/* ============================================================
   数学小星球 · 设计系统
   萌系 / 奶油底 / 圆角厚描边 / 弹簧感动效
   ============================================================ */

:root{
  --cream:#FFFBF3;
  --paper:#FFFFFF;
  --ink:#3D3436;
  --ink-2:#6E6164;
  --ink-3:#A2969A;
  --coral:#FF7A59;
  --coral-d:#E85D3D;
  --mint:#3EC9B0;
  --mint-d:#2BA88F;
  --sky:#58A6FF;
  --sky-d:#3B87E6;
  --lemon:#FFC93C;
  --lemon-d:#F0AE12;
  --grape:#9B7BFF;
  --grape-d:#7E5BF0;
  --pink:#FF8FB1;
  --pink-d:#F06C93;
  --line:#F1E4D6;
  --line-2:#E6D6C6;
  --shadow-s:0 6px 0 rgba(220,198,176,.45);
  --shadow-m:0 12px 32px rgba(140,110,80,.12);
  --shadow-l:0 24px 60px rgba(140,110,80,.16);
  --spring:cubic-bezier(.34,1.56,.64,1);
  --ease:cubic-bezier(.22,.61,.36,1);
  --r-lg:30px;
  --r-md:22px;
  --r-sm:16px;
  --font:"PingFang SC","Hiragino Sans GB","Microsoft YaHei","微软雅黑",system-ui,-apple-system,"Segoe UI",sans-serif;
  --font-num:"Arial Rounded MT Bold","Segoe UI",system-ui,sans-serif;
}

.math-lab{padding:16px 20px;border-top:1px solid var(--line);background:#f3faf8;}
.math-lab-head{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:12px;}
.math-lab-head{flex-wrap:wrap;}
.math-lab-task{display:flex;align-items:center;flex-wrap:wrap;gap:10px;margin-top:12px;font-size:14px;}
.math-lab-task [hidden]{display:none;}
.math-lab-head b{font-size:15px;color:#237b69;}
.math-lab-head .pill-btn{font-size:12px;padding:6px 12px;}
.math-lab-control{display:grid;grid-template-columns:70px 32px minmax(0,1fr) 32px 32px;align-items:center;gap:8px;margin:10px 0;font-size:14px;}
.lab-adjust{width:32px;height:36px;padding:0;border:1px solid #b8d8cf;border-radius:6px;background:#fff;color:#237b69;font-size:20px;cursor:pointer;touch-action:manipulation;}
.lab-adjust:disabled{opacity:.4;cursor:default;}
.math-lab-control input{width:100%;min-width:0;accent-color:#238b75;cursor:pointer;min-height:32px;}
.math-lab-control output{font-variant-numeric:tabular-nums;text-align:right;font-weight:800;}
.math-lab-result{margin:8px 0 0;font-size:15px;font-weight:700;color:#237b69;overflow-wrap:anywhere;}
.math-lab-result:empty{display:none;}
.stage.solid-volume-stage{width:100%;height:400px;min-height:0;aspect-ratio:auto;background:#f7faf9;}
.solid-volume-stage .stage-svg,.solid-volume-stage .stage-clouds{visibility:hidden;}
.solid-volume-stage::after{box-shadow:inset 0 0 0 1px rgba(255,255,255,.9);}
.solid-volume-view{position:absolute;inset:0;background:#f7faf9;}
.solid-volume-caption{position:absolute;top:12px;left:12px;right:48px;font-size:14px;color:#435b54;text-align:center;}
.solid-volume-canvas{position:absolute;inset:42px 0 32px;}
.solid-volume-canvas canvas{display:block;width:100%;height:100%;touch-action:none;cursor:grab;}
.solid-volume-canvas canvas:active{cursor:grabbing;}
.solid-volume-canvas canvas:focus-visible{outline:2px solid #168b75;outline-offset:-3px;}
.solid-volume-home{position:absolute;right:10px;top:8px;width:32px;height:32px;font-size:24px;color:#315c50;border-radius:6px;}
.solid-volume-home:hover{background:#deeee8;}
.solid-volume-label{position:absolute;transform:translate(-50%,0);font-size:13px;font-weight:700;white-space:nowrap;pointer-events:none;}
.volume-lab{background:#fff;border-top-color:#dbe8e1;border-radius:0 0 20px 20px;}
.volume-heading{display:flex;flex-wrap:wrap;justify-content:space-between;align-items:center;gap:6px 12px;font-size:14px;}
.volume-status{font-size:13px;color:#5a7166;font-variant-numeric:tabular-nums;}
.volume-field{display:grid;grid-template-columns:90px minmax(40px,1fr) 64px;gap:10px;align-items:center;margin:10px 0;font-size:13px;}
.volume-field input{width:100%;min-width:0;min-height:32px;accent-color:#168b75;}
.volume-field output{text-align:right;font-variant-numeric:tabular-nums;}
.volume-actions{display:flex;flex-wrap:wrap;gap:8px;}
.volume-action{min-height:40px;padding:6px 14px;border:1px solid #bfd4ca;border-radius:6px;font-size:14px;color:#126d58;background:#f3faf6;}
.volume-action:first-child{color:#fff;background:#18745c;border-color:#18745c;}
.volume-action:disabled{opacity:.45;cursor:default;}
.volume-formula,.volume-result{margin:10px 0 0;font-size:14px;line-height:1.7;overflow-wrap:anywhere;font-variant-numeric:tabular-nums;}
.volume-formula{font-weight:700;color:#305447;}
.volume-result{color:#5b655f;}
.stage.volume-has-relation{width:100%;height:500px;min-height:0;aspect-ratio:auto;background:#f7faf9;}
.volume-has-relation .solid-volume-canvas{bottom:166px;}
.volume-has-relation .stage-svg{height:calc(100% - 144px);}
.solid-volume-part-label{padding:1px 5px;background:rgba(255,255,255,.85);border-radius:3px;font-size:12px;transform:translate(-50%,-50%);}
.solid-volume-evidence{position:absolute;z-index:2;left:14px;right:14px;bottom:12px;height:132px;border-top:1px solid #d6e4de;text-align:center;pointer-events:none;}
.solid-volume-evidence svg{width:100%;height:92px;max-width:400px;margin:0 auto;}
.volume-ratio-equation{display:flex;align-items:center;justify-content:center;gap:10px;font-size:17px;font-weight:700;color:#31564b;height:40px;line-height:1.2;}
.volume-fraction{display:inline-grid;grid-template-rows:1fr 1fr;min-width:22px;text-align:center;font-size:16px;}
.volume-fraction span:first-child{border-bottom:1.5px solid currentColor;padding:0 4px 2px;}
.volume-fraction span:last-child{padding-top:2px;}
.volume-shares{border:0;padding:0;margin:12px 0;display:flex;flex-wrap:wrap;gap:8px;}
.volume-shares legend{font-size:13px;margin-bottom:6px;}
.volume-shares label{display:flex;align-items:center;gap:5px;font-size:13px;cursor:pointer;padding:5px 8px;border:1px solid #d9e4de;border-radius:5px;}
.volume-shares label:has(input:checked){border-color:var(--portion-color);background:#f6faf8;}
.volume-shares input{accent-color:var(--portion-color);}
.volume-swatch{width:12px;height:12px;background:var(--portion-color);border-radius:2px;}
.volume-parts-summary{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));max-width:420px;margin:8px auto 0;gap:6px;color:#43534f;line-height:1.4;}
.volume-parts-summary>div{border-bottom:2px solid transparent;padding-bottom:3px;}
.volume-parts-summary>div.is-selected{border-bottom-color:var(--piece-color);}
.volume-parts-summary span,.volume-parts-summary b,.volume-parts-summary small{display:block;}
.volume-parts-summary span{font-size:12px;white-space:nowrap;}
.volume-parts-summary i{display:inline-block;width:9px;height:9px;margin-right:4px;border-radius:2px;}
.volume-parts-summary b{font-size:15px;}
.volume-parts-summary small{font-size:11px;color:#66786f;}
.volume-parts-equation{height:24px;line-height:24px;font-size:15px;color:#43534f;}
.volume-parts-summary~.volume-ratio-equation{height:32px;font-size:15px;}
.stage.volume-distribute-stage{height:560px;}
.solid-volume-vessel-label{white-space:pre-line;text-align:center;line-height:1.6;font-variant-numeric:tabular-nums;padding:2px 6px;border-radius:4px;background:rgba(247,250,249,.94);}
.solid-volume-vessel-label.is-filling{outline:2px solid currentColor;outline-offset:2px;}
.solid-volume-transfer{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;overflow:visible;display:none;}
@media(max-width:640px){
  .stage.volume-distribute-stage{height:650px;}
}
@media(max-width:480px){
  .stage.solid-volume-stage{height:310px;}
  .stage.volume-has-relation{height:430px;}
  .stage.volume-distribute-stage{height:650px;}
  .volume-has-relation .solid-volume-canvas{bottom:152px;}
  .solid-volume-evidence{height:120px;left:8px;right:8px;}
  .solid-volume-evidence svg{height:82px;}
  .volume-ratio-equation{gap:7px;font-size:14px;height:38px;}
  .volume-fraction{font-size:14px;min-width:18px;}
  .solid-volume-caption{font-size:12px;}
  .solid-volume-label{font-size:11px;}
  .volume-field{grid-template-columns:78px minmax(32px,1fr) 56px;gap:6px;}
  .volume-parts-summary{margin-top:5px;gap:2px;}
  .volume-parts-summary span{font-size:11px;}
  .volume-parts-summary b{font-size:13px;}
  .volume-parts-summary small{font-size:10px;}
  .volume-parts-equation{font-size:13px;height:22px;line-height:22px;}
  .volume-parts-summary~.volume-ratio-equation{height:30px;font-size:14px;}
}
[data-fraction-part][role="button"]{cursor:pointer;touch-action:manipulation;}
[data-fraction-part][role="button"]:focus-visible{outline:3px solid #238b75;outline-offset:3px;}
[data-fraction-part][role="button"]:hover{filter:brightness(.95);}
[data-angle-handle],[data-numberline-handle]{cursor:grab;touch-action:none;}
[data-angle-handle]:active,[data-numberline-handle]:active{cursor:grabbing;}
[data-angle-handle]:focus-visible,[data-numberline-handle]:focus-visible{outline:3px solid #238b75;outline-offset:4px;}
[data-clock-handle]{cursor:grab;touch-action:none;}
[data-clock-handle]:active{cursor:grabbing;}
[data-clock-handle]:focus-visible{outline:3px solid #3B87E6;outline-offset:4px;}
button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid #238b75;outline-offset:4px;}
@media(max-width:480px){.math-lab{padding:12px;}.math-lab-control{grid-template-columns:60px 32px minmax(0,1fr) 32px 26px;gap:5px;}}
*{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;
  background:var(--cream);
  color:var(--ink);
  font-family:var(--font);
  font-size:16px;
  line-height:1.7;
  -webkit-font-smoothing:antialiased;
  overflow-x:hidden;
}
a{color:inherit;text-decoration:none;}
button{font-family:inherit;cursor:pointer;border:none;background:none;color:inherit;}
img,svg{display:block;}
::selection{background:#FFE7A8;color:var(--ink);}

/* ---------- 背景装饰 ---------- */
.bg-deco{position:fixed;inset:0;z-index:0;pointer-events:none;overflow:hidden;}
.blob{position:absolute;border-radius:50%;filter:blur(60px);opacity:.55;}
.b1{width:520px;height:520px;left:-160px;top:-180px;background:#FFE7B8;}
.b2{width:420px;height:420px;right:-130px;top:120px;background:#D6F5EE;}
.b3{width:380px;height:380px;left:36%;bottom:-180px;background:#FFDFE8;}
.b4{width:300px;height:300px;right:18%;bottom:-120px;background:#E3DCFF;opacity:.4;}

.wrap{position:relative;z-index:1;max-width:1200px;margin:0 auto;padding:0 24px 60px;}

/* ---------- 顶栏 ---------- */
.topbar{
  position:sticky;top:0;z-index:50;
  display:flex;align-items:center;justify-content:space-between;
  gap:16px;padding:14px 6px 14px;
  backdrop-filter:blur(14px);
  background:linear-gradient(180deg,rgba(255,251,243,.94),rgba(255,251,243,.72) 70%,rgba(255,251,243,0));
}
.brand{display:flex;align-items:center;gap:11px;}
.brand-mark{width:44px;height:44px;flex:0 0 44px;filter:drop-shadow(0 4px 6px rgba(160,130,90,.18));}
.brand-mark svg{width:100%;height:100%;}
.brand-text{display:flex;flex-direction:column;line-height:1.15;}
.brand-text b{font-size:19px;letter-spacing:.5px;font-weight:800;}
.brand-text em{font-style:normal;font-size:9.5px;letter-spacing:2.6px;color:var(--ink-3);font-weight:700;}
.topnav{display:flex;align-items:center;gap:6px;font-size:14px;font-weight:700;}
.topnav a{padding:8px 14px;border-radius:999px;color:var(--ink-2);transition:background .2s,color .2s,box-shadow .2s;}
.topnav a:hover{background:#fff;color:var(--ink);box-shadow:0 4px 14px rgba(160,130,90,.12);}
.topnav a.on{background:var(--ink);color:#fff;}
.ver-pill{
  margin-left:6px;padding:6px 13px;border-radius:999px;
  background:#FFF0C9;color:#9A6B00;font-size:12.5px;font-weight:800;letter-spacing:.4px;
  border:1.5px solid #FFE39B;
}
.icon-btn{
  flex:0 0 34px;width:34px;height:34px;display:grid;place-items:center;
  border-radius:50%;background:#fff;border:1.5px solid var(--line-2);
  color:var(--ink-2);box-shadow:0 3px 0 var(--line);
  transition:transform .18s var(--spring),box-shadow .18s,color .2s;
}
.icon-btn svg{width:16px;height:16px;}
.icon-btn:hover{color:var(--coral-d);transform:translateY(-2px);box-shadow:0 5px 0 var(--line);}
.icon-btn:active{transform:translateY(2px);box-shadow:0 1px 0 var(--line);}
.top-reset{margin-left:2px;}

/* ---------- 通用按钮 ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:14px 26px;border-radius:999px;font-size:15.5px;font-weight:800;
  letter-spacing:.3px;transition:transform .18s var(--spring),box-shadow .18s,background .2s;
  white-space:nowrap;
}
.btn-primary{background:var(--coral);color:#fff;box-shadow:0 5px 0 var(--coral-d),0 12px 24px rgba(255,122,89,.25);}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 7px 0 var(--coral-d),0 18px 30px rgba(255,122,89,.28);}
.btn-primary:active{transform:translateY(3px);box-shadow:0 2px 0 var(--coral-d);}
.btn-ghost{background:#fff;color:var(--ink);border:2px solid var(--line-2);box-shadow:0 5px 0 var(--line);}
.btn-ghost:hover{transform:translateY(-2px);box-shadow:0 7px 0 var(--line);}
.btn-ghost:active{transform:translateY(3px);box-shadow:0 2px 0 var(--line);}

/* ---------- 首页 HERO ---------- */
.hero{
  display:grid;grid-template-columns:1.02fr .98fr;align-items:center;gap:30px;
  padding:26px 0 10px;min-height:520px;
}
.eyebrow{
  display:inline-flex;align-items:center;gap:9px;
  padding:8px 16px;border-radius:999px;background:#fff;
  border:1.5px solid var(--line);font-size:12.5px;font-weight:800;color:var(--ink-2);
  letter-spacing:.6px;box-shadow:0 4px 12px rgba(160,130,90,.08);
}
.eyebrow .dot{width:8px;height:8px;border-radius:50%;background:var(--mint);box-shadow:0 0 0 4px #D9F6F0;animation:pulse-dot 2.4s infinite;}
.hero h1{
  font-size:clamp(40px,5.2vw,66px);line-height:1.14;letter-spacing:-1px;
  font-weight:900;margin:20px 0 16px;
}
.hero h1 .hl{position:relative;z-index:0;white-space:nowrap;}
.hero h1 .hl::before{
  content:"";position:absolute;left:-6px;right:-6px;bottom:4px;height:38%;
  background:linear-gradient(90deg,#FFE39B,#FFD166);border-radius:10px;
  transform:rotate(-1.4deg);z-index:-1;
}
.hero .sub{font-size:16px;color:var(--ink-2);max-width:440px;margin:0 0 26px;line-height:1.85;}
.hero-actions{display:flex;gap:12px;flex-wrap:wrap;}
.hero-stats{display:flex;gap:26px;margin-top:34px;}
.stat{display:flex;flex-direction:column;gap:2px;}
.stat b{font-family:var(--font-num);font-size:26px;font-weight:800;line-height:1;letter-spacing:-.5px;}
.stat span{font-size:12px;color:var(--ink-3);font-weight:700;letter-spacing:.5px;}
.stat i{font-style:normal;color:var(--coral);}

.hero-art{position:relative;display:flex;align-items:center;justify-content:center;min-height:440px;}
.hero-art .halo{
  position:absolute;width:360px;height:360px;border-radius:50%;
  background:radial-gradient(circle at 50% 45%,#FFF2C4 0%,#FFE9AE 42%,rgba(255,233,174,0) 70%);
  filter:blur(4px);animation:breathe 6s ease-in-out infinite;
}
.hero-art svg.mascot-big{width:400px;height:400px;position:relative;z-index:2;animation:float-y 5.2s ease-in-out infinite;}
.chip{
  position:absolute;z-index:3;display:flex;align-items:center;gap:8px;
  padding:10px 16px;border-radius:16px;background:#fff;border:2px solid var(--line);
  font-size:13px;font-weight:800;box-shadow:0 8px 20px rgba(160,130,90,.14);
  animation:float-y 4.4s ease-in-out infinite;
}
.chip .em{font-size:17px;line-height:1;}
.chip.c1{top:56px;left:6%;animation-delay:-.8s;transform:rotate(-5deg);}
.chip.c2{top:150px;right:0;animation-delay:-2.1s;transform:rotate(4deg);}
.chip.c3{bottom:74px;left:2%;animation-delay:-3.2s;transform:rotate(3deg);}
.chip.c1,.chip.c2,.chip.c3{color:var(--ink-2);}
.spark{position:absolute;font-size:20px;opacity:.8;animation:twinkle 3s ease-in-out infinite;}

/* ---------- 目录区 ---------- */
.catalog{padding-top:26px;scroll-margin-top:90px;}
.section-head{display:flex;align-items:flex-end;justify-content:space-between;gap:18px;flex-wrap:wrap;margin-bottom:18px;}
.section-head h2{font-size:26px;font-weight:900;margin:0;letter-spacing:-.4px;}
.section-head p{margin:4px 0 0;font-size:13.5px;color:var(--ink-3);font-weight:600;}

.edition-tabs{display:inline-flex;gap:6px;padding:6px;background:#fff;border:2px solid var(--line);border-radius:999px;box-shadow:var(--shadow-s);}
.edition-tabs button{
  padding:9px 18px;border-radius:999px;font-size:13.5px;font-weight:800;color:var(--ink-2);
  transition:.22s var(--spring);white-space:nowrap;
}
.edition-tabs button:hover{background:#FFF6E8;}
.edition-tabs button.active{background:var(--ink);color:#fff;transform:translateY(-1px);box-shadow:0 4px 10px rgba(61,52,54,.22);}

.grade-grid{display:grid;grid-template-columns:repeat(6,1fr);gap:12px;margin:18px 0 20px;}
.grade-card{
  position:relative;background:#fff;border:2px solid var(--line);border-radius:24px;
  padding:16px 14px 15px;text-align:left;transition:.24s var(--spring);
  box-shadow:0 6px 0 var(--line);
}
.grade-card:hover{transform:translateY(-5px);box-shadow:0 11px 0 var(--line);}
.grade-card .g-num{
  font-family:var(--font-num);font-size:32px;font-weight:900;line-height:1;
  letter-spacing:-1px;display:flex;align-items:baseline;gap:2px;
}
.grade-card .g-num i{font-style:normal;font-size:13px;font-weight:800;letter-spacing:0;}
.grade-card .g-name{font-size:13.5px;font-weight:800;margin-top:2px;color:var(--ink-2);}
.grade-card .g-meta{font-size:11px;color:var(--ink-3);font-weight:700;margin-top:6px;}
.grade-card .g-dots{display:flex;gap:4px;margin-top:9px;}
.grade-card .g-dots i{width:6px;height:6px;border-radius:50%;background:currentColor;opacity:.22;}
.grade-card.active{transform:translateY(-5px);border-color:transparent;color:#fff;box-shadow:0 11px 0 rgba(0,0,0,.13);}
.grade-card.active .g-name,.grade-card.active .g-meta{color:rgba(255,255,255,.85);}
.grade-card.active .g-dots i{opacity:.6;background:#fff;}
.grade-card[data-g="1"]{color:#E46B45;}
.grade-card[data-g="2"]{color:#D9A21B;}
.grade-card[data-g="3"]{color:#2BA88F;}
.grade-card[data-g="4"]{color:#3B87E6;}
.grade-card[data-g="5"]{color:#7E5BF0;}
.grade-card[data-g="6"]{color:#E0618A;}
.grade-card.active[data-g="1"]{background:linear-gradient(135deg,#FF9A73,#FF7A59);}
.grade-card.active[data-g="2"]{background:linear-gradient(135deg,#FFD166,#F5B823);}
.grade-card.active[data-g="3"]{background:linear-gradient(135deg,#5FD9C0,#35B79D);}
.grade-card.active[data-g="4"]{background:linear-gradient(135deg,#7BBDFF,#4A93EE);}
.grade-card.active[data-g="5"]{background:linear-gradient(135deg,#B39DFF,#8466F5);}
.grade-card.active[data-g="6"]{background:linear-gradient(135deg,#FFA8C2,#EE6E96);}

.subbar{display:flex;align-items:center;justify-content:space-between;gap:14px;flex-wrap:wrap;margin:6px 0 16px;}
.segmented{display:inline-flex;background:#fff;border:2px solid var(--line);border-radius:14px;padding:4px;gap:2px;box-shadow:0 4px 0 var(--line);}
.segmented button{padding:7px 20px;border-radius:10px;font-size:13px;font-weight:800;color:var(--ink-2);transition:.2s;}
.segmented button.active{background:#FFEFD2;color:#9A6B00;box-shadow:inset 0 0 0 1.5px #FFDB9B;}
.unit-note{font-size:12.5px;color:var(--ink-3);font-weight:700;}

.unit-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;}
.unit-card{
  display:flex;align-items:center;gap:14px;background:#fff;border:2px solid var(--line);
  border-radius:20px;padding:14px 16px;transition:.22s var(--spring);
  box-shadow:0 5px 0 var(--line);position:relative;overflow:hidden;
}
.unit-card::after{
  content:"";position:absolute;inset:0;border-radius:18px;
  background:linear-gradient(120deg,#FFF6E4,#fff 55%);opacity:0;transition:.25s;z-index:0;
}
.unit-card:hover{transform:translateY(-4px);box-shadow:0 9px 0 var(--line);border-color:#FFD9A8;}
.unit-card:hover::after{opacity:1;}
.unit-card>*{position:relative;z-index:1;}
.unit-no{
  flex:0 0 42px;width:42px;height:42px;border-radius:14px;display:grid;place-items:center;
  font-family:var(--font-num);font-size:16px;font-weight:900;
  background:#FFF3DC;color:#C98A1B;
}
.unit-card:nth-child(3n+2) .unit-no{background:#E4F8F3;color:#2BA88F;}
.unit-card:nth-child(3n) .unit-no{background:#EDE9FF;color:#7E5BF0;}
.unit-main{flex:1;min-width:0;display:flex;flex-direction:column;}
.unit-name{font-size:14.5px;font-weight:800;line-height:1.4;}
.unit-meta{font-size:11.5px;color:var(--ink-3);font-weight:700;margin-top:2px;display:flex;align-items:center;gap:6px;}
.unit-meta .dotline{width:3px;height:3px;border-radius:50%;background:var(--ink-3);}
.unit-arrow{flex:0 0 26px;width:26px;height:26px;border-radius:50%;display:grid;place-items:center;background:#FFF3DC;color:#C98A1B;transition:.22s var(--spring);font-size:13px;font-weight:900;}
.unit-card:hover .unit-arrow{transform:translateX(4px);background:var(--coral);color:#fff;}
.unit-card.done .unit-arrow{background:var(--mint);color:#fff;}

/* ---------- 单元页：课时卡片 ---------- */
.hour-grid{grid-template-columns:repeat(3,1fr);}
.hour-card{padding:13px 15px;}
.hour-card .unit-name{font-size:14px;}
.crumb a{color:var(--ink-3);text-decoration:none;border-bottom:1.5px dashed rgba(0,0,0,.18);}
.crumb a:hover{color:var(--coral);border-color:var(--coral);}
.hour-nav{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-top:18px;flex-wrap:wrap;}
.hour-nav .pill-btn{text-decoration:none;display:inline-flex;align-items:center;}

.empty-card{
  grid-column:1/-1;text-align:center;padding:36px;border:2px dashed var(--line-2);
  border-radius:22px;color:var(--ink-3);font-weight:700;background:rgba(255,255,255,.6);
}

/* ---------- 单元学习页 ---------- */
.lesson{padding-top:8px;animation:ui-in .45s var(--ease) both;}
.lesson-head{display:flex;align-items:center;gap:14px;margin-bottom:16px;flex-wrap:wrap;}
.icon-btn{
  width:44px;height:44px;border-radius:14px;display:grid;place-items:center;
  background:#fff;border:2px solid var(--line);box-shadow:0 4px 0 var(--line);
  font-size:17px;font-weight:900;transition:.2s var(--spring);
}
.icon-btn:hover{transform:translateY(-2px);box-shadow:0 6px 0 var(--line);}
.icon-btn:active{transform:translateY(2px);box-shadow:0 2px 0 var(--line);}
.lesson-title{flex:1;min-width:200px;}
.crumb{font-size:12px;font-weight:800;color:var(--ink-3);letter-spacing:.4px;display:flex;align-items:center;gap:6px;flex-wrap:wrap;}
.crumb b{color:var(--coral);}
.lesson-title h2{font-size:clamp(21px,2.4vw,29px);font-weight:900;margin:2px 0 0;letter-spacing:-.4px;line-height:1.3;}
.lesson-tags{display:flex;gap:6px;flex-wrap:wrap;}
.tag{
  padding:5px 12px;border-radius:999px;font-size:11.5px;font-weight:800;
  background:#fff;border:1.5px solid var(--line);color:var(--ink-2);
}
.tag.mint{background:#E6F9F4;border-color:#C6F1E5;color:#238B76;}
.tag.sun{background:#FFF6D9;border-color:#FFE7A8;color:#A17400;}

.lesson-body{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(310px,.9fr);gap:18px;align-items:start;}
.side{display:flex;flex-direction:column;gap:16px;min-width:0;}

.stage-card{
  background:#fff;border:2px solid var(--line);border-radius:32px;padding:10px;
  box-shadow:var(--shadow-m);position:sticky;top:86px;
}
.stage{
  position:relative;aspect-ratio:16/10;border-radius:24px;overflow:hidden;
  background:linear-gradient(180deg,#E9F7FF 0%,#F3FBFF 42%,#FFF8E9 100%);
  border:2px solid #FFF;
}
.stage::after{
  content:"";position:absolute;inset:0;border-radius:22px;pointer-events:none;
  box-shadow:inset 0 0 0 1px rgba(255,255,255,.9),inset 0 -30px 60px rgba(255,225,180,.25);
}
.stage-svg{position:absolute;inset:0;width:100%;height:100%;}
.stage.paused svg *{animation-play-state:paused !important;}
.stage-clouds{position:absolute;inset:0;pointer-events:none;overflow:hidden;}
.stage-clouds i{
  position:absolute;width:90px;height:26px;border-radius:99px;background:#fff;opacity:.55;
  box-shadow:26px -12px 0 0 #fff,52px 2px 0 0 #fff;filter:blur(.4px);
  animation:cloud-drift 26s linear infinite;
}
.stage-clouds i:nth-child(1){top:9%;left:-14%;animation-duration:34s;}
.stage-clouds i:nth-child(2){top:22%;left:-30%;animation-duration:46s;animation-delay:-12s;transform:scale(.7);}
.stage-clouds i:nth-child(3){top:4%;left:-50%;animation-duration:58s;animation-delay:-30s;transform:scale(1.25);}

.stage-bar{display:flex;align-items:center;gap:10px;padding:10px 8px 2px;}
.pill-btn{
  display:inline-flex;align-items:center;gap:6px;padding:9px 15px;border-radius:12px;
  background:#FFF6E7;border:1.5px solid #FFE6C4;color:#A9741A;font-size:12.5px;font-weight:800;
  transition:.18s var(--spring);
}
.pill-btn:hover{background:#FFEFD6;transform:translateY(-1px);}
.pill-btn:disabled{opacity:.4;cursor:not-allowed;transform:none;}
.play-btn{
  width:46px;height:46px;flex:0 0 46px;border-radius:16px;display:grid;place-items:center;
  background:var(--ink);color:#fff;font-size:15px;
  box-shadow:0 4px 0 rgba(0,0,0,.22);transition:.18s var(--spring);
}
.play-btn:hover{transform:translateY(-2px);box-shadow:0 6px 0 rgba(0,0,0,.22);}
.play-btn:active{transform:translateY(2px);box-shadow:0 2px 0 rgba(0,0,0,.22);}
.progress{flex:1;height:8px;border-radius:99px;background:#F2E9DF;overflow:hidden;margin:0 4px;}
.progress i{display:block;height:100%;width:100%;border-radius:99px;background:linear-gradient(90deg,#FFC93C,#FF7A59);transform-origin:left;transform:scaleX(0);}
.progress i.run{animation:bar-grow linear both;animation-duration:var(--dur,6s);}
.step-count{font-family:var(--font-num);font-size:12.5px;font-weight:800;color:var(--ink-3);flex:0 0 auto;padding-right:4px;}
.stage-settings{
  display:flex;align-items:center;justify-content:space-between;gap:10px 16px;flex-wrap:wrap;
  padding:8px 8px 4px;margin-top:4px;border-top:1.5px dashed var(--line);
}
.set-group{display:flex;align-items:center;gap:8px;}
.set-label{font-size:11.5px;font-weight:800;color:var(--ink-3);letter-spacing:.3px;white-space:nowrap;}
.segmented.mini{padding:3px;border-radius:12px;box-shadow:0 3px 0 var(--line);}
.segmented.mini button{padding:5px 12px;border-radius:8px;font-size:11.5px;}

/* 右侧讲解面板 */
.panel{
  background:#fff;border:2px solid var(--line);border-radius:30px;padding:20px;
  box-shadow:var(--shadow-m);display:flex;flex-direction:column;gap:14px;
}
.panel-head{display:flex;align-items:center;gap:10px;}
.panel-head .avatar{width:44px;height:44px;flex:0 0 44px;border-radius:50%;background:#FFF6D9;display:grid;place-items:center;border:1.5px solid #FFE9AE;}
.panel-head .avatar svg{width:34px;height:34px;}
.panel-head .who b{display:block;font-size:14px;font-weight:900;}
.panel-head .who span{display:block;font-size:11px;color:var(--ink-3);font-weight:700;}
.speech{
  position:relative;background:#FFF9EC;border:1.5px solid #FFEBC4;border-radius:16px;
  padding:13px 15px;font-size:14px;line-height:1.8;color:var(--ink);min-height:96px;
  animation:ui-in .35s var(--ease) both;
}
.speech::before{
  content:"";position:absolute;top:-8px;left:24px;width:14px;height:14px;background:#FFF9EC;
  border-left:1.5px solid #FFEBC4;border-top:1.5px solid #FFEBC4;transform:rotate(45deg);
}
.speech .k{color:var(--coral-d);font-weight:900;}
.speech .num{font-family:var(--font-num);font-weight:900;color:var(--sky-d);}

.step-list{display:flex;flex-direction:column;gap:6px;max-height:320px;overflow:auto;padding-right:4px;}
.step-item{
  display:flex;align-items:center;gap:10px;padding:9px 11px;border-radius:12px;
  font-size:13px;font-weight:700;color:var(--ink-2);transition:.18s;text-align:left;width:100%;
}
.step-item:hover{background:#FFF7EA;}
.step-item .idx{
  width:22px;height:22px;flex:0 0 22px;border-radius:50%;display:grid;place-items:center;
  background:#F4EDE4;color:var(--ink-3);font-family:var(--font-num);font-size:11px;font-weight:900;
}
.step-item.active{background:#FFF1DA;color:#9A6B00;}
.step-item.active .idx{background:var(--coral);color:#fff;}
.step-item.done .idx{background:var(--mint);color:#fff;}

.mini-note{font-size:11.5px;color:var(--ink-3);font-weight:700;line-height:1.7;border-top:1px dashed var(--line-2);padding-top:12px;}

/* 小结 & 测评 */
.recap{display:flex;flex-direction:column;gap:10px;}
.recap h3{font-size:14.5px;font-weight:900;margin:0;display:flex;align-items:center;gap:6px;}
.recap ul{margin:0;padding:0;list-style:none;display:flex;flex-direction:column;gap:8px;}
.recap li{display:flex;gap:9px;font-size:13px;line-height:1.65;color:var(--ink-2);}
.recap li::before{content:"🌱";font-size:12px;line-height:1.9;}

/* 家长陪学 */
.parent-panel{
  border-color:#FFE0CB;
  background:linear-gradient(180deg,#FFFDF9,#FFF7EF);
}
.p-head .who{flex:1;min-width:0;}
.p-avatar{
  width:44px;height:44px;flex:0 0 44px;border-radius:50%;
  background:#FFE9DA;border:1.5px solid #FFD6BF;
  display:grid;place-items:center;font-size:20px;
}
.p-toggle{
  flex:none;display:flex;align-items:center;gap:6px;
  padding:5px 10px 5px 5px;border-radius:999px;
  background:#F4EDE4;border:1.5px solid var(--line-2);
  font-size:11px;font-weight:800;color:var(--ink-3);
  transition:background .2s,border-color .2s,color .2s;
}
.p-toggle i{
  width:26px;height:16px;border-radius:999px;background:#DCCFC2;position:relative;
  transition:background .2s;
}
.p-toggle i::after{
  content:"";position:absolute;top:2px;left:2px;width:12px;height:12px;
  border-radius:50%;background:#fff;transition:left .22s var(--spring);
}
.p-toggle.on{background:#E9FBF5;border-color:#BDEBDD;color:var(--mint-d);}
.p-toggle.on i{background:var(--mint);}
.p-toggle.on i::after{left:12px;}
.p-body{display:flex;flex-direction:column;gap:10px;animation:ui-in .3s var(--ease) both;}
.p-body[hidden]{display:none;}
.p-row{display:flex;gap:8px;align-items:flex-start;}
.p-tag{
  flex:none;margin-top:2px;padding:2px 8px;border-radius:8px;
  background:#FFEDE6;color:var(--coral-d);font-size:10.5px;font-weight:900;
}
.p-tag.ask{background:#EAF3FF;color:var(--sky-d);}
.p-tag.warn{background:#FFF6DB;color:#9A6B00;}
.p-row p{margin:0;font-size:12.5px;line-height:1.7;color:var(--ink-2);}
.p-act{
  display:flex;flex-direction:column;gap:4px;padding:10px 12px;border-radius:14px;
  background:#fff;border:1.5px dashed #FFD9BF;
}
.p-act b{font-size:11.5px;color:var(--coral-d);}
.p-act span{font-size:12.5px;line-height:1.65;color:var(--ink-2);}
.p-steps{
  display:flex;flex-direction:column;gap:3px;
  border-top:1px dashed var(--line-2);padding-top:10px;
}
.p-steps b{font-size:11px;color:var(--ink-3);letter-spacing:.3px;}
.p-steps span{font-size:11px;line-height:1.6;color:var(--ink-3);}
.p-hint{margin:0;font-size:11px;line-height:1.65;color:var(--ink-3);}
.p-hint[hidden]{display:none;}

/* 题目插图：把数量关系画出来，做题时也能数形结合；标题栏可展开 / 收起 */
.q-vis{margin:2px 0 12px;border-radius:16px;overflow:hidden;
  background:linear-gradient(180deg,#FFFDF8,#FFF8EC);border:1.5px solid #FFE9C9;
  box-shadow:0 2px 0 rgba(220,198,176,.35);}
.q-vis-toggle{
  display:flex;align-items:center;gap:8px;width:100%;padding:9px 12px;
  background:linear-gradient(180deg,#FFF7E6,#FFF1DA);border-bottom:1.5px solid #FFE9C9;
  font-size:12.5px;font-weight:800;color:#A9741A;text-align:left;
  transition:background .18s;
}
.q-vis-toggle:hover{background:linear-gradient(180deg,#FFF2D9,#FFE9C6);}
.q-vis-toggle .vt-ico{flex:0 0 15px;display:grid;place-items:center;color:var(--coral-d);}
.q-vis-toggle .vt-ico svg{width:15px;height:15px;}
.q-vis-toggle .vt-arrow{
  margin-left:auto;width:8px;height:8px;border-right:2.4px solid #C08A2E;border-bottom:2.4px solid #C08A2E;
  transform:rotate(225deg) translate(-2px,-1px);transition:transform .26s var(--spring);
}
.q-vis.collapsed .q-vis-toggle{border-bottom-color:transparent;}
.q-vis.collapsed .q-vis-toggle .vt-arrow{transform:rotate(45deg) translate(-2px,-1px);}
/* 收起靠 max-height 过渡：比 display:none 更顺滑，也不依赖新语法 */
.q-vis-body{max-height:900px;overflow:hidden;
  transition:max-height .32s var(--ease),opacity .22s var(--ease);}
.q-vis.collapsed .q-vis-body{max-height:0;opacity:0;}
.q-vis-inner{padding:10px 12px 8px;}
.q-vis svg{display:block;width:100%;height:auto;max-width:600px;margin:0 auto;}
.q-vis text{font-family:inherit;}
/* 插图下面的说明文字：用 HTML 画，手机上也是清晰的正文字号 */
.q-note{margin:0 0 4px;font-size:12.5px;line-height:1.55;text-align:center;font-weight:700;color:var(--ink-3);}
.quiz-card{display:flex;flex-direction:column;gap:12px;}
.quiz-q{font-size:15px;font-weight:900;line-height:1.65;}
.quiz-q .qtag{display:inline-block;padding:3px 9px;border-radius:8px;background:#FFE9E0;color:var(--coral-d);font-size:11px;margin-right:7px;vertical-align:2px;}
.quiz-q .qtag.num{background:#EAF3FF;color:var(--sky-d);}
/* 一个专题多道挑战题 */
.quiz-head{display:flex;align-items:center;gap:9px;padding:9px 12px;border-radius:12px;background:#FFF6E0;border:1.5px solid #FFE1A6;}
.quiz-head b{font-size:13.5px;color:#A9741A;}
.quiz-head span{font-size:12px;color:#B98B3E;}
.quiz-head i{margin-left:auto;font-style:normal;font-size:12.5px;font-weight:800;color:var(--mint-d);}
.quiz-block{display:flex;flex-direction:column;gap:9px;padding-bottom:14px;border-bottom:1px dashed var(--line-2);}
.quiz-block:last-child{padding-bottom:0;border-bottom:none;}
.quiz-block .quiz-actions{margin-top:2px;}
.opts{display:flex;flex-direction:column;gap:9px;}
.opt{
  display:flex;align-items:center;gap:11px;padding:12px 14px;border-radius:14px;
  border:2px solid var(--line);background:#fff;font-size:14px;font-weight:800;text-align:left;
  transition:.18s var(--spring);
}
.opt .ltr{
  width:26px;height:26px;flex:0 0 26px;border-radius:9px;display:grid;place-items:center;
  background:#FFF4E3;color:#B8821E;font-family:var(--font-num);font-size:12px;font-weight:900;
}
.opt:hover{border-color:#FFD9A8;transform:translateX(3px);}
.opt.right{background:#E8FAF4;border-color:#8FE6D2;}
.opt.right .ltr{background:var(--mint);color:#fff;}
.opt.wrong{background:#FFEEF2;border-color:#FFB9CB;animation:shake .42s;}
.opt.wrong .ltr{background:var(--pink);color:#fff;}
.opt:disabled{cursor:default;transform:none;}
.quiz-fb{font-size:13px;line-height:1.7;color:var(--ink-2);background:#F8F4ED;border-radius:12px;padding:11px 13px;animation:ui-in .3s both;}
.quiz-fb b{color:var(--mint-d);}
.quiz-fb.bad b{color:var(--pink-d);}
.quiz-actions{display:flex;gap:8px;flex-wrap:wrap;}

/* 填空题与判断题 */
.quiz-q .qtag.fill{background:#EFE7FF;color:#6B4FBF;}
.fill-row{display:flex;gap:8px;align-items:center;}
.fill-in{
  flex:1;min-width:0;padding:12px 14px;border-radius:14px;border:2px solid var(--line);
  background:#fff;font:inherit;font-size:15px;font-weight:800;color:var(--ink);
  transition:.18s var(--spring);
}
.fill-in::placeholder{color:#B9A99C;font-weight:700;}
.fill-in:focus{outline:none;border-color:var(--lemon);box-shadow:0 0 0 3px rgba(255,201,60,.22);}
.fill-in:disabled{background:#F6F1EA;color:var(--ink-2);}
.fill-in.shake{animation:shake .42s;}
.fill-go{flex:0 0 auto;}
.ans-line{margin-top:6px;font-size:13px;font-weight:700;color:var(--ink-2);}
.ans-line b{color:var(--mint-d);}

/* 单元测评入口与页面 */
.exam-entry{margin-top:18px;}
.exam-card{background:linear-gradient(180deg,#FFF9EC,#FFF2DA);border-color:#FFE1A6;}
.exam-card .unit-no{background:#FFF0D4;color:#A9741A;font-size:15px;}
.exam-note{
  margin:4px 0 16px;padding:12px 15px;border-radius:14px;background:#F3F7FF;
  border:1.5px solid #DCE9FF;color:var(--ink-2);font-size:13px;font-weight:700;line-height:1.75;
}
.exam-page .panel{margin-bottom:16px;}

/* 题目讲解：思路 → 分步推理 → 家长怎么讲 */
.quiz-fb .ex-idea{
  display:block;margin:6px 0 8px;padding:9px 12px;border-radius:10px;
  background:#FFF6E0;border-left:4px solid var(--lemon);color:var(--ink);font-weight:700;
}
.quiz-fb .ex-idea b{
  display:inline-block;margin-right:7px;padding:2px 8px;border-radius:999px;
  background:var(--lemon);color:#7A5600;font-size:11.5px;font-weight:800;letter-spacing:.3px;
}
.quiz-fb .ex-steps{margin:0 0 8px;padding:0 0 0 2px;list-style:none;counter-reset:ex;}
.quiz-fb .ex-steps li{
  position:relative;padding:7px 0 7px 30px;border-bottom:1px dashed var(--line-2);
  line-height:1.75;color:var(--ink-2);
}
.quiz-fb .ex-steps li:last-child{border-bottom:none;}
.quiz-fb .ex-steps li::before{
  counter-increment:ex;content:counter(ex);position:absolute;left:0;top:8px;
  width:20px;height:20px;border-radius:50%;background:var(--sky);color:#fff;
  font-size:11.5px;font-weight:800;display:grid;place-items:center;
}
.quiz-fb .ex-parent{
  display:block;margin-top:8px;padding:9px 12px;border-radius:10px;
  background:#EAF7F3;border-left:4px solid var(--mint);color:#26695C;
}
.quiz-fb .ex-parent b{
  display:inline-block;margin-right:7px;padding:2px 8px;border-radius:999px;
  background:var(--mint);color:#fff;font-size:11.5px;font-weight:800;letter-spacing:.3px;
}

.celebrate{position:absolute;inset:0;pointer-events:none;overflow:hidden;z-index:5;}
.confetti{position:absolute;width:9px;height:14px;border-radius:3px;opacity:0;animation:confetti 1.6s var(--ease) forwards;}

/* toast */
.toast{
  position:fixed;left:50%;bottom:30px;transform:translate(-50%,20px);z-index:99;
  background:var(--ink);color:#fff;padding:12px 22px;border-radius:14px;font-size:13px;font-weight:800;
  opacity:0;pointer-events:none;transition:.28s var(--spring);box-shadow:0 12px 30px rgba(0,0,0,.2);
}
.toast.show{opacity:1;transform:translate(-50%,0);}

/* footer */
.foot{margin-top:54px;padding-top:26px;border-top:2px dashed var(--line-2);text-align:center;}
.foot p{margin:0;font-size:13px;font-weight:800;color:var(--ink-2);}
.foot .tiny{margin-top:6px;font-size:11.5px;color:var(--ink-3);font-weight:600;}

/* ============================================================
   SVG 场景通用动画
   ============================================================ */
.stage-svg text{font-family:var(--font);}
/* 观察物体：立体图可拖动旋转，对应视图卡片同步高亮 */
.view3d{cursor:grab;touch-action:none;}
.view3d.dragging{cursor:grabbing;}
.view-panel{transition:filter .2s ease;}
.view-panel.on{filter:drop-shadow(0 0 8px rgba(88,166,255,.55));}
.s-pop{animation:s-pop .55s var(--spring) both;transform-box:fill-box;transform-origin:center;}
.s-fade{animation:s-fade .6s ease both;}
.s-rise{animation:s-rise .55s var(--spring) both;transform-box:fill-box;}
.s-drop{animation:s-drop .6s var(--spring) both;transform-box:fill-box;}
.s-bob{animation:s-bob 2.4s ease-in-out infinite;transform-box:fill-box;transform-origin:center;}
.s-wiggle{animation:s-wiggle 1.6s ease-in-out infinite;transform-box:fill-box;transform-origin:bottom center;}
.s-pulse{animation:s-pulse 1.6s ease-in-out infinite;transform-box:fill-box;transform-origin:center;}
.s-draw{stroke-dasharray:var(--len,320);stroke-dashoffset:var(--len,320);animation:s-draw 1.3s ease forwards;}
.s-spin{transform-box:fill-box;transform-origin:center;animation:s-spin 12s linear infinite;}
.s-slide-r{animation:s-slide-r 1s var(--spring) both;transform-box:fill-box;}
.s-slide-l{animation:s-slide-l 1s var(--spring) both;transform-box:fill-box;}
.s-grow-x{transform-box:fill-box;transform-origin:left center;animation:s-grow-x .8s var(--spring) both;}
.s-grow-up{transform-box:fill-box;transform-origin:bottom center;animation:s-grow-up .8s var(--spring) both;}
.s-blur-in{animation:s-blur-in .7s ease both;}
.s-shake{animation:shake .5s;}

/* ============================================================
   关键帧
   ============================================================ */
@keyframes s-pop{0%{opacity:0;transform:scale(.15) rotate(-14deg)}55%{opacity:1;transform:scale(1.14) rotate(5deg)}100%{opacity:1;transform:scale(1) rotate(0)}}
@keyframes s-fade{from{opacity:0}to{opacity:1}}
@keyframes s-rise{0%{opacity:0;transform:translateY(26px)}100%{opacity:1;transform:translateY(0)}}
@keyframes s-drop{0%{opacity:0;transform:translateY(-46px)}68%{opacity:1;transform:translateY(5px)}100%{transform:translateY(0)}}
@keyframes s-bob{0%,100%{transform:translateY(0)}50%{transform:translateY(-7px)}}
@keyframes s-wiggle{0%,100%{transform:rotate(-4deg)}50%{transform:rotate(4deg)}}
@keyframes s-spin{to{transform:rotate(360deg)}}
@keyframes s-pulse{0%,100%{transform:scale(1);opacity:.9}50%{transform:scale(1.07);opacity:1}}
@keyframes s-draw{to{stroke-dashoffset:0}}
@keyframes s-slide-r{0%{opacity:0;transform:translateX(-70px)}100%{opacity:1;transform:translateX(0)}}
@keyframes s-slide-l{0%{opacity:0;transform:translateX(70px)}100%{opacity:1;transform:translateX(0)}}
@keyframes s-grow-x{0%{transform:scaleX(0)}100%{transform:scaleX(1)}}
@keyframes s-grow-up{0%{transform:scaleY(0)}100%{transform:scaleY(1)}}
@keyframes s-blur-in{0%{opacity:0;filter:blur(8px)}100%{opacity:1;filter:blur(0)}}

@keyframes ui-in{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}
@keyframes float-y{0%,100%{transform:translateY(0)}50%{transform:translateY(-13px)}}
@keyframes breathe{0%,100%{transform:scale(1);opacity:.85}50%{transform:scale(1.06);opacity:1}}
@keyframes pulse-dot{0%,100%{box-shadow:0 0 0 4px #D9F6F0}50%{box-shadow:0 0 0 7px #E8FBF7}}
@keyframes twinkle{0%,100%{opacity:.25;transform:scale(.85) rotate(0)}50%{opacity:.9;transform:scale(1.1) rotate(12deg)}}
@keyframes cloud-drift{0%{transform:translateX(0)}100%{transform:translateX(140vw)}}
@keyframes bar-grow{from{transform:scaleX(0)}to{transform:scaleX(1)}}
@keyframes shake{0%,100%{transform:translateX(0)}20%{transform:translateX(-6px)}40%{transform:translateX(6px)}60%{transform:translateX(-4px)}80%{transform:translateX(4px)}}
@keyframes confetti{0%{opacity:1;transform:translate(0,0) rotate(0)}100%{opacity:0;transform:translate(var(--cx,0),var(--cy,220px)) rotate(var(--cr,540deg))}}

/* ============================================================
   响应式
   ============================================================ */
@media (max-width:1000px){
  .lesson-body{grid-template-columns:1fr;}
  .stage-card{position:static;}
  .panel{order:2;}
  .unit-grid{grid-template-columns:repeat(2,1fr);}
}
@media (max-width:860px){
  .hero{grid-template-columns:1fr;min-height:auto;padding-top:10px;gap:8px;}
  .hero-art{order:-1;min-height:320px;}
  .hero-art svg.mascot-big{width:290px;height:290px;}
  .hero-art .halo{width:260px;height:260px;}
  .hero h1{font-size:clamp(34px,8vw,48px);}
  .grade-grid{grid-template-columns:repeat(3,1fr);}
  .chip{display:none;}
}
@media (max-width:640px){
  .wrap{padding:0 14px 40px;}
  .topnav a{padding:7px 10px;font-size:13px;}
  .ver-pill{display:none;}
  .icon-btn{flex-basis:30px;width:30px;height:30px;}
  .icon-btn svg{width:14px;height:14px;}
  .brand-text em{display:none;}
  .grade-grid{grid-template-columns:repeat(2,1fr);gap:9px;}
  .grade-card{padding:13px 12px;border-radius:20px;}
  .grade-card .g-num{font-size:26px;}
  .unit-grid{grid-template-columns:1fr;}
  .hour-grid{grid-template-columns:1fr;}
  .unit-name{font-size:13.5px;}
  .unit-meta{font-size:10.5px;flex-wrap:wrap;row-gap:2px;}
  .hero-stats{gap:18px;}
  .stat b{font-size:22px;}
  .stage-card{padding:7px;border-radius:24px;}
  .stage-bar{gap:6px;padding:9px 4px 1px;}
  .stage-settings{padding:7px 4px 2px;gap:8px 10px;}
  .set-label{font-size:10.5px;}
  .segmented.mini button{padding:5px 9px;font-size:11px;}
  .pill-btn{padding:8px 10px;font-size:11.5px;}
  .play-btn{width:42px;height:42px;flex-basis:42px;border-radius:14px;}
  .panel{padding:16px;border-radius:24px;}
  .step-list{max-height:none;}
  .lesson-tags{display:none;}
}
/* ============================================================
   拓展模块：奥数启蒙 / 课后练习
   ============================================================ */
.topnav a.active{color:var(--coral-d);background:#FFEDE6;}

.module{padding:34px 0 12px;}
.module-hero{max-width:720px;}
.module-hero h1{font-size:clamp(30px,4.4vw,46px);line-height:1.24;margin:14px 0 12px;letter-spacing:-.02em;}
.module-hero h1 .hl{color:var(--coral);position:relative;display:inline-block;}
.module-hero h1 .hl::after{content:"";position:absolute;left:2px;right:2px;bottom:4px;height:10px;border-radius:6px;background:#FFE1A6;z-index:-1;}
.module-hero .sub{font-size:14.5px;line-height:1.8;color:var(--ink-2);max-width:600px;}
.module-stats{display:flex;flex-wrap:wrap;gap:22px;margin-top:18px;font-size:12.5px;color:var(--ink-3);}
.module-stats b{font-family:var(--font-num);font-size:20px;color:var(--coral-d);margin-right:4px;}
.module .subbar{margin-top:26px;}

.unit-meta .mini-tag{display:inline-block;padding:2px 8px;border-radius:8px;background:#F3EEFF;color:var(--grape-d);font-size:10.5px;font-weight:800;}

.extend{margin-top:44px;}
.extend-grid{display:grid;grid-template-columns:1fr 1fr;gap:16px;}
.extend-card{display:flex;align-items:center;gap:15px;padding:19px 20px;background:var(--paper);border:2px solid var(--line);border-radius:26px;box-shadow:var(--shadow-s);transition:transform .25s var(--spring),box-shadow .25s var(--ease),border-color .25s;}
.extend-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-m);border-color:#FFD9A8;}
.extend-card.warm{background:linear-gradient(135deg,#FFF6E9,#FFFCF2);}
.extend-emoji{font-size:30px;line-height:1;width:52px;height:52px;display:grid;place-items:center;background:#FFF3E4;border-radius:18px;flex:none;}
.extend-card.warm .extend-emoji{background:#FFE9DA;}
.extend-body{display:flex;flex-direction:column;gap:4px;flex:1;min-width:0;}
.extend-body b{font-size:16px;color:var(--ink);}
.extend-body span{font-size:12.5px;line-height:1.6;color:var(--ink-3);}
.extend-arrow{font-weight:900;color:var(--coral);font-size:18px;flex:none;}

.practice{padding-bottom:40px;}
.practice-bar{flex-wrap:wrap;gap:10px;}
.practice-note{margin:4px 0 18px;font-size:11.5px;line-height:1.7;color:var(--ink-3);}
.pq-list{display:flex;flex-direction:column;gap:16px;}
.pq{padding:18px;background:var(--paper);border:2px solid var(--line);border-radius:24px;box-shadow:var(--shadow-s);}
.pq-head{display:flex;align-items:center;gap:10px;margin-bottom:18px;}
.pq-no{font-family:var(--font-num);font-size:13px;color:var(--ink-3);}
.qtag.exam{background:#EAF3FF;color:var(--sky-d);}
.pq .quiz-q{margin-bottom:12px;font-size:14.5px;}
.pq .quiz-fb{margin-top:12px;}
.pq[hidden]{display:none;}
.qtag.level{background:#F4EDE4;color:var(--ink-2);}
.fb-link{
  display:inline-block;margin-left:8px;margin-top:4px;padding:0;border:none;background:none;
  font-family:inherit;font-size:12px;font-weight:800;color:var(--sky-d);
  text-decoration:underline;text-underline-offset:3px;
}
.pq.flash{animation:flashCard 1.6s var(--ease);}
@keyframes flashCard{
  0%,100%{border-color:var(--line);box-shadow:var(--shadow-s);}
  30%{border-color:var(--sky);box-shadow:0 0 0 4px rgba(88,166,255,.22),var(--shadow-s);}
}

/* 错题本 */
.wrong-card .pq-head{justify-content:space-between;flex-wrap:wrap;}
.wrong-meta{font-size:10.5px;font-weight:700;color:var(--ink-3);}
.wrong-actions{display:flex;flex-wrap:wrap;gap:8px;margin-top:12px;}
.wrong-actions .pill-btn{font-size:12px;padding:9px 14px;}
.wrong-card .opt:disabled{cursor:default;opacity:.72;}

/* 知识地图 */
.map-domains{display:grid;grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:16px;margin:6px 0 34px;}
.map-card{padding:18px;background:var(--paper);border:2px solid var(--line);border-radius:24px;box-shadow:var(--shadow-s);}
.map-head{display:flex;align-items:center;gap:11px;margin-bottom:12px;}
.map-emoji{width:42px;height:42px;flex:0 0 42px;border-radius:50%;background:#FFF3E4;display:grid;place-items:center;font-size:21px;}
.map-title{flex:1;min-width:0;display:flex;flex-direction:column;line-height:1.4;}
.map-title b{font-size:15px;font-weight:900;}
.map-title span{font-size:11px;color:var(--ink-3);}
.map-count{flex:none;font-size:10.5px;font-weight:800;color:var(--ink-3);background:#F6EEE3;border-radius:999px;padding:3px 9px;}
.map-chips{display:flex;flex-wrap:wrap;gap:7px;}
.map-chip{
  padding:6px 11px;border-radius:999px;background:#fff;border:1.5px solid var(--line);
  font-size:11.5px;font-weight:700;color:var(--ink-2);transition:.18s;
}
.map-chip:hover{border-color:var(--sky);color:var(--sky-d);transform:translateY(-1px);}
.map-methods{margin-top:6px;}
.method-list{display:flex;flex-direction:column;gap:8px;}
.method-row{
  display:grid;grid-template-columns:150px minmax(0,1fr) auto;align-items:center;gap:12px;
  padding:12px 15px;background:#fff;border:1.5px solid var(--line);border-radius:16px;
  transition:.18s;
}
.method-row:hover{border-color:var(--sky);box-shadow:0 6px 16px rgba(88,166,255,.12);transform:translateY(-1px);}
.method-name{font-size:13px;font-weight:900;}
.method-use{font-size:11.5px;color:var(--ink-3);}
.method-link{font-size:11.5px;font-weight:800;color:var(--sky-d);white-space:nowrap;}
.extend-card.cool{background:#FFF4EF;}
.extend-card.mint{background:#EFFBF7;}
@media (max-width:640px){
  .method-row{grid-template-columns:minmax(0,1fr) auto;row-gap:3px;padding:11px 13px;}
  .method-use{grid-column:1 / -1;font-size:11px;}
  .map-domains{grid-template-columns:1fr;}
}

@media (max-width:860px){
  .extend-grid{grid-template-columns:1fr;}
  .module-hero .sub{font-size:14px;}
}
@media (max-width:640px){
  .module{padding-top:22px;}
  .module-hero h1{font-size:29px;}
  .brand-text{white-space:nowrap;}
  .brand-text b{font-size:15px;letter-spacing:.2px;}
  .topnav{flex-wrap:nowrap;gap:1px;}
  .topnav a{white-space:nowrap;flex:none;padding:6px 6px;font-size:11.5px;}
  .segmented{flex-wrap:nowrap;overflow-x:auto;max-width:100%;scrollbar-width:none;}
  .segmented::-webkit-scrollbar{display:none;}
  .segmented button{white-space:nowrap;flex:none;padding:7px 9px;font-size:12px;}
  .module-stats{gap:14px;font-size:11.5px;}
  .module-stats b{font-size:18px;}
  .extend-card{padding:16px;border-radius:22px;gap:12px;}
  .extend-emoji{width:46px;height:46px;font-size:26px;}
  .extend-body b{font-size:14.5px;}
  .extend-body span{font-size:11.5px;}
  .pq{padding:15px;border-radius:20px;}
  .practice-bar .pill-btn{width:auto;margin-left:auto;}
  /* 手机上插图铺满屏幕宽度，字才够大；题干和选项也放大一点 */
  .q-vis{margin-left:calc(50% - 50vw);margin-right:calc(50% - 50vw);border-radius:0;border-left:none;border-right:none;}
  .q-vis-inner{padding:11px 12px 6px;}
  .q-vis-toggle{padding:10px 12px;font-size:13px;}
  .q-note{font-size:13px;}
  .quiz-q,.pq .quiz-q{font-size:16px;}
  .opt{font-size:15px;}
}

@media (max-width:420px){
  .brand-text{display:none;}
  .brand{gap:0;}
  .topbar{gap:8px;}
}

/* 320–360 的窄屏：压缩顶栏，保证清除记录按钮完整可见 */
@media (max-width:360px){
  .topbar{gap:6px;padding-left:2px;padding-right:2px;}
  .brand-mark{width:38px;height:38px;flex:0 0 38px;}
  .topnav{gap:0;min-width:0;}
  .topnav a{padding:6px 4px;font-size:11px;}
  .icon-btn.top-reset{flex-basis:28px;width:28px;height:28px;}
}

@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{animation-duration:.001s !important;animation-iteration-count:1 !important;transition-duration:.001s !important;}
}