/* ═══════ Shell Design System — 灵矩AI v2 ═══════ */
:root {
  /* Colors */
  --bg: #080b12;
  --bg2: #0d1117;
  --surface: #131722;
  --card: #1a1f2e;
  --border: #252b3b;
  --border2: #323a50;

  /* Primary accent */
  --pri: #7c3aed;
  --pri2: #a78bfa;
  --pri3: #8b5cf6;
  --pri-glow: rgba(124,58,237,.25);

  /* Gold accent (director/creation) */
  --gold: #d4a853;
  --gold2: #e8c97a;

  /* Text */
  --text: #e2e4e9;
  --text2: #9498a3;
  --text3: #5c6070;
  --white: #f0f2f5;

  /* Status */
  --green: #10b981;
  --red: #ef4444;
  --yellow: #f59e0b;
  --blue: #3b82f6;

  /* Layout */
  --sidebar-w: 220px;
  --topbar-h: 52px;
  --radius: 10px;
  --radius-sm: 7px;
  --radius-lg: 14px;

  /* Typography */
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'SF Mono', 'Cascadia Code', 'Fira Code', monospace;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0,0,0,.3);
  --shadow: 0 4px 16px rgba(0,0,0,.4);
  --shadow-lg: 0 8px 32px rgba(0,0,0,.6);

  /* Transitions */
  --ease: cubic-bezier(.4,0,.2,1);
  --ease-bounce: cubic-bezier(.34,1.56,.64,1);
}

/* ═══════ Reset ═══════ */
*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{font-family:var(--font);background:var(--bg);color:var(--text);line-height:1.6;min-height:100vh;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}
a{color:var(--pri2);text-decoration:none;transition:color .2s}
a:hover{color:var(--pri)}
img,svg{max-width:100%}
button{cursor:pointer;border:none;outline:none;font-family:inherit}
input,textarea,select{font-family:inherit;outline:none}
::selection{background:var(--pri);color:#fff}

/* ═══════ Shell Layout ═══════ */
.shell{display:flex;min-height:100vh}

/* Sidebar */
.shell-sidebar{
  width:var(--sidebar-w);
  min-width:var(--sidebar-w);
  background:var(--bg2);
  border-right:1px solid var(--border);
  display:flex;
  flex-direction:column;
  position:fixed;
  top:0;left:0;bottom:0;
  z-index:100;
  transition:transform .3s var(--ease);
}
.sidebar-brand{
  padding:16px 18px;
  display:flex;
  align-items:center;
  gap:10px;
  border-bottom:1px solid var(--border);
}
.sidebar-brand .brand-logo{width:36px;height:36px;border-radius:10px;display:flex;align-items:center;justify-content:center;flex-shrink:0}
.sidebar-brand .brand-logo svg{width:30px;height:30px}
.sidebar-brand .brand-name{font-size:18px;font-weight:800;letter-spacing:-.5px;background:linear-gradient(135deg,var(--pri2),var(--pri3));-webkit-background-clip:text;-webkit-text-fill-color:transparent}
.sidebar-brand .brand-version{font-size:10px;color:var(--text3);margin-left:2px}

.sidebar-nav{
  flex:1;
  padding:8px;
  overflow-y:auto;
  display:flex;
  flex-direction:column;
  gap:2px;
}
.nav-section{margin-top:12px;margin-bottom:2px}
.nav-section-title{
  padding:6px 12px 4px;
  font-size:10px;
  text-transform:uppercase;
  letter-spacing:1.5px;
  color:var(--text3);
  font-weight:700;
}
.nav-item{
  display:flex;
  align-items:center;
  gap:10px;
  padding:9px 12px;
  border-radius:var(--radius-sm);
  font-size:13px;
  font-weight:500;
  color:var(--text2);
  transition:all .2s var(--ease);
  cursor:pointer;
  text-decoration:none;
  border:none;
  background:none;
  width:100%;
  text-align:left;
  position:relative;
}
.nav-item:hover{background:rgba(124,58,237,.08);color:var(--text)}
.nav-item.active{
  background:linear-gradient(135deg,rgba(124,58,237,.15),rgba(124,58,237,.08));
  color:var(--pri2);
  font-weight:600;
}
.nav-item.active::before{
  content:'';
  position:absolute;
  left:0;top:50%;
  transform:translateY(-50%);
  width:3px;height:20px;
  background:var(--pri);
  border-radius:0 3px 3px 0;
}
.nav-item .nav-badge{
  margin-left:auto;
  padding:2px 7px;
  border-radius:10px;
  font-size:10px;
  font-weight:700;
  background:var(--red);
  color:#fff;
  line-height:1.4;
}
.nav-item .nav-icon{font-size:16px;width:20px;text-align:center;flex-shrink:0}

.sidebar-footer{
  padding:12px 16px;
  border-top:1px solid var(--border);
  font-size:11px;
  color:var(--text3);
  display:flex;
  flex-direction:column;
  gap:4px;
}
.sidebar-footer a{color:var(--text2);text-decoration:none}
.sidebar-footer a:hover{color:var(--pri2)}

/* Main area */
.shell-main{
  flex:1;
  margin-left:var(--sidebar-w);
  display:flex;
  flex-direction:column;
  min-height:100vh;
}

/* Top bar */
.shell-topbar{
  position:sticky;
  top:0;
  z-index:90;
  height:var(--topbar-h);
  background:rgba(13,17,23,.85);
  backdrop-filter:blur(16px);
  -webkit-backdrop-filter:blur(16px);
  border-bottom:1px solid var(--border);
  display:flex;
  align-items:center;
  justify-content:space-between;
  padding:0 20px;
  gap:16px;
}
.topbar-left{display:flex;align-items:center;gap:12px;flex:1;max-width:400px}
.topbar-left .search-box{
  position:relative;
  width:100%;
  max-width:320px;
}
.topbar-left .search-box input{
  width:100%;
  padding:8px 12px 8px 34px;
  background:var(--surface);
  border:1px solid var(--border);
  border-radius:20px;
  font-size:13px;
  color:var(--text);
  transition:all .2s var(--ease);
}
.topbar-left .search-box input:focus{border-color:var(--pri);box-shadow:0 0 0 3px var(--pri-glow)}
.topbar-left .search-box .search-icon{
  position:absolute;
  left:12px;top:50%;
  transform:translateY(-50%);
  font-size:14px;
  color:var(--text3);
  pointer-events:none;
}
.topbar-right{display:flex;align-items:center;gap:8px}
.topbar-btn{
  width:36px;height:36px;
  border-radius:10px;
  background:transparent;
  color:var(--text2);
  font-size:16px;
  display:flex;
  align-items:center;
  justify-content:center;
  transition:all .2s var(--ease);
  position:relative;
}
.topbar-btn:hover{background:var(--surface);color:var(--text)}
.topbar-btn .dot{
  position:absolute;
  top:7px;right:7px;
  width:7px;height:7px;
  border-radius:50%;
  background:var(--red);
  border:2px solid var(--bg2);
}

/* User menu */
.user-menu{
  display:flex;
  align-items:center;
  gap:8px;
  padding:4px 8px 4px 4px;
  border-radius:10px;
  cursor:pointer;
  transition:all .2s var(--ease);
  border:1px solid transparent;
}
.user-menu:hover{background:var(--surface);border-color:var(--border)}
.user-avatar{
  width:32px;height:32px;
  border-radius:9px;
  background:linear-gradient(135deg,var(--pri),var(--pri3));
  color:#fff;
  font-size:13px;
  font-weight:700;
  display:flex;
  align-items:center;
  justify-content:center;
  flex-shrink:0;
}
.user-name{font-size:13px;color:var(--text);font-weight:500}
.user-role{
  font-size:10px;
  padding:1px 6px;
  border-radius:6px;
  font-weight:600;
  margin-left:2px;
}
.user-role.teacher{background:rgba(59,130,246,.15);color:var(--blue)}
.user-role.student{background:rgba(16,185,129,.15);color:var(--green)}
.user-role.admin{background:rgba(239,68,68,.15);color:var(--red)}

/* Dropdown */
.user-dropdown{
  position:absolute;
  top:calc(100% + 4px);
  right:0;
  background:var(--card);
  border:1px solid var(--border);
  border-radius:var(--radius);
  min-width:180px;
  padding:6px;
  box-shadow:var(--shadow-lg);
  display:none;
  z-index:200;
}
.user-dropdown.show{display:block;animation:fade-in .15s var(--ease)}
.user-dropdown-item{
  display:flex;
  align-items:center;
  gap:8px;
  padding:8px 12px;
  border-radius:var(--radius-sm);
  font-size:13px;
  color:var(--text2);
  cursor:pointer;
  transition:all .15s var(--ease);
  background:none;
  border:none;
  width:100%;
  text-align:left;
}
.user-dropdown-item:hover{background:rgba(124,58,237,.08);color:var(--text)}
.user-dropdown-item.danger{color:var(--red)}
.user-dropdown-item.danger:hover{background:rgba(239,68,68,.1)}
.user-dropdown hr{height:1px;background:var(--border);border:none;margin:4px 0}

/* Content */
.shell-content{
  flex:1;
  padding:20px;
  max-width:1200px;
  width:100%;
  margin:0 auto;
}

/* Footer */
.shell-footer{
  padding:14px 20px;
  border-top:1px solid var(--border);
  font-size:11px;
  color:var(--text3);
  display:flex;
  align-items:center;
  justify-content:space-between;
  flex-wrap:wrap;
  gap:8px;
}
.shell-footer a{color:var(--text3);text-decoration:none}
.shell-footer a:hover{color:var(--text2)}

/* ═══════ Shared Components ═══════ */

/* Cards */
.sh-card{
  background:var(--card);
  border:1px solid var(--border);
  border-radius:var(--radius-lg);
  padding:20px;
  transition:all .25s var(--ease);
}
.sh-card:hover{border-color:var(--border2);box-shadow:var(--shadow-sm)}
.sh-card-header{font-size:16px;font-weight:700;margin-bottom:12px;color:var(--white)}

/* Buttons */
.sh-btn{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:9px 18px;
  border-radius:var(--radius);
  font-size:13px;
  font-weight:600;
  transition:all .2s var(--ease);
  border:none;
  cursor:pointer;
  text-decoration:none;
}
.sh-btn-pri{background:linear-gradient(135deg,var(--pri),var(--pri3));color:#fff;box-shadow:0 2px 8px var(--pri-glow)}
.sh-btn-pri:hover{transform:translateY(-1px);box-shadow:0 4px 16px var(--pri-glow)}
.sh-btn-ghost{background:transparent;color:var(--text2);border:1px solid var(--border)}
.sh-btn-ghost:hover{background:var(--surface);color:var(--text)}
.sh-btn-sm{padding:5px 12px;font-size:12px}
.sh-btn-danger{background:rgba(239,68,68,.1);color:var(--red)}
.sh-btn-danger:hover{background:rgba(239,68,68,.2)}

/* Tags */
.sh-tag{
  display:inline-flex;
  align-items:center;
  padding:3px 10px;
  border-radius:12px;
  font-size:11px;
  font-weight:600;
  background:rgba(124,58,237,.12);
  color:var(--pri2);
  border:1px solid rgba(124,58,237,.15);
}

/* Toast */
.sh-toast{
  position:fixed;
  bottom:24px;
  left:50%;
  transform:translateX(-50%);
  background:var(--card);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:12px 24px;
  font-size:13px;
  color:var(--text);
  box-shadow:var(--shadow-lg);
  z-index:9999;
  animation:toast-in .3s var(--ease);
}
.sh-toast.error{border-color:rgba(239,68,68,.3);color:var(--red)}
.sh-toast.success{border-color:rgba(16,185,129,.3);color:var(--green)}

/* Badge */
.sh-badge{
  padding:2px 8px;
  border-radius:10px;
  font-size:10px;
  font-weight:700;
  line-height:1.5;
}
.sh-badge-new{background:var(--pri);color:#fff}
.sh-badge-beta{background:var(--gold);color:#000}

/* Empty state */
.sh-empty{
  text-align:center;
  padding:60px 20px;
  color:var(--text3);
}
.sh-empty .icon{font-size:48px;margin-bottom:16px;opacity:.5}
.sh-empty h3{font-size:18px;color:var(--text2);margin-bottom:8px}
.sh-empty p{font-size:13px;max-width:360px;margin:0 auto 20px;line-height:1.6}

/* Skeleton */
.sh-skeleton{
  background:linear-gradient(90deg,var(--surface) 25%,var(--card) 50%,var(--surface) 75%);
  background-size:200% 100%;
  animation:shimmer 1.5s infinite;
  border-radius:var(--radius-sm);
}
.sh-skeleton-text{height:14px;margin-bottom:8px}
.sh-skeleton-title{height:20px;width:60%;margin-bottom:12px}
.sh-skeleton-card{height:120px;margin-bottom:12px}

/* Page header */
.page-header{
  display:flex;
  align-items:center;
  justify-content:space-between;
  margin-bottom:24px;
  flex-wrap:wrap;
  gap:12px;
}
.page-header h1{font-size:24px;font-weight:800;letter-spacing:-.5px}
.page-header .breadcrumb{
  font-size:12px;
  color:var(--text3);
  display:flex;
  align-items:center;
  gap:6px;
}
.page-header .breadcrumb a{color:var(--text3)}
.page-header .breadcrumb a:hover{color:var(--pri2)}
.page-header .breadcrumb .sep{color:var(--text3);margin:0 2px}

/* Stats row */
.stats-row{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:12px;margin-bottom:24px}
.stat-card{
  background:var(--card);
  border:1px solid var(--border);
  border-radius:var(--radius-lg);
  padding:16px;
  display:flex;
  align-items:center;
  gap:14px;
  transition:all .25s var(--ease);
}
.stat-card:hover{border-color:var(--border2)}
.stat-icon{
  width:44px;height:44px;
  border-radius:12px;
  display:flex;
  align-items:center;
  justify-content:center;
  font-size:20px;
  flex-shrink:0;
}
.stat-icon.purple{background:rgba(124,58,237,.15);color:var(--pri2)}
.stat-icon.green{background:rgba(16,185,129,.15);color:var(--green)}
.stat-icon.blue{background:rgba(59,130,246,.15);color:var(--blue)}
.stat-icon.gold{background:rgba(212,168,83,.15);color:var(--gold)}
.stat-info{flex:1;min-width:0}
.stat-value{font-size:22px;font-weight:800;line-height:1.2;color:var(--white)}
.stat-label{font-size:11px;color:var(--text3);margin-top:2px}

/* Grid */
.grid-2{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:16px}
.grid-3{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:14px}

/* ═══════ Animations ═══════ */
@keyframes fade-in{from{opacity:0;transform:translateY(-4px)}to{opacity:1;transform:translateY(0)}}
@keyframes toast-in{from{opacity:0;transform:translate(-50%,10px)}to{opacity:1;transform:translate(-50%,0)}}
@keyframes shimmer{0%{background-position:200% 0}100%{background-position:-200% 0}}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:.5}}

/* ═══════ Responsive ═══════ */
@media(max-width:768px){
  .shell-sidebar{transform:translateX(-100%)}
  .shell-sidebar.open{transform:translateX(0)}
  .shell-main{margin-left:0}
  .shell-topbar{padding:0 12px}
  .topbar-left .search-box{max-width:200px}
  .shell-content{padding:12px}
  .page-header h1{font-size:20px}
  .stats-row{grid-template-columns:repeat(2,1fr)}

  /* Mobile hamburger */
  .mobile-toggle{
    display:flex !important;
    width:36px;height:36px;
    align-items:center;
    justify-content:center;
    border-radius:8px;
    font-size:20px;
    color:var(--text2);
    cursor:pointer;
    margin-right:8px;
  }
}
@media(min-width:769px){.mobile-toggle{display:none !important}}

/* ═══════ Dark scrollbar ═══════ */
::-webkit-scrollbar{width:6px;height:6px}
::-webkit-scrollbar-track{background:transparent}
::-webkit-scrollbar-thumb{background:var(--border2);border-radius:3px}
::-webkit-scrollbar-thumb:hover{background:var(--text3)}

/* ═══ 浅色模式 ═══ */
body.light-mode {
  --bg: #f5f5f7;
  --card: #ffffff;
  --card2: #f0f0f5;
  --pri: #6366f1;
  --pri2: #4f46e5;
  --text: #1e1e2e;
  --sub: #6b6b80;
  --green: #16a34a;
  --red: #dc2626;
  --orange: #d97706;
  --border: #e2e2e8;
  --hover: #f0f0f5;
  --sidebar-bg: #1e1e2e;
  --sidebar-text: #e0e0f0;
  --topbar-bg: #ffffff;
  --shadow: 0 2px 12px rgba(0,0,0,.06);
}
body.light-mode .shell-sidebar {
  background: var(--sidebar-bg);
}
body.light-mode .shell-sidebar * {
  color: var(--sidebar-text);
}
body.light-mode .shell-topbar {
  background: var(--topbar-bg);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
}
body.light-mode .sidebar-brand { color: #fff; }

/* ═══ 通知下拉 ═══ */
.notif-dropdown {
  position: fixed;
  width: 320px;
  max-height: 360px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: 0 12px 40px rgba(0,0,0,.35);
  z-index: 200;
  overflow: hidden;
}
.notif-header {
  padding: 14px 16px;
  border-bottom: 1px solid var(--border);
  font-size: 14px;
}
.notif-list { max-height: 300px; overflow-y: auto; }
.notif-empty { padding: 24px; text-align: center; color: var(--sub); font-size: 13px; }
.notif-item { padding: 12px 16px; border-bottom: 1px solid var(--border); cursor: pointer; transition: background .15s; }
.notif-item:hover { background: var(--hover); }
.notif-item-title { font-size: 13px; margin-bottom: 2px; }
.notif-item-time { font-size: 11px; color: var(--sub); }