:root{
  --bg:#f4f7fb; --card:#ffffff; --ink:#1f2937; --muted:#6b7280; --line:#e5e9f0;
  --brand:#2563eb; --brand-d:#1d4ed8; --ok:#16a34a; --ok-bg:#dcfce7; --bad:#dc2626; --bad-bg:#fee2e2;
  --warn:#d97706; --warn-bg:#fef3c7; --chinese:#c0392b; --math:#2563eb; --english:#0891b2;
  --shadow:0 1px 3px rgba(16,24,40,.08),0 6px 20px rgba(16,24,40,.06); --r:14px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{font-family:"PingFang SC","Microsoft YaHei","Segoe UI",system-ui,sans-serif;background:var(--bg);color:var(--ink);line-height:1.7;font-size:16px}
a{color:var(--brand);text-decoration:none}
button{font-family:inherit;cursor:pointer}
.hidden{display:none!important}

/* 顶栏 */
.topbar{position:sticky;top:0;z-index:50;display:flex;align-items:center;gap:14px;padding:10px 20px;background:linear-gradient(90deg,#1e3a8a,#2563eb);color:#fff;box-shadow:var(--shadow)}
.topbar .logo{font-weight:800;font-size:18px;letter-spacing:.5px;display:flex;align-items:center;gap:8px;cursor:pointer}
.topbar .logo small{font-weight:500;opacity:.8;font-size:12px}
.topbar .spacer{flex:1}
.pill{display:inline-flex;align-items:center;gap:6px;background:rgba(255,255,255,.16);padding:5px 12px;border-radius:999px;font-size:13px;font-weight:600}
.pill.gold{background:rgba(250,204,21,.25)}
.topbar .navbtn{background:rgba(255,255,255,.14);border:0;color:#fff;padding:7px 13px;border-radius:9px;font-size:14px;font-weight:600}
.topbar .navbtn:hover{background:rgba(255,255,255,.28)}

.wrap{max-width:1080px;margin:0 auto;padding:22px 20px 80px}

/* 卡片 */
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);box-shadow:var(--shadow);padding:22px;margin-bottom:18px}
.card h2{margin:.1em 0 .5em}
.grid{display:grid;gap:16px}
.grid.cols-3{grid-template-columns:repeat(3,1fr)}
.grid.cols-2{grid-template-columns:repeat(2,1fr)}
@media(max-width:820px){.grid.cols-3,.grid.cols-2{grid-template-columns:1fr}}

/* 按钮 */
.btn{background:var(--brand);color:#fff;border:0;padding:11px 20px;border-radius:10px;font-size:15px;font-weight:700;transition:.15s}
.btn:hover{background:var(--brand-d);transform:translateY(-1px)}
.btn:disabled{background:#cbd5e1;cursor:not-allowed;transform:none}
.btn.ghost{background:#eef2ff;color:var(--brand)}
.btn.ghost:hover{background:#e0e7ff}
.btn.sm{padding:7px 14px;font-size:13px}
.btn.ok{background:var(--ok)} .btn.ok:hover{background:#15803d}

/* 登录 */
.login-wrap{min-height:100vh;display:flex;align-items:center;justify-content:center;background:linear-gradient(135deg,#1e3a8a,#3b82f6 60%,#22d3ee)}
.login-card{background:#fff;border-radius:20px;box-shadow:0 20px 60px rgba(0,0,0,.25);padding:38px 34px;width:min(430px,92vw)}
.login-card h1{margin:0 0 4px;font-size:24px}
.login-card .sub{color:var(--muted);margin-bottom:22px;font-size:14px}
.field{margin-bottom:16px}
.field label{display:block;font-size:13px;font-weight:600;color:#374151;margin-bottom:6px}
.field input,.field select{width:100%;padding:12px 14px;border:1.5px solid var(--line);border-radius:10px;font-size:15px;font-family:inherit}
.field input:focus,.field select:focus{outline:none;border-color:var(--brand)}
.login-card .btn{width:100%;padding:13px}
.err{color:var(--bad);font-size:13px;margin-top:8px;min-height:18px}
.creed{margin-top:20px;padding:14px;background:#f8fafc;border-radius:12px;font-size:13px;color:#475569;border-left:4px solid var(--brand)}

/* 学科卡 */
.subject-card{position:relative;overflow:hidden;cursor:pointer;transition:.18s}
.subject-card:hover{transform:translateY(-3px);box-shadow:0 10px 28px rgba(16,24,40,.14)}
.subject-card .ico{font-size:34px}
.subject-card .name{font-size:20px;font-weight:800;margin:6px 0}
.subject-card .meta{color:var(--muted);font-size:13px}
.bar{height:8px;background:#eef2f7;border-radius:999px;overflow:hidden;margin-top:10px}
.bar > i{display:block;height:100%;background:var(--brand);border-radius:999px;transition:width .5s}

/* 课程行 */
.lesson-row{display:flex;align-items:center;gap:14px;padding:14px 16px;border:1px solid var(--line);border-radius:12px;margin-bottom:10px;background:#fff;cursor:pointer;transition:.15s}
.lesson-row:hover{border-color:var(--brand);background:#f8faff}
.lesson-row .idx{width:34px;height:34px;border-radius:50%;background:#eef2ff;color:var(--brand);display:flex;align-items:center;justify-content:center;font-weight:800;flex:0 0 auto}
.lesson-row .t{flex:1}
.lesson-row .t b{font-size:16px}
.lesson-row .t small{color:var(--muted);display:block}
.tag{display:inline-block;padding:2px 9px;border-radius:999px;font-size:12px;font-weight:700}
.tag.done{background:var(--ok-bg);color:var(--ok)} .tag.doing{background:var(--warn-bg);color:var(--warn)} .tag.todo{background:#eef2f7;color:var(--muted)}
.tag.master{background:#ede9fe;color:#7c3aed}

/* 课程内导航 */
.stepnav{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:18px}
.stepnav button{border:1.5px solid var(--line);background:#fff;color:#374151;padding:9px 15px;border-radius:999px;font-weight:700;font-size:14px}
.stepnav button.active{background:var(--brand);color:#fff;border-color:var(--brand)}
.stepnav button.done{border-color:var(--ok);color:var(--ok)}
.stepnav button.locked{opacity:.5;cursor:not-allowed}

/* AI 老师 */
.teacher{display:flex;gap:14px;align-items:flex-start;background:linear-gradient(135deg,#eff6ff,#f0fdfa);border:1px solid #dbeafe;border-radius:16px;padding:18px}
.teacher .avatar{width:52px;height:52px;border-radius:50%;background:linear-gradient(135deg,#3b82f6,#22d3ee);display:flex;align-items:center;justify-content:center;font-size:28px;flex:0 0 auto;box-shadow:0 4px 12px rgba(59,130,246,.3)}
.teacher .bubble{flex:1}
.teacher .bubble .who{font-weight:800;color:var(--brand);font-size:13px}
.teacher .bubble .txt{white-space:pre-wrap}
.keypoints{margin:12px 0 0;padding:12px 14px;background:#fffbeb;border-left:4px solid var(--warn);border-radius:8px}
.keypoints li{margin:3px 0}
.example{margin-top:10px;padding:10px 14px;background:#f1f5f9;border-radius:8px;font-size:14px}
.progress-dots{display:flex;gap:6px;margin:16px 0}
.progress-dots i{width:24px;height:6px;border-radius:99px;background:#dbe3ee}
.progress-dots i.on{background:var(--brand)}

/* 题目 */
.q{border:1px solid var(--line);border-radius:14px;padding:18px 20px;margin-bottom:16px}
.q .qhead{display:flex;gap:8px;align-items:center;margin-bottom:8px}
.q .qhead .qtype{font-size:12px;font-weight:700;color:#fff;background:var(--brand);padding:2px 8px;border-radius:6px}
.q .qhead .kp{font-size:12px;color:var(--muted)}
.q .stem{font-size:16px;font-weight:600;margin-bottom:12px}
.opts{display:flex;flex-direction:column;gap:9px}
.opt{display:flex;align-items:center;gap:10px;padding:11px 14px;border:1.5px solid var(--line);border-radius:10px;cursor:pointer;transition:.12s;background:#fff}
.opt:hover{border-color:var(--brand);background:#f8faff}
.opt.sel{border-color:var(--brand);background:#eff6ff}
.opt.correct{border-color:var(--ok);background:var(--ok-bg)}
.opt.wrong{border-color:var(--bad);background:var(--bad-bg)}
.opt .mk{width:24px;height:24px;border-radius:50%;border:2px solid #cbd5e1;display:flex;align-items:center;justify-content:center;font-weight:800;flex:0 0 auto;font-size:13px}
.opt.sel .mk{border-color:var(--brand);color:var(--brand)}
.fillbox{width:100%;padding:11px 14px;border:1.5px solid var(--line);border-radius:10px;font-size:15px;font-family:inherit}
.feedback{margin-top:12px;padding:12px 14px;border-radius:10px;font-size:14px;animation:pop .25s}
.feedback.ok{background:var(--ok-bg);color:#14532d;border-left:4px solid var(--ok)}
.feedback.bad{background:var(--bad-bg);color:#7f1d1d;border-left:4px solid var(--bad)}
.feedback .expl{margin-top:6px;color:#374151;background:rgba(255,255,255,.6);padding:8px 10px;border-radius:8px}
@keyframes pop{from{transform:scale(.96);opacity:0}to{transform:scale(1);opacity:1}}
.hintline{font-size:13px;color:var(--warn);margin-top:8px;cursor:pointer}

/* 阅读 */
.article{max-width:760px}
.article .abody{white-space:pre-wrap;font-size:16px;line-height:1.9;color:#1f2937}
.article .ameta{color:var(--muted);font-size:13px;margin-bottom:14px}
.reflect{background:#f8fafc;border-radius:10px;padding:12px 16px;margin-top:14px}

/* 视频 */
.player{background:#0f172a;border-radius:16px;overflow:hidden;color:#fff;position:relative}
.player .screen{min-height:300px;padding:34px 32px;display:flex;flex-direction:column;justify-content:center}
.player .screen h3{font-size:24px;margin:0 0 14px;color:#93c5fd}
.player .screen .narr{font-size:16px;opacity:.92;line-height:1.9}
.player .screen ul{margin-top:14px}
.player .screen li{margin:6px 0;font-size:15px}
.player .ctrl{display:flex;align-items:center;gap:12px;padding:12px 18px;background:#1e293b}
.player .ctrl .seek{flex:1;height:6px;background:#334155;border-radius:99px;overflow:hidden}
.player .ctrl .seek > i{display:block;height:100%;background:#38bdf8;width:0;transition:width .3s linear}
.player .ctrl button{background:#38bdf8;color:#04263a;border:0;width:40px;height:40px;border-radius:50%;font-size:16px;font-weight:800}

/* 分析 */
.kpi{display:flex;gap:14px;flex-wrap:wrap}
.kpi .box{flex:1;min-width:130px;background:linear-gradient(135deg,#eff6ff,#f0fdfa);border:1px solid #e0e7ff;border-radius:14px;padding:16px;text-align:center}
.kpi .box .n{font-size:30px;font-weight:900;color:var(--brand)}
.kpi .box .l{font-size:13px;color:var(--muted)}
.comment{background:linear-gradient(135deg,#fff7ed,#fef2f2);border:1px solid #fed7aa;border-radius:14px;padding:18px 20px;line-height:1.9}
.comment .who{font-weight:800;color:#b45309;margin-bottom:6px}
.hbar{display:flex;align-items:center;gap:10px;margin:7px 0}
.hbar .lab{width:120px;font-size:13px;color:#374151;text-align:right;flex:0 0 auto;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.hbar .track{flex:1;height:18px;background:#eef2f7;border-radius:99px;overflow:hidden}
.hbar .track > i{display:block;height:100%;border-radius:99px}
.hbar .val{width:44px;font-size:13px;font-weight:700;flex:0 0 auto}

/* 错题本 */
.mistake{border:1px solid var(--line);border-left:4px solid var(--bad);border-radius:10px;padding:14px 16px;margin-bottom:12px}
.mistake.resolved{border-left-color:var(--ok);opacity:.85}
.mistake .mh{display:flex;justify-content:space-between;gap:10px;font-size:13px;color:var(--muted);margin-bottom:6px}

.toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%) translateY(120px);background:#111827;color:#fff;padding:12px 22px;border-radius:12px;box-shadow:0 10px 30px rgba(0,0,0,.3);font-weight:700;z-index:100;transition:.35s;max-width:90vw;text-align:center}
.toast.show{transform:translateX(-50%) translateY(0)}
.toast.ok{background:#166534} .toast.bad{background:#991b1b}

.badge-float{position:fixed;top:70px;right:24px;background:#fff;border-radius:14px;box-shadow:var(--shadow);padding:14px 18px;border-left:5px solid #facc15;transform:translateX(140%);transition:.4s;z-index:90}
.badge-float.show{transform:translateX(0)}

/* 语音讲解条 */
.voicebar{display:flex;align-items:center;flex-wrap:wrap;gap:8px;background:#f0f9ff;border:1px solid #bae6fd;border-radius:12px;padding:8px 12px;margin-bottom:14px}
.voicebar.speaking{background:#ecfdf5;border-color:#6ee7b7}
.voicebar .vlabel{display:inline-flex;align-items:center;gap:5px;font-size:13px;color:#475569}
.voicebar input[type=range]{width:90px;vertical-align:middle}
.voicebar.muted{background:#f8fafc;border-color:var(--line);color:var(--muted);font-size:13px}
.speaking-dot{display:inline-block;width:8px;height:8px;border-radius:50%;background:#10b981;margin-right:4px;animation:pulse 1s infinite}
@keyframes pulse{0%,100%{opacity:.3}50%{opacity:1}}

/* 朗读录音记录 */
.rec-item{display:flex;align-items:center;gap:10px;flex-wrap:wrap;padding:8px 0;border-bottom:1px dashed var(--line)}
.rec-item audio{height:34px;max-width:min(360px,60vw)}
.rec-item .meta{font-size:12px;color:var(--muted)}

.empty{text-align:center;color:var(--muted);padding:40px 20px}
.breadcrumb{font-size:13px;color:var(--muted);margin-bottom:14px}
.breadcrumb a{cursor:pointer}
.loading{text-align:center;padding:50px;color:var(--muted)}
.spin{display:inline-block;width:26px;height:26px;border:3px solid #dbe3ee;border-top-color:var(--brand);border-radius:50%;animation:sp 1s linear infinite}
@keyframes sp{to{transform:rotate(360deg)}}

/* ===== 学习能力模块 ===== */
/* 成长飞轮 */
.fw-wrap{display:flex;align-items:stretch;gap:6px;flex-wrap:wrap}
.fw-stage{flex:1;min-width:170px;border:1.5px solid var(--line);border-radius:12px;padding:12px;background:#f8fafc;opacity:.75;display:flex;flex-direction:column;gap:8px}
.fw-stage.lit{border-color:#7c3aed;background:linear-gradient(135deg,#f5f3ff,#eff6ff);opacity:1}
.fw-stage.focus{box-shadow:0 0 0 3px rgba(124,58,237,.25);opacity:1}
.fw-head{display:flex;align-items:center;gap:6px;flex-wrap:wrap}
.fw-num{width:22px;height:22px;border-radius:50%;background:#7c3aed;color:#fff;font-size:12px;font-weight:800;display:inline-flex;align-items:center;justify-content:center}
.fw-head small{color:var(--muted)}
.fw-ok{margin-left:auto;font-size:11px;font-weight:800;color:#7c3aed;background:#ede9fe;padding:2px 8px;border-radius:99px}
.fw-now{margin-left:auto;font-size:11px;font-weight:800;color:#b45309;background:#fef3c7;padding:2px 8px;border-radius:99px}
.fw-ev{font-size:13px;color:#334155;flex:1}
.fw-arrow{align-self:center;color:#7c3aed;font-weight:900;font-size:18px}
@media(max-width:820px){.fw-arrow{display:none}}
/* 推送卡片 */
.feed-wrap{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:12px;margin-top:12px}
.feed-card{border:1px solid var(--line);border-radius:12px;padding:14px;background:#fff}
.feed-card b{font-size:15px}
/* 演示模态框 */
.demo-ov{position:fixed;inset:0;background:rgba(15,23,42,.55);z-index:220;display:flex;align-items:center;justify-content:center;padding:16px;overflow:auto}
.demo-card{max-width:640px;width:100%;margin:0;max-height:88vh;overflow:auto}

/* ===== 名人堂 ===== */
.master-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:12px;margin-top:10px}
.master-card{border:1px solid var(--line);border-radius:14px;padding:16px 12px;text-align:center;cursor:pointer;background:#fff;transition:.15s}
.master-card:hover{transform:translateY(-3px);box-shadow:0 8px 22px rgba(16,24,40,.12);border-color:var(--brand)}
.master-card.locked{opacity:.72;background:#f8fafc}
.master-card.locked:hover{border-color:#cbd5e1;transform:none}
.master-avatar{width:56px;height:56px;border-radius:50%;margin:0 auto 8px;display:flex;align-items:center;justify-content:center;color:#fff;font-size:24px;font-weight:800;box-shadow:0 3px 10px rgba(0,0,0,.15)}
.master-avatar.locked{background:#e2e8f0;color:#94a3b8;box-shadow:none}
.master-name{font-weight:800;font-size:16px}
.master-title{color:var(--muted);font-size:12px;margin-top:2px;min-height:16px}
.master-badge{margin-top:8px;font-size:11px;color:var(--muted);background:#f1f5f9;border-radius:99px;padding:3px 8px;display:inline-block}
.master-badge.open{color:#7c3aed;background:#ede9fe;font-weight:700}
/* 详情 */
.master-tabs{display:flex;gap:8px;margin:14px 0 10px;border-bottom:1px solid var(--line)}
.mt-btn{background:none;border:0;padding:8px 12px;font-size:14px;font-weight:700;color:var(--muted);border-bottom:2px solid transparent;margin-bottom:-1px}
.mt-btn.active{color:var(--brand);border-bottom-color:var(--brand)}
.master-bio{background:#f8fafc;border-radius:12px;padding:12px 14px;line-height:1.8}
.master-quote{border-left:4px solid #a78bfa;background:#f5f3ff;padding:8px 14px;border-radius:8px;margin:6px 0;font-style:italic;color:#5b21b6}
.master-story{background:#fffbeb;border-left:4px solid var(--warn);border-radius:8px;padding:10px 14px;line-height:1.8}
/* 问大师聊天 */
.ask-log{max-height:44vh;overflow:auto;padding:8px;background:#f8fafc;border-radius:12px;margin-bottom:10px}
.ask-msg{display:flex;gap:8px;margin:8px 0;align-items:flex-start}
.ask-msg.me{flex-direction:row-reverse}
.ask-av{width:32px;height:32px;border-radius:50%;color:#fff;font-weight:800;display:flex;align-items:center;justify-content:center;flex:0 0 auto;font-size:14px}
.ask-bubble{max-width:76%;padding:9px 13px;border-radius:12px;background:#fff;border:1px solid var(--line);line-height:1.7;white-space:pre-wrap}
.ask-msg.me .ask-bubble{background:var(--brand);color:#fff;border-color:var(--brand)}
.ask-samples{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:10px}
.ask-chip{font-size:12px;background:#eef2ff;color:var(--brand);border-radius:99px;padding:5px 11px;cursor:pointer;border:1px solid #e0e7ff}
.ask-chip:hover{background:#e0e7ff}
.ask-input{display:flex;gap:8px}
.ask-input .fillbox{flex:1}