/* Mobile-first Responsive CSS */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{--primary:#3b82f6;--primary-dark:#2563eb;--success:#10b981;--danger:#ef4444;--warning:#f59e0b;--bg:#0f172a;--bg-card:#1e293b;--bg-input:#334155;--text:#f1f5f9;--text-muted:#94a3b8;--border:#334155;--radius:10px;--shadow:0 4px 20px rgba(0,0,0,.3);--safe-bottom:env(safe-area-inset-bottom, 12px)}
html{font-size:16px;-webkit-text-size-adjust:100%;-ms-text-size-adjust:100%}
body{
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,'PingFang SC','Microsoft YaHei',sans-serif;
  background:var(--bg);color:var(--text);line-height:1.6;
  min-height:100vh;overflow-x:hidden;
  -webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;
}
a{color:var(--primary);text-decoration:none;-webkit-tap-highlight-color:transparent}
img{max-width:100%;height:auto}
.container{max-width:1280px;margin:0 auto;padding:0 12px}

/* Touch-friendly buttons: min 44px tap target */
button, .btn, [role="button"], a.btn, a.nav-link {
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}

/* Prevent form zoom on iOS */
input[type="text"], input[type="search"], input[type="password"],
input[type="email"], textarea, select {
  font-size: 16px !important;
}

/* Buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;padding:10px 20px;border-radius:var(--radius);font-size:14px;font-weight:600;cursor:pointer;border:2px solid transparent;white-space:nowrap;touch-action:manipulation}
.btn-primary{background:var(--primary);color:#fff;border-color:var(--primary)}
.btn-success{background:var(--success);color:#fff}
.btn-outline{background:transparent;border-color:var(--border);color:var(--text)}
.btn-danger{background:var(--danger);color:#fff}
.btn-sm{padding:6px 14px;font-size:13px}
.btn-lg{padding:14px 28px;font-size:16px}
.btn-block{width:100%}
.btn:disabled{opacity:.5}

/* Header */
.site-header{background:rgba(15,23,42,.95);backdrop-filter:blur(12px);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:100}
.header-inner{display:flex;align-items:center;justify-content:space-between;padding:10px 16px;flex-wrap:wrap}
.logo{font-size:20px;font-weight:800;color:var(--text)!important}
.menu-toggle{display:none;background:none;border:none;color:var(--text);font-size:26px;cursor:pointer;padding:4px 8px}
.main-nav{display:flex;gap:2px;flex-wrap:wrap}
.nav-link{padding:8px 12px;border-radius:var(--radius);color:var(--text-muted)!important;font-size:14px;font-weight:500}
.nav-link:hover{background:var(--bg-card);color:var(--text)!important}
.user-nav{display:flex;gap:6px;align-items:center}
.user-dropdown{position:relative}
.btn-user{background:var(--bg-card);border:1px solid var(--border);color:var(--text);padding:7px 14px;border-radius:var(--radius);cursor:pointer;font-size:14px}
.dropdown-menu{display:none;position:absolute;right:0;top:100%;margin-top:4px;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);min-width:130px;overflow:hidden;z-index:50}
.dropdown-menu a{display:block;padding:10px 14px;color:var(--text)!important;font-size:14px}
.dropdown-menu a:hover{background:var(--bg-input)}

/* Mobile nav */
@media(max-width:768px){
  .menu-toggle{display:block}
  .main-nav{display:none;flex-direction:column;width:100%;padding:8px 0}
  .main-nav.open{display:flex}
  .logo{font-size:18px}
}

/* Hero */
.hero{text-align:center;padding:40px 16px 30px;background:linear-gradient(135deg,#1e293b,#0f172a,#1e293b);border-radius:0 0 24px 24px;margin-bottom:30px}
.hero h1{font-size:28px;margin-bottom:8px}
.hero-subtitle{color:var(--text-muted);font-size:15px;margin-bottom:24px}
.hero-stats{display:flex;justify-content:center;gap:12px;flex-wrap:wrap}
.stat-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:16px 24px;text-align:center;min-width:80px;flex:1}
.stat-number{font-size:28px;font-weight:800;color:var(--primary)}
.stat-label{font-size:12px;color:var(--text-muted);margin-top:2px}
.stat-card.highlight .stat-number{color:var(--warning)}

@media(max-width:480px){
  .hero h1{font-size:22px}
  .hero{padding:28px 12px 20px}
  .stat-card{padding:12px 16px}
  .stat-number{font-size:22px}
}

/* Home sections */
.home-sections{display:flex;flex-direction:column;gap:36px;padding-bottom:40px}
.section-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px;flex-wrap:wrap;gap:8px}
.section-header h2{font-size:18px}

/* Grids */
.analysis-grid,.video-grid,.links-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:12px}
.books-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(160px,1fr));gap:12px}
@media(max-width:480px){
  .analysis-grid,.video-grid,.links-grid{grid-template-columns:1fr}
  .books-grid{grid-template-columns:repeat(2,1fr)}
}

/* Cards */
.analysis-card,.video-card,.book-card{display:block;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);color:var(--text)!important;overflow:hidden}
.analysis-card{padding:16px}
.card-badge{display:inline-block;background:rgba(59,130,246,.2);color:var(--primary);padding:2px 8px;border-radius:20px;font-size:12px;font-weight:600;margin-bottom:6px}
.analysis-card h3,.video-card h4,.book-card h4{font-size:15px;margin-bottom:6px}
.card-summary{font-size:13px;color:var(--text-muted);margin-bottom:10px;display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden}
.card-meta{display:flex;gap:10px;font-size:12px;color:var(--text-muted);flex-wrap:wrap}
.model-badge{background:rgba(16,185,129,.2);color:var(--success);padding:1px 6px;border-radius:20px;font-size:11px}
.file-type-badge{background:rgba(245,158,11,.2);color:var(--warning);padding:1px 6px;border-radius:4px;font-size:10px;font-weight:700}

/* Video thumb */
.video-thumb{background:linear-gradient(135deg,#1e3a5f,#0f172a);height:140px;display:flex;align-items:center;justify-content:center;position:relative}
.play-icon{font-size:36px;opacity:.8}
.duration-badge{position:absolute;bottom:6px;right:6px;background:rgba(0,0,0,.8);padding:2px 6px;border-radius:4px;font-size:11px}
.category-tag{position:absolute;top:6px;left:6px;background:var(--primary);padding:2px 8px;border-radius:4px;font-size:10px}
.video-card h4{padding:10px 12px 4px}
.video-card .card-meta{padding:0 12px 12px}

/* Book */
.book-cover{width:100%;height:200px;background:var(--bg-input);display:flex;align-items:center;justify-content:center;overflow:hidden}
.book-cover img{width:100%;height:100%;object-fit:cover}
.book-cover-placeholder{font-size:50px}
.book-cover-placeholder.large{font-size:70px;min-height:200px;display:flex;align-items:center;justify-content:center}
.book-card h4{padding:10px 10px 4px;font-size:13px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.book-card .card-meta{padding:0 10px}
.book-card-footer{padding:8px 10px 10px;font-size:11px;color:var(--text-muted);display:flex;justify-content:space-between}

/* Auth */
.auth-page{display:flex;align-items:center;justify-content:center;min-height:60vh;padding:30px 16px}
.auth-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:32px 24px;width:100%;max-width:400px}
.auth-card h1{text-align:center;margin-bottom:24px;font-size:22px}
.auth-form{display:flex;flex-direction:column;gap:14px}
.form-group label{display:block;margin-bottom:4px;font-size:13px;font-weight:500;color:var(--text-muted)}
.form-group input,.form-group textarea,.form-group select{width:100%;padding:10px 12px;background:var(--bg-input);border:1px solid var(--border);border-radius:8px;color:var(--text);font-size:15px;outline:none;font-family:inherit;-webkit-appearance:none}
.form-group input:focus,.form-group textarea:focus{border-color:var(--primary)}
.form-group textarea{resize:vertical}
.required{color:var(--danger)}
.form-hint{font-size:12px;color:var(--text-muted);margin-top:3px}
.auth-switch{text-align:center;margin-top:16px;font-size:14px;color:var(--text-muted)}
.alert{padding:12px 14px;border-radius:8px;font-size:14px;margin-bottom:14px}
.alert-error{background:rgba(239,68,68,.15);color:var(--danger);border:1px solid rgba(239,68,68,.3)}
.alert-success{background:rgba(16,185,129,.15);color:var(--success);border:1px solid rgba(16,185,129,.3)}

/* Page header */
.page-header{text-align:center;padding:24px 0 16px}
.page-header h1{font-size:24px;margin-bottom:6px}
.page-desc{color:var(--text-muted);font-size:14px}
.page-actions{margin-top:12px}

/* Category filter */
.category-filter{display:flex;gap:6px;flex-wrap:wrap;margin-bottom:20px;overflow-x:auto}
.filter-tag{padding:6px 12px;border-radius:20px;background:var(--bg-card);border:1px solid var(--border);color:var(--text-muted)!important;font-size:13px;white-space:nowrap}
.filter-tag.active{background:var(--primary);border-color:var(--primary);color:#fff!important}

/* Forum */
.forum-toolbar{display:flex;justify-content:space-between;align-items:center;margin-bottom:16px;flex-wrap:wrap;gap:8px}
.forum-sort{display:flex;gap:6px;flex-wrap:wrap}
.forum-sort a{padding:6px 12px;border-radius:20px;font-size:13px;color:var(--text-muted)!important;background:var(--bg-card);border:1px solid var(--border)}
.forum-sort a.active{background:var(--primary);border-color:var(--primary);color:#fff!important}
.post-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:10px}
.post-card h3{font-size:16px;margin-bottom:6px}
.post-card h3 a{color:var(--text)!important}
.post-preview{font-size:13px;color:var(--text-muted);margin-bottom:10px;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
.post-meta{display:flex;gap:12px;font-size:11px;color:var(--text-muted);flex-wrap:wrap}
.post-cat{background:rgba(59,130,246,.15);color:var(--primary);padding:1px 8px;border-radius:20px;font-size:11px}

/* Forum post detail */
.forum-post-main{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:20px;margin-bottom:20px}
.forum-post-main h1{font-size:20px;margin-bottom:8px}
.post-meta-big{display:flex;gap:12px;font-size:12px;color:var(--text-muted);margin-bottom:16px;flex-wrap:wrap}
.forum-post-body{font-size:15px;line-height:1.8;margin-bottom:16px;word-wrap:break-word;white-space:pre-wrap}
.forum-post-attach{display:flex;gap:8px;flex-wrap:wrap;margin:12px 0}
.attach-item{display:inline-flex;align-items:center;gap:4px;background:var(--bg-input);padding:6px 12px;border-radius:6px;font-size:13px;color:var(--primary)!important}

/* Replies */
.reply-item{background:var(--bg);border:1px solid var(--border);border-radius:8px;padding:14px;margin-bottom:8px}
.reply-floor{font-weight:700;color:var(--primary);font-size:14px;margin-bottom:4px}
.reply-author{font-weight:600;font-size:13px;margin-right:8px}
.reply-time{font-size:11px;color:var(--text-muted)}
.reply-content{font-size:14px;line-height:1.6;margin:8px 0;word-wrap:break-word}
.reply-actions{display:flex;gap:8px;font-size:12px}
.like-btn{background:none;border:none;color:var(--text-muted);cursor:pointer;font-size:13px;padding:2px 8px;border-radius:12px;touch-action:manipulation}
.like-btn.liked{color:var(--danger)}
.reply-form{display:flex;gap:8px;margin:16px 0;flex-wrap:wrap}
.reply-form textarea{flex:1;min-width:200px;padding:10px;background:var(--bg-input);border:1px solid var(--border);border-radius:8px;color:var(--text);font-family:inherit;font-size:15px;resize:vertical}

/* Upload */
.upload-page{padding:20px 0}
.upload-tabs{display:flex;gap:4px;margin-bottom:24px;flex-wrap:wrap;overflow-x:auto}
.upload-tab{padding:12px 20px;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);color:var(--text-muted)!important;font-size:14px;cursor:pointer;text-align:center;flex:1;min-width:100px}
.upload-tab.active{background:var(--primary);border-color:var(--primary);color:#fff!important}
.upload-form{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:20px}
.upload-form h3{margin-bottom:16px;font-size:17px}
.file-drop-zone{border:2px dashed var(--border);border-radius:var(--radius);padding:40px 20px;text-align:center;cursor:pointer;margin-bottom:16px}
.file-drop-zone input[type=file]{display:none}
.file-drop-zone .icon{font-size:40px;margin-bottom:8px}
.file-drop-zone p{color:var(--text-muted);font-size:14px}

/* Articles */
.article-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:10px}
.article-card h3{font-size:16px;margin-bottom:6px}
.article-card h3 a{color:var(--text)!important}
.article-meta{display:flex;gap:10px;font-size:12px;color:var(--text-muted);flex-wrap:wrap}
.ai-analyze-btn{background:linear-gradient(135deg,#8b5cf6,#3b82f6);color:#fff;border:none;padding:8px 16px;border-radius:20px;font-size:13px;cursor:pointer;margin-top:8px;touch-action:manipulation}
.ai-result{background:linear-gradient(135deg,rgba(139,92,246,.1),rgba(59,130,246,.1));border:1px solid rgba(139,92,246,.3);border-radius:var(--radius);padding:16px;margin-top:12px;max-height:60vh;overflow-y:auto;font-size:14px;line-height:1.8}

/* Detail */
.detail-page{max-width:100%;margin:0 auto;padding:16px 0 30px}
.back-link{display:inline-block;margin-bottom:14px;color:var(--text-muted)!important;font-size:14px}
.detail-content{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:20px;overflow-wrap:break-word}
.detail-header{margin-bottom:20px}
.detail-badge{display:inline-block;background:rgba(59,130,246,.2);color:var(--primary);padding:3px 10px;border-radius:20px;font-size:13px;margin-bottom:8px}
.detail-header h1{font-size:20px;margin-bottom:8px}
.detail-meta{display:flex;gap:12px;font-size:12px;color:var(--text-muted);flex-wrap:wrap}
.markdown-body{font-size:15px;line-height:1.8;word-wrap:break-word}
.markdown-body h2{font-size:18px;border-bottom:1px solid var(--border);padding-bottom:6px;margin:20px 0 10px}
.markdown-body h3{font-size:16px;margin:16px 0 8px}
.markdown-body p{margin-bottom:10px}
.markdown-body strong{color:#fbbf24}

/* Comments */
.comments-section{margin-top:30px}
.comments-section h2{margin-bottom:14px;font-size:17px}
.comment-form{display:flex;gap:8px;margin-bottom:16px;flex-wrap:wrap}
.comment-form textarea{flex:1;min-width:200px;padding:10px;background:var(--bg-input);border:1px solid var(--border);border-radius:8px;color:var(--text);resize:vertical;font-family:inherit;font-size:15px}
.comment-item{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:14px;margin-bottom:8px}
.comment-author{font-weight:600;font-size:14px}
.comment-date{font-size:11px;color:var(--text-muted);margin-bottom:6px}
.comment-content{font-size:14px;line-height:1.6}
.comment-login-hint{font-size:14px;color:var(--text-muted);margin-bottom:12px}

/* Video player */
.video-play-page{padding:12px 0 30px}
.video-player-container{background:#000;border-radius:var(--radius);overflow:hidden;margin-bottom:16px}
.video-js{width:100%!important;max-height:60vh}
.video-info-bar{display:flex;gap:14px;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:24px;flex-wrap:wrap}
.video-info{flex:1;min-width:200px}
.video-info h1{font-size:18px;margin-bottom:6px}
.video-meta{display:flex;gap:10px;font-size:12px;color:var(--text-muted);flex-wrap:wrap}

/* Book detail */
.book-detail-layout{display:flex;gap:20px;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:20px;margin-bottom:24px;flex-wrap:wrap}
.book-detail-cover{width:200px;flex-shrink:0;border-radius:8px;overflow:hidden;background:var(--bg-input);display:flex;align-items:center;justify-content:center;min-height:280px}
.book-detail-cover img{width:100%;height:100%;object-fit:cover}
.book-detail-info{flex:1;min-width:250px}
.book-detail-info h1{font-size:20px;margin-bottom:12px}
.book-meta{display:grid;grid-template-columns:1fr 1fr;gap:8px;margin-bottom:14px}
.meta-item{font-size:13px}

/* Links */
.link-card{display:flex;align-items:center;gap:10px;background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:14px;color:var(--text)!important}
.link-icon{font-size:24px;flex-shrink:0}
.link-info{flex:1;min-width:0}
.link-info h4{font-size:14px;margin-bottom:2px}
.link-info p{font-size:12px;color:var(--text-muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.link-category{display:inline-block;background:var(--bg-input);padding:2px 8px;border-radius:20px;font-size:10px;margin-top:2px}
.link-arrow{font-size:18px;color:var(--text-muted)}

/* AI input */
.ai-input-area{max-width:100%;margin:0 auto 30px}
.ai-input-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:20px}
.ai-input-card h3{margin-bottom:12px;font-size:16px}
.input-row{display:flex;gap:8px;margin-bottom:10px;flex-wrap:wrap}
.input-code{flex:1;min-width:120px;padding:10px 12px;background:var(--bg-input);border:1px solid var(--border);border-radius:8px;color:var(--text);font-size:15px}
.input-title{flex:2;min-width:150px;padding:10px 12px;background:var(--bg-input);border:1px solid var(--border);border-radius:8px;color:var(--text);font-size:15px}
#analysisInput{width:100%;padding:12px;background:var(--bg-input);border:1px solid var(--border);border-radius:8px;color:var(--text);font-size:15px;resize:vertical;font-family:inherit}
.ai-actions{display:flex;align-items:center;gap:12px;margin-top:10px;flex-wrap:wrap}
.ai-hint{font-size:12px;color:var(--text-muted)}
.analysis-result{margin-top:20px;padding-top:20px;border-top:1px solid var(--border)}
.analysis-result.hidden{display:none}
.analysis-loading{text-align:center;padding:30px}
.spinner{width:36px;height:36px;border:3px solid var(--border);border-top-color:var(--primary);border-radius:50%;animation:spin .8s linear infinite;margin:0 auto 12px}
@keyframes spin{to{transform:rotate(360deg)}}
.spinner-sm{width:16px;height:16px;border:2px solid rgba(255,255,255,.25);border-top-color:#fff;border-radius:50%;animation:spin .6s linear infinite;display:inline-block;flex-shrink:0}
.analysis-actions{display:flex;gap:8px;flex-wrap:wrap}

/* Admin */
.admin-page h1{margin-bottom:20px}
.admin-stats{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:20px}
.admin-nav{display:flex;border-bottom:2px solid var(--border);margin-bottom:16px;flex-wrap:wrap;overflow-x:auto}
.nav-tab{padding:10px 14px;cursor:pointer;color:var(--text-muted);font-size:13px;font-weight:500;border-bottom:2px solid transparent;margin-bottom:-2px;white-space:nowrap;background:none;border:none}
.nav-tab.active{color:var(--primary);border-bottom-color:var(--primary)}
.tab-panel{display:none}
.tab-panel.active{display:block}
.admin-table{width:100%;border-collapse:collapse;font-size:13px;overflow-x:auto;display:block}
.admin-table thead,.admin-table tbody{display:table;width:100%}
.admin-table th,.admin-table td{padding:8px 10px;text-align:left;border-bottom:1px solid var(--border);white-space:nowrap}
.admin-table th{color:var(--text-muted);font-weight:600;font-size:11px}
.btn-xs{padding:4px 8px;font-size:11px;border-radius:4px;cursor:pointer;border:1px solid var(--border);background:var(--bg-card);color:var(--text)}
.btn-xs.danger{border-color:var(--danger);color:var(--danger)}
.btn-xs.success{border-color:var(--success);color:var(--success)}
.btn-xs.warning{border-color:var(--warning);color:var(--warning)}
.badge{display:inline-block;padding:1px 6px;border-radius:10px;font-size:10px;font-weight:600}
.badge-admin{background:rgba(239,68,68,.2);color:var(--danger)}
.badge-user{background:rgba(59,130,246,.2);color:var(--primary)}
.badge-yes{background:rgba(16,185,129,.2);color:var(--success)}
.toolbar{display:flex;gap:8px;align-items:center;margin-bottom:10px;flex-wrap:wrap}
.search-box{padding:8px 10px;background:var(--bg-input);border:1px solid var(--border);border-radius:6px;color:var(--text);font-size:13px;width:180px}

/* Pagination */
.pagination{display:flex;justify-content:center;gap:6px;margin-top:24px;flex-wrap:wrap}
.page-link{padding:6px 12px;border:1px solid var(--border);border-radius:6px;color:var(--text-muted)!important;font-size:13px}
.page-link.active{background:var(--primary);border-color:var(--primary);color:#fff!important}

/* Error/Empty */
.error-page{display:flex;align-items:center;justify-content:center;min-height:40vh}
.error-card{text-align:center;padding:40px 20px}
.error-icon{font-size:56px;margin-bottom:12px}
.error-actions{display:flex;gap:10px;justify-content:center;margin-top:16px}
.empty-state{text-align:center;padding:40px 20px;color:var(--text-muted);grid-column:1/-1}
.empty-state .empty-icon{font-size:3rem;margin-bottom:12px;opacity:.7}
.empty-state .empty-title{font-size:1rem;font-weight:600;color:var(--text);margin-bottom:6px}
.empty-state .empty-desc{font-size:.82rem;color:var(--text-muted);margin-bottom:16px;max-width:320px;margin-left:auto;margin-right:auto;line-height:1.6}
.empty-state .btn{margin-top:4px}
.empty-hint{font-size:14px;color:var(--text-muted);padding:20px;text-align:center}

/* ===== Skeleton Loading ===== */
.skeleton{background:linear-gradient(90deg,var(--bg-input) 25%,var(--bg-card) 50%,var(--bg-input) 75%);background-size:200% 100%;animation:skeleton-shimmer 1.5s ease-in-out infinite;border-radius:6px}
.skeleton-text{height:14px;margin-bottom:8px}
.skeleton-text.short{width:60%}
.skeleton-text.medium{width:80%}
.skeleton-title{height:18px;width:70%;margin-bottom:12px}
.skeleton-avatar{width:40px;height:40px;border-radius:50%;flex-shrink:0}
.skeleton-card{background:var(--bg-card);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:10px}
.skeleton-card-row{display:flex;align-items:center;gap:12px}
.skeleton-card-body{flex:1;min-width:0}
@keyframes skeleton-shimmer{0%{background-position:200% 0}100%{background-position:-200% 0}}
/* Skeleton reveal: fade out skeletons, fade in real content */
.skel-wrap{position:relative}
.skel-wrap .skel-placeholder{transition:opacity .3s}
.skel-wrap .skel-real{transition:opacity .3s}
.skel-wrap.loaded .skel-placeholder{opacity:0;pointer-events:none;position:absolute;top:0;left:0;right:0}
.skel-wrap.loaded .skel-real{opacity:1}
@media(max-width:480px){.empty-state{padding:30px 14px}.empty-state .empty-icon{font-size:2.4rem}}

/* Footer */
.site-footer{text-align:center;padding:24px 16px;color:var(--text-muted);font-size:12px;border-top:1px solid var(--border);margin-top:30px}

/* Mobile base overrides */
@media (max-width: 768px) {
  .container { padding: 0 10px; }
  .page-header { padding: 16px 0 10px; }
  .page-header h1 { font-size: 1.15rem; }
  .page-desc { font-size: .78rem; }
  .btn { min-height: 44px; padding: 10px 18px; font-size: .9rem; }
  .btn-sm { min-height: 36px; padding: 6px 14px; font-size: .82rem; }
  /* Body padding for bottom nav */
  body { padding-bottom: calc(70px + var(--safe-bottom)); }
}
/* Mobile nav hide-on-scroll */
.mobile-nav{transition:transform .3s ease}
.mobile-nav.nav-hidden{transform:translateY(100%)}
@media (max-width: 768px) {
  .mobile-nav.nav-hidden{transform:translateY(calc(100% + 12px))}
}
@media (max-width: 480px) {
  html { font-size: 15px; }
  .container { padding: 0 8px; }
  .btn { padding: 10px 16px; font-size: .88rem; }
  .auth-card { padding: 24px 16px; }
  .detail-content,.upload-form,.forum-post-main { padding: 14px; }
  .video-info-bar { flex-direction: column; }
  .book-detail-layout { flex-direction: column; }
  .book-detail-cover { width: 100%; min-height: 200px; }
  .input-row { flex-direction: column; }
  .admin-stats .stat-card { flex: 1 1 40%; }
}

/* Favorite button */
.vote-btn.fav-active { border-color:#f59e0b;color:#f59e0b;background:rgba(245,158,11,.08); }

/* Mobile specific overrides */
@media(max-width:480px){
  html{font-size:15px}
  .container{padding:0 10px}
  .btn{padding:10px 16px;font-size:14px}
  .auth-card{padding:24px 16px}
  .detail-content,.upload-form,.forum-post-main{padding:14px}
  .video-info-bar{flex-direction:column}
  .book-detail-layout{flex-direction:column}
  .book-detail-cover{width:100%;min-height:200px}
  .input-row{flex-direction:column}
  .admin-stats .stat-card{flex:1 1 40%}
}

/* ===== 回到顶部按钮 (全端) ===== */
#backToTop {
  position:fixed;bottom:90px;right:16px;z-index:150;
  width:44px;height:44px;border-radius:50%;
  background:rgba(30,41,59,.9);backdrop-filter:blur(8px);
  -webkit-backdrop-filter:blur(8px);
  border:1px solid rgba(255,255,255,.12);
  color:rgba(255,255,255,.7);
  font-size:1.2rem;font-weight:700;cursor:pointer;
  display:none;align-items:center;justify-content:center;
  transition:all .25s ease;touch-action:manipulation;
  box-shadow:0 2px 12px rgba(0,0,0,.3);
}
#backToTop:hover {
  background:rgba(59,130,246,.2);
  border-color:var(--primary);color:var(--primary);
  transform:translateY(-2px);
  box-shadow:0 4px 18px rgba(59,130,246,.15);
}
#backToTop:active {transform:scale(.9)}
@media (min-width: 769px) {
  #backToTop {bottom:28px;right:28px;width:48px;height:48px;font-size:1.4rem;}
}

/* ===== 页间过渡动画 ===== */
@keyframes page-fade-in {
  from {opacity:0;transform:translateY(6px)}
  to {opacity:1;transform:translateY(0)}
}
.page-transition {
  animation:page-fade-in .3s ease-out;
}
/* 导航链接过渡 */
.nav-link {
  transition:color .2s,background .2s,transform .15s;
}
.nav-link:hover {transform:translateY(-1px)}

/* ===== 图片懒加载占位 ===== */
img.lazy-img {
  opacity:0;transition:opacity .4s ease;
  background:var(--bg-input);
}
img.lazy-img.loaded {opacity:1}

/* ===== 主题切换按钮 ===== */
.theme-toggle {
  background:none;border:1px solid var(--border);color:var(--text-muted);
  width:36px;height:36px;border-radius:50%;cursor:pointer;
  font-size:1rem;display:inline-flex;align-items:center;justify-content:center;
  transition:all .2s;touch-action:manipulation;margin-right:4px;
}
.theme-toggle:hover {border-color:var(--primary);color:var(--primary);transform:rotate(20deg)}
.theme-toggle:active {transform:rotate(20deg) scale(.9)}