/* 于鸿瑞 · 高中数学 */
:root{
  --ink:#1f2933; --muted:#6b7785; --line:#e3ded1; --bg:#f7f5ee; --card:#fffdf8;
  --brand:#1c4e80; --brand-2:#2f6db0; --brand-soft:#e8f0f9; --accent:#c0533f; --gold:#d9a441;
  --radius:16px; --shadow:0 8px 24px rgba(31,41,51,.08);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);
  font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei","Segoe UI",sans-serif;
  line-height:1.75;-webkit-font-smoothing:antialiased}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
.wrap{max-width:1080px;margin:0 auto;padding:0 20px}
/* 顶栏 */
.topbar{position:sticky;top:0;z-index:50;background:rgba(247,245,238,.92);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.tb-inner{max-width:1080px;margin:0 auto;padding:10px 20px;display:flex;align-items:center;justify-content:space-between;gap:14px;flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:10px;color:inherit;text-decoration:none}
.logo{width:42px;height:42px;border-radius:12px;background:linear-gradient(135deg,#1c4e80,#2f6db0);color:#fff;display:flex;align-items:center;justify-content:center;font-size:24px;font-weight:700;box-shadow:0 6px 14px rgba(28,78,128,.25)}
.brand-txt{display:flex;flex-direction:column;line-height:1.2}
.brand-txt b{font-size:16px}
.brand-txt small{font-size:11.5px;color:var(--muted)}
.topnav{display:flex;gap:6px;flex-wrap:wrap}
.topnav a{padding:7px 12px;border-radius:999px;color:var(--ink);font-size:13.5px;font-weight:600}
.topnav a:hover{background:#fff;text-decoration:none}
.topnav a.on{background:var(--brand);color:#fff}
/* 首页 hero */
.hero{display:grid;grid-template-columns:1.5fr 1fr;gap:22px;align-items:center;margin:26px 0 10px;
  background:linear-gradient(120deg,#eef3ea 0%,#f8f4e8 60%,#f3eee2 100%);
  border:1px solid var(--line);border-radius:26px;padding:30px 30px;box-shadow:var(--shadow);position:relative;overflow:hidden}
.hero:before{content:"";position:absolute;right:-40px;top:-40px;width:180px;height:180px;border-radius:50%;background:rgba(47,109,176,.08)}
.eyebrow{display:inline-block;background:#fff;border:1px solid var(--line);border-radius:999px;padding:4px 12px;font-size:12px;color:var(--muted);margin-bottom:10px}
.hero h1{font-size:32px;margin:6px 0 10px;line-height:1.3}
.hero p{margin:0 0 18px;color:#3c4854;font-size:14.5px;max-width:56ch}
.hero-btns{display:flex;gap:10px;flex-wrap:wrap}
.hero-side{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.stat{background:#fff;border:1px solid var(--line);border-radius:16px;padding:12px 14px;text-align:center}
.stat b{display:block;font-size:24px;color:var(--brand)}
.stat span{font-size:12px;color:var(--muted)}
@media(max-width:820px){.hero{grid-template-columns:1fr;padding:22px}.hero h1{font-size:25px}}
/* 按钮 */
.btn{display:inline-block;border:1px solid var(--line);background:#fff;color:var(--ink);
  border-radius:12px;padding:10px 18px;font-size:14px;font-weight:700;cursor:pointer;text-decoration:none;font-family:inherit}
.btn:hover{border-color:var(--brand);text-decoration:none}
.btn.primary{background:linear-gradient(135deg,var(--brand),var(--brand-2));border-color:transparent;color:#fff;box-shadow:0 8px 18px rgba(28,78,128,.22)}
.btn.primary:hover{filter:brightness(1.06)}
/* 模块目录 */
.catalog{margin-top:22px}
.mod-head{display:flex;justify-content:space-between;align-items:flex-end;margin:26px 0 12px;padding-bottom:8px;border-bottom:2px solid var(--line)}
.mod-head h2{font-size:20px;margin:0}
.mod-grade{font-size:12.5px;color:var(--muted)}
.ch-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:12px}
.ch-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:15px 16px;color:inherit;display:block;transition:.18s;box-shadow:0 2px 8px rgba(31,41,51,.04)}
.ch-card:hover{transform:translateY(-3px);border-color:var(--brand);box-shadow:var(--shadow);text-decoration:none}
.ch-card.done{border-color:#b9d8b9;background:linear-gradient(180deg,#f4fbf4,#fffdf8)}
.ch-top{display:flex;justify-content:space-between;align-items:center;margin-bottom:6px}
.ch-num{font-size:13px;font-weight:800;color:var(--brand);background:var(--brand-soft);border-radius:8px;padding:2px 8px}
.ch-done{font-size:11px;color:var(--muted);border:1px solid var(--line);border-radius:999px;padding:1px 8px}
.ch-card.done .ch-done{color:#2c7a4b;border-color:#b9d8b9;background:#e9f7ec}
.ch-card h3{font-size:16px;margin:4px 0 3px;line-height:1.4}
.ch-tag{font-size:12px;color:var(--muted);margin:0 0 8px}
.ch-meta{display:flex;gap:12px;font-size:11.5px;color:var(--muted)}
/* 公式 */
.hot-formulas,.road{margin-top:30px}
.formula-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:10px}
.f-card{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:12px 14px;color:inherit}
.f-ch{font-size:11px;color:var(--brand);font-weight:700;margin-bottom:4px}
.f-name{font-size:13px;font-weight:800;color:#3b2f1e;margin-bottom:4px}
.f-expr{font-size:14.5px;font-family:"Cambria Math","Times New Roman",serif;line-height:1.65;word-break:break-word}
.f-note{font-size:11.5px;color:var(--muted);margin-top:5px;border-top:1px dashed var(--line);padding-top:5px}
.more{font-size:13.5px;font-weight:700}
/* 学习路线 */
.road-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:12px;margin-top:12px}
.road-card{background:#fff;border:1px solid var(--line);border-radius:14px;padding:14px 16px}
.road-card b{display:inline-block;background:var(--brand-soft);color:var(--brand);border-radius:8px;padding:2px 10px;font-size:12.5px;margin-bottom:6px}
.road-card p{margin:0;font-size:13px;color:#3c4854}
.guide-strip{display:flex;justify-content:space-between;align-items:center;gap:18px;flex-wrap:wrap;
  background:#fff;border:1px solid var(--line);border-radius:18px;padding:18px 22px;margin:30px 0 10px}
.guide-strip h3{margin:0 0 4px;font-size:16px}
.guide-strip p{margin:0;font-size:13px;color:var(--muted);max-width:62ch}
/* 章节页 */
.crumb{font-size:12.5px;color:var(--muted);margin:20px 0 8px}
.chapter{background:var(--card);border:1px solid var(--line);border-radius:22px;padding:24px 26px;box-shadow:var(--shadow);margin-bottom:18px}
.ch-head{display:flex;justify-content:space-between;align-items:flex-start;gap:14px;flex-wrap:wrap;border-bottom:1px solid var(--line);padding-bottom:14px;margin-bottom:8px}
.ch-badge{display:inline-block;background:var(--brand);color:#fff;border-radius:999px;padding:2px 12px;font-size:12px}
.ch-head h1{font-size:26px;margin:8px 0 2px}
.ch-sub{margin:0;color:var(--muted);font-size:13.5px}
.done-btn{background:#fff;border:1px solid var(--line);border-radius:12px;padding:9px 16px;font-weight:700;cursor:pointer;font-family:inherit;font-size:13.5px}
.done-btn.on{background:#e9f7ec;border-color:#8fca9a;color:#2c7a4b}
.block{margin:22px 0}
.block h2{font-size:17px;margin:0 0 10px;padding-left:10px;border-left:4px solid var(--brand)}
.points{margin:0;padding-left:20px}
.points li{margin:6px 0;font-size:14px}
.traps{margin:0;padding-left:20px}
.traps li{margin:6px 0;font-size:13.5px;color:#8a4b3a}
.example{background:#fff;border:1px solid var(--line);border-radius:14px;padding:14px 16px;margin:10px 0}
.ex-q b{color:var(--brand)}
.ex-q p{margin:4px 0 8px;font-size:14.5px}
.example details summary{cursor:pointer;font-size:13.5px;color:var(--brand);font-weight:700}
.example details ol{margin:10px 0 4px;padding-left:20px;font-size:13.5px}
.ex-a{margin:6px 0 0;font-size:14px;color:#2c7a4b}
/* 自测 */
.quizbox{background:#fbfaf4;border:1px dashed #d8d0bc;border-radius:18px;padding:18px 20px}
.quiz-q{margin:14px 0 18px}
.qq{margin:0 0 8px;font-weight:700;font-size:14.5px}
.opts{display:grid;gap:7px}
.opts label{display:flex;gap:9px;align-items:flex-start;background:#fff;border:1px solid var(--line);border-radius:10px;padding:9px 12px;font-size:14px;cursor:pointer}
.opts label:hover{border-color:var(--brand)}
.opts input{margin-top:5px;accent-color:var(--brand)}
.opts label.right{border-color:#5fa86f;background:#eef8f0}
.opts label.wrong{border-color:#d07a6a;background:#fcf0ee}
.q-fb{font-size:13px;margin-top:6px;color:var(--muted)}
.q-fb.ok{color:#2c7a4b}
.q-fb.no{color:#a54a3c}
.quiz-actions{display:flex;gap:14px;align-items:center;flex-wrap:wrap;margin-top:6px}
.quiz-score{font-size:14px;font-weight:800;color:var(--brand)}
.chapter-nav{display:flex;justify-content:space-between;gap:10px;margin:8px 0 30px;flex-wrap:wrap}
/* 公式页 */
.page-title{font-size:27px;margin:26px 0 6px}
.page-lead{color:var(--muted);font-size:14px;margin:0 0 16px;max-width:70ch}
.search-row{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin:14px 0 6px;position:sticky;top:64px;background:var(--bg);padding:8px 0;z-index:10}
.search-row input{flex:1;min-width:220px;padding:11px 14px;border:1px solid var(--line);border-radius:12px;font:inherit;font-size:14.5px;background:#fff}
.search-row input:focus{outline:2px solid var(--brand-soft);border-color:var(--brand)}
#formulaCount{font-size:12.5px;color:var(--muted)}
.f-chapter{margin:14px 0 18px}
.f-chapter h3{font-size:15px;margin:0 0 8px}
.f-chapter h3 a{color:var(--ink)}
.f-chapter.hide,.f-card.hide{display:none}
.hint{font-size:12.5px;color:var(--muted)}
.notfound{text-align:center;padding:70px 10px}
.notfound h1{font-size:64px;margin:0;color:var(--brand)}
/* 页脚 */
.foot{border-top:1px solid var(--line);margin-top:36px;padding:20px 0 40px;font-size:12.5px;color:var(--muted)}
.foot .wrap{max-width:1080px}
@media print{
  .topbar,.foot,.done-btn,.chapter-nav,.quiz-actions,.hero-btns,.search-row,.guide-strip{display:none!important}
  body{background:#fff}
  .chapter,.f-card,.block{box-shadow:none;border:1px solid #ddd}
}


/* 高二优化 */
.hero-note{font-size:13px;color:#7a6a4f;margin:-6px 0 16px}
.mod-badge{font-size:12px;font-weight:800;color:#b05a2a;background:#fdf0e4;border:1px solid #f2d3b3;border-radius:999px;padding:3px 12px;white-space:nowrap}
.daily{margin:30px 0 10px;background:linear-gradient(135deg,#eef6f0,#fdf8ec);border:1px solid var(--line);border-radius:20px;padding:20px 22px;box-shadow:var(--shadow)}
.daily h2{margin:0 0 6px;font-size:19px}
.daily .dq-ch{font-size:12px;color:var(--muted);margin-bottom:8px}
.daily .dq-q{font-size:15.5px;font-weight:700;margin:0 0 12px}
.dq-opts{display:grid;gap:8px;max-width:640px}
.dq-opts button{text-align:left;border:1px solid var(--line);background:#fff;border-radius:12px;padding:11px 14px;font:inherit;font-size:14.5px;cursor:pointer}
.dq-opts button:hover{border-color:var(--brand)}
.dq-opts button.right{border-color:#5fa86f;background:#eef8f0}
.dq-opts button.wrong{border-color:#d07a6a;background:#fcf0ee}
.dq-fb{margin:10px 0 6px;font-size:13.5px;line-height:1.7;min-height:20px}
.dq-fb.ok{color:#2c7a4b}.dq-fb.no{color:#a54a3c}
.dq-actions{margin-top:8px}


/* 高考标准型数学排版 */
.f-expr,.mfrac,.mrad{font-family:"Cambria Math","Times New Roman",Georgia,serif}
.f-expr{font-size:15.5px;line-height:2}
.mfrac{display:inline-flex;flex-direction:column;align-items:center;justify-content:center;vertical-align:middle;text-align:center;margin:0 .18em;font-size:.94em;line-height:1.15;position:relative;top:-.05em}
.mfrac>.num{display:block;padding:0 .28em .08em;border-bottom:1.2px solid currentColor;white-space:nowrap}
.mfrac>.den{display:block;padding:.08em .28em 0;white-space:nowrap}
.mrad{display:inline-block;border-top:1.4px solid currentColor;padding:0 .12em 0 .04em;margin-left:-.02em;line-height:1.25;vertical-align:baseline}
.f-expr .mfrac{top:-.02em}