@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=Plus+Jakarta+Sans:wght@400;500;600;700;800&display=swap');

:root {
  --bg-primary: #FAFBFC;
  --bg-card: #FFFFFF;
  --bg-card-hover: #F8F9FB;
  --bg-surface: #F0F2F5;
  --text-primary: #1A1D26;
  --text-secondary: #4A5068;
  --text-muted: #8891A5;
  --text-accent: #2563EB;
  --accent-1: #2563EB;
  --accent-2: #3B82F6;
  --accent-3: #60A5FA;
  --accent-warm: #F59E0B;
  --gradient-main: linear-gradient(135deg, #2563EB, #3B82F6, #60A5FA);
  --gradient-text: linear-gradient(90deg, #2563EB, #3B82F6, #7C3AED);
  --gradient-subtle: linear-gradient(135deg, rgba(37,99,235,0.06), rgba(59,130,246,0.06));
  --border-color: rgba(0,0,0,0.08);
  --border-accent: rgba(37,99,235,0.25);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.06), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 30px rgba(0,0,0,0.08), 0 4px 8px rgba(0,0,0,0.04);
  --shadow-glow: 0 4px 20px rgba(37,99,235,0.12);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --font-main: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-display: 'Plus Jakarta Sans', 'Inter', sans-serif;
  --transition-fast: 0.2s cubic-bezier(0.4,0,0.2,1);
  --transition-smooth: 0.3s cubic-bezier(0.4,0,0.2,1);
  --transition-spring: 0.4s cubic-bezier(0.34,1.56,0.64,1);
}

*,*::before,*::after{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%;font-size:16px}
body{font-family:var(--font-main);background:var(--bg-primary);color:var(--text-primary);line-height:1.7;-webkit-font-smoothing:antialiased;overflow-x:hidden;min-height:100vh}
::-webkit-scrollbar{width:6px}
::-webkit-scrollbar-track{background:var(--bg-primary)}
::-webkit-scrollbar-thumb{background:var(--accent-2);border-radius:3px}
h1,h2,h3,h4,h5,h6{font-family:var(--font-display);font-weight:700;line-height:1.2;letter-spacing:-0.02em;color:var(--text-primary)}
h1{font-size:clamp(1.8rem,5vw,2.8rem);font-weight:800}
h2{font-size:clamp(1.4rem,3.5vw,2rem)}
h3{font-size:clamp(1.1rem,2.5vw,1.4rem);font-weight:600}
p{color:var(--text-secondary);margin-bottom:1rem;font-size:0.93rem}
a{color:var(--text-accent);text-decoration:none;transition:color var(--transition-fast)}
a:hover{color:var(--accent-1)}
strong,b{font-weight:600;color:var(--text-primary)}
.gradient-text{background:var(--gradient-text);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.reading-progress{position:fixed;top:0;left:0;width:0%;height:3px;background:var(--gradient-main);z-index:9999;transition:width 0.1s linear}
.top-nav{position:sticky;top:0;z-index:100;background:rgba(250,251,252,0.92);backdrop-filter:blur(20px);-webkit-backdrop-filter:blur(20px);border-bottom:1px solid var(--border-color);padding:0.7rem 1.25rem}
.nav-inner{max-width:900px;margin:0 auto;display:flex;align-items:center;justify-content:space-between;gap:1rem}
.nav-brand{display:flex;align-items:center;gap:0.5rem;font-family:var(--font-display);font-weight:700;font-size:1.05rem;color:var(--text-primary);text-decoration:none}
.nav-brand .brand-dot{width:8px;height:8px;border-radius:50%;background:var(--gradient-main)}
.breadcrumb{display:flex;align-items:center;gap:0.4rem;font-size:0.78rem;color:var(--text-muted);flex-wrap:wrap}
.breadcrumb a{color:var(--text-muted)}
.breadcrumb a:hover{color:var(--text-accent)}
.breadcrumb .sep{opacity:0.5}
.breadcrumb .current{color:var(--text-secondary);font-weight:500}
.container{max-width:900px;margin:0 auto;padding:1.5rem 1.25rem 3rem}
.hero{text-align:center;padding:2.5rem 0 2rem;position:relative}
.hero::before{content:'';position:absolute;top:-60px;left:50%;transform:translateX(-50%);width:400px;height:400px;background:radial-gradient(circle,rgba(37,99,235,0.05) 0%,transparent 70%);pointer-events:none}
.hero-badge{display:inline-flex;align-items:center;gap:0.5rem;padding:0.35rem 0.9rem;background:var(--gradient-subtle);border:1px solid var(--border-accent);border-radius:100px;font-size:0.72rem;font-weight:600;color:var(--text-accent);margin-bottom:1.25rem;text-transform:uppercase;letter-spacing:0.05em}
.hero-badge .pulse-dot{width:6px;height:6px;border-radius:50%;background:var(--accent-2);animation:pulse 2s ease-in-out infinite}
@keyframes pulse{0%,100%{opacity:1;transform:scale(1)}50%{opacity:0.5;transform:scale(0.8)}}
.hero h1,.hero-title{margin-bottom:0.75rem}
.hero .subtitle,.hero-subtitle{color:var(--text-secondary);font-size:0.95rem;max-width:500px;margin:0 auto 1.5rem;line-height:1.6}
.stats-bar{display:flex;justify-content:center;gap:2rem;flex-wrap:wrap;margin-bottom:2rem}
.stats-container{display:flex;justify-content:center;gap:2rem;flex-wrap:wrap}
.stat-item{text-align:center}
.stat-value,.stat-number{font-family:var(--font-display);font-size:1.5rem;font-weight:800;background:var(--gradient-text);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.stat-label{font-size:0.68rem;color:var(--text-muted);text-transform:uppercase;letter-spacing:0.08em;margin-top:0.1rem}
.exam-info{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-xl);padding:1.25rem;margin:0 1.25rem 2rem;box-shadow:var(--shadow-sm);max-width:900px;margin-left:auto;margin-right:auto}
.exam-info-title{font-family:var(--font-display);font-size:0.8rem;font-weight:700;color:var(--text-accent);text-transform:uppercase;letter-spacing:0.06em;margin-bottom:0.75rem;display:flex;align-items:center;gap:0.5rem}
.exam-info-container{max-width:900px;margin:0 auto}
.exam-info-grid,.exam-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(130px,1fr));gap:0.6rem}
.exam-info-item,.exam-stat{background:var(--bg-surface);border-radius:var(--radius-md);padding:0.85rem;text-align:center}
.exam-info-icon{margin-bottom:0.3rem}
.exam-info-icon i{font-size:18px;color:var(--accent-2)}
.exam-info-value,.exam-stat-value{font-family:var(--font-display);font-size:1.5rem;font-weight:800;color:var(--text-primary)}
.exam-info-label,.exam-stat-label{font-size:0.7rem;color:var(--text-muted);margin-top:0.2rem}
.section-label{font-family:var(--font-display);font-size:0.7rem;font-weight:700;color:var(--text-muted);text-transform:uppercase;letter-spacing:0.1em;margin-bottom:0.75rem;margin-top:1.5rem;padding-left:0.25rem}
.chapters-section{max-width:900px;margin:0 auto;padding:0 1.25rem}
.chapters-grid{display:grid;grid-template-columns:1fr;gap:0.6rem}
.chapter-card{display:flex;align-items:center;gap:1rem;background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:0.9rem 1.1rem;text-decoration:none;color:inherit;transition:all var(--transition-smooth);position:relative;overflow:hidden;box-shadow:var(--shadow-sm)}
.chapter-card::before{content:'';position:absolute;inset:0;background:var(--gradient-subtle);opacity:0;transition:opacity var(--transition-smooth)}
.chapter-card:hover{border-color:var(--border-accent);transform:translateY(-2px);box-shadow:var(--shadow-lg)}
.chapter-card:hover::before{opacity:1}
.chapter-card:active{transform:translateY(0)}
.card-icon{position:relative;z-index:1;width:42px;height:42px;min-width:42px;border-radius:var(--radius-md);background:var(--gradient-subtle);display:flex;align-items:center;justify-content:center;transition:all var(--transition-smooth)}
.chapter-card:hover .card-icon{background:var(--gradient-main)}
.card-icon i{font-size:18px;color:var(--accent-2);transition:color var(--transition-fast)}
.chapter-card:hover .card-icon i{color:#fff}
.card-content{position:relative;z-index:1;flex:1;min-width:0}
.card-chapter-num{font-size:0.62rem;font-weight:700;color:var(--text-muted);text-transform:uppercase;letter-spacing:0.1em;margin-bottom:0.1rem}
.card-title{font-family:var(--font-display);font-size:0.85rem;font-weight:600;color:var(--text-primary);line-height:1.3}
.card-arrow{position:relative;z-index:1;color:var(--text-muted);transition:all var(--transition-smooth);flex-shrink:0}
.chapter-card:hover .card-arrow{color:var(--text-accent);transform:translateX(4px)}
.card-arrow i{font-size:16px}
.chapter-header{padding:1.5rem 0 1.25rem;border-bottom:1px solid var(--border-color);margin-bottom:1.75rem}
.chapter-number{font-size:0.68rem;font-weight:700;text-transform:uppercase;letter-spacing:0.12em;color:var(--text-accent);margin-bottom:0.4rem}
.chapter-title{font-family:var(--font-display);font-size:clamp(1.4rem,4vw,2rem);font-weight:800;line-height:1.15;margin-bottom:0.5rem}
.chapter-desc{color:var(--text-secondary);font-size:0.92rem;line-height:1.6}
.toc{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:1.1rem;margin-bottom:1.75rem;box-shadow:var(--shadow-sm)}
.toc-title{font-family:var(--font-display);font-size:0.75rem;font-weight:700;color:var(--text-muted);text-transform:uppercase;letter-spacing:0.08em;margin-bottom:0.6rem}
.toc-list{list-style:none;padding:0;display:grid;gap:0.2rem}
.toc-list a{display:flex;align-items:center;gap:0.5rem;padding:0.35rem 0.5rem;border-radius:var(--radius-sm);color:var(--text-secondary);font-size:0.82rem;transition:all var(--transition-fast)}
.toc-list a:hover{background:rgba(37,99,235,0.06);color:var(--text-accent)}
.toc-list a::before{content:'';width:4px;height:4px;border-radius:50%;background:var(--text-muted);flex-shrink:0;transition:background var(--transition-fast)}
.toc-list a:hover::before{background:var(--accent-2)}
.content-section{margin-bottom:2.25rem}
.section-title{font-family:var(--font-display);font-size:1.15rem;font-weight:700;color:var(--text-primary);margin-bottom:0.75rem;padding-bottom:0.4rem;border-bottom:2px solid transparent;border-image:var(--gradient-main) 1;display:flex;align-items:center;gap:0.5rem}
.section-title i{font-size:18px;color:var(--accent-2);flex-shrink:0}
.subsection{margin-bottom:1.25rem}
.subsection-title{font-size:0.95rem;font-weight:600;color:var(--text-primary);margin-bottom:0.4rem}
.content-text{color:var(--text-secondary);font-size:0.9rem;line-height:1.75;margin-bottom:0.6rem}
.signal-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(110px,1fr));gap:0.75rem;margin:1rem 0}
.signal-item{display:flex;flex-direction:column;align-items:center;text-align:center;gap:0.4rem;padding:0.6rem;background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-md);transition:all var(--transition-smooth);box-shadow:var(--shadow-sm)}
.signal-item:hover{transform:translateY(-2px);box-shadow:var(--shadow-md);border-color:var(--border-accent)}
.signal-item img{width:72px;height:72px;object-fit:contain;transition:transform var(--transition-spring)}
.signal-item img:hover{transform:scale(1.15)}
.signal-item .signal-name{font-size:0.68rem;color:var(--text-muted);line-height:1.3;font-weight:500}
.content-list{list-style:none;margin:0.6rem 0 1rem;padding:0}
.content-list li{position:relative;padding-left:1.4rem;margin-bottom:0.4rem;color:var(--text-secondary);font-size:0.9rem;line-height:1.6}
.content-list li::before{content:'';position:absolute;left:0;top:0.55em;width:5px;height:5px;border-radius:50%;background:var(--accent-2)}
.info-box{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:1.1rem;margin:1rem 0;position:relative;overflow:hidden;box-shadow:var(--shadow-sm)}
.info-box::before{content:'';position:absolute;left:0;top:0;bottom:0;width:3px}
.info-box .box-title,.info-box .info-box-title{font-family:var(--font-display);font-size:0.78rem;font-weight:700;text-transform:uppercase;letter-spacing:0.06em;margin-bottom:0.4rem;display:flex;align-items:center;gap:0.4rem}
.info-box .box-title i,.info-box .info-box-title i{font-size:14px}
.info-box .box-content,.info-box p:not(.box-title){font-size:0.88rem;line-height:1.6;color:var(--text-secondary)}
.info-box.tip::before{background:var(--gradient-main)}
.info-box.tip .box-title,.info-box.tip .info-box-title{color:var(--accent-2)}
.info-box.warning{background:linear-gradient(135deg,rgba(245,158,11,0.04),rgba(245,158,11,0.02))}
.info-box.warning::before{background:#F59E0B}
.info-box.warning .box-title,.info-box.warning .info-box-title{color:#D97706}
.info-box.trick{background:linear-gradient(135deg,rgba(124,58,237,0.04),rgba(37,99,235,0.04));border-color:rgba(124,58,237,0.15)}
.info-box.trick::before{background:linear-gradient(180deg,#7C3AED,#3B82F6)}
.info-box.trick .box-title,.info-box.trick .info-box-title{color:#7C3AED}
.info-box.important{background:linear-gradient(135deg,rgba(239,68,68,0.04),rgba(239,68,68,0.02))}
.info-box.important::before{background:#EF4444}
.info-box.important .box-title,.info-box.important .info-box-title{color:#DC2626}
.table-wrapper{overflow-x:auto;margin:1rem 0;border-radius:var(--radius-md);border:1px solid var(--border-color);box-shadow:var(--shadow-sm)}
.data-table{width:100%;border-collapse:collapse;font-size:0.83rem}
.data-table thead{background:var(--gradient-subtle)}
.data-table th{padding:0.7rem 0.8rem;text-align:left;font-weight:600;color:var(--accent-1);font-size:0.72rem;text-transform:uppercase;letter-spacing:0.06em;border-bottom:1px solid var(--border-color);white-space:nowrap}
.data-table td{padding:0.55rem 0.8rem;border-bottom:1px solid var(--border-color);color:var(--text-secondary)}
.data-table tbody tr:last-child td{border-bottom:none}
.data-table tbody tr{transition:background var(--transition-fast)}
.data-table tbody tr:hover{background:rgba(37,99,235,0.03)}
.chapter-nav{display:grid;grid-template-columns:1fr 1fr;gap:0.75rem;margin-top:2.5rem;padding-top:1.5rem;border-top:1px solid var(--border-color)}
.chapter-nav-link{display:flex;flex-direction:column;gap:0.2rem;padding:0.9rem;background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-md);text-decoration:none;transition:all var(--transition-smooth);box-shadow:var(--shadow-sm)}
.chapter-nav-link:hover{border-color:var(--border-accent);background:var(--bg-card-hover);transform:translateY(-2px);box-shadow:var(--shadow-md)}
.chapter-nav-link.next{text-align:right}
.nav-label{font-size:0.62rem;font-weight:700;text-transform:uppercase;letter-spacing:0.1em;color:var(--text-muted)}
.nav-title{font-family:var(--font-display);font-size:0.82rem;font-weight:600;color:var(--text-primary);line-height:1.3}
.back-to-top{position:fixed;bottom:1.5rem;right:1.5rem;width:42px;height:42px;border-radius:50%;background:var(--gradient-main);border:none;cursor:pointer;display:flex;align-items:center;justify-content:center;opacity:0;transform:translateY(10px);transition:all var(--transition-smooth);z-index:50;box-shadow:var(--shadow-lg)}
.back-to-top.visible{opacity:1;transform:translateY(0)}
.back-to-top:hover{transform:translateY(-2px);box-shadow:var(--shadow-glow)}
.back-to-top i{font-size:18px;color:#fff}
.footer{text-align:center;padding:1.5rem 1.25rem;border-top:1px solid var(--border-color);margin-top:2rem}
.footer p{font-size:0.72rem;color:var(--text-muted)}
.footer .footer-brand,.footer-brand{font-family:var(--font-display);font-weight:700;background:var(--gradient-text);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.footer-container{text-align:center}
.footer-author{font-size:0.68rem;color:var(--text-muted);margin-top:0.25rem}
.section-divider{height:1px;background:var(--gradient-main);opacity:0.15;margin:1.5rem 0;border:none}
@keyframes fadeInUp{from{opacity:0;transform:translateY(16px)}to{opacity:1;transform:translateY(0)}}
.fade-in{animation:fadeInUp 0.5s ease both}
@media(max-width:480px){.container{padding:1rem 1rem 2rem}.hero{padding:1.5rem 0 1.25rem}.stats-bar,.stats-container{gap:1.25rem}.chapter-card{padding:0.75rem 0.9rem}.card-icon{width:36px;height:36px;min-width:36px}.card-icon i{font-size:16px}.card-title{font-size:0.8rem}.exam-grid,.exam-info-grid{grid-template-columns:repeat(2,1fr)}.chapter-nav{grid-template-columns:1fr}.signal-grid{grid-template-columns:repeat(auto-fill,minmax(90px,1fr))}.signal-item img{width:56px;height:56px}}
@media print{body{background:#fff;color:#000}.top-nav,.reading-progress,.back-to-top,.chapter-nav{display:none}.info-box{border:1px solid #ccc}}