/* ==================== 全站样式（一般不用动） ==================== */
:root{
  --brand:#e8590c;        /* 主色·活力橙 */
  --brand-dark:#d9480f;
  --brand-soft:#fff4e6;
  --ink:#26221e;          /* 正文深色 */
  --muted:#8a8178;        /* 次要文字 */
  --line:#f3e6d8;         /* 分隔线 */
  --bg:#fffdfb;
  --card:#ffffff;
  --bili:#00a1d6;         /* B站蓝 */
  --green:#2f9e44;
  --radius:14px;
  --shadow:0 2px 10px rgba(120,72,20,.08);
  --shadow-hover:0 10px 30px rgba(120,72,20,.16);
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei","Segoe UI",sans-serif;
  color:var(--ink);background:var(--bg);line-height:1.75;font-size:16px;
}
img{max-width:100%;display:block}
a{color:var(--brand);text-decoration:none}
a:hover{color:var(--brand-dark)}
.wrap{max-width:1100px;margin:0 auto;padding:0 20px}
section{padding:64px 0}
.sec-title{font-size:30px;font-weight:800;letter-spacing:.5px}
.sec-sub{color:var(--muted);margin-top:6px;font-size:15px}
.sec-head{text-align:center;margin-bottom:40px}
.sec-head .bar{width:56px;height:4px;background:var(--brand);border-radius:2px;margin:14px auto 0}

/* ---------- 导航栏 ---------- */
.nav{position:sticky;top:0;z-index:100;background:rgba(255,253,251,.92);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.nav-inner{max-width:1100px;margin:0 auto;padding:0 20px;height:60px;display:flex;align-items:center;justify-content:space-between}
.nav-logo{display:flex;align-items:center;gap:10px;font-weight:800;font-size:18px;color:var(--ink)}
.nav-logo img{height:34px;width:auto}
.nav-logo .dot{color:var(--brand)}
.nav-links{display:flex;gap:6px;list-style:none;align-items:center}
.nav-links a{display:block;padding:8px 16px;border-radius:8px;color:var(--ink);font-size:15px;font-weight:500}
.nav-links a:hover{background:var(--brand-soft);color:var(--brand)}
.nav-links a.hl{background:var(--brand);color:#fff}
.nav-links a.hl:hover{background:var(--brand-dark)}
.nav-toggle{display:none;background:none;border:0;font-size:24px;cursor:pointer;color:var(--ink)}

/* ---------- 首屏·书籍推荐 ---------- */
.hero{background:linear-gradient(160deg,#fff7ec 0%,#ffefd9 45%,#ffe3c2 100%);overflow:hidden}
.hero-inner{display:flex;gap:56px;align-items:center;padding:56px 0 64px}
.hero-cover{flex:0 0 320px;position:relative}
.hero-cover::before{content:"";position:absolute;inset:-36px;background:radial-gradient(closest-side,rgba(255,150,60,.5),transparent 72%);filter:blur(8px);z-index:0}
.hero-cover img{
  position:relative;z-index:1;width:320px;border-radius:10px;
  box-shadow:0 34px 64px rgba(120,60,0,.35),0 10px 22px rgba(120,60,0,.20);
  transition:transform .45s cubic-bezier(.16,1,.3,1),box-shadow .45s;
}
.hero-cover img:hover{transform:translateY(-8px);box-shadow:0 44px 80px rgba(120,60,0,.42),0 14px 28px rgba(120,60,0,.24)}
.hero-info{flex:1;min-width:0}
.hero-badge{display:inline-block;background:var(--brand);color:#fff;font-size:13px;font-weight:600;padding:4px 14px;border-radius:999px;letter-spacing:1px}
.hero-title{font-size:42px;font-weight:900;line-height:1.3;margin:16px 0 4px}
.hero-title em{font-style:normal;color:var(--brand)}
.hero-sub{font-size:21px;font-weight:700;color:#5c4a38}
.hero-meta{margin:18px 0;padding:14px 18px;background:rgba(255,255,255,.72);border:1px solid var(--line);border-radius:var(--radius);font-size:14.5px;color:#5c564e}
.hero-meta b{color:var(--ink)}
.hero-desc{color:#4a443d;font-size:16px}
.hero-tags{margin:16px 0 22px;display:flex;flex-wrap:wrap;gap:8px}
.hero-tags span{background:#fff;border:1px solid var(--line);color:#8a5a2b;font-size:13px;padding:3px 12px;border-radius:999px}
.btn{display:inline-block;padding:12px 28px;border-radius:10px;font-weight:700;font-size:16px;transition:all .25s;border:0;cursor:pointer}
.btn-buy{background:var(--brand);color:#fff;box-shadow:0 6px 16px rgba(232,89,12,.35)}
.btn-buy:hover{background:var(--brand-dark);transform:translateY(-2px);color:#fff}
.btn-ghost{background:#fff;color:var(--brand);border:1.5px solid var(--brand);margin-left:12px}
.btn-ghost:hover{background:var(--brand-soft)}
.buy-row{display:flex;align-items:center;flex-wrap:wrap;gap:10px;margin-top:8px}
.buy-links{font-size:14px;color:var(--muted)}
.buy-links a{margin:0 4px}

/* ---------- 详细介绍 ---------- */
.intro-block{display:flex;gap:44px;align-items:center;margin-bottom:56px}
.intro-block:last-child{margin-bottom:0}
.intro-block.rev{flex-direction:row-reverse}
.intro-block .txt{flex:1}
.intro-block .txt h3{font-size:24px;font-weight:800;margin-bottom:14px}
.intro-block .txt h3 .no{color:var(--brand);margin-right:8px}
.intro-block .txt p{color:#4a443d;margin-bottom:10px}
.intro-block .pic{flex:0 0 400px}
.intro-block .pic img{border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid var(--line)}
.intro-block ul{list-style:none;margin-top:6px}
.intro-block ul li{padding:6px 0 6px 26px;position:relative;color:#4a443d}
.intro-block ul li::before{content:"";position:absolute;left:2px;top:15px;width:10px;height:10px;border-radius:3px;background:var(--brand)}

/* 章节速览卡 */
.parts{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;margin-top:44px}
.part-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:26px 24px;box-shadow:var(--shadow);transition:all .3s}
.part-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-hover)}
.part-card .pn{font-size:13px;font-weight:700;letter-spacing:2px;color:var(--brand)}
.part-card h4{font-size:19px;font-weight:800;margin:8px 0 8px}
.part-card p{font-size:14.5px;color:var(--muted)}
.part-card .range{display:inline-block;margin-top:12px;font-size:13px;background:var(--brand-soft);color:#8a5a2b;padding:3px 12px;border-radius:999px}

/* 适合人群卡 */
.audience{display:grid;grid-template-columns:repeat(4,1fr);gap:20px;margin-top:0}
.au-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:30px 22px;text-align:center;box-shadow:var(--shadow);transition:all .3s}
.au-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-hover)}
.au-card .ico{width:76px;height:76px;margin:0 auto 16px;border-radius:50%;display:flex;align-items:center;justify-content:center}
.au-card .ico svg{width:52px;height:52px}
.au-card h4{font-size:16.5px;font-weight:800;margin-bottom:8px}
.au-card p{font-size:13.5px;color:var(--muted);text-align:justify;text-align-last:left;line-height:1.7}

/* ---------- B站教程（threejs-journey 风格课程目录） ---------- */
.bili{background:radial-gradient(1000px 500px at 50% -80px,#1b4a6b 0%,#0d1f2d 55%,#0a1822 100%);color:#fff}
.bili .sec-title{color:#fff;font-size:34px}
.bili .sec-sub{color:#8fa9bd}
.bili .bar{background:var(--bili)}
.bili-wrap{max-width:860px;margin:0 auto}
.bili-stats{display:flex;justify-content:space-between;align-items:flex-end;gap:20px;flex-wrap:wrap;margin-bottom:14px}
.progress-num{font-size:42px;font-weight:900;color:#4fc3f7;line-height:1.1}
.progress-num small{font-size:15px;color:#8fa9bd;font-weight:500;margin-left:6px}
.progress-note{font-size:14px;color:#8fa9bd}
.progress{height:8px;background:rgba(255,255,255,.1);border-radius:999px;overflow:hidden;margin-bottom:34px}
.progress i{display:block;height:100%;width:31.6%;background:linear-gradient(90deg,#00a1d6,#4fc3f7);border-radius:999px;box-shadow:0 0 12px rgba(79,195,247,.7)}
.curriculum{border:1px solid rgba(255,255,255,.12);border-radius:16px;overflow:hidden;background:rgba(255,255,255,.03)}
.lesson{display:flex;align-items:center;gap:18px;padding:15px 22px;border-bottom:1px solid rgba(255,255,255,.08);color:#dcebf5;transition:background .2s}
.lesson:last-child{border-bottom:0}
.lesson .no{flex:0 0 34px;font-family:Consolas,Menlo,monospace;font-size:14px;color:rgba(255,255,255,.38);letter-spacing:1px}
.lesson .name{flex:1;font-size:15.5px;font-weight:500;min-width:0}
.lesson .tag{flex:0 0 auto;font-size:12px;font-weight:700;padding:3px 12px;border-radius:999px;letter-spacing:1px}
.lesson .tag.ok{background:rgba(0,161,214,.22);border:1px solid rgba(79,195,247,.55);color:#7fd8ff}
.lesson .tag.wait{background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.1);color:rgba(255,255,255,.38)}
.lesson .play{flex:0 0 auto;width:32px;height:32px;border-radius:50%;background:var(--bili);color:#fff;display:flex;align-items:center;justify-content:center;font-size:12px;box-shadow:0 0 14px rgba(0,161,214,.55);transition:transform .2s}
a.lesson{text-decoration:none;color:#dcebf5}
a.lesson:hover{background:rgba(0,161,214,.13)}
a.lesson:hover .name{color:#8fdcff}
a.lesson:hover .play{transform:scale(1.12)}
.lesson.wait-row .name{color:rgba(255,255,255,.5)}
.bili-cta{display:flex;align-items:center;gap:18px;flex-wrap:wrap;margin-top:30px}
.btn-bili{display:inline-block;background:var(--bili);color:#fff;padding:13px 34px;border-radius:10px;font-weight:700;font-size:16px;box-shadow:0 6px 24px rgba(0,161,214,.45);transition:all .25s}
.btn-bili:hover{background:#23b5e8;transform:translateY(-2px);color:#fff}
.bili-foot{font-size:13.5px;color:#8fa9bd}

/* ---------- 配套资源 ---------- */
.res-grid{display:grid;grid-template-columns:1fr 1fr;gap:24px}
.res-cat{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);overflow:hidden}
.res-cat-head{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:18px 22px;background:var(--brand-soft);border-bottom:1px solid var(--line)}
.res-cat-title{display:flex;align-items:center;gap:12px}
.res-cat-head .ico{width:38px;height:38px;border-radius:10px;background:var(--brand);color:#fff;display:flex;align-items:center;justify-content:center;font-size:19px;font-weight:800}
.res-cat-head h4{font-size:17px;font-weight:800}
.res-cat-head small{display:block;color:var(--muted);font-weight:400;font-size:12.5px}
.res-more-link{font-size:14px;font-weight:700;color:var(--brand);white-space:nowrap;transition:color .2s}
.res-more-link:hover{color:var(--brand-dark);text-decoration:underline}
.res-list{list-style:none;padding:10px 14px}
.res-list li{display:flex;align-items:center;justify-content:space-between;gap:12px;padding:11px 10px;border-bottom:1px dashed var(--line);font-size:14.5px}
.res-list li:last-child{border-bottom:0}
.res-list .fname{color:var(--ink);overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.res-list .fsize{color:var(--muted);font-size:12.5px;flex:0 0 auto}
.dl-btn{flex:0 0 auto;background:var(--green);color:#fff;font-size:13px;font-weight:600;padding:5px 14px;border-radius:7px;transition:background .2s}
.dl-btn:hover{background:#26803a;color:#fff}
.dl-btn.soon{background:#c9c2ba;cursor:pointer}
.res-empty{padding:18px 24px;color:var(--muted);font-size:14px}
.res-tip{text-align:center;color:var(--muted);font-size:13.5px;margin-top:22px}

/* ---------- 知识库入口 ---------- */
.kb{background:#fff8f0}
.kb-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px}
.kb-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:32px 26px;box-shadow:var(--shadow);transition:all .3s;display:block;color:var(--ink)}
.kb-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-hover);color:var(--ink)}
.kb-card .ico{width:52px;height:52px;border-radius:14px;display:flex;align-items:center;justify-content:center;font-size:24px;margin-bottom:16px}
.kb-card h4{font-size:18px;font-weight:800;margin-bottom:8px}
.kb-card p{font-size:14px;color:var(--muted)}
.kb-card .go{margin-top:14px;font-size:14px;font-weight:700;color:var(--brand)}

/* ---------- 页脚 ---------- */
footer{background:#241f1a;color:#b9aea1;padding:44px 0 30px;font-size:14px}
.foot-inner{display:flex;justify-content:space-between;gap:30px;flex-wrap:wrap}
.foot-inner h5{color:#fff;font-size:16px;margin-bottom:12px}
.foot-inner a{color:#d8cfc4}
.foot-inner a:hover{color:#fff}
.foot-links{list-style:none}
.foot-links li{margin-bottom:8px}
.copyright{text-align:center;margin-top:34px;padding-top:20px;border-top:1px solid rgba(255,255,255,.1);font-size:13px;color:#8d8378}
.copyright a{color:#e8a87c}
.beian-line{display:flex;justify-content:center;align-items:center;gap:12px;margin-top:12px;font-size:12px;color:#8d8378;flex-wrap:wrap}
.beian-line a{color:#8d8378;display:inline-flex;align-items:center;transition:color .2s}
.beian-line a:hover{color:#fff}
.beian-line img{width:14px;height:14px;margin-right:4px}
.beian-line .beian-sep{color:#5c5548}

/* ---------- 返回顶部 ---------- */
.to-top{position:fixed;right:26px;bottom:26px;width:46px;height:46px;border-radius:50%;background:var(--brand);color:#fff;border:0;font-size:20px;cursor:pointer;box-shadow:0 6px 18px rgba(232,89,12,.4);opacity:0;pointer-events:none;transition:opacity .3s;z-index:99}
.to-top.show{opacity:1;pointer-events:auto}

/* ---------- 弹窗（待上传提示） ---------- */
.modal-mask{position:fixed;inset:0;background:rgba(30,20,10,.5);display:none;align-items:center;justify-content:center;z-index:200}
.modal-mask.show{display:flex}
.modal{background:#fff;border-radius:16px;padding:34px 38px;max-width:380px;text-align:center;box-shadow:0 20px 60px rgba(0,0,0,.3)}
.modal h4{font-size:19px;margin-bottom:10px}
.modal p{color:var(--muted);font-size:14.5px;margin-bottom:20px}

/* ---------- 响应式 ---------- */
@media (max-width:900px){
  .hero-inner{flex-direction:column;text-align:center;gap:36px}
  .hero-tags,.buy-row{justify-content:center}
  .intro-block,.intro-block.rev{flex-direction:column;gap:24px}
  .intro-block .pic{flex:none;width:100%}
  .parts,.kb-grid{grid-template-columns:1fr}
  .res-grid{grid-template-columns:1fr}
  .audience{grid-template-columns:repeat(2,1fr)}
  .hero-title{font-size:32px}
  .nav-links{display:none;position:absolute;top:60px;left:0;right:0;background:#fff;flex-direction:column;padding:12px;border-bottom:1px solid var(--line);box-shadow:var(--shadow-hover)}
  .nav-links.open{display:flex}
  .nav-toggle{display:block}
}

/* ---------- 读者反馈 ---------- */
.reviews{background:#fff8f0}
.review-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:22px}
.review-card{position:relative;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:30px 28px 24px;box-shadow:var(--shadow);transition:all .3s;overflow:hidden}
.review-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-hover)}
.review-card .quote{position:absolute;top:6px;right:16px;font-family:Georgia,serif;font-size:66px;line-height:1;color:var(--brand);opacity:.15}
.review-card blockquote{position:relative;font-size:15.5px;line-height:1.85;color:#3d3831;margin:0 0 18px;font-weight:500}
.review-card figcaption{display:flex;flex-direction:column;gap:6px;border-top:1px dashed var(--line);padding-top:14px}
.src-badge{display:inline-block;align-self:flex-start;font-size:12px;font-weight:700;padding:3px 12px;border-radius:999px;letter-spacing:.5px}
.src-badge.zhihu{background:#e1ecf4;color:#175199}
.src-badge.csdn{background:#e8f3e8;color:#2f9e44}
.src-badge.sohu{background:#fde8e8;color:#d9480f}
.src-badge.pub{background:var(--brand-soft);color:#8a5a2b}
.src-text{font-size:13px;color:var(--muted);text-decoration:none}
.src-text:hover{color:var(--brand);text-decoration:underline}

/* ---------- 联系我们 ---------- */
.contact{background:#fffdfb}
.contact-inner{display:grid;grid-template-columns:1.4fr 1fr;gap:48px;align-items:center;padding:8px 0}
.contact .bar{margin:14px 0 18px}
.contact-desc{color:#4a443d;font-size:15.5px;margin-bottom:22px}
.contact-list{list-style:none}
.contact-list li{display:flex;align-items:center;gap:10px;padding:9px 0;font-size:15.5px;color:#3d3831}
.contact-list a{color:var(--brand);font-weight:600}
.contact-list b{color:var(--ink)}
.ci-ico{width:30px;height:30px;border-radius:8px;background:var(--brand-soft);color:var(--brand);display:inline-flex;align-items:center;justify-content:center;font-size:15px;flex:0 0 auto}
.contact-qr{background:#fff;border:1px solid var(--line);border-radius:18px;padding:26px;text-align:center;box-shadow:var(--shadow)}
.contact-qr img{width:200px;height:200px;margin:0 auto;border-radius:10px}
.contact-qr p{margin-top:14px;font-size:13.5px;color:var(--muted)}

@media (max-width:900px){
  .review-grid{grid-template-columns:1fr}
  .contact-inner{grid-template-columns:1fr;gap:28px}
}

/* ---------- 资源下载中心（download.htm） ---------- */
.dl-hero{background:linear-gradient(135deg,#fff4e6 0%,#fffdfb 70%);padding:54px 0 44px;text-align:center;border-bottom:1px solid var(--line)}
.dl-hero h1{font-size:34px;font-weight:800;letter-spacing:.5px;color:var(--ink)}
.dl-hero p{color:var(--muted);font-size:15.5px;max-width:640px;margin:14px auto 0;line-height:1.8}
.dl-stats{display:flex;justify-content:center;gap:14px;margin-top:24px;flex-wrap:wrap}
.dl-stats span{background:#fff;border:1px solid var(--line);border-radius:999px;padding:8px 20px;font-size:14px;color:#5c554c;box-shadow:var(--shadow)}
.dl-stats b{color:var(--brand);font-size:17px;margin-right:3px}
.dl-src{padding:50px 0 20px;background:var(--bg)}
.dl-src .sec-head{text-align:center;margin-bottom:30px}
.dl-src .sec-head .bar{width:56px;height:4px;background:var(--brand);border-radius:2px;margin:14px auto 0}
.part-title{font-size:18px;font-weight:800;color:var(--ink);margin:30px 0 12px;padding-left:14px;border-left:4px solid var(--brand)}
.res-list.wide{display:grid;grid-template-columns:1fr 1fr;gap:0 30px}
.res-list.wide li{border-bottom:1px dashed var(--line)}
.dl-others{padding:30px 0 56px;background:var(--bg)}
.res-grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.res-back{text-align:center;margin-top:24px;font-size:14px}
.res-back a{color:var(--brand);font-weight:600}
.res-back a:hover{text-decoration:underline}

@media (max-width:900px){
  .res-grid3{grid-template-columns:1fr}
  .res-list.wide{grid-template-columns:1fr}
}