/* 全局重置与变量 */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
    --bg: #f0f2f5;
    --bg-card: rgba(255,255,255,0.7);
    --text: #1a1a2e;
    --text-secondary: #4a4a6a;
    --primary: #6c63ff;
    --primary-dark: #4a3fcf;
    --accent: #ff6584;
    --glass-bg: rgba(255,255,255,0.25);
    --glass-border: rgba(255,255,255,0.3);
    --shadow: 0 8px 32px rgba(0,0,0,0.08);
    --shadow-hover: 0 12px 48px rgba(0,0,0,0.15);
    --radius: 20px;
    --radius-sm: 12px;
    --transition: 0.3s cubic-bezier(0.4,0,0.2,1);
    --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
    --header-height: 72px;
}

[data-theme="dark"] {
    --bg: #0f0f1a;
    --bg-card: rgba(30,30,50,0.8);
    --text: #e8e8f0;
    --text-secondary: #a0a0b8;
    --glass-bg: rgba(30,30,50,0.4);
    --glass-border: rgba(255,255,255,0.1);
    --shadow: 0 8px 32px rgba(0,0,0,0.4);
    --shadow-hover: 0 12px 48px rgba(0,0,0,0.6);
}

html { scroll-behavior: smooth; }

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    transition: background 0.3s, color 0.3s;
    min-height: 100vh;
}

a { color: var(--primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--primary-dark); }

img, svg { max-width: 100%; height: auto; display: block; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }

/* Header & Nav */
header {
    position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
    height: var(--header-height);
    background: var(--glass-bg);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid var(--glass-border);
    transition: background 0.3s, box-shadow 0.3s;
}

header.scrolled { box-shadow: var(--shadow); }

nav {
    display: flex; align-items: center; justify-content: space-between;
    height: 100%; padding: 0 24px; max-width: 1200px; margin: 0 auto;
}

.logo {
    display: flex; align-items: center; gap: 12px;
    font-size: 1.5rem; font-weight: 700; color: var(--text);
    cursor: pointer;
}

.logo svg { width: 40px; height: 40px; }

.nav-links { display: flex; gap: 32px; list-style: none; align-items: center; }

.nav-links a {
    color: var(--text-secondary); font-weight: 500; font-size: 0.95rem;
    padding: 8px 0; border-bottom: 2px solid transparent;
    transition: color var(--transition), border-color var(--transition);
}

.nav-links a:hover, .nav-links a.active { color: var(--primary); border-bottom-color: var(--primary); }

.nav-actions { display: flex; align-items: center; gap: 16px; }

.theme-toggle, .menu-toggle {
    background: var(--glass-bg); border: 1px solid var(--glass-border);
    border-radius: 50%; width: 40px; height: 40px;
    display: flex; align-items: center; justify-content: center;
    cursor: pointer; color: var(--text); font-size: 1.2rem;
    backdrop-filter: blur(10px); transition: background var(--transition);
}

.theme-toggle:hover, .menu-toggle:hover { background: var(--bg-card); }

.menu-toggle { display: none; }

.mobile-menu {
    display: none; position: fixed; top: var(--header-height); left: 0; right: 0;
    background: var(--bg); padding: 24px; border-bottom: 1px solid var(--glass-border);
    box-shadow: var(--shadow); z-index: 999;
}

.mobile-menu.open { display: block; }

.mobile-menu ul { list-style: none; display: flex; flex-direction: column; gap: 16px; }

.mobile-menu a { color: var(--text-secondary); font-size: 1.1rem; padding: 8px 0; display: block; }

/* Hero Banner */
.hero {
    padding-top: calc(var(--header-height) + 40px);
    padding-bottom: 60px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    position: relative; overflow: hidden;
}

.hero::before {
    content: ''; position: absolute; top: -50%; left: -50%; width: 200%; height: 200%;
    background: radial-gradient(circle at 30% 50%, rgba(255,255,255,0.1) 0%, transparent 60%);
    animation: heroGlow 8s ease-in-out infinite alternate;
}

@keyframes heroGlow { 0% { transform: translate(0,0); } 100% { transform: translate(5%,5%); } }

.hero .container { position: relative; z-index: 1; }

.hero-content { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; }

.hero-text h1 { font-size: 3.2rem; font-weight: 800; color: #fff; line-height: 1.2; margin-bottom: 24px; }

.hero-text p { font-size: 1.2rem; color: rgba(255,255,255,0.85); margin-bottom: 32px; max-width: 500px; }

.hero-buttons { display: flex; gap: 16px; flex-wrap: wrap; }

.btn {
    display: inline-flex; align-items: center; gap: 8px;
    padding: 14px 32px; border-radius: 50px; font-weight: 600;
    border: none; cursor: pointer; transition: all var(--transition);
    font-size: 1rem;
}

.btn-primary { background: #fff; color: var(--primary); }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 32px rgba(0,0,0,0.2); }

.btn-outline { background: transparent; border: 2px solid rgba(255,255,255,0.5); color: #fff; }
.btn-outline:hover { border-color: #fff; background: rgba(255,255,255,0.1); }

.hero-visual {
    display: flex; justify-content: center; align-items: center;
    position: relative;
}

.hero-card {
    background: var(--glass-bg); backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border); border-radius: var(--radius);
    padding: 40px; width: 100%; max-width: 440px;
    box-shadow: var(--shadow); text-align: center;
}

.hero-card svg { width: 120px; height: 120px; margin: 0 auto 20px; }
.hero-card h3 { color: #fff; font-size: 1.5rem; margin-bottom: 12px; }
.hero-card p { color: rgba(255,255,255,0.8); }

/* Sections */
section { padding: 80px 0; }

.section-title {
    text-align: center; margin-bottom: 56px;
    font-size: 2.4rem; font-weight: 700;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text; -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-subtitle {
    text-align: center; color: var(--text-secondary); margin-top: -40px; margin-bottom: 56px;
    font-size: 1.1rem;
}

.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }

.card {
    background: var(--bg-card); backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border); border-radius: var(--radius);
    padding: 32px; box-shadow: var(--shadow);
    transition: all var(--transition);
}

.card:hover { transform: translateY(-6px); box-shadow: var(--shadow-hover); }

.card-icon { margin-bottom: 16px; }
.card-icon svg { width: 48px; height: 48px; }
.card h3 { font-size: 1.3rem; margin-bottom: 12px; color: var(--text); }
.card p { color: var(--text-secondary); font-size: 0.95rem; }

/* Timeline */
.timeline { position: relative; padding-left: 40px; }

.timeline::before {
    content: ''; position: absolute; left: 16px; top: 0; bottom: 0;
    width: 2px; background: linear-gradient(to bottom, var(--primary), var(--accent));
}

.timeline-item { position: relative; margin-bottom: 40px; }

.timeline-item::before {
    content: ''; position: absolute; left: -28px; top: 8px;
    width: 16px; height: 16px; border-radius: 50%;
    background: var(--primary); border: 3px solid var(--bg);
}

.timeline-item .year { font-weight: 700; color: var(--primary); font-size: 1.2rem; }
.timeline-item p { color: var(--text-secondary); }

/* Testimonials */
.testimonial-card { text-align: center; }

.testimonial-card .avatar {
    width: 64px; height: 64px; border-radius: 50%; margin: 0 auto 16px;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    display: flex; align-items: center; justify-content: center;
    color: #fff; font-weight: 700; font-size: 1.5rem;
}

.testimonial-card .quote { font-style: italic; color: var(--text-secondary); margin-bottom: 16px; }
.testimonial-card .author { font-weight: 600; color: var(--text); }

/* FAQ */
.faq-item {
    background: var(--bg-card); backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border); border-radius: var(--radius-sm);
    margin-bottom: 16px; overflow: hidden; transition: box-shadow var(--transition);
}

.faq-item:hover { box-shadow: var(--shadow); }

.faq-question {
    padding: 20px 24px; cursor: pointer; display: flex; justify-content: space-between;
    align-items: center; font-weight: 600; color: var(--text);
    transition: background var(--transition);
}

.faq-question:hover { background: rgba(108,99,255,0.05); }

.faq-question .icon { transition: transform var(--transition); font-size: 1.2rem; }

.faq-item.open .faq-question .icon { transform: rotate(45deg); }

.faq-answer {
    max-height: 0; overflow: hidden; transition: max-height 0.4s ease, padding 0.3s ease;
    padding: 0 24px; color: var(--text-secondary);
}

.faq-item.open .faq-answer { max-height: 500px; padding: 0 24px 20px; }

/* HowTo */
.howto-steps { counter-reset: step; }

.howto-step {
    display: flex; gap: 20px; margin-bottom: 24px;
    background: var(--bg-card); backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border); border-radius: var(--radius-sm);
    padding: 24px; transition: transform var(--transition);
}

.howto-step:hover { transform: translateX(8px); }

.howto-step .step-num {
    counter-increment: step;
    width: 48px; height: 48px; border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: #fff; display: flex; align-items: center; justify-content: center;
    font-weight: 700; font-size: 1.2rem; flex-shrink: 0;
}

.howto-step .step-num::before {
    content: counter(step);
}

/* Article cards */
.article-card { display: flex; flex-direction: column; }
.article-card .date { font-size: 0.85rem; color: var(--text-secondary); margin-bottom: 8px; }
.article-card h4 { font-size: 1.1rem; margin-bottom: 8px; }
.article-card p { font-size: 0.9rem; color: var(--text-secondary); flex: 1; }
.article-card .read-more { margin-top: 12px; color: var(--primary); font-weight: 500; cursor: pointer; display: inline-flex; align-items: center; gap: 4px; }

/* Footer */
footer {
    background: var(--bg-card); backdrop-filter: blur(20px);
    border-top: 1px solid var(--glass-border); padding: 60px 0 30px;
}

.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }

.footer-col h4 { font-size: 1.1rem; margin-bottom: 16px; color: var(--text); }
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 8px; }
.footer-col a { color: var(--text-secondary); font-size: 0.9rem; }
.footer-col a:hover { color: var(--primary); }

.footer-bottom {
    border-top: 1px solid var(--glass-border); padding-top: 24px;
    display: flex; justify-content: space-between; align-items: center;
    flex-wrap: wrap; gap: 16px; font-size: 0.85rem; color: var(--text-secondary);
}

.footer-bottom-links { display: flex; gap: 24px; }

/* Back to top */
.back-to-top {
    position: fixed; bottom: 32px; right: 32px; z-index: 999;
    width: 48px; height: 48px; border-radius: 50%;
    background: var(--primary); color: #fff; border: none; cursor: pointer;
    display: flex; align-items: center; justify-content: center;
    font-size: 1.4rem; box-shadow: var(--shadow);
    opacity: 0; visibility: hidden; transform: translateY(20px);
    transition: all var(--transition);
}

.back-to-top.visible { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { background: var(--primary-dark); transform: translateY(-4px); }

/* Search modal */
.search-overlay {
    position: fixed; top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0,0,0,0.5); backdrop-filter: blur(8px);
    z-index: 2000; display: none; align-items: center; justify-content: center;
}

.search-overlay.open { display: flex; }

.search-modal {
    background: var(--bg); border-radius: var(--radius);
    padding: 40px; width: 90%; max-width: 600px;
    box-shadow: var(--shadow-hover); border: 1px solid var(--glass-border);
}

.search-modal input {
    width: 100%; padding: 16px 20px; border: 2px solid var(--glass-border);
    border-radius: var(--radius-sm); font-size: 1.1rem;
    background: var(--bg-card); color: var(--text);
    outline: none; transition: border-color var(--transition);
}

.search-modal input:focus { border-color: var(--primary); }

.search-results { margin-top: 24px; max-height: 400px; overflow-y: auto; }

.search-results div { padding: 12px 0; border-bottom: 1px solid var(--glass-border); cursor: pointer; }
.search-results div:hover { color: var(--primary); }

/* Breadcrumb */
.breadcrumb { padding: 16px 0; font-size: 0.9rem; color: var(--text-secondary); }
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb a:hover { color: var(--primary); }
.breadcrumb span { margin: 0 8px; }

/* Animations */
.fade-in { opacity: 0; transform: translateY(30px); transition: opacity 0.6s ease, transform 0.6s ease; }
.fade-in.visible { opacity: 1; transform: translateY(0); }

.counter-number { font-size: 2.5rem; font-weight: 700; color: var(--primary); display: inline-block; }

/* Responsive */
@media (max-width: 1024px) {
    .hero-content { grid-template-columns: 1fr; text-align: center; }
    .hero-text p { margin: 0 auto 32px; }
    .hero-buttons { justify-content: center; }
    .grid-4 { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
    .nav-links { display: none; }
    .menu-toggle { display: flex; }
    .hero-text h1 { font-size: 2.2rem; }
    .section-title { font-size: 1.8rem; }
    .grid-2, .grid-3 { grid-template-columns: 1fr; }
    .grid-4 { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: 1fr; }
    .footer-bottom { flex-direction: column; text-align: center; }
    .back-to-top { bottom: 16px; right: 16px; width: 40px; height: 40px; font-size: 1.2rem; }
}

@media (max-width: 480px) {
    .container { padding: 0 16px; }
    .hero-text h1 { font-size: 1.8rem; }
    .hero-card { padding: 24px; }
    .card { padding: 20px; }
}