:root {
    --primary-color: #007aff;
    --bg-dark: #050505;
    --bg-card: #111111;
    --text-main: #ffffff;
    --text-muted: #888888;
    --accent-color: #00d2ff;
    --transition-smooth: all 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-main);
    line-height: 1.6;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    padding: 1.5rem 0;
    background: rgba(5, 5, 5, 0.8);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: 2px;
}

.logo span {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-left: 8px;
    font-weight: 300;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 3rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-main);
    font-size: 0.9rem;
    font-weight: 400;
    transition: var(--transition-smooth);
    opacity: 0.7;
}

.nav-links a:hover {
    opacity: 1;
    color: var(--primary-color);
}

/* Hero Section */
.hero {
    height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 50% 50%, #0a0a0a 0%, #050505 100%);
    z-index: -1;
}

#kline-canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0.6;
    filter: blur(0.3px);
}

.hero-background::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(rgba(18, 16, 16, 0) 50%, rgba(0, 0, 0, 0.25) 50%), linear-gradient(90deg, rgba(255, 0, 0, 0.06), rgba(0, 255, 0, 0.02), rgba(0, 0, 255, 0.06));
    z-index: 2;
    background-size: 100% 2px, 3px 100%;
    pointer-events: none;
}

.overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 50% 50%, transparent 0%, rgba(5, 5, 5, 0.4) 100%);
    z-index: 3;
}

.hero-content {
    text-align: center;
    max-width: 800px;
}

.hero h1 {
    font-size: 4rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    letter-spacing: -1px;
    background: linear-gradient(to right, #fff, #888);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-muted);
    margin-bottom: 2.5rem;
    font-weight: 300;
}

.btn {
    display: inline-block;
    padding: 1rem 2.5rem;
    border-radius: 4px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition-smooth);
    margin: 0 0.5rem;
    font-size: 0.9rem;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(0, 122, 255, 0.3);
}

.btn-outline {
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: white;
}

.btn-outline:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: white;
}

/* Sections */
.section {
    padding: 100px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 80px;
}

.section-header h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.section-header p {
    color: var(--text-muted);
    font-size: 1.1rem;
}

/* Tech Grid */
.grid {
    display: grid;
    gap: 2rem;
}

.tech-grid {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.card {
    background: var(--bg-card);
    padding: 3rem;
    border-radius: 8px;
    border: 1px solid rgba(255, 255, 255, 0.05);
    transition: var(--transition-smooth);
}

.card:hover {
    border-color: var(--primary-color);
    transform: translateY(-5px);
}

.card-icon {
    font-size: 0.8rem;
    color: var(--primary-color);
    font-weight: 700;
    margin-bottom: 1.5rem;
    opacity: 0.5;
}

.card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

/* Formula Specific Styles (Minimal) */
.math-formula {
    font-size: 2.2rem; /* 大字体，类似原本的 stat-value */
    margin-bottom: 1rem;
    color: var(--primary-color);
    text-shadow: 0 0 15px rgba(0, 122, 255, 0.4);
    display: flex;
    justify-content: center;
    align-items: center;
}

.math-formula .katex-display {
    margin: 0;
}

.card p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Stats Section */
.stats-section {
    background: #0a0a0a;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    text-align: center;
}

.stat-item .stat-value {
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.stat-item .stat-label {
    color: var(--text-muted);
    font-size: 0.9rem;
    letter-spacing: 1px;
    text-transform: uppercase;
}

/* Tabs Styles */
.tabs-container {
    max-width: 900px;
    margin: 0 auto;
}

.tabs-nav {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    list-style: none;
    padding: 0;
}

.tab-btn {
    padding: 0.8rem 2rem;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-muted);
    cursor: pointer;
    border-radius: 4px;
    transition: var(--transition-smooth);
    font-weight: 600;
}

.tab-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    box-shadow: 0 5px 15px rgba(0, 122, 255, 0.3);
}

.tab-content {
    display: none;
    text-align: center;
    animation: fadeIn 0.5s ease;
}

.tab-content.active {
    display: block;
}

.formula-explanation {
    margin-top: 2rem;
    color: var(--text-muted);
    font-size: 1.1rem;
    max-width: 850px;
    margin-left: auto;
    margin-right: auto;
    line-height: 1.8;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Footer */
.footer {
    padding: 80px 0 40px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    margin-bottom: 60px;
}

.footer-info p {
    color: var(--text-muted);
    margin-top: 1rem;
    max-width: 300px;
}

.footer-contact h4 {
    margin-bottom: 1.5rem;
}

.footer-contact p {
    color: var(--text-muted);
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

.footer-bottom {
    text-align: center;
    padding-top: 40px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    color: #444;
    font-size: 0.8rem;
}

/* Animations */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: var(--transition-smooth);
}

.reveal.active {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 3rem;
    }
}