/* ==================== Global Styles & Components ==================== */

/* 3. 全局基础样式 (Global Styles) */
*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'PingFang SC', sans-serif;
    font-size: 15px;
    line-height: 1.7;
    color: var(--text-primary);
    background: var(--bg-secondary);
    margin: 0;
    padding: 0;
}

/* 链接无下划线，使用过渡 */
a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
}

a:visited {
    color: inherit;
}

/* 响应式容器 */
.container,
.md3-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 24px;
}

@media (max-width: 768px) {

    .container,
    .md3-container {
        padding: 0 16px;
    }
}

/* Main Content Padding for Fixed Header */
.main-content {
    padding-top: 64px;
    min-height: 100vh;
}

/* ==================== 4. 关键组件 (Components) ==================== */

/* 4.1 顶部导航栏 (Header) */
.md3-top-app-bar {
    position: fixed;
    top: 0;
    right: 0;
    left: 0;
    height: 64px;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    /* Safari support */
    border-bottom: 1px solid var(--md-outline-variant);
    z-index: 1000;
    transition: var(--transition);
}

/* Dark Mode adaptation */
@media (prefers-color-scheme: dark) {
    .md3-top-app-bar {
        background: rgba(26, 28, 30, 0.9);
    }
}

.md3-top-app-bar-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 24px;
}

@media (max-width: 768px) {
    .md3-top-app-bar-container {
        padding: 0 16px;
    }
}

.md3-brand-title {
    font-size: 22px;
    font-weight: 600;
    background: var(--primary-gradient);
    /* 渐变文字 */
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: transparent;
    /* Fallback */
    margin: 0;
}

.md3-actions {
    display: flex;
    align-items: center;
    gap: 16px;
}

/* 4.3 按钮 (Buttons) */
.md3-fab-primary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    height: 40px;
    padding: 0 20px;
    background: var(--md-primary);
    color: var(--md-on-primary);
    border-radius: var(--md-shape-corner-full);
    /* Pill shape */
    font-weight: 500;
    box-shadow: var(--md-elevation-level1);
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 14px;
}

.md3-fab-primary:visited,
.md3-fab-primary:active {
    color: var(--md-on-primary);
}

.md3-fab-primary:hover {
    background: var(--md-primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--md-elevation-level2);
}

/* 4.2 卡片 (Card) */
.md3-card {
    background: var(--md-surface-container);
    border-radius: var(--md-shape-corner-large);
    /* 16px */
    border: 1px solid var(--md-outline-variant);
    transition: var(--transition);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.md3-card:hover {
    transform: translateY(-4px);
    background: var(--md-surface);
    border-color: var(--md-primary);
    box-shadow: var(--shadow-md);
}

.card-image {
    width: 100%;
    height: 200px;
    background-color: var(--md-surface-variant);
    object-fit: cover;
    display: block;
}

.card-content {
    padding: 24px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.card-title {
    margin: 0 0 8px 0;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.card-description {
    margin: 0 0 24px 0;
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    flex: 1;
}

.tech-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 24px;
}

.tech-tag {
    font-size: 12px;
    font-weight: 500;
    padding: 4px 10px;
    background-color: var(--md-surface-variant);
    color: var(--md-on-surface-variant);
    border-radius: 6px;
    border: 1px solid var(--md-outline-variant);
}

.card-actions {
    margin-top: auto;
}

/* Grid Layout */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
    padding: 40px 0;
}

/* Hero Section */
.hero {
    padding: 80px 0 60px 0;
    text-align: center;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: var(--md-primary);
    margin-bottom: 24px;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto 40px auto;
}

/* Footer Section */
.footer {
    margin-top: 60px;
    padding: 40px 0;
    border-top: 1px solid var(--md-outline-variant);
    text-align: center;
    color: var(--text-secondary);
}

.footer p {
    margin: 0;
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.mb-4 {
    margin-bottom: 1rem;
}