:root {
  --bg: #eef5f2;
  --card: #ffffff;
  --primary: #2f9e8f;
  --primary-soft: #e3f3ef;
  --text: #243a35;
  --muted: #7c928c;
  --line: #e4ece9;
  --radius: 16px;
  --shadow: 0 4px 20px rgba(47, 158, 143, 0.08);
  --tabbar-h: 64px;
  --topbar-h: 54px;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg); color: var(--text); line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  overflow: hidden; height: 100dvh;
}
.hidden { display: none !important; }
.muted { color: var(--muted); font-size: 13px; margin-top: 6px; }

/* ---------- 登录 ---------- */
.auth-view {
  height: 100dvh; display: flex; align-items: center; justify-content: center;
  padding: 20px; background: linear-gradient(160deg, #ddeeec 0%, #eef5f2 100%);
}
.auth-card {
  width: 100%; max-width: 360px; background: var(--card);
  border-radius: var(--radius); box-shadow: var(--shadow); padding: 28px 22px;
}
.brand { text-align: center; margin-bottom: 20px; }
.brand-logo { font-size: 40px; }
.brand h1 { font-size: 24px; letter-spacing: 4px; margin-top: 4px; }
.brand-sub { color: var(--muted); font-size: 13px; margin-top: 2px; }
.tabs { display: flex; gap: 8px; margin-bottom: 16px; }
.tab { flex:1; padding:10px; border:none; border-radius:10px; background:var(--bg); color:var(--muted); font-size:14px; cursor:pointer; }
.tab.active { background: var(--primary); color: #fff; }
.auth-form { display: flex; flex-direction: column; gap: 10px; }
.inp, .auth-form input {
  width:100%; padding:11px 14px; border:1px solid var(--line); border-radius:10px;
  font-size:15px; background:#fbfdfc; outline:none; transition:border-color .2s;
}
.inp:focus, .auth-form input:focus { border-color: var(--primary); }
.btn-primary {
  padding:11px; border:none; border-radius:10px; background:var(--primary);
  color:#fff; font-size:15px; cursor:pointer; transition:opacity .2s;
}
.btn-primary:hover { opacity:.9; }
.btn-ghost {
  padding:8px 12px; border:1px solid var(--line); border-radius:10px;
  background:#fff; color:var(--text); font-size:13px; cursor:pointer;
}
.btn-ghost:hover { background:var(--bg); }
.auth-msg { text-align:center; color:#d9534f; font-size:13px; min-height:18px; margin-top:8px; }

/* ---------- 主视图 ---------- */
.home-view {
  height: 100dvh; display: flex; flex-direction: column;
  background: var(--bg);
}
.topbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 16px; height: var(--topbar-h); background: var(--card);
  box-shadow: 0 1px 8px rgba(47,158,143,0.06); flex-shrink:0;
}
.topbar-title { font-size: 17px; font-weight: 600; letter-spacing: 1px; }
.topbar-user { display: flex; align-items: center; gap: 10px; font-size: 13px; color: var(--muted); }
.topbar-user #user-name { display: flex; align-items: center; }

.main-content {
  flex:1; overflow:hidden; position:relative;
  display:flex; flex-direction:column;
}

/* ---------- 面板系统 ---------- */
.panel {
  display: none; flex:1; overflow:hidden;
}
.panel.active { display: flex; flex-direction: column; }
.panel-scroll {
  flex:1; overflow-y:auto; -webkit-overflow-scrolling:touch;
  padding: 12px 12px 8px; display:flex; flex-direction:column; gap:12px;
}

/* ---------- TabBar（手机） ---------- */
.tabbar {
  display: flex; background: var(--card); border-top: 1px solid var(--line);
  height: var(--tabbar-h); flex-shrink:0;
}
.tabbar-item {
  flex:1; display:flex; flex-direction:column; align-items:center;
  justify-content:center; gap:2px; border:none; background:transparent;
  color:var(--muted); font-size:11px; cursor:pointer; padding:4px 0;
  transition:color .2s; position:relative;
}
.tabbar-item.active { color: var(--primary); }
.tabbar-item.active::after {
  content:''; position:absolute; top:0; left:20%; right:20%; height:2px;
  background:var(--primary); border-radius:0 0 2px 2px;
}
.tabbar-icon { font-size:20px; line-height:1; }
.tabbar-label { font-size:10px; }

/* ---------- 卡片 ---------- */
.card {
  background: var(--card); border-radius: var(--radius); padding: 16px;
  box-shadow: var(--shadow);
}
.card h2 { font-size: 15px; margin-bottom: 10px; font-weight: 600; }
.row { display: flex; gap: 8px; flex-wrap: wrap; }
.streak { font-size:14px; margin-bottom:10px; }
.streak b { color:var(--primary); font-size:18px; }
.status-pills { display:flex; gap:6px; margin-bottom:10px; flex-wrap:wrap; }
.pill {
  padding:7px 12px; border:1px solid var(--line); border-radius:16px;
  background:#fff; color:var(--text); font-size:13px; cursor:pointer;
}
.pill.active { background:var(--primary); color:#fff; border-color:var(--primary); }

.list { list-style:none; margin-top:8px; display:flex; flex-direction:column; gap:6px; }
.list li { padding:8px 10px; background:var(--bg); border-radius:10px; font-size:13px; }
.list li a { color:var(--primary); text-decoration:none; }
.list li .ans { color:var(--muted); display:block; margin-top:3px; font-size:12px; }

.mini-form { display:flex; gap:6px; margin-top:10px; flex-wrap:wrap; }
.mini-form .inp { flex:1; min-width:100px; }

/* ---------- 聊天 ---------- */
.chat-box {
  height: 45vh; max-height:400px; overflow-y:auto; background:var(--bg);
  border-radius:12px; padding:10px; display:flex; flex-direction:column; gap:6px;
}
.chat-box .msg { font-size:14px; }
.chat-box .msg b { color:var(--primary); }
.chat-box .sys { color:var(--muted); font-size:12px; text-align:center; }

/* ---------- 监督 ---------- */
.monitor-mode { display:flex; gap:6px; flex-wrap:wrap; margin-bottom:10px; }
.cam-container {
  position:relative; width:100%; border-radius:12px; overflow:hidden;
  background:#000; aspect-ratio:4/3;
}
.cam { width:100%; height:100%; object-fit:cover; }
.cam-mask {
  position:absolute; top:50%; left:50%; transform:translate(-50%,-50%);
  font-size:80px; pointer-events:none; user-select:none; opacity:0.8;
  filter:drop-shadow(0 2px 8px rgba(0,0,0,0.3));
}
.cam-controls {
  display:flex; align-items:center; gap:8px; margin-top:10px; flex-wrap:wrap;
}
.toggle-label {
  display:flex; align-items:center; gap:4px; font-size:13px; color:var(--text);
  cursor:pointer;
}
.toggle-label input[type="checkbox"] {
  width:16px; height:16px; accent-color:var(--primary);
}

/* ---------- 桌面端（≥760px） ---------- */
@media (min-width: 760px) {
  .tabbar { display: none; }
  .home-view { flex-direction: row; }
  .topbar { display: none; }
  .main-content { flex:1; }
  .panel.active { display: flex; }
  .panel-scroll {
    max-width: 900px; margin: 0 auto; width:100%;
    display: grid; grid-template-columns: 1fr 1fr; gap: 16px; padding: 20px;
  }
  .panel-scroll > .card-chat { grid-column: 1 / -1; }
  .panel-scroll > .card { margin:0; }
  /* 桌面侧边导航 */
  .home-view::before {
    content: ''; width: 200px; flex-shrink:0;
    background: var(--card); border-right: 1px solid var(--line);
    background-image:
      radial-gradient(circle at 50% 60px, var(--primary-soft) 0%, transparent 70%),
      url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='%232f9e8f' opacity='0.06'%3E%3Crect x='2' y='2' width='20' height='4' rx='2'/%3E%3Crect x='2' y='10' width='16' height='4' rx='2'/%3E%3Crect x='2' y='18' width='12' height='4' rx='2'/%3E%3C/svg%3E");
    background-repeat: no-repeat, repeat;
    background-position: center 60px, 0 0;
    background-size: auto, 24px;
    padding-top: 80px;
  }
  .home-view::after {
    content: '📚 自习室' ' AA.warte.top';
    position: fixed; left: 0; top: 0; width: 200px;
    display: flex; flex-direction: column; align-items: center;
    padding: 24px 12px; font-size: 18px; font-weight: 600;
    color: var(--primary); letter-spacing: 2px;
    background: var(--card);
  }
}

/* ---------- 管理员截图 ---------- */
.snap-grid { display:grid; grid-template-columns:repeat(auto-fill,minmax(110px,1fr)); gap:10px; margin-top:10px; }
.snap-card { background:var(--bg); border-radius:10px; padding:6px; text-align:center; cursor:pointer; }
.snap-card:hover { background:var(--primary-soft); }
.snap-card img { width:100%; height:80px; object-fit:cover; border-radius:6px; background:#ccc; }
.snap-card span { display:block; font-size:11px; margin-top:3px; color:var(--text); }
.live-view { margin-top:14px; border-top:1px solid var(--line); padding-top:12px; }
.live-img { width:100%; max-height:320px; object-fit:contain; border-radius:10px; background:#000; margin-top:6px; }

/* ---------- Toast ---------- */
.toast {
  position:fixed; bottom:80px; left:50%; transform:translateX(-50%);
  background:var(--text); color:#fff; padding:8px 16px; border-radius:16px;
  font-size:13px; z-index:100; opacity:0; transition:opacity .25s; pointer-events:none;
}
.toast.show { opacity:.95; }