/* ===================================
   Abyss Theme - Main Stylesheet
   =================================== */

/* ===================================
   1. CSS Reset
   =================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* ===================================
   2. CSS Variables
   =================================== */
:root {
    /* Colors - Background */
    --color-bg: #000000;
    --color-bg-overlay: rgba(0, 0, 0, 0.8);
    --color-video-overlay-start: rgba(0, 0, 0, 0.4);
    --color-video-overlay-mid: rgba(20, 20, 20, 0.3);
    --color-video-overlay-end: rgba(40, 40, 40, 0.2);

    /* Colors - Text */
    --color-text-primary: #f5f5f7;
    --color-text-secondary: #a1a1a6;
    --color-text-tertiary: #86868b;
    --color-text-bright: #d5d9dd;
    --color-text-hover: #e2e5e8;
    --color-text-modal: #d2d2d7;
    --color-text-card: #f4f6f8;

    /* Colors - Accent (Gradient) */
    --color-accent-start: #ff4500;
    --color-accent-mid: #ff6b35;
    --color-accent-end: #ff8c42;

    /* Colors - Card */
    --color-card-bg-start: rgba(255, 255, 255, 0.1);
    --color-card-bg-end: rgba(255, 255, 255, 0.05);
    --color-card-border: rgba(255, 255, 255, 0.1);
    --color-card-border-hover: rgba(255, 107, 53, 0.3);
    --color-card-overlay: rgba(255, 69, 0, 0.1);
    --color-card-overlay-mid: rgba(255, 107, 53, 0.05);
    --color-card-shadow: rgba(255, 69, 0, 0.15);

    /* Colors - Modal */
    --color-modal-bg: rgba(0, 0, 0, 0.8);
    --color-modal-content-start: rgba(29, 29, 31, 0.95);
    --color-modal-content-end: rgba(45, 45, 47, 0.9);
    --color-modal-content-overlay-start: rgba(29, 29, 31, 0.75);
    --color-modal-content-overlay-end: rgba(45, 45, 47, 0.7);

    /* Typography */
    --font-primary: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', Roboto, sans-serif;
    --font-size-base: 16px;
    --font-size-sm: 14px;
    --font-size-md: 17px;
    --font-size-lg: 18px;
    --font-size-xl: 21px;
    --font-size-2xl: 24px;
    --font-size-3xl: 32px;
    --font-size-hero: 56px;

    /* Spacing */
    --spacing-xs: 8px;
    --spacing-sm: 12px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
    --spacing-2xl: 40px;
    --spacing-3xl: 60px;
    --spacing-4xl: 80px;

    /* Layout */
    --container-max-width: 1440px;
    --container-padding: 22px;
    --header-padding: 12px 0;
    --card-gap: 40px;
    --card-min-width: 400px;

    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 18px;
    --radius-lg: 20px;

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-smooth: 0.4s ease;
    --transition-card: 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);

    /* Effects */
    --blur-amount: 20px;
    --video-opacity: 0.6;

    /* Z-index */
    --z-video: -2;
    --z-video-overlay: -1;
    --z-header: 100;
    --z-modal: 1000;
    --z-modal-content: 2;
    --z-modal-close: 3;
}

/* ===================================
   3. Global Styles
   =================================== */
body {
    font-family: var(--font-primary);
    background-color: var(--color-bg);
    color: var(--color-text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    position: relative;
    font-size: var(--font-size-base);
}

/* ===================================
   4. Component Styles
   =================================== */

/* ===== Video Background ===== */
.video-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: var(--z-video);
    opacity: var(--video-opacity);
}

.video-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(
        135deg,
        var(--color-video-overlay-start),
        var(--color-video-overlay-mid),
        var(--color-video-overlay-end)
    );
    z-index: var(--z-video-overlay);
}

/* ===== Container ===== */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* ===== Header ===== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: var(--color-bg-overlay);
    -webkit-backdrop-filter: blur(var(--blur-amount));
    backdrop-filter: blur(var(--blur-amount));
    border-bottom: 1px solid var(--color-card-border);
    z-index: var(--z-header);
    padding: var(--header-padding);
}

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

.logo {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-text-primary);
    text-decoration: none;
    letter-spacing: -0.5px;
}

.back-btn {
    color: var(--color-text-bright);
    text-decoration: none;
    font-size: var(--font-size-md);
    font-weight: 400;
    transition: color var(--transition-normal);
}

.back-btn:hover {
    color: var(--color-text-hover);
}

/* ===== Hero Section ===== */
.hero {
    padding: 120px 0 var(--spacing-4xl);
    text-align: center;
}

.hero-title {
    font-size: var(--font-size-hero);
    font-weight: 600;
    letter-spacing: -0.015em;
    margin-bottom: var(--spacing-md);
    background: linear-gradient(
        135deg,
        var(--color-accent-start),
        var(--color-accent-mid),
        var(--color-accent-end)
    );
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    font-weight: 400;
    color: var(--color-text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* ===== Cards Section ===== */
.cards-section {
    padding: var(--spacing-3xl) 0;
}

.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(var(--card-min-width), 1fr));
    gap: var(--card-gap);
    max-width: 1200px;
    margin: 0 auto;
}

/* ===== Card ===== */
.card {
    background: linear-gradient(
        135deg,
        var(--color-card-bg-start),
        var(--color-card-bg-end)
    );
    border: 1px solid var(--color-card-border);
    border-radius: var(--radius-md);
    padding: var(--spacing-2xl);
    transition: all var(--transition-card);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(
        135deg,
        var(--color-card-overlay),
        var(--color-card-overlay-mid)
    );
    opacity: 0;
    transition: opacity var(--transition-smooth);
    border-radius: var(--radius-md);
}

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

.card:hover {
    transform: translateY(-8px) scale(1.02);
    border-color: var(--color-card-border-hover);
    box-shadow: 0 25px 50px var(--color-card-shadow);
}

.card-content {
    position: relative;
    z-index: var(--z-modal-content);
}

.card-title {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
}

.card-excerpt {
    font-size: var(--font-size-base);
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: var(--spacing-lg);
    display: -webkit-box;
    -webkit-line-clamp: 4;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.card-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--font-size-sm);
    color: var(--color-text-tertiary);
}

.card-date {
    color: var(--color-text-tertiary);
}

.read-more {
    color: var(--color-text-card);
    font-weight: 500;
    text-decoration: none;
}

.read-more:hover {
    color: var(--color-text-card);
}

/* ===== Modal ===== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--color-modal-bg);
    -webkit-backdrop-filter: blur(var(--blur-amount));
    backdrop-filter: blur(var(--blur-amount));
    z-index: var(--z-modal);
    padding: var(--spacing-2xl) 20px;
    overflow-y: auto;
}

.modal-content {
    max-width: 800px;
    margin: 0 auto;
    background: linear-gradient(
        135deg,
        var(--color-modal-content-start),
        var(--color-modal-content-end)
    );
    border: 1px solid var(--color-card-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-3xl);
    position: relative;
    background-size: cover;
    background-position: center center;
    background-repeat: no-repeat;
    min-height: 70vh;
}

.modal-content::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(
        135deg,
        var(--color-modal-content-overlay-start),
        var(--color-modal-content-overlay-end)
    );
    border-radius: var(--radius-lg);
    z-index: 1;
}

.modal-content > * {
    position: relative;
    z-index: var(--z-modal-content);
}

.modal-close {
    position: absolute;
    top: 20px;
    right: 25px;
    background: none;
    border: none;
    color: var(--color-text-secondary);
    font-size: 28px;
    cursor: pointer;
    transition: color var(--transition-normal);
    z-index: var(--z-modal-close);
}

.modal-close:hover {
    color: var(--color-text-primary);
}

.modal-title {
    font-size: var(--font-size-3xl);
    font-weight: 600;
    margin-bottom: 30px;
    color: var(--color-text-primary);
}

.modal-text {
    font-size: var(--font-size-lg);
    line-height: 1.8;
    color: var(--color-text-modal);
    white-space: pre-wrap;
}

/* ===== Footer ===== */
.footer {
    padding: var(--spacing-3xl) 0 var(--spacing-lg);
    text-align: center;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
}

.copyright {
    color: var(--color-text-tertiary);
    font-size: var(--font-size-sm);
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
}

.social-link {
    color: var(--color-text-secondary);
    text-decoration: none;
    font-size: var(--font-size-sm);
    transition: color var(--transition-normal);
}

.social-link:hover {
    color: var(--color-text-primary);
}

/* ===== Single Article Page ===== */
.single-article {
    padding: 120px 0 var(--spacing-3xl);
}

.article-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.article-title {
    font-size: var(--font-size-3xl);
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
}

.article-subtitle {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
}

.article-meta {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-md);
    color: var(--color-text-tertiary);
    font-size: var(--font-size-sm);
}

.article-date {
    color: var(--color-text-tertiary);
}

.article-categories,
.article-tags {
    display: flex;
    gap: var(--spacing-xs);
}

.category,
.tag {
    background: var(--color-card-bg-start);
    padding: 4px 12px;
    border-radius: var(--radius-sm);
    font-size: var(--font-size-sm);
}

.article-content {
    max-width: 800px;
    margin: 0 auto var(--spacing-3xl);
    font-size: var(--font-size-lg);
    line-height: 1.8;
}

.article-content h1,
.article-content h2,
.article-content h3 {
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
}

.article-content p {
    margin-bottom: var(--spacing-md);
}

.article-content a {
    color: var(--color-accent-mid);
    text-decoration: underline;
}

.article-content a:hover {
    color: var(--color-accent-end);
}

.article-content ul,
.article-content ol {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-xl);
}

.article-content li {
    margin-bottom: var(--spacing-xs);
}

.article-content img {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    margin: var(--spacing-lg) 0;
}

.article-content blockquote {
    border-left: 4px solid var(--color-accent-mid);
    padding-left: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
    color: var(--color-text-secondary);
    font-style: italic;
}

.article-content code {
    background: var(--color-card-bg-start);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'Monaco', 'Courier New', monospace;
    font-size: 0.9em;
}

.article-content pre {
    background: var(--color-card-bg-start);
    padding: var(--spacing-md);
    border-radius: var(--radius-sm);
    overflow-x: auto;
    margin: var(--spacing-lg) 0;
}

.article-content pre code {
    background: none;
    padding: 0;
}

.article-navigation {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    gap: var(--spacing-lg);
}

.prev-article,
.next-article {
    flex: 1;
    padding: var(--spacing-lg);
    background: var(--color-card-bg-start);
    border: 1px solid var(--color-card-border);
    border-radius: var(--radius-md);
    text-decoration: none;
    color: var(--color-text-primary);
    transition: all var(--transition-normal);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.prev-article:hover,
.next-article:hover {
    border-color: var(--color-card-border-hover);
    transform: translateY(-4px);
}

.nav-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-tertiary);
}

.nav-title {
    font-size: var(--font-size-base);
    font-weight: 500;
}

/* ===== List Page ===== */
.list-header {
    padding: 120px 0 var(--spacing-3xl);
    text-align: center;
}

.list-title {
    font-size: var(--font-size-3xl);
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: var(--color-text-primary);
}

.list-description {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-3xl);
}

.pagination-prev,
.pagination-next {
    color: var(--color-text-primary);
    text-decoration: none;
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--color-card-bg-start);
    border: 1px solid var(--color-card-border);
    border-radius: var(--radius-sm);
    transition: all var(--transition-normal);
}

.pagination-prev:hover,
.pagination-next:hover {
    border-color: var(--color-card-border-hover);
    transform: translateY(-2px);
}

.pagination-info {
    color: var(--color-text-tertiary);
    font-size: var(--font-size-sm);
}

.no-content {
    text-align: center;
    color: var(--color-text-secondary);
    font-size: var(--font-size-xl);
    padding: var(--spacing-3xl) 0;
}

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

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

/* ===================================
   6. Responsive Design
   =================================== */

/* Tablet and below (max-width: 1024px) */
@media (max-width: 1024px) {
    .cards-grid {
        grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
        gap: 30px;
    }
}

/* Mobile and below (max-width: 768px) */
@media (max-width: 768px) {
    :root {
        --container-padding: 16px;
        --font-size-hero: 40px;
        --font-size-xl: 19px;
        --card-gap: 24px;
        --card-min-width: 100%;
    }

    .container {
        padding: 0 var(--container-padding);
    }

    .hero {
        padding: 100px 0 var(--spacing-3xl);
    }

    .hero-title {
        font-size: var(--font-size-hero);
    }

    .hero-subtitle {
        font-size: var(--font-size-xl);
    }

    .cards-grid {
        grid-template-columns: 1fr;
        gap: var(--card-gap);
    }

    .card {
        padding: var(--spacing-xl) var(--spacing-lg);
    }

    .modal-content {
        padding: var(--spacing-2xl);
    }

    .article-navigation {
        flex-direction: column;
    }

    .single-article {
        padding: 100px 0 var(--spacing-lg);
    }

    .list-header {
        padding: 100px 0 var(--spacing-lg);
    }
}

/* Small mobile (max-width: 480px) */
@media (max-width: 480px) {
    :root {
        --font-size-hero: 32px;
        --font-size-3xl: 24px;
        --spacing-2xl: 24px;
        --spacing-3xl: 40px;
    }

    .modal-close {
        top: 15px;
        right: 15px;
        font-size: 24px;
    }

    .modal-title {
        font-size: var(--font-size-3xl);
        margin-bottom: var(--spacing-lg);
    }

    .modal-text {
        font-size: var(--font-size-base);
    }
}

/* ===================================
   7. Keyboard Navigation Styles
   =================================== */

/* 默认隐藏焦点轮廓（鼠标用户） */
* {
    outline: none;
}

/* 键盘导航时显示焦点样式 */
body.keyboard-nav *:focus {
    outline: 2px solid var(--color-accent-mid);
    outline-offset: 4px;
}

/* 卡片焦点样式 */
body.keyboard-nav .card:focus {
    border-color: var(--color-card-border-hover);
    box-shadow: 0 0 0 4px rgba(255, 107, 53, 0.2);
}

/* 按钮和链接焦点样式 */
body.keyboard-nav button:focus,
body.keyboard-nav a:focus {
    outline: 2px solid var(--color-accent-mid);
    outline-offset: 2px;
}

/* 模态框关闭按钮焦点 */
body.keyboard-nav .modal-close:focus {
    outline: 2px solid var(--color-text-primary);
    outline-offset: 4px;
}