduced-motion: reduce){*{animation:none!important;transition:none!important}}

/* Layout: same sticker-card board game as 数学岛, moved to a green lagoon; one map per language, switched by a big tab. */
:root{--sea:#2A8A72;--sea-deep:#185C4B;--foam:#D2F2E6;--plum:#7B5CC9}
.subj-tabs{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:0 0 18px}
.subj-tab{border:3px solid var(--ink);border-radius:18px;padding:10px 12px;background:rgba(255,255,255,.35);font-family:var(--f-display);font-size:22px;color:var(--ink);box-shadow:0 5px 0 var(--ink);display:flex;align-items:center;justify-content:center;gap:8px}
.subj-tab small{font-family:var(--f-body);font-size:13px;font-weight:700;opacity:.8}
.subj-tab.on{background:var(--sun)}
.subj-tab:active{transform:translateY(3px);box-shadow:0 2px 0 var(--ink)}
.islands.six{grid-template-columns:repeat(3,minmax(0,1fr))}
@media (max-width:700px){.islands.six{grid-template-columns:repeat(2,minmax(0,1fr))}}
.big-char{font-size:96px;line-height:1.05;font-family:"Kaiti SC","STKaiti","KaiTi","Noto Serif SC","Noto Sans SC",serif;font-weight:700;background:#fff;border:3px solid var(--ink);border-radius:18px;padding:4px 22px;box-shadow:0 5px 0 var(--ink)}
.tiles{display:flex;gap:6px;flex-wrap:wrap;justify-content:center;align-items:center}
.tiles span{width:44px;height:54px;border:3px solid var(--ink);border-radius:10px;background:#fff;display:grid;place-items:center;font-family:var(--f-num);font-weight:800;font-size:30px}
.tiles span.b{background:var(--sun)}
.tiles .pic{font-size:46px;border:0;background:none;width:auto;margin-right:8px}
.wchips{display:flex;flex-wrap:wrap;gap:8px;justify-content:center}
.wchips span{background:#fff;border:3px solid var(--ink);border-radius:12px;padding:6px 12px;font-weight:700;font-size:20px}
.wchips.order span{background:#FFF6D8}
.passage{background:#fff;border:3px solid var(--ink);border-radius:16px;padding:12px 16px;max-width:62ch;text-align:left;font-size:17px;line-height:1.75;font-weight:500}
.passage h4{margin:0 0 4px;font-family:var(--f-display);font-weight:400;font-size:20px}
.passage p{margin:0}
.tt2{border-collapse:collapse;background:#fff;border:3px solid var(--ink);font-weight:600}
.tt2 th,.tt2 td{border:1px solid #E6DCC4;padding:6px 12px;font-size:16px;text-align:left}
.tt2 thead th{background:var(--sand-2)}
.say{background:#fff;border:2px solid var(--ink);border-radius:12px;padding:3px 12px;font-size:14px;font-weight:700;box-shadow:0 2px 0 var(--ink)}
.say.big{font-size:20px;padding:10px 22px;border-width:3px;box-shadow:0 4px 0 var(--ink);background:var(--sun)}
.qtools{display:flex;justify-content:space-between;align-items:center;gap:8px;margin-top:12px;flex-wrap:wrap}
.opt.txt{font-family:var(--f-body);font-size:19px;line-height:1.35}
.opt.zh-big{font-family:"Kaiti SC","STKaiti","KaiTi","Noto Serif SC","Noto Sans SC",serif;font-size:30px}
.zh-note{display:block;font-size:14px;color:var(--ink-soft);font-weight:500;margin-top:4px}
.l-body .zh-note{font-size:15px}
.subj-h{font-family:var(--f-display);font-weight:400;font-size:22px;margin:12px 0 6px}

/* grade + subject switcher */
:root{--sea:#2B7FA0;--sea-deep:#1A5670}
.grade-row{display:grid;grid-template-columns:repeat(6,minmax(0,1fr));gap:6px;margin:0 0 10px}
.grade-chip{border:3px solid var(--ink);border-radius:14px;padding:4px 2px;background:var(--sand);font-family:var(--f-display);font-size:18px;line-height:1.15;display:flex;flex-direction:column;align-items:center;box-shadow:0 3px 0 var(--ink);color:var(--ink)}
.grade-chip small{font-family:var(--f-num);font-size:11px;font-weight:800;color:var(--ink-soft)}
.grade-chip.on{background:var(--coral);color:#fff}.grade-chip.on small{color:#fff}
.grade-chip.off{opacity:.45;box-shadow:none;border-style:dashed}
.grade-chip.off small{font-family:var(--f-body);font-size:10px}
.subj-tabs.n3{grid-template-columns:repeat(3,minmax(0,1fr))}.subj-tabs.n4{grid-template-columns:repeat(4,minmax(0,1fr))}
.subj-tab{flex-direction:column;gap:0;padding:8px 4px;font-size:clamp(15px,3.8vw,21px);line-height:1.2}
.subj-tab small{font-size:12px}
@media (max-width:440px){.grade-chip{font-size:15px}}
.count-grid{display:grid;grid-template-columns:repeat(5,auto);gap:4px 10px;font-size:34px;line-height:1.1;justify-content:center}
.count-grid.ten{grid-template-columns:repeat(10,auto);font-size:24px}
.icon-btn.rl{width:auto;padding:0 10px;font-size:14px;font-weight:700;white-space:nowrap}.icon-btn.rl b{font-family:var(--f-num);margin-left:3px}
.toast{position:fixed;left:50%;bottom:calc(24px + env(safe-area-inset-bottom,0px));transform:translateX(-50%);z-index:12;background:var(--ink);color:var(--sand);padding:10px 16px;border-radius:14px;font-weight:700;font-size:15px;max-width:calc(100vw - 32px);text-align:center;box-shadow:0 4px 0 rgba(0,0,0,.25)}
@media (max-width:440px){.brand-name{display:none}}
.vrow{display:grid;grid-template-columns:auto 1fr auto;gap:8px;align-items:center;margin:6px 0}.vrow label{font-weight:700}.vrow select{min-width:0;width:100%;font:inherit;padding:6px 8px;border:2px solid var(--ink);border-radius:10px;background:#fff}
.tile{position:relative}.cont{position:absolute;top:-10px;right:-6px;background:var(--coral);color:#fff;border:3px solid var(--ink);border-radius:999px;padding:1px 9px;font-size:13px;font-weight:800;font-family:var(--f-num);box-shadow:0 2px 0 var(--ink)}
.renew{margin-left:auto;font-size:14px;white-space:nowrap}.renew.armed{background:var(--coral);color:#fff}
.visual:has(.anat-wrap){flex-direction:column;align-items:stretch;overflow:visible;min-width:0;max-width:100%}.anat-wrap{width:100%;max-width:100%;overflow-x:auto;-webkit-overflow-scrolling:touch;border-radius:12px;background:#FFFBEF}.anat-fig{margin:0 auto;width:100%;max-width:580px}.anat{display:block;width:100%;height:auto}.swipe{display:none;margin:4px 0 0;text-align:center;font-size:13px;color:var(--ink-soft);font-weight:700}
@media (max-width:560px){.anat-fig{min-width:520px}.swipe{display:block}}
.sp-atlas{width:100%;background:#FCE4EF;margin-top:12px}.atlas{display:grid;gap:18px;grid-template-columns:minmax(0,1fr)}.atlas>*{min-width:0}.atlas-card .visual{margin-bottom:6px}
/* animated knowledge diagrams */
.anim-ready .st{opacity:0;transition:opacity .45s ease,transform .6s cubic-bezier(.2,.9,.3,1.25);transform-box:fill-box;transform-origin:center}
.anim-ready .st.pop{transform:scale(.35)}.anim-ready .st.drop{transform:translateY(-46px)}.anim-ready .st.slide{transform:translateX(-36px)}.anim-ready .st.mv{transform:translate(var(--fx),var(--fy));transition:opacity .3s,transform .9s ease-in-out}
.anim-ready .st.co{transform:none}
.anim-ready .st.on{opacity:1;transform:none}
.anim-ready .co .cl,.anim-ready .dr{stroke-dasharray:1;stroke-dashoffset:1;transition:stroke-dashoffset .7s ease}
.anim-ready .on .cl,.anim-ready .on .dr,.anim-ready .on.dr{stroke-dashoffset:0}
.anim-ready .co .ct{opacity:0;transition:opacity .4s ease .4s}.anim-ready .co.on .ct{opacity:1}
.anim-ready .rot{transform:rotate(0deg);transition:transform 2.4s ease-in-out}.anim-ready .rot.on{transform:rotate(var(--r))}
/* video */
.sp-video{width:100%;background:#FFE3DA;margin-top:12px}
.vmodal{position:fixed;inset:0;z-index:20;background:rgba(20,30,40,.6);display:flex;align-items:center;justify-content:center;padding:16px}
.vbox{background:var(--sand,#FFF6E0);border:3px solid var(--ink);border-radius:18px;width:100%;max-width:720px;max-height:calc(100vh - 32px);overflow:auto;padding:12px 14px;box-shadow:0 6px 0 rgba(0,0,0,.3)}
.vhead{display:flex;justify-content:space-between;align-items:center;gap:8px;margin-bottom:8px;font-size:17px}
.vframe{position:relative;width:100%;aspect-ratio:16/9;background:#000;border-radius:12px;overflow:hidden}.vframe iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.vtitle{font-weight:800;margin:8px 0 2px}.vurl{margin:2px 0;font-size:13px;word-break:break-all}.vurl a{color:var(--sea-deep)}
.vbtns{display:flex;flex-wrap:wrap;gap:8px;margin:10px 0 4px}.vbtns .btn{text-decoration:none;color:var(--ink);display:inline-flex;align-items:center}.vbtns .btn.primary{color:#fff}
.vnote{font-size:12px;color:var(--ink-soft);margin:6px 0 0}
.vlist{display:grid;gap:14px;grid-template-columns:repeat(auto-fill,minmax(min(100%,300px),1fr))}.vlist>*{min-width:0}
.vthumb{position:relative;display:block;width:100%;aspect-ratio:16/9;border:3px solid var(--ink);border-radius:12px;overflow:hidden;padding:0;background:#222;cursor:pointer}
.vthumb img{width:100%;height:100%;object-fit:cover;display:block}.vplay{position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);width:56px;height:56px;border-radius:50%;background:rgba(255,80,60,.92);color:#fff;font-size:24px;display:flex;align-items:center;justify-content:center;border:3px solid #fff}
/* two-video + card animations */
.visual:has(.vpair){display:block;overflow:visible}.vpair{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,200px),1fr));gap:10px;width:100%}
.vthumb .vno{position:absolute;left:8px;top:8px;background:var(--coral);color:#fff;border-radius:999px;padding:1px 9px;font-size:13px;font-weight:800}
.vthumb .vcap{position:absolute;left:0;right:0;bottom:0;background:linear-gradient(transparent,rgba(0,0,0,.8));color:#fff;font-size:13px;font-weight:700;padding:16px 8px 6px;text-align:left;line-height:1.25}
.vtabs{display:flex;gap:6px;margin-bottom:8px}.vtab{border:2px solid var(--ink);border-radius:999px;padding:4px 14px;background:#fff;font-weight:800}.vtab.on{background:var(--coral);color:#fff}
@keyframes aPop{from{opacity:0;transform:scale(.4)}60%{opacity:1;transform:scale(1.08)}to{opacity:1;transform:none}}
@keyframes aDraw{from{stroke-dasharray:1;stroke-dashoffset:1}to{stroke-dasharray:1;stroke-dashoffset:0}}
@keyframes aHl{from{background-size:0% 100%}to{background-size:100% 100%}}
@keyframes aRise{from{opacity:0;transform:translateY(14px)}to{opacity:1;transform:none}}
.a-pop{animation:aPop .55s cubic-bezier(.2,.9,.3,1.3) both;transform-box:fill-box;transform-origin:center}
.a-draw{animation:aDraw .7s ease both}
.a-hl{background-image:linear-gradient(transparent 55%,#FFE066 55%);background-repeat:no-repeat;animation:aHl .6s ease both}
.a-rise{animation:aRise .5s ease both}
.replay{display:block;margin:6px auto 0;border:2px solid var(--ink);border-radius:999px;background:#fff;padding:4px 14px;font-weight:700;font-size:14px}
@media (prefers-reduced-motion:reduce){.a-pop,.a-draw,.a-hl,.a-rise{animation:none}.a-hl{background-size:100% 100%}}
.vout{display:flex;align-items:center;justify-content:center;flex-direction:column;gap:10px;text-decoration:none;background:linear-gradient(135deg,#1F2A36,#3B2B4F)}.vout img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;opacity:.55}
.vbig{position:relative;width:84px;height:84px;border-radius:50%;background:#FF3B30;color:#fff;font-size:38px;display:flex;align-items:center;justify-content:center;border:4px solid #fff;box-shadow:0 4px 0 rgba(0,0,0,.35)}
.vtip{position:relative;color:#fff;font-weight:800;font-size:18px;text-shadow:0 2px 4px rgba(0,0,0,.6)}.vwhy{font-size:13px;color:var(--ink-soft);margin:6px 0 0}
.exv{margin:8px 0;font-size:14px}.exv summary{cursor:pointer;font-weight:800;color:var(--sea-deep)}.exv ol{margin:6px 0 0;padding-left:22px}.exv li{margin:6px 0;word-break:break-all}.exv a{font-size:12px;color:var(--ink-soft)}
.linkish{background:none;border:0;padding:0;font:inherit;font-weight:700;color:var(--ink);cursor:pointer;text-align:left}.say.cv{background:#FFE3DA}
.bigq{font-family:var(--f-num);font-weight:800;font-size:1.5em}