:root {
  --bg: #f8fafc;--card: #fff;--text: #1e293b;--muted: #94a3b8;--border: #e2e8f0;
  --primary: #6366f1;--danger: #ef4444;--success: #16a34a;--warning: #f59e0b;--radius: 12px;
}
*{margin:0;padding:0;box-sizing:border-box}
body{font-family:'PingFang SC','Microsoft YaHei',sans-serif;background:var(--bg);color:var(--text);min-height:100vh}
.app{max-width:480px;margin:0 auto;min-height:100vh;position:relative}

.navbar{background:var(--card);border-bottom:1px solid var(--border);padding:0 16px;height:56px;display:flex;align-items:center;justify-content:space-between;position:sticky;top:0;z-index:50}
.navbar-brand{font-weight:700;font-size:16px;display:flex;align-items:center;gap:8px}
.icon-sm{width:32px;height:32px;background:linear-gradient(135deg,var(--primary),#8b5cf6);border-radius:8px;display:flex;align-items:center;justify-content:center;font-size:16px}
.navbar-user{font-size:13px;color:var(--muted);display:flex;align-items:center;gap:8px}
.role-badge{padding:2px 8px;border-radius:10px;font-size:11px;font-weight:600}
.role-admin{background:#eef2ff;color:var(--primary)}.role-student{background:#f1f5f9;color:var(--muted)}
.btn-logout{padding:6px 12px;border:1px solid var(--border);border-radius:8px;background:var(--card);color:var(--text);font-size:12px;cursor:pointer}

.tabbar{position:fixed;bottom:0;left:50%;transform:translateX(-50%);width:100%;max-width:480px;background:var(--card);border-top:1px solid var(--border);display:flex;height:56px;z-index:50}
.tabbar-item{flex:1;display:flex;flex-direction:column;align-items:center;justify-content:center;font-size:11px;color:var(--muted);cursor:pointer;border:none;background:none;transition:color .15s}
.tabbar-item.active{color:var(--primary)}.tabbar-item .tab-icon{font-size:20px;margin-bottom:2px}

.page{display:none;padding:16px;padding-bottom:72px}.page.active{display:block}
.card{background:var(--card);border-radius:var(--radius);padding:20px;box-shadow:0 1px 3px rgba(0,0,0,.06);margin-bottom:16px}
.card-title{font-size:14px;font-weight:700;margin-bottom:12px;display:flex;align-items:center;gap:8px}

.form-group{margin-bottom:12px}.form-label{display:block;font-size:13px;font-weight:600;margin-bottom:4px}
.form-input,.form-textarea,.form-select{width:100%;padding:10px 14px;border:1px solid var(--border);border-radius:10px;font-size:14px;outline:none;background:var(--bg);color:var(--text)}
.form-input:focus,.form-textarea:focus,.form-select:focus{border-color:var(--primary);box-shadow:0 0 0 3px rgba(99,102,241,.08)}
.form-textarea{resize:vertical;min-height:80px;font-family:inherit}.form-select{cursor:pointer}

.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;padding:10px 20px;border-radius:10px;font-size:14px;font-weight:600;cursor:pointer;border:none}
.btn:active{opacity:.75}.btn-primary{background:linear-gradient(135deg,var(--primary),#8b5cf6);color:#fff;width:100%}
.btn-outline{background:var(--card);border:1px solid var(--border);color:var(--text)}
.btn-danger{background:var(--danger);color:#fff}.btn-success{background:var(--success);color:#fff}
.btn-warning{background:var(--warning);color:#fff}
.btn-sm{padding:6px 12px;font-size:12px}.btn-block{width:100%}.btn-xs{padding:3px 8px;font-size:10px;border-radius:6px}

.toast{position:fixed;top:16px;left:50%;transform:translateX(-50%);z-index:200;padding:10px 20px;border-radius:10px;font-size:13px;font-weight:500;display:none;max-width:90vw;text-align:center;animation:toastIn .25s}
.toast-error{background:#fef2f2;color:var(--danger);border:1px solid #fecaca}
.toast-success{background:#f0fdf4;color:var(--success);border:1px solid #bbf7d0}
.toast-info{background:#eff6ff;color:var(--primary);border:1px solid #bfdbfe}
@keyframes toastIn{from{opacity:0;transform:translateX(-50%) translateY(-10px)}to{opacity:1;transform:translateX(-50%) translateY(0)}}

.quick-actions{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:16px}
.quick-action{background:var(--card);border-radius:var(--radius);padding:16px;cursor:pointer;border:1px solid var(--border);display:flex;align-items:center;gap:10px;font-size:14px;font-weight:600}
.quick-action:active{border-color:var(--primary);opacity:.8}.quick-action .qa-icon{font-size:24px}
.announcement{background:#eff6ff;border-left:3px solid var(--primary);padding:10px 14px;border-radius:0 8px 8px 0;margin-bottom:8px;font-size:13px;display:flex;align-items:center;justify-content:space-between}
.save-item{display:flex;align-items:center;gap:12px;padding:12px;border:1px solid var(--border);border-radius:10px;margin-bottom:8px}
.save-item .si-icon{width:36px;height:36px;border-radius:8px;display:flex;align-items:center;justify-content:center;font-size:18px;flex-shrink:0}
.save-item .si-info{flex:1;min-width:0}.save-item .si-title{font-size:13px;font-weight:600}.save-item .si-meta{font-size:11px;color:var(--muted)}
.skeleton{background:linear-gradient(90deg,var(--border) 25%,#f1f5f9 50%,var(--border) 75%);background-size:200% 100%;animation:shimmer 1.5s infinite;border-radius:6px;height:14px;margin-bottom:8px}
@keyframes shimmer{0%{background-position:200% 0}100%{background-position:-200% 0}}
.spinner{width:20px;height:20px;border:2px solid var(--border);border-top-color:var(--primary);border-radius:50%;animation:spin .6s linear infinite;margin:20px auto}
@keyframes spin{to{transform:rotate(360deg)}}

.admin-tabs{display:flex;gap:4px;margin-bottom:16px;overflow-x:auto;flex-wrap:wrap}
.admin-tab{padding:6px 10px;border:1px solid var(--border);border-radius:8px;font-size:11px;font-weight:500;cursor:pointer;white-space:nowrap;background:var(--card);color:var(--muted)}
.admin-tab.active{background:var(--primary);color:#fff;border-color:var(--primary)}

.voc-preview-table{width:100%;font-size:12px;border-collapse:collapse}
.voc-preview-table td{padding:6px 8px;border-bottom:1px solid var(--border)}.vp-check{width:30px;text-align:center}
.simple-table{width:100%;font-size:12px;border-collapse:collapse}.simple-table td,.simple-table th{padding:6px 8px;border-bottom:1px solid var(--border);text-align:left}
.simple-table th{font-weight:600;color:var(--muted);font-size:11px}

.train-header{background:var(--card);border-bottom:1px solid var(--border);padding:12px 16px;display:flex;align-items:center;gap:12px;position:sticky;top:0;z-index:40}
.train-header .back-btn{font-size:20px;cursor:pointer;padding:4px;color:var(--muted)}
.train-info{flex:1;min-width:0}.train-title{font-size:14px;font-weight:600}.train-sub{font-size:11px;color:var(--muted)}.train-timer{font-size:12px;color:var(--muted);font-family:monospace}

.chat-area{flex:1;overflow-y:auto;padding:16px;padding-bottom:80px;min-height:60vh;max-height:calc(100vh-180px)}
.chat-msg{display:flex;margin-bottom:12px;animation:fadeIn .3s}.chat-msg.user{justify-content:flex-end}
.chat-msg .bubble{max-width:80%;padding:10px 14px;border-radius:16px;font-size:14px;line-height:1.5;word-break:break-word}
.chat-msg.user .bubble{background:linear-gradient(135deg,var(--primary),#8b5cf6);color:#fff;border-bottom-right-radius:4px}
.chat-msg.agent .bubble,.chat-msg.system .bubble{background:var(--card);border:1px solid var(--border);border-bottom-left-radius:4px}
.chat-msg.system{justify-content:center}.chat-msg.system .bubble{background:var(--bg);border:none;color:var(--muted);font-size:12px;padding:6px 14px;border-radius:20px}
@keyframes fadeIn{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:translateY(0)}}

.chat-input-bar{position:fixed;bottom:0;left:50%;transform:translateX(-50%);width:100%;max-width:480px;background:var(--card);border-top:1px solid var(--border);padding:10px 16px;display:flex;gap:8px;z-index:50}
.chat-input-bar textarea{flex:1;border:1px solid var(--border);border-radius:20px;padding:8px 14px;font-size:14px;outline:none;resize:none;background:var(--bg);color:var(--text);max-height:80px;font-family:inherit}
.chat-input-bar textarea:focus{border-color:var(--primary)}
.chat-input-bar button{width:40px;height:40px;border-radius:50%;border:none;background:linear-gradient(135deg,var(--primary),#8b5cf6);color:#fff;font-size:18px;cursor:pointer}

.voc-cat-item{display:flex;align-items:center;justify-content:space-between;padding:14px 16px;border:1px solid var(--border);border-radius:10px;margin-bottom:8px;cursor:pointer;font-size:14px;font-weight:500}
.voc-cat-item:active{border-color:var(--primary);opacity:.8}.voc-cat-item .count{font-size:12px;color:var(--muted)}
.cascade-path{display:flex;align-items:center;gap:6px;flex-wrap:wrap;margin-bottom:12px;font-size:13px;color:var(--muted)}
.cascade-path span{color:var(--primary);font-weight:600}
.empty-state{text-align:center;padding:40px 20px;color:var(--muted)}.empty-icon{font-size:48px;margin-bottom:12px}
.logo-big{width:72px;height:72px;background:linear-gradient(135deg,#6366f1,#8b5cf6);border-radius:20px;display:flex;align-items:center;justify-content:center;margin:0 auto 16px;font-size:36px}
.link-text{text-align:center;margin-top:12px;font-size:13px;color:var(--primary);cursor:pointer}

.debug-panel{background:#fefce8;border:1px solid #fde68a;border-radius:8px;padding:8px 12px;margin-bottom:12px;font-size:11px}
.mini-bar{background:#e5e7eb;border-radius:4px;height:8px;margin:4px 0}.mini-bar div{border-radius:4px;height:8px}
.lb-row{display:flex;align-items:center;gap:8px;padding:8px;border-bottom:1px solid var(--border);font-size:13px}
.lb-row.lb-me{background:#eef2ff;border-radius:6px}.lb-rank{width:24px;text-align:center}.lb-name{flex:1;font-weight:600}.lb-group{font-size:11px;color:var(--muted);max-width:60px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}.lb-score{font-weight:700;color:var(--primary)}

.stat-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:16px}
.stat-box{background:var(--card);border-radius:var(--radius);padding:16px;text-align:center;box-shadow:0 1px 3px rgba(0,0,0,.06)}
.stat-val{font-size:28px;font-weight:800}.stat-lbl{font-size:11px;color:var(--muted);margin-top:2px}

.log-row{display:flex;align-items:center;gap:8px;padding:6px 0;border-bottom:1px solid var(--border);font-size:12px}

.mode-select{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin:16px 0}
.mode-card{background:var(--card);border:2px solid var(--border);border-radius:var(--radius);padding:20px;text-align:center;cursor:pointer;font-size:15px;font-weight:600;transition:border-color .2s}
.mode-card:hover{border-color:var(--primary)}.mode-icon{font-size:32px;margin-bottom:8px}
.typing-bubble{color:var(--muted)!important}

@media(min-width:768px){.app{max-width:720px}}