:root{
  --bg:#070912;
  --panel:rgba(19,24,44,.72);
  --line:rgba(255,255,255,.08);
  --line-strong:rgba(255,255,255,.16);
  --text:#eef1ff;
  --muted:#8b93b8;
  --cyan:#22d3ee;
  --violet:#a855f7;
  --amber:#fbbf24;
  --pink:#f472b6;
  --radius:16px;
}
*,*::before,*::after{box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  margin:0;
  background:var(--bg);
  color:var(--text);
  font-family:"PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;
  -webkit-font-smoothing:antialiased;
  min-height:100vh;
  line-height:1.6;
  overflow-x:hidden;
}
body::before{
  content:"";
  position:fixed;inset:0;
  background:
    radial-gradient(900px 620px at 12% -12%, rgba(34,211,238,.16), transparent 62%),
    radial-gradient(820px 620px at 92% -4%, rgba(168,85,247,.18), transparent 62%),
    radial-gradient(900px 700px at 50% 110%, rgba(59,130,246,.10), transparent 65%);
  pointer-events:none;
  z-index:0;
}
img,svg{display:block;}
a{color:inherit;text-decoration:none;}
button{font-family:inherit;color:inherit;border:none;background:none;cursor:pointer;}
h1,h2,h3,h4,p{margin:0;}
.wrap{max-width:1260px;margin:0 auto;padding:0 20px;position:relative;z-index:1;}

/* ============ 导航 ============ */
.nav{
  position:sticky;top:0;z-index:50;
  backdrop-filter:blur(18px);
  -webkit-backdrop-filter:blur(18px);
  background:rgba(7,9,18,.78);
  border-bottom:1px solid var(--line);
}
.nav-inner{display:flex;align-items:center;gap:28px;height:64px;}
.logo{display:flex;align-items:center;gap:10px;flex-shrink:0;}
.logo img{height:32px;width:auto;display:block;}
.nav-links{display:flex;gap:4px;margin-left:8px;}
.nav-links a{
  padding:8px 14px;border-radius:999px;font-size:14px;color:var(--muted);
  transition:.2s;cursor:pointer;user-select:none;
}
.nav-links a:hover{color:var(--text);background:rgba(255,255,255,.05);}
.nav-links a.active{
  color:var(--text);background:rgba(34,211,238,.12);
  box-shadow:inset 0 0 0 1px rgba(34,211,238,.28);
}
.nav-actions{margin-left:auto;display:flex;align-items:center;gap:10px;}
.icon-btn{
  width:36px;height:36px;border-radius:50%;
  display:grid;place-items:center;color:var(--muted);
  transition:.2s;
}
.icon-btn:hover{color:var(--text);background:rgba(255,255,255,.07);}
.btn-ghost{
  padding:8px 16px;border-radius:999px;font-size:14px;color:var(--muted);
  border:1px solid var(--line-strong);transition:.2s;
}
.btn-ghost:hover{color:var(--text);border-color:rgba(255,255,255,.3);}
.btn-primary{
  padding:8px 18px;border-radius:999px;font-size:14px;font-weight:600;
  background:linear-gradient(135deg,var(--cyan),var(--violet));
  color:#fff;transition:.25s;
  box-shadow:0 6px 20px rgba(124,58,237,.32);
}
.btn-primary:hover{transform:translateY(-1px);box-shadow:0 10px 26px rgba(124,58,237,.45);}

/* ============ 布局 ============ */
.layout{
  display:grid;
  grid-template-columns:minmax(0,1fr) 348px;
  gap:32px;
  padding:26px 0 72px;
}

/* ============ 播放器 ============ */
.player{
  position:relative;
  border-radius:var(--radius);
  overflow:hidden;
  background:#04060f;
  border:1px solid var(--line);
  box-shadow:0 24px 60px -20px rgba(0,0,0,.9), 0 0 0 1px rgba(255,255,255,.02) inset;
  scroll-margin-top:84px;
}
.stage{
  position:relative;
  aspect-ratio:16/9;
  overflow:hidden;
  background:radial-gradient(circle at 50% 50%, #10142c 0%, #05070f 70%);
}
.stars{
  position:absolute;inset:0;
  background-image:
    radial-gradient(1.6px 1.6px at 8% 18%, #fff, transparent),
    radial-gradient(1.2px 1.2px at 22% 62%, #cfe4ff, transparent),
    radial-gradient(1.8px 1.8px at 35% 12%, #fff, transparent),
    radial-gradient(1.2px 1.2px at 48% 78%, #b9d4ff, transparent),
    radial-gradient(1.5px 1.5px at 62% 28%, #fff, transparent),
    radial-gradient(1.2px 1.2px at 74% 66%, #d5e6ff, transparent),
    radial-gradient(1.7px 1.7px at 86% 22%, #fff, transparent),
    radial-gradient(1.3px 1.3px at 92% 74%, #c6dcff, transparent),
    radial-gradient(1.4px 1.4px at 15% 88%, #fff, transparent),
    radial-gradient(1.1px 1.1px at 55% 45%, #9fb8e6, transparent);
  opacity:.65;
  animation:twinkle 5s ease-in-out infinite;
}
@keyframes twinkle{0%,100%{opacity:.5}50%{opacity:.9}}
.nebula{
  position:absolute;inset:0;
  background:
    radial-gradient(420px 260px at 26% 22%, rgba(99,102,241,.22), transparent 70%),
    radial-gradient(380px 240px at 78% 72%, rgba(168,85,247,.2), transparent 70%);
  filter:blur(6px);
}
.bh-scene{
  position:absolute;inset:0;
  display:grid;place-items:center;
  perspective:1000px;
}
.disk{
  position:absolute;
  width:min(64%,430px);aspect-ratio:1;border-radius:50%;
  background:conic-gradient(from 90deg,
    rgba(34,211,238,0) 0deg,
    rgba(34,211,238,.85) 55deg,
    rgba(129,140,248,.9) 120deg,
    rgba(168,85,247,.95) 185deg,
    rgba(251,191,36,.95) 250deg,
    rgba(244,114,182,.75) 305deg,
    rgba(34,211,238,0) 360deg);
  filter:blur(13px);
  -webkit-mask:radial-gradient(circle, transparent 23%, #000 31%, #000 70%, transparent 80%);
  mask:radial-gradient(circle, transparent 23%, #000 31%, #000 70%, transparent 80%);
  transform:rotateX(74deg);
  animation:disk-spin 7s linear infinite;
  animation-play-state:paused;
  opacity:.95;
}
@keyframes disk-spin{
  from{transform:rotateX(74deg) rotate(0deg);}
  to{transform:rotateX(74deg) rotate(360deg);}
}
.horizon{
  position:absolute;
  width:min(30%,186px);aspect-ratio:1;border-radius:50%;
  background:#000;
  z-index:2;
  box-shadow:
    0 0 0 1.5px rgba(255,255,255,.07),
    0 0 70px 14px rgba(168,85,247,.4),
    0 0 24px 4px rgba(34,211,238,.28),
    inset 0 0 30px rgba(0,0,0,1);
}
.photon{
  position:absolute;
  width:min(34%,212px);aspect-ratio:1;border-radius:50%;
  border:2px solid rgba(255,214,150,.75);
  filter:blur(1.4px);
  z-index:3;
  box-shadow:
    0 0 34px rgba(251,191,36,.55),
    inset 0 0 26px rgba(251,191,36,.4);
  animation:photon-pulse 3.6s ease-in-out infinite;
  animation-play-state:paused;
}
@keyframes photon-pulse{
  0%,100%{opacity:.75;transform:scale(1);}
  50%{opacity:1;transform:scale(1.035);}
}
.bh-glow{
  position:absolute;
  width:min(52%,340px);aspect-ratio:1;border-radius:50%;
  background:radial-gradient(circle, rgba(168,85,247,.22), transparent 68%);
  filter:blur(20px);
  z-index:1;
}
.player.playing .disk,
.player.playing .photon{animation-play-state:running;}
.player.playing .bh-scene{animation:zoom-in .8s ease forwards;}
@keyframes zoom-in{from{transform:scale(1)}to{transform:scale(1.04)}}

.stage-caption{
  position:absolute;left:0;right:0;top:0;
  padding:clamp(20px,4vw,38px);
  z-index:6;
  transition:opacity .5s ease, transform .5s ease;
  pointer-events:none;
}
.stage-caption .chip{
  display:inline-block;
  font-size:11px;letter-spacing:1.4px;text-transform:uppercase;
  color:var(--cyan);
  padding:5px 12px;border-radius:999px;
  background:rgba(34,211,238,.1);
  border:1px solid rgba(34,211,238,.3);
  margin-bottom:14px;
}
.stage-caption h2{
  font-size:clamp(20px,3.2vw,34px);
  font-weight:800;letter-spacing:.5px;
  text-shadow:0 4px 24px rgba(0,0,0,.8);
  line-height:1.25;
}
.stage-caption p{
  margin-top:8px;font-size:clamp(12px,1.5vw,14px);
  color:rgba(220,228,255,.7);
  text-shadow:0 2px 12px rgba(0,0,0,.8);
}
.player.playing .stage-caption{opacity:0;transform:translateY(-12px);}

.big-play{
  position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);
  width:74px;height:74px;border-radius:50%;
  display:grid;place-items:center;
  background:rgba(255,255,255,.1);
  backdrop-filter:blur(10px);
  -webkit-backdrop-filter:blur(10px);
  border:1px solid rgba(255,255,255,.28);
  color:#fff;
  z-index:7;
  transition:.3s cubic-bezier(.34,1.56,.64,1);
  box-shadow:0 0 0 0 rgba(34,211,238,.5);
}
.big-play::before{
  content:"";position:absolute;inset:-10px;border-radius:50%;
  border:1px solid rgba(34,211,238,.4);
  animation:ripple 2.4s ease-out infinite;
}
@keyframes ripple{
  0%{transform:scale(.9);opacity:.9}
  100%{transform:scale(1.5);opacity:0}
}
.big-play:hover{transform:translate(-50%,-50%) scale(1.08);background:rgba(34,211,238,.22);}
.big-play svg{width:28px;height:28px;margin-left:4px;}
.player.playing .big-play{opacity:0;pointer-events:none;transform:translate(-50%,-50%) scale(.7);}

.stage-hint{
  position:absolute;left:50%;bottom:16px;transform:translateX(-50%);
  font-size:11.5px;color:rgba(200,212,255,.45);
  letter-spacing:.6px;z-index:6;
  transition:opacity .4s;
  white-space:nowrap;
}
.player.playing .stage-hint{opacity:0;}

.subtitle{
  position:absolute;left:50%;bottom:52px;transform:translateX(-50%);
  max-width:82%;
  padding:9px 18px;border-radius:10px;
  background:rgba(6,9,20,.72);
  backdrop-filter:blur(8px);
  -webkit-backdrop-filter:blur(8px);
  border:1px solid rgba(255,255,255,.1);
  font-size:clamp(12px,1.7vw,15px);
  color:#e8eeff;text-align:center;
  z-index:6;
  opacity:0;transition:opacity .35s;
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis;
  max-width:86%;
}
.player.playing .subtitle{opacity:1;}

.controls{
  display:flex;align-items:center;gap:14px;
  padding:12px 18px;
  background:linear-gradient(180deg,rgba(10,14,28,.96),rgba(8,11,22,.99));
  border-top:1px solid var(--line);
}
.ctrl{
  width:34px;height:34px;border-radius:9px;
  display:grid;place-items:center;color:#c3ccea;
  transition:.18s;flex-shrink:0;
}
.ctrl:hover{color:#fff;background:rgba(255,255,255,.09);}
.ctrl svg{width:19px;height:19px;}
.time{
  font-size:12.5px;color:var(--muted);
  font-variant-numeric:tabular-nums;
  flex-shrink:0;letter-spacing:.4px;
}
.track{
  position:relative;flex:1;height:5px;border-radius:99px;
  background:rgba(255,255,255,.1);
  cursor:pointer;transition:height .18s;
}
.track:hover{height:8px;}
.track-fill{
  position:absolute;left:0;top:0;bottom:0;width:0;
  border-radius:99px;
  background:linear-gradient(90deg,var(--cyan),var(--violet));
  box-shadow:0 0 12px rgba(34,211,238,.6);
}
.track-dot{
  position:absolute;top:50%;left:0;
  width:13px;height:13px;border-radius:50%;
  background:#fff;transform:translate(-50%,-50%) scale(0);
  transition:transform .18s;
  box-shadow:0 0 10px rgba(255,255,255,.8);
}
.track:hover .track-dot{transform:translate(-50%,-50%) scale(1);}

/* ============ 主栏内容 ============ */
.title-block{margin-top:24px;}
.title-block h1{
  font-size:clamp(21px,2.7vw,30px);
  font-weight:800;line-height:1.32;letter-spacing:.3px;
}
.meta-row{
  display:flex;align-items:center;gap:16px;
  margin-top:18px;flex-wrap:wrap;
}
.author{display:flex;align-items:center;gap:11px;}
.avatar{
  width:42px;height:42px;border-radius:50%;
  display:grid;place-items:center;
  font-weight:700;font-size:15px;color:#050912;
  background:linear-gradient(135deg,#22d3ee,#a855f7);
  flex-shrink:0;
  box-shadow:0 0 0 2px rgba(255,255,255,.06);
}
.author-info strong{display:block;font-size:14.5px;font-weight:600;}
.author-info span{font-size:12px;color:var(--muted);}
.follow-btn{
  padding:6px 16px;border-radius:999px;font-size:13px;font-weight:600;
  background:linear-gradient(135deg,var(--cyan),var(--violet));
  color:#fff;margin-left:6px;transition:.22s;
}
.follow-btn:hover{transform:translateY(-1px);}
.follow-btn.following{
  background:transparent;color:var(--muted);
  box-shadow:inset 0 0 0 1px var(--line-strong);
}
.meta-stats{
  display:flex;align-items:center;gap:14px;
  font-size:12.5px;color:var(--muted);flex-wrap:wrap;
}
.meta-stats .dot{width:3px;height:3px;border-radius:50%;background:var(--muted);opacity:.6;}
.action-row{margin-left:auto;display:flex;gap:8px;}
.act-btn{
  display:flex;align-items:center;gap:7px;
  padding:8px 15px;border-radius:999px;font-size:13px;
  color:var(--muted);
  box-shadow:inset 0 0 0 1px var(--line-strong);
  transition:.22s;
}
.act-btn:hover{color:var(--text);background:rgba(255,255,255,.05);}
.act-btn svg{width:16px;height:16px;}
.act-btn.active{color:var(--cyan);box-shadow:inset 0 0 0 1px rgba(34,211,238,.45);background:rgba(34,211,238,.08);}
.act-btn.active.like{color:var(--pink);box-shadow:inset 0 0 0 1px rgba(244,114,182,.45);background:rgba(244,114,182,.08);}

.tags{display:flex;flex-wrap:wrap;gap:8px;margin-top:18px;}
.tag{
  font-size:12.5px;padding:5px 13px;border-radius:999px;
  color:#9fb0e0;background:rgba(99,102,241,.1);
  border:1px solid rgba(99,102,241,.22);
  transition:.2s;
}
.tag:hover{background:rgba(99,102,241,.2);color:#c7d2ff;}

.desc{
  margin-top:20px;padding:18px 20px;border-radius:14px;
  background:var(--panel);border:1px solid var(--line);
  font-size:14px;color:#b9c2e4;line-height:1.85;
}
.desc strong{color:#e6ecff;}

.section{margin-top:34px;}
.section-head{
  display:flex;align-items:center;gap:10px;margin-bottom:16px;
}
.section-head h3{font-size:17px;font-weight:700;letter-spacing:.3px;}
.section-head .line{
  flex:1;height:1px;background:linear-gradient(90deg,var(--line),transparent);
}
.section-head .count{
  font-size:12px;color:var(--muted);
  padding:3px 10px;border-radius:999px;background:rgba(255,255,255,.05);
}
.chapters{display:grid;grid-template-columns:repeat(2,1fr);gap:10px;}
.chap{
  display:flex;align-items:center;gap:13px;
  padding:13px 16px;border-radius:12px;text-align:left;
  background:rgba(255,255,255,.025);
  border:1px solid var(--line);
  transition:.22s;
}
.chap:hover{background:rgba(34,211,238,.07);border-color:rgba(34,211,238,.3);transform:translateX(3px);}
.chap.active{background:rgba(34,211,238,.11);border-color:rgba(34,211,238,.45);}
.chap-time{
  font-size:12px;font-variant-numeric:tabular-nums;
  color:var(--cyan);font-weight:600;flex-shrink:0;
  padding:3px 8px;border-radius:6px;background:rgba(34,211,238,.1);
}
.chap-text{font-size:13.5px;color:#c3cbe9;}

.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;}
.card{
  position:relative;overflow:hidden;
  padding:20px;border-radius:14px;
  background:var(--panel);
  border:1px solid var(--line);
  transition:.28s;
}
.card::after{
  content:"";position:absolute;inset:0;
  background:linear-gradient(135deg,rgba(34,211,238,.1),transparent 60%);
  opacity:0;transition:.3s;
}
.card:hover{transform:translateY(-4px);border-color:rgba(34,211,238,.35);box-shadow:0 16px 34px -14px rgba(34,211,238,.4);}
.card:hover::after{opacity:1;}
.card-ico{
  width:38px;height:38px;border-radius:11px;
  display:grid;place-items:center;margin-bottom:14px;
  background:rgba(34,211,238,.12);color:var(--cyan);
  position:relative;z-index:1;
}
.card:nth-child(2) .card-ico{background:rgba(168,85,247,.14);color:#c084fc;}
.card:nth-child(3) .card-ico{background:rgba(251,191,36,.13);color:var(--amber);}
.card-ico svg{width:20px;height:20px;}
.card h4{font-size:14.5px;font-weight:700;margin-bottom:8px;position:relative;z-index:1;}
.card p{font-size:13px;color:var(--muted);line-height:1.75;position:relative;z-index:1;}

/* 评论 */
.comment-box{
  padding:20px;border-radius:14px;
  background:var(--panel);border:1px solid var(--line);
}
.comment-input{display:flex;gap:12px;margin-bottom:22px;}
.comment-input .avatar{width:38px;height:38px;font-size:14px;}
.comment-input input{
  flex:1;padding:11px 16px;border-radius:999px;
  background:rgba(255,255,255,.05);
  border:1px solid var(--line);
  color:var(--text);font-size:13.5px;outline:none;
  transition:.2s;font-family:inherit;
}
.comment-input input::placeholder{color:#5f6890;}
.comment-input input:focus{border-color:rgba(34,211,238,.45);background:rgba(34,211,238,.05);}
.comment-input button{
  padding:0 22px;border-radius:999px;font-size:13.5px;font-weight:600;
  background:linear-gradient(135deg,var(--cyan),var(--violet));color:#fff;
  transition:.22s;
}
.comment-input button:hover{transform:translateY(-1px);box-shadow:0 8px 20px rgba(124,58,237,.4);}

.comment{display:flex;gap:12px;padding:16px 0;border-top:1px solid var(--line);}
.comment:first-of-type{border-top:none;padding-top:0;}
.comment .avatar{width:36px;height:36px;font-size:13px;}
.c-body{flex:1;min-width:0;}
.c-head{display:flex;align-items:center;gap:9px;margin-bottom:5px;flex-wrap:wrap;}
.c-head strong{font-size:13.5px;font-weight:600;}
.c-head .badge{
  font-size:10.5px;padding:2px 8px;border-radius:999px;
  background:rgba(34,211,238,.13);color:var(--cyan);
  border:1px solid rgba(34,211,238,.25);
}
.c-head time{font-size:11.5px;color:#5f6890;margin-left:auto;}
.c-text{font-size:13.5px;color:#b0b9db;line-height:1.75;}
.c-actions{display:flex;gap:18px;margin-top:8px;}
.c-actions button{
  display:flex;align-items:center;gap:5px;
  font-size:12px;color:#5f6890;transition:.2s;
}
.c-actions button:hover{color:var(--cyan);}
.c-actions button.on{color:var(--pink);}
.c-actions svg{width:14px;height:14px;}

/* ============ 侧栏 ============ */
.aside{display:flex;flex-direction:column;gap:20px;}
.panel{
  padding:20px;border-radius:14px;
  background:var(--panel);border:1px solid var(--line);
}
.panel-head{
  display:flex;align-items:center;justify-content:space-between;
  margin-bottom:16px;
}
.panel-head h3{font-size:15px;font-weight:700;}
.panel-head span{font-size:12px;color:var(--muted);}

.rec-list{display:flex;flex-direction:column;gap:14px;}
.rec{
  display:flex;gap:12px;align-items:flex-start;
  transition:.22s;border-radius:10px;padding:6px;margin:-6px;
}
button.rec{
  width:100%;
  font:inherit;
  color:inherit;
  text-align:left;
  background:none;
  border:none;
  cursor:pointer;
}
.rec:hover{background:rgba(255,255,255,.05);}
.rec:hover .rec-title{color:var(--cyan);}
.rec.playing{
  background:rgba(34,211,238,.09);
  box-shadow:inset 0 0 0 1px rgba(34,211,238,.3);
}
.rec.playing .rec-title{color:var(--cyan);}
.rec-thumb{
  position:relative;flex-shrink:0;
  width:104px;aspect-ratio:16/10;border-radius:9px;
  overflow:hidden;
  background:linear-gradient(135deg,var(--g1,#22d3ee),var(--g2,#a855f7));
}
.rec-thumb::before{
  content:"";position:absolute;inset:0;
  background:
    radial-gradient(circle at 68% 42%, rgba(255,255,255,.4) 0 6%, transparent 7%),
    radial-gradient(circle at 30% 70%, rgba(0,0,0,.35), transparent 62%);
}
.rec-thumb::after{
  content:"";position:absolute;inset:0;
  background:linear-gradient(180deg,transparent 55%,rgba(0,0,0,.55));
}
.rec-dur{
  position:absolute;right:5px;bottom:5px;z-index:2;
  font-size:10.5px;padding:1px 6px;border-radius:4px;
  background:rgba(0,0,0,.72);color:#dfe6ff;
  font-variant-numeric:tabular-nums;
}
.rec-info{min-width:0;flex:1;padding-top:2px;}
.rec-title{
  font-size:13.2px;font-weight:600;line-height:1.5;
  transition:.2s;
  display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden;
}
.rec-meta{font-size:11.5px;color:#5f6890;margin-top:6px;}

.quiz{
  padding:20px;border-radius:14px;
  background:linear-gradient(160deg,rgba(34,211,238,.09),rgba(168,85,247,.09));
  border:1px solid rgba(34,211,238,.2);
}
.quiz-head{display:flex;align-items:center;gap:9px;margin-bottom:6px;}
.quiz-head .qi{
  width:26px;height:26px;border-radius:8px;display:grid;place-items:center;
  background:linear-gradient(135deg,var(--cyan),var(--violet));color:#040c18;
  font-size:13px;font-weight:800;
}
.quiz-head h3{font-size:14.5px;font-weight:700;}
.quiz-q{font-size:13.5px;color:#c3cbe9;line-height:1.7;margin:10px 0 14px;}
.quiz-opt{
  display:block;width:100%;text-align:left;
  padding:11px 14px;margin-bottom:8px;border-radius:10px;
  font-size:13px;color:#b9c2e4;
  background:rgba(255,255,255,.04);
  border:1px solid var(--line);
  transition:.2s;
}
.quiz-opt:hover:not(.correct):not(.wrong){background:rgba(34,211,238,.1);border-color:rgba(34,211,238,.35);color:#e4ecff;}
.quiz-opt.correct{background:rgba(52,211,153,.16);border-color:rgba(52,211,153,.55);color:#a7f3d0;}
.quiz-opt.wrong{background:rgba(244,114,182,.14);border-color:rgba(244,114,182,.5);color:#fbcfe8;}
.quiz-result{font-size:12.5px;color:var(--muted);margin-top:10px;min-height:20px;line-height:1.6;}

.topic-tags{display:flex;flex-wrap:wrap;gap:8px;}
.topic-tags a{
  font-size:12.5px;padding:6px 13px;border-radius:999px;
  color:#9fb0e0;background:rgba(255,255,255,.04);
  border:1px solid var(--line);transition:.2s;
}
.topic-tags a:hover{color:var(--cyan);border-color:rgba(34,211,238,.4);background:rgba(34,211,238,.08);}

.footer{
  border-top:1px solid var(--line);
  padding:28px 0 40px;
  text-align:center;
  font-size:12.5px;color:#4e577a;
  position:relative;z-index:1;
}
.footer a{color:#6b76a0;transition:.2s;}
.footer a:hover{color:var(--cyan);}

/* ============================================================
   导航弹出面板（发现 / 专栏 / 我的学习）
   ============================================================ */
.nav-panel{position:fixed;inset:0;z-index:100;display:none;}
.nav-panel.open{display:block;}
.nav-panel-mask{
  position:absolute;inset:0;
  background:rgba(3,5,12,.72);
  backdrop-filter:blur(10px);
  -webkit-backdrop-filter:blur(10px);
  animation:npFade .25s ease;
}
@keyframes npFade{from{opacity:0}to{opacity:1}}
.nav-panel-box{
  position:absolute;left:50%;top:50%;
  transform:translate(-50%,-50%);
  width:min(880px,calc(100% - 36px));
  max-height:min(78vh,680px);
  overflow:auto;
  padding:26px 26px 30px;
  border-radius:20px;
  background:linear-gradient(180deg,rgba(21,26,48,.99),rgba(11,15,30,.995));
  border:1px solid var(--line-strong);
  box-shadow:0 40px 100px -30px rgba(0,0,0,.95), 0 0 0 1px rgba(255,255,255,.03) inset;
  animation:npIn .32s cubic-bezier(.22,1,.36,1);
  scrollbar-width:thin;
}
.nav-panel-box::-webkit-scrollbar{width:8px;}
.nav-panel-box::-webkit-scrollbar-thumb{background:rgba(255,255,255,.12);border-radius:99px;}
@keyframes npIn{
  from{opacity:0;transform:translate(-50%,-46%) scale(.97);}
  to{opacity:1;transform:translate(-50%,-50%) scale(1);}
}
.np-head{display:flex;align-items:flex-start;justify-content:space-between;gap:16px;margin-bottom:22px;}
.np-chip{
  display:inline-block;font-size:11px;letter-spacing:1.4px;text-transform:uppercase;
  color:var(--cyan);padding:4px 11px;border-radius:999px;
  background:rgba(34,211,238,.1);border:1px solid rgba(34,211,238,.3);
  margin-bottom:10px;
}
.np-head h2{font-size:21px;font-weight:800;letter-spacing:.3px;}
.np-close{
  width:36px;height:36px;border-radius:50%;flex-shrink:0;
  display:grid;place-items:center;color:var(--muted);
  background:rgba(255,255,255,.05);
  transition:.25s;
}
.np-close:hover{color:#fff;background:rgba(255,255,255,.12);transform:rotate(90deg);}
.np-close svg{width:18px;height:18px;}

.np-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;}
.np-card{
  display:flex;gap:13px;align-items:center;text-align:left;
  padding:11px;border-radius:13px;
  background:rgba(255,255,255,.03);
  border:1px solid var(--line);
  transition:.22s;
  font:inherit;color:inherit;cursor:pointer;
}
.np-card:hover{background:rgba(34,211,238,.08);border-color:rgba(34,211,238,.35);transform:translateY(-2px);}
.np-thumb{
  position:relative;flex-shrink:0;width:118px;aspect-ratio:16/10;border-radius:9px;overflow:hidden;
  background:linear-gradient(135deg,var(--g1,#22d3ee),var(--g2,#a855f7));
}
.np-thumb::before{
  content:"";position:absolute;inset:0;
  background:radial-gradient(circle at 68% 42%,rgba(255,255,255,.4) 0 6%,transparent 7%),
             radial-gradient(circle at 30% 70%,rgba(0,0,0,.35),transparent 62%);
}
.np-thumb::after{
  content:"";position:absolute;inset:0;
  background:linear-gradient(180deg,transparent 55%,rgba(0,0,0,.55));
}
.np-dur{
  position:absolute;right:5px;bottom:5px;z-index:2;
  font-size:10.5px;padding:1px 6px;border-radius:4px;
  background:rgba(0,0,0,.72);color:#dfe6ff;font-variant-numeric:tabular-nums;
}
.np-card-body{min-width:0;flex:1;}
.np-card-title{font-size:13.5px;font-weight:600;line-height:1.5;color:#dde4ff;}
.np-card-meta{font-size:11.5px;color:#5f6890;margin-top:5px;}

.np-cols{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;}
.np-col{
  display:flex;align-items:center;gap:13px;
  padding:16px;border-radius:14px;
  background:rgba(255,255,255,.03);
  border:1px solid var(--line);
  transition:.22s;
}
.np-col:hover{border-color:rgba(34,211,238,.3);background:rgba(34,211,238,.05);}
.np-col .avatar{width:46px;height:46px;font-size:16px;}
.np-col-info{flex:1;min-width:0;}
.np-col-info strong{display:block;font-size:14px;font-weight:600;}
.np-col-info span{font-size:12px;color:var(--muted);}
.np-follow{
  padding:6px 15px;border-radius:999px;font-size:12.5px;font-weight:600;flex-shrink:0;
  background:linear-gradient(135deg,var(--cyan),var(--violet));color:#fff;
  transition:.22s;cursor:pointer;
}
.np-follow:hover{transform:translateY(-1px);}
.np-follow.following{background:transparent;color:var(--muted);box-shadow:inset 0 0 0 1px var(--line-strong);}

.np-learn{display:flex;flex-direction:column;gap:18px;}
.np-learn-item{display:flex;flex-direction:column;gap:9px;}
.np-learn-top{display:flex;align-items:center;justify-content:space-between;gap:12px;font-size:13.5px;}
.np-learn-top strong{font-weight:600;color:#dde4ff;}
.np-learn-top em{font-style:normal;font-size:12px;color:var(--cyan);font-variant-numeric:tabular-nums;}
.np-bar{height:6px;border-radius:99px;background:rgba(255,255,255,.09);overflow:hidden;}
.np-bar i{
  display:block;height:100%;border-radius:99px;
  background:linear-gradient(90deg,var(--cyan),var(--violet));
  box-shadow:0 0 12px rgba(34,211,238,.5);
  transition:width .6s cubic-bezier(.22,1,.36,1);
}

/* 响应式 */
@media (max-width:1080px){
  .layout{grid-template-columns:1fr;gap:26px;}
  .aside{display:grid;grid-template-columns:1fr 1fr;gap:18px;align-items:start;}
  .aside .panel:first-of-type{grid-column:1/-1;}
  .rec-list{display:grid;grid-template-columns:1fr 1fr;gap:14px;}
  .quiz{grid-column:1/-1;}
}
@media (max-width:760px){
  .nav-links{display:none;}
  .cards{grid-template-columns:1fr;}
  .chapters{grid-template-columns:1fr;}
  .aside{grid-template-columns:1fr;}
  .rec-list{grid-template-columns:1fr;}
  .action-row{margin-left:0;width:100%;}
  .meta-row{gap:12px;}
  .stage-caption{padding:18px;}
  .subtitle{bottom:44px;font-size:12px;padding:7px 13px;}
  .controls{gap:9px;padding:10px 12px;}
  .ctrl{width:30px;height:30px;}
  .time{font-size:11.5px;}
  .logo img{height:26px;}
  .np-grid,.np-cols{grid-template-columns:1fr;}
  .nav-panel-box{padding:20px;max-height:84vh;}
  .np-thumb{width:96px;}
}
@media (max-width:420px){
  .wrap{padding:0 14px;}
  .big-play{width:60px;height:60px;}
  .big-play svg{width:22px;height:22px;}
}