/* =========================================================
   theme.css — 站点共享设计系统
   与课程页保持同一套视觉语言：深色底、青紫渐变、克制的发光
   ========================================================= */

:root{
  --bg:#05080f;
  --bg-soft:#080c15;
  --panel:rgba(255,255,255,.035);
  --panel-2:rgba(255,255,255,.055);
  --line:rgba(255,255,255,.085);
  --line-2:rgba(255,255,255,.14);
  --txt:#e8edf7;
  --dim:#8b97ad;
  --mute:#5d6a80;
  --cyan:#22d3ee;
  --violet:#a78bfa;
  --amber:#fbbf24;
  --green:#34d399;
  --pink:#f472b6;
  --r-sm:10px;
  --r-md:14px;
  --r-lg:20px;
  --r-xl:26px;
  --mono:ui-monospace,"SF Mono","JetBrains Mono",Menlo,Consolas,monospace;
}

*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;scroll-padding-top:88px}
body{
  background:var(--bg);color:var(--txt);line-height:1.7;overflow-x:hidden;
  font-family:"PingFang SC","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
  min-height:100vh;
}
body::before{
  content:"";position:fixed;inset:0;z-index:0;pointer-events:none;
  background:
    radial-gradient(1000px 620px at 10% -8%,rgba(34,211,238,.14),transparent 62%),
    radial-gradient(880px 600px at 92% 4%,rgba(167,139,250,.13),transparent 60%),
    radial-gradient(760px 520px at 48% 108%,rgba(52,211,153,.07),transparent 62%);
}
body::after{
  content:"";position:fixed;inset:0;z-index:0;pointer-events:none;opacity:.35;
  background-image:linear-gradient(rgba(255,255,255,.028) 1px,transparent 1px),
                   linear-gradient(90deg,rgba(255,255,255,.028) 1px,transparent 1px);
  background-size:64px 64px;
  mask-image:radial-gradient(ellipse 80% 60% at 50% 0%,#000 18%,transparent 78%);
  -webkit-mask-image:radial-gradient(ellipse 80% 60% at 50% 0%,#000 18%,transparent 78%);
}
::selection{background:rgba(34,211,238,.3);color:#fff}
a{color:inherit;text-decoration:none}
button{font-family:inherit}
.mono{font-family:var(--mono)}

.wrap{max-width:1160px;margin:0 auto;padding:0 26px;position:relative;z-index:1}
.wrap-narrow{max-width:920px}

/* ---------------- 顶部滚动条 ---------------- */
.topbar{position:fixed;top:0;left:0;right:0;height:2px;z-index:120;background:rgba(255,255,255,.04)}
.topbar i{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--cyan),var(--violet));box-shadow:0 0 12px rgba(34,211,238,.7);transition:width .1s linear}

/* ---------------- 导航 ---------------- */
.site-nav{
  position:fixed;top:0;left:0;right:0;z-index:100;height:64px;
  display:flex;align-items:center;
  background:rgba(5,8,15,.72);backdrop-filter:blur(18px);-webkit-backdrop-filter:blur(18px);
  border-bottom:1px solid rgba(255,255,255,.06);
}
.site-nav .wrap{display:flex;align-items:center;gap:18px;width:100%;height:100%}
.brand{display:flex;align-items:center;gap:11px;font-weight:700;font-size:15px;letter-spacing:.3px;white-space:nowrap;flex:0 0 auto}
.brand .mark{
  width:24px;height:24px;border-radius:8px;position:relative;flex:0 0 auto;
  background:linear-gradient(135deg,var(--cyan),var(--violet));
  box-shadow:0 0 18px rgba(34,211,238,.5);
}
.brand .mark::after{
  content:"";position:absolute;inset:6px;border-radius:3px;
  background:rgba(5,8,15,.92);
  box-shadow:inset 0 0 0 1px rgba(255,255,255,.18);
}
.brand b{font-weight:800}
.brand small{display:block;font-size:10px;letter-spacing:2.4px;color:var(--mute);font-weight:600;line-height:1;margin-top:2px}

.nav-menu{display:flex;gap:2px;list-style:none;margin-left:22px}
.nav-menu a{
  display:block;padding:7px 13px;border-radius:9px;font-size:13.5px;color:var(--dim);transition:.2s;white-space:nowrap;
}
.nav-menu a:hover{color:var(--txt);background:rgba(255,255,255,.06)}

.nav-user{margin-left:auto;display:flex;align-items:center;gap:8px}
.nav-link{
  display:inline-flex;align-items:center;gap:6px;padding:7px 11px;border-radius:9px;
  font-size:13px;color:var(--dim);transition:.2s;white-space:nowrap;
}
.nav-link:hover{color:var(--txt);background:rgba(255,255,255,.06)}
.user-chip{
  display:flex;align-items:center;gap:9px;padding:5px 12px 5px 5px;border-radius:100px;
  border:1px solid var(--line);background:rgba(255,255,255,.04);transition:.22s;
}
.user-chip:hover{border-color:rgba(34,211,238,.35);background:rgba(34,211,238,.06)}
.avatar{
  width:28px;height:28px;border-radius:50%;display:flex;align-items:center;justify-content:center;
  font-size:12.5px;font-weight:800;color:#04121a;flex:0 0 auto;
  background:linear-gradient(135deg,var(--cyan),var(--violet));
  box-shadow:0 0 14px rgba(34,211,238,.4);
}
.user-meta{display:flex;flex-direction:column;line-height:1.25}
.user-meta b{font-size:12.5px;font-weight:600;color:var(--txt);max-width:120px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.user-meta i{font-size:10px;font-style:normal;color:var(--mute);letter-spacing:.6px}
.icon-btn{
  width:34px;height:34px;border-radius:9px;display:inline-flex;align-items:center;justify-content:center;
  border:1px solid var(--line);background:rgba(255,255,255,.03);color:var(--dim);cursor:pointer;transition:.2s;
}
.icon-btn:hover{color:var(--pink);border-color:rgba(244,114,182,.4);background:rgba(244,114,182,.08)}

/* ---------------- 按钮 ---------------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:9px;
  padding:13px 24px;border-radius:12px;font-size:14.5px;font-weight:600;
  border:1px solid transparent;cursor:pointer;transition:.24s;white-space:nowrap;
}
.btn-primary{
  background:linear-gradient(135deg,var(--cyan),#6366f1);color:#03121a;
  box-shadow:0 10px 30px -8px rgba(34,211,238,.6);
}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 16px 38px -8px rgba(34,211,238,.78)}
.btn-primary:active{transform:translateY(0)}
.btn-ghost{background:rgba(255,255,255,.05);border-color:var(--line-2);color:var(--txt)}
.btn-ghost:hover{background:rgba(255,255,255,.09);border-color:rgba(255,255,255,.24)}
.btn-sm{padding:8px 16px;font-size:13px;border-radius:10px}
.btn-block{width:100%}
.btn[disabled]{opacity:.5;cursor:not-allowed;transform:none!important}

/* ---------------- 标题 ---------------- */
.eyebrow{
  display:inline-flex;align-items:center;gap:9px;font-size:12px;letter-spacing:2.2px;
  color:var(--cyan);text-transform:uppercase;font-weight:600;
  padding:6px 14px;border:1px solid rgba(34,211,238,.25);border-radius:100px;
  background:rgba(34,211,238,.06);
}
.eyebrow::before{content:"";width:5px;height:5px;border-radius:50%;background:var(--cyan);box-shadow:0 0 8px var(--cyan)}
h1{font-weight:800;letter-spacing:-1.2px;line-height:1.14}
h1 em{
  font-style:normal;
  background:linear-gradient(100deg,var(--cyan),var(--violet) 48%,var(--pink));
  -webkit-background-clip:text;background-clip:text;color:transparent;
}
.sec-num{
  font-family:var(--mono);font-size:12px;letter-spacing:2.6px;color:var(--cyan);
  margin-bottom:14px;display:flex;align-items:center;gap:12px;
}
.sec-num::after{content:"";height:1px;width:110px;background:linear-gradient(90deg,rgba(34,211,238,.45),transparent)}
h2{font-size:clamp(24px,2.9vw,34px);line-height:1.3;letter-spacing:-.6px;font-weight:750}
.sec-head{max-width:720px;margin-bottom:44px}
.sec-head p{margin-top:15px;color:var(--dim);font-size:15px;line-height:1.85}
.sec-head p b{color:#dbe4f2;font-weight:600}

/* ---------------- 卡片 ---------------- */
.lesson-card{
  position:relative;display:flex;flex-direction:column;padding:26px 24px 22px;border-radius:var(--r-lg);overflow:hidden;
  border:1px solid var(--line);
  background:linear-gradient(170deg,rgba(255,255,255,.045),rgba(255,255,255,.012));
  transition:transform .3s cubic-bezier(.2,.7,.3,1),border-color .3s,box-shadow .3s;
}
.lesson-card::before{
  content:"";position:absolute;inset:0;opacity:0;transition:.35s;pointer-events:none;
  background:radial-gradient(420px 200px at 20% 0%,rgba(34,211,238,.14),transparent 70%);
}
.lesson-card:hover{transform:translateY(-5px);border-color:rgba(34,211,238,.34);box-shadow:0 26px 54px -28px rgba(34,211,238,.55)}
.lesson-card:hover::before{opacity:1}
.lesson-card .idx{
  font-family:var(--mono);font-size:12px;letter-spacing:2px;color:var(--mute);margin-bottom:16px;
  display:flex;align-items:center;justify-content:space-between;
}
.lesson-card h3{font-size:16.5px;font-weight:700;margin-bottom:8px;letter-spacing:.2px}
.lesson-card p{font-size:13.5px;color:var(--dim);line-height:1.8;flex:1 1 auto}
.lesson-card .meta{
  margin-top:18px;padding-top:14px;border-top:1px solid rgba(255,255,255,.06);
  display:flex;align-items:center;justify-content:space-between;font-size:12px;color:var(--mute);
  font-family:var(--mono);
}
.lesson-card .meta .go{display:flex;align-items:center;gap:5px;color:var(--cyan);opacity:0;transform:translateX(-4px);transition:.3s}
.lesson-card:hover .meta .go{opacity:1;transform:none}
.lock-badge{
  display:inline-flex;align-items:center;gap:5px;font-size:10.5px;letter-spacing:.8px;
  padding:3px 8px;border-radius:6px;color:var(--amber);
  background:rgba(251,191,36,.1);border:1px solid rgba(251,191,36,.25);
  font-family:var(--mono);font-weight:600;
}
.free-badge{
  display:inline-flex;align-items:center;gap:5px;font-size:10.5px;letter-spacing:.8px;
  padding:3px 8px;border-radius:6px;color:var(--green);
  background:rgba(52,211,153,.1);border:1px solid rgba(52,211,153,.25);
  font-family:var(--mono);font-weight:600;
}

/* ---------------- 表单 ---------------- */
.field{margin-bottom:16px}
.field label{display:block;font-size:12px;letter-spacing:1.4px;color:var(--mute);margin-bottom:8px;font-weight:600}
.input-wrap{position:relative;display:flex;align-items:center}
.input{
  width:100%;padding:13px 15px;border-radius:12px;font-size:14px;color:var(--txt);
  background:rgba(255,255,255,.04);border:1px solid var(--line);
  transition:.2s;font-family:inherit;outline:none;
}
.input::placeholder{color:#404b60}
.input:hover{border-color:rgba(255,255,255,.16)}
.input:focus{border-color:rgba(34,211,238,.55);background:rgba(34,211,238,.05);box-shadow:0 0 0 3px rgba(34,211,238,.1)}
.input.has-btn{padding-right:48px}
.pwd-toggle{
  position:absolute;right:6px;width:34px;height:34px;border-radius:8px;border:none;background:transparent;
  color:var(--mute);cursor:pointer;display:flex;align-items:center;justify-content:center;transition:.2s;
}
.pwd-toggle:hover{color:var(--cyan);background:rgba(34,211,238,.1)}
.hint{font-size:12px;color:var(--mute);margin-top:7px;line-height:1.6}

/* ---------------- 提示 ---------------- */
.app-toast{
  position:fixed;top:78px;left:50%;transform:translate(-50%,-14px);z-index:200;
  padding:11px 20px;border-radius:11px;font-size:13.5px;font-weight:600;
  background:rgba(16,22,34,.96);border:1px solid rgba(34,211,238,.35);color:var(--cyan);
  box-shadow:0 20px 46px -20px rgba(0,0,0,.9);
  opacity:0;pointer-events:none;transition:.28s cubic-bezier(.2,.7,.3,1);
}
.app-toast.show{opacity:1;transform:translate(-50%,0)}
.app-toast.err{border-color:rgba(244,114,182,.4);color:var(--pink)}
.app-toast.ok{border-color:rgba(52,211,153,.4);color:var(--green)}

/* ---------------- 页脚 ---------------- */
.site-foot{
  position:relative;z-index:1;padding:54px 0 44px;margin-top:40px;
  border-top:1px solid rgba(255,255,255,.06);text-align:center;
}
.site-foot .l1{font-size:13px;color:var(--mute);letter-spacing:.4px}
.site-foot .l2{font-size:11.5px;color:#3b4558;margin-top:8px;letter-spacing:.6px}
.site-foot a{color:var(--dim);transition:.2s}
.site-foot a:hover{color:var(--cyan)}

/* ---------------- 动效 ---------------- */
.reveal{opacity:0;transform:translateY(24px);transition:opacity .75s cubic-bezier(.2,.7,.3,1),transform .75s cubic-bezier(.2,.7,.3,1)}
.reveal.in{opacity:1;transform:none}
@keyframes shake{
  0%,100%{transform:translateX(0)}
  15%,55%{transform:translateX(-7px)}
  35%,75%{transform:translateX(7px)}
}
.shake{animation:shake .42s cubic-bezier(.36,.07,.19,.97)}
@keyframes floaty{0%,100%{transform:translateY(0)}50%{transform:translateY(-9px)}}
@keyframes fadeUp{from{opacity:0;transform:translateY(18px)}to{opacity:1;transform:none}}

/* ---------------- 响应式 ---------------- */
@media(max-width:900px){
  .nav-menu{display:none}
  .user-meta{display:none}
  .user-chip{padding:4px}
  .nav-link-t{display:none}
  .nav-link{padding:7px 9px}
}
@media(max-width:560px){
  .wrap{padding:0 18px}
  .btn{padding:12px 18px;font-size:14px}
  .site-nav{height:58px}
  .brand small{display:none}
  .brand{font-size:13.5px;gap:9px}
  .brand .mark{width:21px;height:21px}
  .site-nav .wrap{gap:10px}
}