/* ===========================================================
   知库 · 首页
   深色 / 渐变光晕 / 大字号首屏
   =========================================================== */
:root{
  --bg:#08090c;
  --bg-2:#0b0d12;
  --ink:#eceef1;
  --sub:#9aa1ab;
  --muted:#6a7280;
  --line:rgba(255,255,255,.085);
  --line-2:rgba(255,255,255,.05);
  --surface:rgba(255,255,255,.032);
  --accent:#ff6a3d;
  --accent-2:#ff9d72;
  --violet:#7c8cff;
  --sans:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --mono:"SFMono-Regular",Consolas,Menlo,monospace;
  --pad:clamp(20px,4vw,40px);
  --max:1120px;
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;
  background:var(--bg);
  color:var(--ink);
  font-family:var(--sans);
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
  overflow-x:hidden;
}
a{color:inherit;text-decoration:none}
::selection{background:rgba(255,106,61,.28);color:#fff}

/* ---------- 背景层 ---------- */
.bg{position:fixed;inset:0;z-index:0;pointer-events:none;overflow:hidden}
.orb{
  position:absolute;border-radius:50%;
  filter:blur(90px);
  opacity:.5;
  will-change:transform;
}
.o1{
  width:52vw;height:52vw;min-width:420px;min-height:420px;
  left:-10vw;top:-16vw;
  background:radial-gradient(circle at 40% 40%,rgba(255,106,61,.55),rgba(255,106,61,0) 66%);
  animation:drift1 26s ease-in-out infinite;
}
.o2{
  width:46vw;height:46vw;min-width:380px;min-height:380px;
  right:-8vw;top:2vw;
  background:radial-gradient(circle at 55% 45%,rgba(124,140,255,.42),rgba(124,140,255,0) 68%);
  animation:drift2 32s ease-in-out infinite;
}
.o3{
  width:40vw;height:40vw;min-width:300px;min-height:300px;
  left:26vw;top:44vh;
  background:radial-gradient(circle at 50% 50%,rgba(255,157,114,.18),rgba(255,157,114,0) 70%);
  animation:drift3 38s ease-in-out infinite;
}
@keyframes drift1{0%,100%{transform:translate3d(0,0,0) scale(1)}50%{transform:translate3d(6vw,4vh,0) scale(1.08)}}
@keyframes drift2{0%,100%{transform:translate3d(0,0,0) scale(1)}50%{transform:translate3d(-5vw,6vh,0) scale(1.12)}}
@keyframes drift3{0%,100%{transform:translate3d(0,0,0) scale(1)}50%{transform:translate3d(-4vw,-6vh,0) scale(1.1)}}

.mesh{
  position:absolute;inset:-20%;
  background:
    repeating-linear-gradient(0deg,transparent 0 71px,rgba(255,255,255,.028) 71px 72px),
    repeating-linear-gradient(90deg,transparent 0 71px,rgba(255,255,255,.028) 71px 72px);
  mask-image:radial-gradient(ellipse 70% 55% at 50% 30%,#000 20%,transparent 78%);
  -webkit-mask-image:radial-gradient(ellipse 70% 55% at 50% 30%,#000 20%,transparent 78%);
}
.noise{
  position:absolute;inset:0;opacity:.045;mix-blend-mode:overlay;
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='3'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* ---------- 导航 ---------- */
.nav{
  position:fixed;top:0;left:0;right:0;z-index:20;
  display:flex;align-items:center;gap:28px;
  height:64px;padding:0 var(--pad);
  background:rgba(8,9,12,.55);
  backdrop-filter:saturate(180%) blur(18px);
  -webkit-backdrop-filter:saturate(180%) blur(18px);
  border-bottom:1px solid transparent;
  transition:border-color .3s,background .3s;
}
.nav.scrolled{border-bottom-color:var(--line);background:rgba(8,9,12,.82)}
.logo{display:flex;align-items:center;gap:9px;font-size:16px;font-weight:600;letter-spacing:.02em}
.logo .mark{
  width:15px;height:15px;border-radius:5px;
  background:linear-gradient(140deg,var(--accent),var(--accent-2));
  box-shadow:0 0 18px rgba(255,106,61,.55);
}
.nav-links{display:flex;gap:26px;margin-left:auto;font-size:14px;color:var(--sub)}
.nav-links a{transition:color .2s}
.nav-links a:hover{color:var(--ink)}
.btn-nav{
  display:inline-flex;align-items:center;gap:6px;
  height:34px;padding:0 15px;border-radius:9px;
  font-size:13.5px;color:var(--ink);
  border:1px solid var(--line);background:var(--surface);
  transition:all .22s ease;
}
.btn-nav:hover{border-color:rgba(255,255,255,.2);background:rgba(255,255,255,.07)}
.btn-nav .arr{transition:transform .22s}
.btn-nav:hover .arr{transform:translateX(3px)}

/* ---------- 首屏 ---------- */
main{position:relative;z-index:1}
.hero{
  max-width:var(--max);margin:0 auto;
  padding:clamp(120px,17vh,190px) var(--pad) 0;
  position:relative;
}
.eyebrow{
  display:inline-flex;align-items:center;gap:9px;
  font-size:12.5px;letter-spacing:.04em;color:var(--sub);
  padding:6px 12px 6px 10px;border-radius:100px;
  border:1px solid var(--line);background:rgba(255,255,255,.025);
}
.eyebrow b{color:var(--ink);font-weight:600;font-variant-numeric:tabular-nums}
.pulse{
  width:6px;height:6px;border-radius:50%;background:var(--accent);
  box-shadow:0 0 0 0 rgba(255,106,61,.7);
  animation:pulse 2.4s infinite;
}
@keyframes pulse{
  0%{box-shadow:0 0 0 0 rgba(255,106,61,.6)}
  70%{box-shadow:0 0 0 9px rgba(255,106,61,0)}
  100%{box-shadow:0 0 0 0 rgba(255,106,61,0)}
}

h1{
  margin:26px 0 0;
  font-size:clamp(38px,6.6vw,80px);
  line-height:1.1;
  letter-spacing:-.045em;
  font-weight:700;
}
.grad{
  background:linear-gradient(96deg,var(--accent) 8%,var(--accent-2) 55%,#ffd0b8 96%);
  -webkit-background-clip:text;background-clip:text;
  -webkit-text-fill-color:transparent;color:transparent;
  position:relative;
}
.lede{
  margin:26px 0 0;max-width:640px;
  font-size:clamp(14.5px,1.35vw,16.5px);
  line-height:1.95;color:var(--sub);
}
.cta{display:flex;flex-wrap:wrap;gap:12px;margin-top:38px}
.btn{
  display:inline-flex;align-items:center;justify-content:center;
  height:46px;padding:0 24px;border-radius:12px;
  font-size:14.5px;font-weight:500;letter-spacing:.01em;
  transition:transform .22s cubic-bezier(.2,.7,.2,1),box-shadow .25s,background .25s,border-color .25s;
}
.btn.primary{
  background:linear-gradient(140deg,var(--accent),#ff8a5c);
  color:#1a0d07;
  box-shadow:0 10px 30px -10px rgba(255,106,61,.7),inset 0 1px 0 rgba(255,255,255,.3);
}
.btn.primary:hover{transform:translateY(-2px);box-shadow:0 16px 38px -12px rgba(255,106,61,.85),inset 0 1px 0 rgba(255,255,255,.35)}
.btn.ghost{
  border:1px solid var(--line);color:var(--ink);background:rgba(255,255,255,.02);
}
.btn.ghost:hover{background:rgba(255,255,255,.06);border-color:rgba(255,255,255,.18);transform:translateY(-2px)}

.scroll-hint{
  margin:64px 0 0;height:44px;display:flex;justify-content:flex-start;
}
.scroll-hint span{
  display:block;width:1px;height:44px;
  background:linear-gradient(to bottom,rgba(255,255,255,.35),transparent);
  animation:hint 2.6s ease-in-out infinite;
}
@keyframes hint{0%,100%{transform:scaleY(.35);transform-origin:top;opacity:.4}50%{transform:scaleY(1);opacity:1}}

/* ---------- 数字条 ---------- */
.stats{
  max-width:var(--max);margin:96px auto 0;
  padding:0 var(--pad);
  display:grid;grid-template-columns:repeat(4,1fr);
  border-top:1px solid var(--line-2);
}
.stat{padding:30px 0 34px;border-right:1px solid var(--line-2)}
.stat:last-child{border-right:0}
.stat b{
  display:block;font-size:clamp(28px,3.4vw,40px);font-weight:600;
  letter-spacing:-.03em;font-variant-numeric:tabular-nums;
  background:linear-gradient(180deg,#fff,#9aa1ab);
  -webkit-background-clip:text;background-clip:text;
  -webkit-text-fill-color:transparent;
}
.stat span{display:block;margin-top:4px;font-size:13px;color:var(--muted);letter-spacing:.02em}

/* ---------- 区块 ---------- */
.block{max-width:var(--max);margin:0 auto;padding:clamp(80px,10vw,130px) var(--pad) 0}
.block-head{margin-bottom:34px}
.block-head h2{
  margin:0;font-size:clamp(22px,2.6vw,28px);font-weight:600;letter-spacing:-.02em;
}
.block-head p{margin:8px 0 0;font-size:14px;color:var(--muted)}

/* ---------- 卡片 ---------- */
.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}
.card{
  position:relative;display:flex;flex-direction:column;
  min-height:196px;padding:22px 22px 18px;
  border-radius:16px;border:1px solid var(--line);
  background:linear-gradient(180deg,rgba(255,255,255,.045),rgba(255,255,255,.015));
  transition:transform .3s cubic-bezier(.2,.7,.2,1),border-color .3s,box-shadow .35s,background .3s;
  overflow:hidden;
}
.card::after{
  content:"";position:absolute;inset:0;border-radius:inherit;
  background:radial-gradient(500px circle at var(--mx,50%) var(--my,0%),rgba(255,106,61,.12),transparent 45%);
  opacity:0;transition:opacity .35s;pointer-events:none;
}
.card:hover{transform:translateY(-4px);border-color:rgba(255,106,61,.4);box-shadow:0 22px 50px -28px rgba(255,106,61,.6)}
.card:hover::after{opacity:1}
.card .tag{
  align-self:flex-start;font-size:11.5px;letter-spacing:.04em;
  padding:3px 9px;border-radius:100px;color:var(--accent-2);
  background:rgba(255,106,61,.1);border:1px solid rgba(255,106,61,.22);
}
.card h3{
  margin:14px 0 0;font-size:16.5px;font-weight:600;line-height:1.55;letter-spacing:-.01em;
}
.card p{
  margin:9px 0 0;font-size:13px;line-height:1.75;color:var(--muted);
  display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden;
}
.card .foot{
  margin-top:auto;padding-top:16px;display:flex;justify-content:space-between;
  font-size:12px;color:#5b626d;font-variant-numeric:tabular-nums;
}
.card:hover .foot .go{color:var(--accent-2)}

.skeleton{background:linear-gradient(100deg,rgba(255,255,255,.03) 20%,rgba(255,255,255,.07) 40%,rgba(255,255,255,.03) 60%);
  background-size:220% 100%;animation:shimmer 1.6s infinite linear;border-style:dashed}
@keyframes shimmer{0%{background-position:120% 0}100%{background-position:-120% 0}}

.more{
  display:inline-flex;align-items:center;gap:6px;margin-top:26px;
  font-size:13.5px;color:var(--sub);transition:color .2s,gap .2s;
}
.more:hover{color:var(--ink);gap:10px}

/* ---------- 三步 ---------- */
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}
.step{
  padding:26px 24px 28px;border-radius:16px;
  border:1px solid var(--line-2);background:rgba(255,255,255,.018);
  transition:border-color .3s,background .3s;
}
.step:hover{border-color:var(--line);background:rgba(255,255,255,.035)}
.step .num{
  font-family:var(--mono);font-size:12px;letter-spacing:.14em;color:var(--accent);
  opacity:.85;
}
.step h3{margin:14px 0 0;font-size:16px;font-weight:600;letter-spacing:-.01em}
.step p{margin:10px 0 0;font-size:13.5px;line-height:1.85;color:var(--muted)}

/* ---------- 程序合集 ---------- */
.apps{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}
.app{
  display:flex;align-items:center;gap:14px;
  padding:16px 18px;border-radius:14px;
  border:1px solid var(--line);background:var(--surface);
  transition:transform .28s cubic-bezier(.2,.7,.2,1),border-color .28s,background .28s;
}
.app:hover{transform:translateY(-3px);border-color:rgba(255,106,61,.38);background:rgba(255,255,255,.06)}
.app .ico{
  width:38px;height:38px;flex:0 0 38px;border-radius:11px;
  display:grid;place-items:center;font-size:18px;
  background:linear-gradient(150deg,rgba(255,106,61,.16),rgba(124,140,255,.12));
  border:1px solid var(--line);
}
.app .t{font-size:14px;font-weight:500}
.app .d{margin-top:3px;font-size:12px;color:var(--muted);
  overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:200px}
.empty{grid-column:1/-1;color:var(--muted);font-size:13.5px;
  padding:26px;border:1px dashed var(--line);border-radius:14px;text-align:center}

/* ---------- 引用 ---------- */
.quote{
  max-width:var(--max);margin:0 auto;padding:clamp(90px,12vw,150px) var(--pad) clamp(60px,8vw,100px);
  text-align:center;
}
.quote p{
  margin:0;font-size:clamp(20px,3vw,34px);line-height:1.6;letter-spacing:-.02em;
  color:#c9ccd2;font-weight:300;
}

/* ---------- 页脚 ---------- */
footer{border-top:1px solid var(--line-2);position:relative;z-index:1}
.foot-in{
  max-width:var(--max);margin:0 auto;padding:26px var(--pad);
  display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap;
  font-size:12.5px;color:var(--muted);
}
.foot-links{display:flex;gap:18px}
.foot-links a:hover{color:var(--sub)}

/* ---------- 入场动画 ---------- */
.reveal{opacity:0;transform:translateY(18px);transition:opacity .9s cubic-bezier(.2,.7,.2,1),transform .9s cubic-bezier(.2,.7,.2,1);transition-delay:var(--d,0s)}
.reveal.in{opacity:1;transform:none}

@media (prefers-reduced-motion:reduce){
  .reveal{opacity:1;transform:none;transition:none}
  .orb,.pulse,.scroll-hint span,.skeleton{animation:none}
  html{scroll-behavior:auto}
}

/* ---------- 响应式 ---------- */
@media (max-width:900px){
  .cards,.steps,.apps{grid-template-columns:1fr 1fr}
  .stats{grid-template-columns:1fr 1fr}
  .stat:nth-child(2n){border-right:0}
  .stat{border-bottom:1px solid var(--line-2)}
  .nav-links{display:none}
  .lede br{display:none}
}
@media (max-width:600px){
  .cards,.steps,.apps{grid-template-columns:1fr}
  .hero{padding-top:104px}
  h1{font-size:clamp(26px,8.2vw,36px);letter-spacing:-.03em;line-height:1.22}
  .lede{font-size:14px;line-height:1.85}
  .cta{gap:10px;flex-direction:column;margin-top:30px}
  .btn{width:100%}
  .scroll-hint{margin-top:44px}
  .stats{margin-top:64px}
  .quote p{font-size:19px}
  .foot-in{flex-direction:column;gap:8px}
}