:root {
    --primary-color: #000000;
    --accent-color: #00FF00; /* 亮绿色，Sequesto 的标志性颜色 */
    --text-color: #333333;
    --bg-color: #ffffff;
    --secondary-bg: #f8f9fa;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

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

body {
    font-family: var(--font-family);
    color: var(--text-color);
    line-height: 1.6;
    background-color: var(--bg-color);
}

a {
    text-decoration: none;
    color: inherit;
}

/* Navigation */
nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 5%;
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    z-index: 1000;
    border-bottom: 1px solid #eee;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: -1px;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: var(--accent-color);
}

.cta-button {
    background: var(--primary-color);
    color: white;
    padding: 0.8rem 1.5rem;
    border-radius: 5px;
    font-weight: 600;
    transition: transform 0.2s, background 0.3s;
}

.cta-button:hover {
    background: #222;
    transform: translateY(-2px);
}

/* Hero Section */
.hero {
    padding: 8rem 5% 5rem;
    text-align: center;
    max-width: 900px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 4rem;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    font-weight: 800;
}

.hero p {
    font-size: 1.25rem;
    color: #666;
    margin-bottom: 2.5rem;
}

.hero-btns {
    display: flex;
    justify-content: center;
    gap: 1rem;
}

.btn-outline {
    border: 1px solid #ddd;
    padding: 0.8rem 1.5rem;
    border-radius: 5px;
    font-weight: 600;
}

/* Stats Section */
.stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
    padding: 4rem 5%;
    background: var(--secondary-bg);
    text-align: center;
}

.stat-item h3 {
    font-size: 2.5rem;
    color: var(--primary-color);
}

.stat-item p {
    color: #666;
    font-size: 0.9rem;
}

/* Content Sections */
.section {
    padding: 6rem 5%;
}

.section-title {
    text-align: center;
    margin-bottom: 4rem;
}

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

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 3rem;
}

.feature-card {
    padding: 2rem;
    border: 1px solid #eee;
    border-radius: 12px;
    transition: border-color 0.3s;
}

.feature-card:hover {
    border-color: var(--accent-color);
}

.feature-card h3 {
    margin-bottom: 1rem;
}

/* Footer */
footer {
    padding: 4rem 5%;
    background: #000;
    color: #fff;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 3rem;
}

.footer-col h4 {
    margin-bottom: 1.5rem;
    color: var(--accent-color);
}

.footer-col ul {
    list-style: none;
}

.footer-col ul li {
    margin-bottom: 0.8rem;
    font-size: 0.9rem;
    color: #ccc;
}

@media (max-width: 768px) {
    .hero h1 { font-size: 2.5rem; }
    .nav-links { display: none; }
    .stats { grid-template-columns: repeat(2, 1fr); }
}