:root {
    --bg: #ffffff;
    --fg: #111111;
    --muted: #666666;
    --border: #e0e0e0;
    --bg-alt: #f9f9f9; /* 辅助背景色，如代码块 */
    --radius: 2px;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
    --transition: all 0.2s ease;
}

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

body {
    background: var(--bg);
    color: var(--fg);
    font-family: var(--font);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}

a {
    color: inherit;
    text-decoration: none;
    transition: var(--transition);
}

ul {
    list-style: none;
}

.container {
    width: 100%;
    /* 取消了 max-width 限制，让页面充分铺满 */
    padding: 0 4rem; /* 增加一点两侧的呼吸内边距 */
}

/* 导航栏 */
.navbar {
    border-bottom: 1px solid var(--border);
    padding: 1.5rem 0;
    position: sticky;
    top: 0;
    background: var(--bg);
    z-index: 100;
}

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

.logo {
    font-weight: 800;
    font-size: 1.2rem;
    letter-spacing: 1px;
}

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

.nav-links a {
    font-size: 0.9rem;
    color: var(--muted);
    font-weight: 500;
}

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

.nav-auth {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-left: 1rem;
    border-left: 1px solid var(--border);
    padding-left: 1.5rem;
}

.nav-login {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--fg);
    transition: var(--transition);
}

/* 修复导航栏中 A 标签颜色的层叠问题 */
.nav-links a.btn {
    color: var(--bg); /* 强制白字 */
}

.nav-links a.btn:hover {
    color: var(--fg); /* Hover变黑字 */
}

.hamburger {
    display: none;
    background: none;
    border: none;
    color: var(--fg);
    cursor: pointer;
}

/* 按钮 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    background: var(--fg);
    color: var(--bg); /* 纯白文字 */
    border: 1px solid var(--fg);
    border-radius: var(--radius);
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    cursor: pointer;
    transition: var(--transition);
}

.btn:hover {
    background: transparent;
    color: var(--fg); /* Hover时背景变透明，文字变黑 */
}

.btn-outline {
    background: transparent;
    color: var(--fg);
    border-color: var(--border);
}

.btn-outline:hover {
    border-color: var(--fg);
}

/* 小号按钮 (用于导航栏等紧凑场景) */
.btn-sm {
    padding: 0.5rem 1.2rem;
    font-size: 0.85rem;
    border-radius: var(--radius);
}

/* 页面通用头部 */
.page-header {
    padding: 6rem 0 4rem;
    border-bottom: 1px solid var(--border);
    margin-bottom: 4rem;
}

.page-title {
    font-size: 3.5rem;
    font-weight: 400;
    letter-spacing: -0.03em;
    line-height: 1.1;
    margin-bottom: 1rem;
}

.page-subtitle {
    color: var(--muted);
    font-size: 1.25rem;
    max-width: 600px;
}

/* 网格布局 */
.grid {
    display: grid;
    gap: 2rem;
}

.grid-2 {
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
}

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

/* 卡片 */
.card {
    border: 1px solid var(--border);
    padding: 2.5rem 2rem;
    border-radius: var(--radius);
    background: transparent;
    transition: border-color 0.2s;
}

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

.card-icon {
    margin-bottom: 1.5rem;
    color: var(--fg);
    width: 32px;
    height: 32px;
}

.card-title {
    font-size: 1.2rem;
    font-weight: 500;
    margin-bottom: 1rem;
}

.card-desc {
    color: var(--muted);
    font-size: 0.95rem;
    line-height: 1.6;
}



/* 统计数据 */
.stat-item {
    margin-bottom: 2rem;
}

.stat-number {
    font-size: 4rem;
    font-weight: 300;
    letter-spacing: -0.05em;
    margin-bottom: 0.5rem;
    border-bottom: 1px solid var(--border);
    padding-bottom: 1rem;
    font-family: monospace;
}

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



/* 页脚 */
.footer {
    border-top: 1px solid var(--border);
    padding: 4rem 0 2rem;
    margin-top: 8rem;
    font-size: 0.9rem;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 4rem;
    margin-bottom: 4rem;
}

.footer h4 {
    color: var(--fg);
    margin-bottom: 1.5rem;
    font-weight: 500;
}

.footer ul li {
    margin-bottom: 0.8rem;
}

.footer ul li a {
    color: var(--muted);
}

.footer ul li a:hover {
    color: var(--fg);
}

.footer-bottom {
    border-top: 1px solid var(--border);
    padding-top: 2rem;
    display: flex;
    justify-content: space-between;
    color: var(--muted);
}

/* 巨型可交互底部品牌字 (Canvas 粒子损坏效果) */
.footer-mega-text {
    width: 100%;
    height: clamp(120px, 20vw, 300px); /* 响应式高度 */
    margin-top: 4rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border);
    position: relative;
    overflow: hidden;
}

#footer-canvas {
    width: 100%;
    height: 100%;
    display: block;
    cursor: crosshair; /* 提示可交互 */
}
@media (max-width: 768px) {
    .page-title { font-size: 2.5rem; }
    .grid-2 { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: 1fr; gap: 2rem; }
    .footer-bottom { flex-direction: column; gap: 1rem; text-align: center; }
    
    .nav-links {
        display: none;
    }
    
    .hamburger {
        display: block;
    }
    
    .nav-links.active {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: var(--bg);
        padding: 2rem;
        border-bottom: 1px solid var(--border);
        align-items: flex-start;
    }
    
    .nav-auth {
        margin-left: 0;
        margin-top: 1rem;
        padding-left: 0;
        border-left: none;
        border-top: 1px solid var(--border);
        padding-top: 1.5rem;
        width: 100%;
        justify-content: flex-start;
    }
}