:root {
    --bg-dark: #0d1117;
    --bg-card: #161b22;
    --bg-darker: #0a0d10;
    --border: #30363d;
    --text-primary: #e6edf3;
    --text-secondary: #8b949e;
    --accent: #58a6ff;
    --accent-hover: #79c0ff;
    --tag-bg: #1f6feb;
    --tag-bg-2: #238636;
    --tag-bg-3: #8957e5;
    --danger: #f85149;
    --warning: #d29922;
    --success: #3fb950;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', sans-serif;
    background-color: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.6;
    scroll-behavior: smooth;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(13, 17, 23, 0.9);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    z-index: 100;
}

.nav-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
}

.nav-logo {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--accent);
    text-decoration: none;
}

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

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.95rem;
    transition: color 0.2s;
}

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

.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding-top: 60px;
    background: radial-gradient(ellipse at top, #1a2332 0%, var(--bg-dark) 70%);
}

.hero-content {
    padding: 40px 24px;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 16px;
}

.hero .highlight {
    color: var(--accent);
}

.hero p {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.section {
    padding: 80px 0;
}

.section.bg-darker {
    background-color: var(--bg-darker);
}

.section-title {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 40px;
    color: var(--text-primary);
    border-left: 4px solid var(--accent);
    padding-left: 16px;
}

.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 24px;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 28px;
    cursor: pointer;
    transition: transform 0.25s, border-color 0.25s, box-shadow 0.25s;
    position: relative;
    overflow: hidden;
}

.project-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent), var(--tag-bg-3));
    opacity: 0;
    transition: opacity 0.25s;
}

.project-card:hover {
    transform: translateY(-6px);
    border-color: var(--accent);
    box-shadow: 0 12px 40px rgba(88, 166, 255, 0.15);
}

.project-card:hover::before {
    opacity: 1;
}

.card-icon {
    font-size: 2.5rem;
    margin-bottom: 16px;
}

.project-card h3 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 4px;
}

.card-subtitle {
    font-size: 0.85rem;
    color: var(--accent);
    margin-bottom: 12px;
}

.card-desc {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
    line-height: 1.7;
}

.card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 20px;
}

.tag {
    font-size: 0.75rem;
    padding: 4px 10px;
    border-radius: 20px;
    background: var(--tag-bg);
    color: #fff;
}

.tag:nth-child(2) { background: var(--tag-bg-2); }
.tag:nth-child(3) { background: var(--tag-bg-3); }
.tag:nth-child(4) { background: var(--danger); }

.card-link {
    font-size: 0.9rem;
    color: var(--accent);
    font-weight: 600;
}

.about-content {
    max-width: 700px;
}

.about-content p {
    color: var(--text-secondary);
    margin-bottom: 16px;
    font-size: 1.05rem;
}

.skill-list {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 24px;
}

.skill-badge {
    padding: 6px 14px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 0.85rem;
    color: var(--text-secondary);
    transition: border-color 0.2s, color 0.2s;
}

.skill-badge:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.footer {
    text-align: center;
    padding: 32px;
    border-top: 1px solid var(--border);
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.fade-in {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.7s ease forwards;
}

.delay-1 { animation-delay: 0.2s; }
.delay-2 { animation-delay: 0.4s; }

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 640px) {
    .hero h1 { font-size: 2rem; }
    .project-grid { grid-template-columns: 1fr; }
}