/* MathMind Design System v5.6 — Complete Redesign
   ═══════════════════════════════════════════════════ */
:root {
  /* Brand */
  --mm-bg: #FAFAFA; --mm-surface: #FFFFFF; --mm-surface-hover: #F8F9FF;
  --mm-border: #E5E7EB; --mm-border-subtle: #F3F4F6;
  --mm-text: #171717; --mm-text-2: #4B5563; --mm-text-3: #9CA3AF; --mm-text-4: #D1D5DB;
  --mm-primary: #4F46E5; --mm-primary-light: #6366F1; --mm-primary-dark: #3730A3;
  --mm-primary-bg: #EEF2FF; --mm-primary-border: #C7D2FE;
  --mm-math: #D97706; --mm-math-light: #FEF3C7; --mm-math-border: #FCD34D;
  --mm-success: #059669; --mm-success-bg: #ECFDF5;
  --mm-error: #DC2626; --mm-error-bg: #FEF2F2;
  --mm-warning: #D97706; --mm-warning-bg: #FFFBEB;
  --mm-shadow-xs: 0px 0px 0px 1px rgba(0,0,0,0.05);
  --mm-shadow-sm: 0px 0px 0px 1px rgba(0,0,0,0.05), 0px 1px 2px rgba(0,0,0,0.04);
  --mm-shadow-md: 0px 0px 0px 1px rgba(0,0,0,0.05), 0px 2px 4px rgba(0,0,0,0.04), 0px 8px 16px -4px rgba(0,0,0,0.06);
  --mm-shadow-lg: 0px 0px 0px 1px rgba(0,0,0,0.05), 0px 4px 8px rgba(0,0,0,0.04), 0px 16px 32px -8px rgba(0,0,0,0.08);
  --mm-shadow-glow: 0px 0px 0px 1px rgba(79,70,229,0.15), 0px 0px 24px rgba(79,70,229,0.08);
  --mm-radius-xs: 4px; --mm-radius-sm: 6px; --mm-radius: 10px; --mm-radius-lg: 14px; --mm-radius-xl: 20px;
  --font-sans: 'Geist', system-ui, -apple-system, 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
  --font-mono: 'Geist Mono', ui-monospace, 'Cascadia Code', 'SF Mono', Consolas, monospace;
  --font-serif: 'Noto Serif SC', 'STSong', 'SimSun', 'Songti SC', serif;
  --sidebar-w: 240px; --header-h: 56px;
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
  /* Category colors */
  --cat-geometry: #6C5CE7; --cat-algebra: #00B894; --cat-calc: #E17055;
  --cat-prob: #FDCB6E; --cat-trig: #0984E3; --cat-vectors: #00CEC9;
  --cat-sequence: #E84393; --cat-general: #636E72;
}

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{font-size:16px;-webkit-font-smoothing:antialiased;scroll-behavior:smooth}
.mm-app{font-family:var(--font-sans);color:var(--mm-text);background:var(--mm-bg);line-height:1.6;min-height:100vh;display:flex}
.mm-app ::-webkit-scrollbar{width:6px;height:6px}
.mm-app ::-webkit-scrollbar-track{background:transparent}
.mm-app ::-webkit-scrollbar-thumb{background:var(--mm-text-4);border-radius:3px}

/* ═══ SIDEBAR ═══ */
.mm-app .sidebar{width:var(--sidebar-w);max-width:var(--sidebar-w);height:100vh;position:fixed;left:0;top:0;background:var(--mm-surface);border-right:1px solid var(--mm-border);display:flex;flex-direction:column;z-index:100;transition:transform .3s var(--ease-out);overflow-x:hidden;overflow-y:auto}
.mm-app .sidebar-logo{padding:20px;display:flex;align-items:center;gap:10px;border-bottom:1px solid var(--mm-border-subtle)}
.mm-app .sidebar-logo .logo-icon{width:36px;height:36px;background:linear-gradient(135deg,var(--mm-primary),var(--mm-primary-dark));border-radius:var(--mm-radius);display:flex;align-items:center;justify-content:center;color:#fff;font-size:18px;font-weight:600;flex-shrink:0}
.mm-app .sidebar-logo .logo-text{font-size:18px;font-weight:600;letter-spacing:-.36px}
.mm-app .sidebar-logo .logo-sub{font-size:10px;font-weight:500;color:var(--mm-text-3);letter-spacing:.5px;text-transform:uppercase;margin-top:-2px}
.mm-app .sidebar-nav{flex:1;padding:12px;display:flex;flex-direction:column;gap:2px;overflow-y:auto}
.mm-app .nav-section{padding:16px 8px 6px;font-size:11px;font-weight:600;color:var(--mm-text-3);text-transform:uppercase;letter-spacing:.8px}
.mm-app .nav-item{display:flex;align-items:center;gap:10px;padding:10px 12px;border-radius:var(--mm-radius-sm);font-size:14px;font-weight:500;color:var(--mm-text-2);text-decoration:none;transition:all .15s var(--ease-out);cursor:pointer;border:none;background:none;width:100%;text-align:left;font-family:var(--font-sans)}
.mm-app .nav-item:hover{background:var(--mm-primary-bg);color:var(--mm-primary)}
.mm-app .nav-item.active{background:var(--mm-primary-bg);color:var(--mm-primary);font-weight:600}
.mm-app .nav-item .nav-icon{font-size:18px;width:20px;text-align:center;flex-shrink:0}
.mm-app .nav-item .nav-badge{margin-left:auto;font-size:11px;font-weight:600;background:var(--mm-primary-bg);color:var(--mm-primary);padding:2px 8px;border-radius:999px}
.mm-app .sidebar-footer{padding:16px;border-top:1px solid var(--mm-border-subtle);margin-top:auto}
.mm-app .user-card{display:flex;align-items:center;gap:10px;padding:12px;border-radius:var(--mm-radius);cursor:pointer;transition:background .15s}
.mm-app .user-card:hover{background:var(--mm-primary-bg)}
.mm-app .user-avatar{width:32px;height:32px;border-radius:50%;background:linear-gradient(135deg,var(--mm-primary-light),var(--mm-primary));display:flex;align-items:center;justify-content:center;color:#fff;font-size:13px;font-weight:600;flex-shrink:0}
.mm-app .user-name{font-size:13px;font-weight:600;line-height:1.3}
.mm-app .user-role{font-size:11px;color:var(--mm-text-3)}

/* ═══ MAIN CONTENT ═══ */
.mm-app .main-content{flex:1;margin-left:var(--sidebar-w);display:flex;flex-direction:column;min-height:100vh}
.mm-app .topbar{height:var(--header-h);display:flex;align-items:center;padding:0 24px;background:var(--mm-surface);border-bottom:1px solid var(--mm-border);z-index:50;gap:16px}
.mm-app .mobile-menu-btn{display:none;background:none;border:none;font-size:20px;cursor:pointer;padding:4px 8px;color:var(--mm-text-2);border-radius:var(--mm-radius-sm)}
.mm-app .mobile-menu-btn:hover{background:var(--mm-primary-bg)}
.mm-app .topbar-breadcrumb{font-size:14px;color:var(--mm-text-2);font-weight:500}
.mm-app .topbar-actions{margin-left:auto;display:flex;align-items:center;gap:12px}
.mm-app .content-area{flex:1;padding:24px;max-width:1200px;width:100%;margin:0 auto}

/* ═══ BUTTONS ═══ */
.btn{display:inline-flex;align-items:center;gap:10px;padding:8px 16px;border:1px solid transparent;border-radius:var(--mm-radius-sm);font-size:14px;font-weight:500;font-family:var(--font-sans);cursor:pointer;transition:all .15s var(--ease-out);line-height:1.4;text-decoration:none;white-space:nowrap}
.btn:disabled{opacity:.5;cursor:not-allowed}
.btn:active:not(:disabled){transform:scale(.97)}
.btn-sm{padding:6px 12px;font-size:13px}
.btn-lg{padding:12px 24px;font-size:16px}
.btn-primary{background:var(--mm-primary);color:#fff;border-color:var(--mm-primary)}
.btn-primary:hover:not(:disabled){background:var(--mm-primary-dark)}
.btn-secondary{background:var(--mm-surface);color:var(--mm-text);border-color:var(--mm-border);box-shadow:var(--mm-shadow-xs)}
.btn-secondary:hover:not(:disabled){box-shadow:var(--mm-shadow-sm);background:var(--mm-surface-hover)}
.btn-ghost{background:transparent;color:var(--mm-text-2);border-color:transparent}
.btn-ghost:hover:not(:disabled){background:var(--mm-primary-bg);color:var(--mm-primary)}

/* ═══ CARDS ═══ */
.card{background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);box-shadow:var(--mm-shadow-sm);transition:box-shadow .2s,transform .2s}
.card-header{padding:16px 20px;border-bottom:1px solid var(--mm-border-subtle);font-size:14px;font-weight:600;display:flex;align-items:center;gap:8px}
.card-body{padding:20px}
.card-interactive:hover{box-shadow:var(--mm-shadow-md);transform:translateY(-2px)}

/* ═══ CHIPS & BADGES ═══ */
.chip{display:inline-flex;align-items:center;padding:4px 12px;border-radius:999px;font-size:13px;font-weight:500;background:var(--mm-surface);border:1px solid var(--mm-border-subtle);color:var(--mm-text-2);cursor:pointer;transition:all .15s var(--ease-out);white-space:nowrap}
.filter-select{padding:4px 10px;border-radius:8px;font-size:13px;border:1px solid var(--mm-border);background:var(--mm-surface);color:var(--mm-text-2);cursor:pointer;max-width:220px;outline:none}
.filter-select:focus{border-color:var(--mm-primary)}
.chip:hover{background:var(--mm-primary-bg);border-color:var(--mm-primary-border);color:var(--mm-primary)}
.chip.active{background:var(--mm-primary-bg);color:var(--mm-primary);border-color:var(--mm-primary-border);font-weight:600}
.chip.clickable{cursor:pointer}
.filter-chip{padding:6px 14px;font-size:13px}
.diff-badge{display:inline-flex;align-items:center;gap:4px;padding:2px 8px;border-radius:var(--mm-radius-xs);font-size:12px;font-weight:500}
.region-tag{display:inline-block;padding:2px 6px;border-radius:3px;font-size:10px;font-weight:600;text-transform:uppercase}

/* ═══ FORMS ═══ */
.search-box{position:relative;display:flex;align-items:center;margin-bottom:12px}
.search-box .search-icon{position:absolute;left:12px;color:var(--mm-text-3);font-size:16px;z-index:1}
.search-box input{width:100%;padding:10px 40px 10px 36px;border:1px solid var(--mm-border);border-radius:var(--mm-radius);font-size:14px;font-family:var(--font-sans);background:var(--mm-surface);transition:border-color .2s}
.search-box input:focus{outline:none;border-color:var(--mm-primary);box-shadow:var(--mm-shadow-glow)}
.search-clear{position:absolute;right:8px;background:none;border:none;font-size:16px;cursor:pointer;color:var(--mm-text-3);display:none;padding:4px}
.problem-textarea{width:100%;min-height:120px;padding:16px;border:2px solid var(--mm-border);border-radius:var(--mm-radius-lg);font-size:15px;font-family:var(--font-serif);line-height:1.8;resize:vertical;background:var(--mm-surface);transition:border-color .3s,box-shadow .3s}
.problem-textarea:focus{outline:none;border-color:var(--mm-primary-border);box-shadow:var(--mm-shadow-glow)}
.problem-input-group{position:relative}
.problem-input-footer{display:flex;align-items:center;justify-content:space-between;padding:8px 0 0;flex-wrap:wrap;gap:8px}
.example-hints{display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.hint-label{font-size:12px;color:var(--mm-text-3)}
.hint-tag{display:inline-block;padding:4px 10px;background:var(--mm-primary-bg);color:var(--mm-primary);border-radius:var(--mm-radius-sm);font-size:12px;cursor:pointer;transition:background .15s}
.hint-tag:hover{background:var(--mm-primary-border)}

/* ═══ FILTER BAR ═══ */
.filter-bar{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:16px;align-items:center}
.filter-bar > div{display:flex;flex-wrap:wrap;gap:10px}
.filter-section{margin-bottom:12px}
.filter-label{font-size:12px;font-weight:600;color:var(--mm-text-3);margin-right:8px;text-transform:uppercase}

/* ═══ HERO ═══ */
.hero-section{padding:20px 0 32px}
.hero-title{font-size:28px;font-weight:700;letter-spacing:-.56px;color:var(--mm-text);line-height:1.3;margin-bottom:8px}
.hero-subtitle{font-size:15px;color:var(--mm-text-2);margin-bottom:24px;line-height:1.5}

/* ═══ DASHBOARD ═══ */
.welcome-card{background:linear-gradient(135deg,var(--mm-primary),var(--mm-primary-dark));border-radius:var(--mm-radius-xl);padding:28px 32px;color:#fff;margin-bottom:24px;display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:16px}
.welcome-card .welcome-text{font-size:18px;font-weight:500}
.welcome-card .welcome-actions{display:flex;gap:8px}
.welcome-card .welcome-actions .btn{color:#fff;border-color:rgba(255,255,255,.3)}
.welcome-card .welcome-actions .btn:hover{background:rgba(255,255,255,.15)}
.welcome-card .welcome-actions .btn-primary{background:rgba(255,255,255,.2)}
.stats-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;margin-bottom:24px}
.stat-card{background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);padding:20px;text-align:center;box-shadow:var(--mm-shadow-sm)}
.stat-card .stat-label{font-size:12px;color:var(--mm-text-3);margin-bottom:8px;text-transform:uppercase;letter-spacing:.5px}
.stat-card .stat-value{font-size:32px;font-weight:700;color:var(--mm-text)}
.stat-card .stat-delta{font-size:12px;margin-top:4px;color:var(--mm-text-3)}
.stat-card .stat-delta.up{color:var(--mm-success)}
.quick-actions{display:grid;grid-template-columns:repeat(6,1fr);gap:12px;margin-bottom:24px}
.quick-action-card{background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);padding:20px 12px;text-align:center;cursor:pointer;transition:all .2s var(--ease-out);display:flex;flex-direction:column;align-items:center;gap:8px}
.quick-action-card:hover{box-shadow:var(--mm-shadow-md);transform:translateY(-2px);border-color:var(--mm-primary-border)}
.quick-action-card .qa-icon{font-size:28px}
.quick-action-card .qa-label{font-size:13px;font-weight:500;color:var(--mm-text-2)}
.learning-progress-bar{background:var(--mm-border-subtle);border-radius:999px;height:8px;overflow:hidden;margin:12px 0}
.learning-progress-bar .lp-fill{height:100%;background:linear-gradient(90deg,var(--mm-primary),var(--mm-primary-light));border-radius:999px;transition:width .8s var(--ease-out)}

/* ═══ GENERATE ═══ */
.ocr-upload-zone{border:2px dashed var(--mm-border);border-radius:var(--mm-radius-lg);padding:32px;text-align:center;cursor:pointer;transition:all .2s;background:var(--mm-surface);margin-bottom:12px}
.ocr-upload-zone:hover,.ocr-upload-zone.drag-over{border-color:var(--mm-primary);background:var(--mm-primary-bg)}
.ocr-upload-zone .upload-icon{font-size:36px;margin-bottom:8px}
.ocr-upload-zone .upload-text{font-size:15px;font-weight:500;color:var(--mm-text)}
.ocr-upload-zone .upload-hint{font-size:12px;color:var(--mm-text-3);margin-top:4px}
.ocr-upload-zone input[type=file]{display:none}
.ocr-preview-bar{display:none;align-items:center;gap:12px;padding:12px;background:var(--mm-surface);border:1px solid var(--mm-border);border-radius:var(--mm-radius);margin-bottom:12px}
.ocr-preview-bar img{width:60px;height:60px;object-fit:cover;border-radius:var(--mm-radius-sm);border:1px solid var(--mm-border-subtle)}
.ocr-preview-info{flex:1;min-width:0}
.ocr-fname{font-size:13px;font-weight:500;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.ocr-fmeta{font-size:11px;color:var(--mm-text-3)}
.ocr-math-preview{display:none;margin-bottom:12px;padding:16px;background:var(--mm-math-light);border:1px solid var(--mm-math-border);border-radius:var(--mm-radius);font-size:16px;font-family:var(--font-serif);line-height:2.2;min-height:48px}
.ocr-math-preview.active{display:block}
.ocr-math-preview-label{font-size:12px;font-weight:600;color:var(--mm-math);margin-bottom:8px}
.result-status{display:flex;align-items:center;gap:8px;padding:8px 16px;background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);margin:16px 0;font-size:13px;font-weight:500;flex-wrap:wrap}
.panel-header{padding:16px 20px;border-bottom:1px solid var(--mm-border-subtle);display:flex;align-items:center;gap:8px}
.panel-title{font-weight:600;font-size:14px;display:flex;align-items:center;gap:8px}
.panel-title .dot{width:8px;height:8px;border-radius:50%;background:var(--mm-primary)}

/* ═══ BROWSE ═══ */
.browse-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));gap:12px}
.pagination-bar{display:flex;align-items:center;justify-content:center;gap:10px;padding:24px 0;flex-wrap:wrap}
.pagination-bar button{min-width:36px;height:36px;border:1px solid var(--mm-border);border-radius:6px;background:var(--mm-surface);color:var(--mm-text-2);cursor:pointer;font-size:14px;transition:all .15s}
.pagination-bar button:hover:not(:disabled){border-color:var(--mm-primary);color:var(--mm-primary);background:var(--mm-primary-subtle)}
.pagination-bar button.active{background:var(--mm-primary);color:#fff;border-color:var(--mm-primary);font-weight:600}
.pagination-bar button:disabled{opacity:.35;cursor:not-allowed}
.pagination-bar .page-info{font-size:13px;color:var(--mm-text-3);margin:0 12px}
.question-card{background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);padding:16px;cursor:pointer;transition:all .2s var(--ease-out);position:relative}
.question-card:hover{border-color:var(--mm-primary-border);box-shadow:var(--mm-shadow-md);transform:translateY(-1px)}
.fav-btn{position:absolute;top:12px;right:12px;background:none;border:none;font-size:18px;cursor:pointer;opacity:.4;transition:opacity .15s;z-index:1}
.fav-btn:hover,.fav-btn.active{opacity:1}
.fav-btn.active{color:#F59E0B}
.card-preview{font-size:14px;line-height:1.6;color:var(--mm-text);margin-bottom:8px;max-height:80px;overflow:hidden}

/* ═══ QUESTION DETAIL ═══ */
.detail-overlay{position:fixed;top:0;left:0;right:0;bottom:0;background:var(--mm-bg);z-index:150;overflow-y:auto;padding:20px;display:none}
.detail-card{max-width:960px;margin:0 auto;background:transparent}
.close-btn{position:fixed;top:16px;right:16px;background:var(--mm-surface);border:1px solid var(--mm-border);border-radius:50%;width:36px;height:36px;display:flex;align-items:center;justify-content:center;font-size:16px;cursor:pointer;z-index:151;box-shadow:var(--mm-shadow-sm);transition:all .15s}
.close-btn:hover{background:var(--mm-error-bg);color:var(--mm-error)}
.fav-btn-detail{padding:6px 12px;border:1px solid var(--mm-border);border-radius:var(--mm-radius-sm);background:var(--mm-surface);cursor:pointer;font-size:13px;transition:all .15s}
.fav-btn-detail:hover{background:var(--mm-primary-bg)}
.fav-btn-detail.active{background:#FEF3C7;border-color:#FCD34D;color:#D97706}
.math-content{font-size:15px;line-height:2}
.math-content p{margin-bottom:8px}
.verification-panel{border-left:3px solid var(--mm-primary)}
.v-arrow{font-size:12px;transition:transform .2s;color:var(--mm-text-3)}
.practice-panel{padding:16px;border:1px dashed var(--mm-border);border-radius:var(--mm-radius);background:var(--mm-bg)}
.practice-note{width:100%;min-height:100px;padding:12px;border:1px solid var(--mm-border);border-radius:var(--mm-radius-sm);font-size:14px;font-family:var(--font-sans);resize:vertical;margin-bottom:8px}

/* ═══ MISTAKES ═══ */
.mistake-stats{display:flex;align-items:center;gap:16px;padding:16px 20px;background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);margin-bottom:16px;flex-wrap:wrap}
.mstat-item{text-align:center}
.mstat-val{font-size:24px;font-weight:700;color:var(--mm-primary);display:block}
.mstat-label{font-size:11px;color:var(--mm-text-3);margin-top:2px}
.mstat-bar{flex:1;min-width:100px;height:8px;background:var(--mm-border-subtle);border-radius:999px;overflow:hidden}
.mstat-bar-fill{height:100%;background:var(--mm-success);border-radius:999px;transition:width .5s}
.mstat-pct{font-size:13px;font-weight:600;color:var(--mm-success)}
.mistake-list{display:flex;flex-direction:column;gap:8px}
.mistake-item{display:flex;align-items:center;gap:12px;padding:14px 16px;background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);cursor:pointer;transition:all .15s}
.mistake-item:hover{border-color:var(--mm-primary-border);background:var(--mm-surface-hover)}
.mistake-item .mis-info{flex:1;min-width:0}
.mistake-item .mis-title{font-size:14px;font-weight:500;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.mistake-item .mis-meta{font-size:11px;color:var(--mm-text-3);margin-top:2px}
.mistake-reason-btn{padding:8px 16px;border:1px solid var(--mm-border);border-radius:var(--mm-radius);background:var(--mm-surface);font-size:13px;cursor:pointer;transition:all .15s}
.mistake-reason-btn:hover{border-color:var(--mm-primary-border);background:var(--mm-primary-bg)}
.mistake-reason-btn.selected{border-color:var(--mm-primary);background:var(--mm-primary-bg);color:var(--mm-primary);font-weight:600}

/* ═══ KNOWLEDGE GRAPH ═══ */
.knowledge-view{display:flex;gap:0;min-height:500px;border:1px solid var(--mm-border);border-radius:var(--mm-radius-lg);overflow:hidden;background:var(--mm-surface)}
.knowledge-sidebar{width:200px;border-right:1px solid var(--mm-border);background:var(--mm-bg);overflow-y:auto;flex-shrink:0}
.knowledge-content{flex:1;overflow-y:auto;padding:20px}
.knowledge-loading{padding:20px;color:var(--mm-text-3);font-size:14px}
.module-item{padding:12px 16px;cursor:pointer;font-size:14px;color:var(--mm-text-2);display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--mm-border-subtle);transition:all .15s}
.module-item:hover{background:var(--mm-primary-bg);color:var(--mm-primary)}
.module-item.active{background:var(--mm-primary-bg);color:var(--mm-primary);font-weight:600;border-left:3px solid var(--mm-primary)}
.module-count{font-size:11px;color:var(--mm-text-3);background:var(--mm-border-subtle);padding:1px 8px;border-radius:999px}
.tree-module{padding:8px 0;font-weight:600;font-size:14px;cursor:pointer;display:flex;align-items:center;gap:10px}
.tree-arrow{font-size:10px;transition:transform .2s;display:inline-block}
.tree-module.open .tree-arrow{transform:rotate(90deg)}
.tree-module + div{overflow:hidden;max-height:0;transition:max-height .3s}
.tree-module.open + div{max-height:2000px}
.tree-entity{padding:8px 12px 8px 24px;cursor:pointer;font-size:13px;color:var(--mm-text-2);display:flex;align-items:center;gap:8px;border-radius:var(--mm-radius-sm);transition:all .15s}
.tree-entity:hover{background:var(--mm-primary-bg);color:var(--mm-primary)}
.knowledge-detail{padding:16px;font-size:14px;line-height:1.8;color:var(--mm-text-2)}
.knowledge-detail h2,.knowledge-detail h3{margin:16px 0 8px;color:var(--mm-text)}
.knowledge-detail ul,.knowledge-detail ol{padding-left:24px;margin:8px 0}
.knowledge-detail blockquote{border-left:3px solid var(--mm-primary);padding:8px 16px;margin:12px 0;background:var(--mm-primary-bg);border-radius:0 var(--mm-radius-sm) var(--mm-radius-sm) 0;color:var(--mm-text-2)}

/* ═══ FORMULAS ═══ */
.formula-grid{display:flex;flex-direction:column;gap:12px}
.formula-card{background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);padding:16px 20px;cursor:pointer;transition:all .15s;display:flex;align-items:center;gap:12px;justify-content:space-between}
.formula-card:hover{box-shadow:var(--mm-shadow-sm);border-color:var(--mm-primary-border)}
.formula-card .formula-name{font-size:14px;font-weight:600;min-width:120px}
.formula-card .formula-latex{font-size:16px;font-family:var(--font-serif);color:var(--mm-math);flex:1}
.formula-card .formula-module{font-size:11px;color:var(--mm-text-3);padding:2px 8px;background:var(--mm-border-subtle);border-radius:999px}

/* ═══ EXPORT ═══ */
.export-mode-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-top:16px}
.export-mode-card{background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);padding:24px;text-align:center;transition:all .2s}
.export-mode-card:hover{border-color:var(--mm-primary-border);box-shadow:var(--mm-shadow-md)}
.export-mode-card .em-icon{font-size:36px;margin-bottom:12px}
.export-mode-card .em-title{font-size:16px;font-weight:600;margin-bottom:4px}
.export-mode-card .em-desc{font-size:13px;color:var(--mm-text-3);margin-bottom:12px}
.export-select-card{padding:10px 14px;border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius-sm);cursor:pointer;transition:all .15s;display:flex;align-items:center;gap:10px;font-size:13px}
.export-select-card:hover{background:var(--mm-primary-bg)}
.export-select-card.selected{background:var(--mm-primary-bg);border-color:var(--mm-primary-border)}

/* ═══ HISTORY ═══ */
.history-list{display:flex;flex-direction:column;gap:8px}
.history-item{padding:14px 16px;background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);transition:all .15s}
.history-item:hover{background:var(--mm-surface-hover);border-color:var(--mm-primary-border)}
.history-empty{text-align:center;padding:48px 20px;color:var(--mm-text-3)}

/* ═══ PRICING ═══ */
.pricing-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:20px;max-width:700px;margin:0 auto}
.pricing-card{background:var(--mm-surface);border:1px solid var(--mm-border);border-radius:var(--mm-radius-lg);padding:32px;text-align:center;transition:all .2s}
.pricing-card:hover{box-shadow:var(--mm-shadow-md)}
.pricing-card.featured{border-color:var(--mm-primary);box-shadow:var(--mm-shadow-glow)}
.pricing-features{list-style:none;text-align:left;margin:20px 0;font-size:14px;color:var(--mm-text-2)}
.pricing-features li{padding:6px 0}

/* ═══ SETTINGS ═══ */
.settings-row{display:flex;justify-content:space-between;padding:10px 0;border-bottom:1px solid var(--mm-border-subtle);font-size:14px}
.settings-row:last-child{border-bottom:none}

/* ═══ MOBILE TAB BAR ═══ */
.mobile-tabbar{display:none;position:fixed;bottom:0;left:0;right:0;background:var(--mm-surface);border-top:1px solid var(--mm-border);z-index:200;padding:4px 0;padding-bottom:max(4px, env(safe-area-inset-bottom))}
.mtab-item{display:flex;flex-direction:column;align-items:center;gap:2px;padding:6px 4px;flex:1;background:none;border:none;cursor:pointer;color:var(--mm-text-3);transition:color .15s;font-family:var(--font-sans)}
.mtab-item.active{color:var(--mm-primary)}
.mtab-item .mtab-icon{font-size:20px}
.mtab-item .mtab-label{font-size:10px;font-weight:500}

/* ═══ KNOWLEDGE CARD POPUP ═══ */
.knowledge-card{position:fixed;top:0;right:0;width:480px;max-width:90vw;height:100vh;background:var(--mm-surface);box-shadow:var(--mm-shadow-lg);z-index:250;overflow-y:auto;transform:translateX(100%);transition:transform .3s var(--ease-out);display:flex;flex-direction:column}
.knowledge-card:not(.hidden){transform:translateX(0)}
.knowledge-card.hidden{transform:translateX(100%)}
.knowledge-card-backdrop{position:fixed;top:0;left:0;right:0;bottom:0;background:rgba(0,0,0,.3);z-index:249;transition:opacity .3s}
.knowledge-card-backdrop.hidden{opacity:0;pointer-events:none}
.knowledge-card-header{padding:16px 20px;border-bottom:1px solid var(--mm-border-subtle);display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:8px}
.knowledge-card-title{font-size:16px;font-weight:600}
.knowledge-card-body{padding:20px;flex:1;overflow-y:auto;font-size:14px;line-height:1.8;color:var(--mm-text-2)}
.knowledge-card-body h1,.knowledge-card-body h2,.knowledge-card-body h3{color:var(--mm-text);margin:16px 0 8px}
.knowledge-card-body code{background:var(--mm-border-subtle);padding:2px 6px;border-radius:3px;font-size:13px;font-family:var(--font-mono)}
.knowledge-card-body pre{background:#1a1a2e;color:#e0e0e0;padding:16px;border-radius:var(--mm-radius);overflow-x:auto;font-size:13px;line-height:1.5;margin:12px 0}
.knowledge-card-body pre code{background:none;padding:0;color:inherit}
.knowledge-card-body .wiki-link{color:var(--mm-primary);text-decoration:none;cursor:pointer}
.knowledge-card-body .wiki-link:hover{text-decoration:underline}
.knowledge-card-footer{padding:16px 20px;border-top:1px solid var(--mm-border-subtle)}
.kc-backlinks-label{font-size:12px;font-weight:600;color:var(--mm-text-3);margin-bottom:4px}
.kc-header-left{flex:1;min-width:0}
.kc-header-right{display:flex;gap:8px;align-items:center}

/* ═══ KNOWLEDGE CARD POPUP (old overlay) ═══ */
.knowledge-card-popup .kc-inner{background:var(--mm-surface);border-radius:var(--mm-radius-lg);max-width:800px;width:90%;max-height:85vh;display:flex;flex-direction:column;box-shadow:var(--mm-shadow-lg)}
.knowledge-card-popup .kc-header{padding:16px 20px;border-bottom:1px solid var(--mm-border-subtle);display:flex;align-items:center;justify-content:space-between}

/* ═══ AUTH MODAL ═══ */
#auth-overlay{display:none}

/* ═══ SKELETON ═══ */
.skeleton{background:linear-gradient(90deg,var(--mm-border-subtle) 25%,var(--mm-border) 50%,var(--mm-border-subtle) 75%);background-size:200% 100%;animation:shimmer 1.5s infinite;border-radius:var(--mm-radius-sm)}
.skeleton-card{height:180px}
.skeleton-text{height:14px;margin-bottom:8px}
.skeleton-text.short{width:60%}
.skeleton-block{height:100px;background:linear-gradient(90deg,var(--mm-border-subtle),var(--mm-border),var(--mm-border-subtle));background-size:200% 100%;animation:shimmer 1.5s infinite;border-radius:var(--mm-radius);margin-bottom:12px}
@keyframes shimmer{0%{background-position:200% 0}100%{background-position:-200% 0}}

/* ═══ EMPTY STATE ═══ */
.empty-state{text-align:center;padding:48px 20px;color:var(--mm-text-3)}
.empty-state .empty-icon{font-size:48px;margin-bottom:12px}
.empty-state h3{font-size:16px;color:var(--mm-text-2);margin-bottom:4px}
.empty-state p{font-size:14px}

/* ═══ LOADING ═══ */
.spinner{display:inline-block;width:20px;height:20px;border:2px solid var(--mm-border);border-top-color:var(--mm-primary);border-radius:50%;animation:spin .6s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}
.loading-block{text-align:center;padding:40px;color:var(--mm-text-3)}

/* ═══ TOAST ═══ */
.toast{position:fixed;bottom:24px;left:50%;transform:translateX(-50%);background:#1a1a2e;color:#fff;padding:12px 24px;border-radius:999px;font-size:14px;z-index:500;box-shadow:var(--mm-shadow-lg);animation:toastIn .3s var(--ease-spring)}
@keyframes toastIn{from{opacity:0;transform:translateX(-50%) translateY(12px)}to{opacity:1;transform:translateX(-50%) translateY(0)}}

/* ═══ SEARCH MATCH ═══ */
mark.search-match{background:var(--mm-math-light);color:var(--mm-math);padding:1px 2px;border-radius:2px}

/* ═══ MISTAKE DIALOG ═══ */
#mistake-dialog-overlay,#fav-reason-dialog{display:none}

/* ═══ VERIFICATION ═══ */
.verification-stats-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;margin-bottom:16px}
.verification-module-chart{background:var(--mm-surface);border:1px solid var(--mm-border-subtle);border-radius:var(--mm-radius);padding:20px}

/* ═══ RESPONSIVE ═══ */
@media(max-width:1024px){
  .stats-grid{grid-template-columns:repeat(2,1fr)}
  .quick-actions{grid-template-columns:repeat(3,1fr)}
  .browse-grid{grid-template-columns:repeat(auto-fill,minmax(280px,1fr))}
  .export-mode-grid{grid-template-columns:1fr}
  .verification-stats-grid{grid-template-columns:repeat(2,1fr)}
  .pricing-grid{grid-template-columns:1fr}
}
@media(max-width:768px){
  .mm-app .sidebar{transform:translateX(-100%)}
  .mm-app .sidebar.open{transform:translateX(0)}
  .mm-app .mobile-menu-btn{display:block}
  .mm-app .main-content{margin-left:0}
  .mobile-tabbar{display:flex}
  .content-area{padding:16px;padding-bottom:80px}
  .stats-grid{grid-template-columns:1fr}
  .quick-actions{grid-template-columns:repeat(3,1fr)}
  .browse-grid{grid-template-columns:1fr}
  .hero-title{font-size:22px}
  .knowledge-view{flex-direction:column}
  .knowledge-sidebar{width:100%;max-height:200px;border-right:none;border-bottom:1px solid var(--mm-border)}
  .export-mode-grid{grid-template-columns:1fr}
  .verification-stats-grid{grid-template-columns:1fr}
  .knowledge-card{width:100vw;max-width:100vw}
}

/* ═══ PRINT ═══ */
@media print{
  .sidebar,.topbar,.mobile-tabbar,.knowledge-card,.knowledge-card-backdrop,.fav-btn,.close-btn,#auth-overlay,#fav-reason-dialog,.btn{display:none!important}
  .main-content{margin-left:0!important;padding:0}
  .content-area{padding:0;max-width:100%}
  .card{box-shadow:none;border:1px solid #ddd;break-inside:avoid}
  iframe{min-height:600px}
}

/* ═══ ANIMATIONS ═══ */
.animate-in{animation:fadeSlideIn .4s var(--ease-out)}
@keyframes fadeSlideIn{from{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}
.view{animation:fadeSlideIn .3s var(--ease-out)}

/* ═══ CYTOSCAPE FLOWCHART OVERLAY ═══ */
.cy-graph-wrap {
  position: relative; width: 100%; height: 650px;
  overflow: hidden; background: #FFF;
  border: 1px solid var(--mm-border-subtle);
  border-radius: var(--mm-radius-lg);
  margin-bottom: 16px;
}
.cy-graph-wrap.cy-fullscreen {
  position: fixed !important; top: 0; left: 0; right: 0; bottom: 0;
  width: 100vw !important; height: 100vh !important;
  z-index: 9999; margin: 0; border-radius: 0; border: none;
}
.cy-fs-close {
  position: fixed; top: 16px; right: 16px;
  z-index: 10000; background: rgba(0,0,0,0.75); color: #FFF;
  padding: 8px 16px; border-radius: 8px; font-size: 13px;
  cursor: pointer; user-select: none;
}
.cy-fs-close:hover { background: rgba(0,0,0,0.9); }
.cy-graph-wrap .cy-container { width: 100%; height: 100%; }
.cy-graph-wrap .cy-overlay { position: absolute; top: 0; left: 0; width: 100%; height: 100%; pointer-events: none; z-index: 10; }

.cy-ov-node {
  position: absolute; pointer-events: none;
  display: flex; align-items: center; justify-content: center;
}
.cy-ov-node .cy-inner {
  padding: 10px 18px; border-radius: 10px;
  border: none; background: rgba(238, 242, 255, 1);
  font-size: 14px; line-height: 1.8; color: #1E293B;
  text-align: center; min-width: 60px;
  box-shadow: none;
  font-family: PingFang SC, Microsoft YaHei, sans-serif;
  /* Overlay nodes now VISIBLE — MathJax renders math labels here */
}
/* Overlay node hover disabled — nodes rendered directly by Cytoscape */
.cy-ov-node.cy-sub .cy-inner {
  /* Subgraph styling handled by Cytoscape directly */
  background: transparent; border: none;
  border-radius: 0; padding: 0;
  text-align: left; font-weight: 600; font-size: 1px; color: transparent;
}
.cy-ov-node .cy-inner mjx-container { display: inline-block !important; }

.cy-edge-label {
  position: absolute; pointer-events: none; z-index: 5;
  background: rgba(255,255,255,0.45);
  padding: 2px 8px; border-radius: 4px;
  font-size: 11px; color: #64748B;
  border: none;
  white-space: nowrap;
  transform: translate(-50%, -50%);
}

.cy-loading {
  position: absolute; inset: 0;
  background: rgba(255,255,255,0.9);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  z-index: 200; transition: opacity 0.3s;
}
.cy-loading.done { opacity: 0; pointer-events: none; }
.cy-loading .cy-spinner { width: 36px; height: 36px; border: 3px solid #E5E7EB; border-top-color: var(--mm-primary); border-radius: 50%; animation: cy-spin 0.8s linear infinite; }
@keyframes cy-spin { to { transform: rotate(360deg); } }
.cy-loading .cy-loading-text { margin-top: 10px; color: #6B7280; font-size: 13px; }

.cy-debug-bar {
  position: absolute; bottom: 8px; left: 8px;
  background: rgba(0,0,0,0.7); color: #0F0; padding: 4px 10px;
  border-radius: 4px; font-size: 11px; font-family: monospace;
  z-index: 50; pointer-events: none;
}

/* ═══════════════════════════════════════════════════════
   Flowchart Engine (自研) — fc-* styles
   ═══════════════════════════════════════════════════════ */

.fc-graph-wrap {
  position: relative; width: 100%; min-height: 400px;
  overflow: hidden; background: #FAFBFC;
  border: 1px solid var(--mm-border-subtle, #E5E7EB);
  border-radius: var(--mm-radius, 8px);
  user-select: none;
}

.fc-graph-wrap.fc-fullscreen {
  position: fixed; top: 0; left: 0; width: 100vw; height: 100vh;
  z-index: 9999; background: #FAFBFC; border-radius: 0; border: none;
}

.fc-graph-wrap.fc-fullscreen .fc-graph {
  /* Ensure graph is visible in fullscreen */
}

.fc-fs-close {
  position: fixed; top: 16px; right: 16px; z-index: 10000;
  background: rgba(0,0,0,0.8); color: #fff; padding: 8px 16px;
  border-radius: 8px; cursor: pointer; font-size: 14px;
}
.fc-fs-close:hover { background: rgba(0,0,0,0.9); }

/* Edge hover */
.fc-edge:hover {
  stroke: #6366F1 !important; stroke-width: 3 !important;
}

/* Loading overlay */
.fc-loading {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%;
  display: flex; flex-direction: column; align-items: center;
  justify-content: center; background: rgba(250,251,252,0.85);
  z-index: 200; transition: opacity 0.3s;
}
.fc-loading.done { opacity: 0; pointer-events: none; }
.fc-loading .fc-spinner {
  width: 36px; height: 36px; border: 3px solid #E5E7EB;
  border-top-color: var(--mm-primary, #6366F1);
  border-radius: 50%; animation: fc-spin 0.8s linear infinite;
}
@keyframes fc-spin { to { transform: rotate(360deg); } }
.fc-loading .fc-loading-text { margin-top: 10px; color: #6B7280; font-size: 13px; }

/* Edge label */
.fc-edge-label {
  pointer-events: none;
}

/* SVG edge label background transparency (Mermaid native renderer) */
.fc-graph .edgeLabel rect {
  fill: rgba(255, 255, 255, 0.45) !important;
}
.fc-graph .edgeLabel foreignObject {
  background: transparent !important;
}


/* ══════════════════════════════════════════════════════════
 *  好题本 + 变体题 样式
 * ══════════════════════════════════════════════════════════ */

/* Variant action buttons */
.variant-actions {
  padding: 8px 16px;
  background: #f9fafb;
  border-radius: 0 0 8px 8px;
  border-top: 1px solid #f3f4f6;
}
.variant-actions .btn {
  transition: all 0.2s;
}
.variant-actions .btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

/* Branch selector */
.branch-selector {
  animation: fadeIn 0.3s ease;
}
.branch-selector select {
  font-family: inherit;
  cursor: pointer;
  transition: border-color 0.2s;
}
.branch-selector select:focus {
  outline: none;
  border-color: var(--mm-primary, #6366F1);
  box-shadow: 0 0 0 2px rgba(99,102,241,0.1);
}

/* Variant result cards */
.variant-card {
  transition: box-shadow 0.2s;
}
.variant-card:hover {
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}
.variant-card.diff {
  border-left: 3px solid #7c3aed !important;
}
.variant-badge {
  font-weight: 500;
}
.variant-problem {
  color: #1f2937;
}
.variant-solution {
  color: #4b5563;
}
.variant-empty,
.variant-error {
  padding: 24px;
  text-align: center;
  color: #9ca3af;
  font-size: 13px;
}
.variant-error {
  color: #dc2626;
  background: #fef2f2;
  border-radius: 8px;
}

/* Bookmark tree */
.bookmark-tree {
  transition: box-shadow 0.2s;
}
.bookmark-tree:hover {
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}
.tree-children {
  animation: slideDown 0.3s ease;
}
.tree-node {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 6px 0;
  border-bottom: 1px solid #f3f4f6;
}
.tree-node:last-child {
  border-bottom: none;
}
.tree-node.parent {
  background: #fffbeb;
  margin: 0 -16px;
  padding-left: 16px;
  padding-right: 16px;
}
.tree-node.variant {
  padding-left: 8px;
}

/* Stat cards in bookmarks */
.stat-card {
  transition: transform 0.2s, box-shadow 0.2s;
}
.stat-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes slideDown {
  from { opacity: 0; max-height: 0; }
  to { opacity: 1; max-height: 500px; }
}

/* ── CSS 根号渲染（自研流程图引擎） ── */
.mm-sqrt { white-space: nowrap; }
.mm-sqrt b { text-decoration: overline; font-weight: normal; font-style: normal; }