/* CSS Variables for Theme Switching */
:root {
    /* Light Theme Colors */
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --background-color: #ffffff;
    --surface-color: #f8f9fa;
    --text-color: #2c3e50;
    --text-secondary: #7f8c8d;
    --border-color: #e0e0e0;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    
    /* Dark Theme Colors */
    --dark-primary: #ecf0f1;
    --dark-secondary: #3498db;
    --dark-accent: #e74c3c;
    --dark-background: #1a1a1a;
    --dark-surface: #2d2d2d;
    --dark-text: #ecf0f1;
    --dark-text-secondary: #bdc3c7;
    --dark-border: #404040;
    --dark-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
    transition: background-color 0.3s ease, color 0.3s ease;
}

body.dark-mode {
    --primary-color: var(--dark-primary);
    --secondary-color: var(--dark-secondary);
    --accent-color: var(--dark-accent);
    --background-color: var(--dark-background);
    --surface-color: var(--dark-surface);
    --text-color: var(--dark-text);
    --text-secondary: var(--dark-text-secondary);
    --border-color: var(--dark-border);
    --shadow: var(--dark-shadow);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navigation */
.navbar {
    background-color: var(--surface-color);
    box-shadow: var(--shadow);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: all 0.3s ease;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo a {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--text-color);
    font-weight: bold;
    font-size: 1.2rem;
}

.nav-logo img {
    height: 40px;
    margin-right: 10px;
    border-radius: 5px;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 30px;
}

.nav-link {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    padding: 10px 15px;
    border-radius: 5px;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.nav-link:hover,
.nav-link.active {
    background-color: var(--secondary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(52, 152, 219, 0.3);
}

.nav-link:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 2px;
    background-color: var(--accent-color);
    transition: all 0.3s ease;
    transform: translateX(-50%);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 80%;
}

.nav-controls {
    display: flex;
    align-items: center;
    gap: 15px;
}

.theme-toggle,
.language-toggle {
    background: none;
    border: 1px solid var(--border-color);
    padding: 8px 12px;
    border-radius: 5px;
    cursor: pointer;
    color: var(--text-color);
    display: flex;
    align-items: center;
    gap: 5px;
    transition: all 0.3s ease;
}

.theme-toggle:hover,
.language-toggle:hover {
    background-color: var(--surface-color);
}

.language-dropdown {
    position: relative;
}

.language-menu {
    position: absolute;
    top: 100%;
    right: 0;
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 5px;
    box-shadow: var(--shadow);
    min-width: 150px;
    display: none;
    z-index: 1001;
}

.language-menu.show {
    display: block;
}

.language-menu a {
    display: block;
    padding: 10px 15px;
    text-decoration: none;
    color: var(--text-color);
    transition: background-color 0.3s ease;
}

.language-menu a:hover {
    background-color: var(--secondary-color);
    color: white;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background-color: var(--text-color);
    transition: all 0.3s ease;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--secondary-color), var(--primary-color));
    color: white;
    padding: 80px 0 60px;
    text-align: center;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-top: 70px; /* 确保在导航栏下方 */
}

.hero-content h1 {
    font-size: 3rem;
    margin-bottom: 20px;
    font-weight: 700;
}

.hero-content p {
    font-size: 1.2rem;
    margin-bottom: 30px;
    opacity: 0.9;
}

.hero-links {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
}

.hero-link {
    background-color: rgba(255, 255, 255, 0.2);
    color: white;
    padding: 12px 24px;
    text-decoration: none;
    border-radius: 25px;
    transition: all 0.3s ease;
    border: 2px solid rgba(255, 255, 255, 0.3);
}

.hero-link:hover {
    background-color: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
}

/* Main Content */
.main-content {
    padding: 60px 0;
    min-height: calc(100vh - 200px);
    margin-top: 70px; /* 确保内容在导航栏下方 */
}

.section-title,
.page-title {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 40px;
    color: var(--text-color);
}

/* Articles Grid */
.articles-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 30px;
    margin-bottom: 40px;
}

.article-card {
    background-color: var(--surface-color);
    border-radius: 10px;
    padding: 30px;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.article-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
}

.article-meta {
    display: flex;
    gap: 15px;
    margin-bottom: 15px;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.article-date,
.article-category {
    background-color: var(--background-color);
    padding: 4px 12px;
    border-radius: 15px;
}

.article-title {
    font-size: 1.5rem;
    margin-bottom: 15px;
}

.article-title a {
    text-decoration: none;
    color: var(--text-color);
    transition: all 0.3s ease;
    position: relative;
    display: inline-block;
}

.article-title a:hover {
    color: var(--secondary-color);
    transform: translateX(5px);
}

.article-title a::before {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: -2px;
    left: 0;
    background-color: var(--secondary-color);
    transition: width 0.3s ease;
}

.article-title a:hover::before {
    width: 100%;
}

.article-title a:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 4px;
    border-radius: 2px;
}

.article-excerpt {
    color: var(--text-secondary);
    margin-bottom: 20px;
    line-height: 1.6;
}

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

.read-more {
    color: var(--secondary-color);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 5px;
}

.read-more:hover {
    color: var(--accent-color);
    transform: translateX(3px);
}

.read-more::after {
    content: '→';
    transition: transform 0.3s ease;
}

.read-more:hover::after {
    transform: translateX(3px);
}

.read-more:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
    border-radius: 3px;
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-top: 40px;
}

.page-link {
    padding: 10px 15px;
    text-decoration: none;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    color: var(--text-color);
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.page-link:hover,
.page-link.active {
    background-color: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(52, 152, 219, 0.3);
}

.page-link:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
}

.page-link.disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.page-link.disabled:hover {
    background-color: transparent;
    color: var(--text-color);
    border-color: var(--border-color);
    transform: none;
    box-shadow: none;
}

.page-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s ease;
}

.page-link:hover::before {
    left: 100%;
}

/* Categories Grid */
.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.category-card {
    background-color: var(--surface-color);
    border-radius: 15px;
    padding: 30px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease;
}

.category-card:hover {
    transform: translateY(-5px);
}

.category-icon {
    font-size: 3rem;
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.category-title {
    font-size: 1.5rem;
    margin-bottom: 10px;
    color: var(--text-color);
}

.category-count {
    color: var(--secondary-color);
    font-weight: 600;
    margin-bottom: 10px;
}

.category-desc {
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.category-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background-color: var(--secondary-color);
    color: white;
    padding: 10px 20px;
    text-decoration: none;
    border-radius: 25px;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.category-link:hover {
    background-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(52, 152, 219, 0.4);
}

.category-link:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
}

.category-link::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s ease;
}

.category-link:hover::before {
    left: 100%;
}

.category-link::after {
    content: '→';
    font-weight: bold;
    transition: transform 0.3s ease;
}

.category-link:hover::after {
    transform: translateX(3px);
}

/* About Page */
.about-header {
    text-align: center;
    margin-bottom: 40px;
}

.about-avatar {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    margin-bottom: 20px;
    border: 5px solid var(--secondary-color);
}

.about-content h2 {
    font-size: 1.8rem;
    margin-bottom: 20px;
    color: var(--text-color);
}

.about-content p,
.about-content ul {
    margin-bottom: 30px;
    line-height: 1.8;
}

.about-content ul {
    list-style: none;
    padding-left: 0;
}

.about-content li {
    margin-bottom: 10px;
    padding-left: 25px;
    position: relative;
}

.about-content li:before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--secondary-color);
    font-weight: bold;
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.skill-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 15px;
    background-color: var(--surface-color);
    border-radius: 10px;
    transition: transform 0.3s ease;
}

.skill-item:hover {
    transform: translateY(-2px);
}

.skill-item i {
    font-size: 1.5rem;
    color: var(--secondary-color);
}

.contact-links {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 20px;
    background-color: var(--surface-color);
    color: var(--text-color);
    text-decoration: none;
    border-radius: 25px;
    transition: all 0.3s ease;
}

.contact-link:hover {
    background-color: var(--secondary-color);
    color: white;
}

/* Update History */
.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline:before {
    content: '';
    position: absolute;
    left: 30px;
    top: 0;
    bottom: 0;
    width: 2px;
    background-color: var(--secondary-color);
}

.timeline-item {
    position: relative;
    margin-bottom: 40px;
    padding-left: 80px;
}

.timeline-date {
    position: absolute;
    left: 0;
    top: 0;
    background-color: var(--secondary-color);
    color: white;
    padding: 8px 15px;
    border-radius: 20px;
    font-weight: 600;
}

.timeline-content {
    background-color: var(--surface-color);
    padding: 25px;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

.timeline-content h3 {
    margin-bottom: 15px;
    color: var(--text-color);
}

.timeline-content p {
    margin-bottom: 8px;
    color: var(--text-secondary);
}

/* 404 Page */
.error-section {
    text-align: center;
    padding: 80px 0;
}

.error-content h1 {
    font-size: 6rem;
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.error-content h2 {
    font-size: 2rem;
    margin-bottom: 20px;
    color: var(--text-color);
}

.error-content p {
    font-size: 1.2rem;
    margin-bottom: 30px;
    color: var(--text-secondary);
}

.error-icon {
    font-size: 4rem;
    color: var(--accent-color);
    margin-bottom: 20px;
}

.error-actions {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 40px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 12px 24px;
    text-decoration: none;
    border-radius: 25px;
    font-weight: 500;
    transition: all 0.3s ease;
}

.btn-primary {
    background-color: var(--secondary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-color);
}

.btn-secondary {
    background-color: var(--surface-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--background-color);
}

.error-suggestions {
    max-width: 500px;
    margin: 0 auto;
}

.error-suggestions h3 {
    margin-bottom: 15px;
    color: var(--text-color);
}

.error-suggestions ul {
    list-style: none;
    padding: 0;
}

.error-suggestions li {
    margin-bottom: 10px;
}

.error-suggestions a {
    color: var(--secondary-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

.error-suggestions a:hover {
    color: var(--accent-color);
}

/* Enhanced Link Styles */
/* External link indicator */
a[href^="http"]:not([href*="herobrinexiaofeng"]):not([href*="localhost"])::after {
    content: ' ↗';
    font-size: 0.8em;
    opacity: 0.7;
    transition: opacity 0.3s ease;
}

a[href^="http"]:not([href*="herobrinexiaofeng"]):not([href*="localhost"]):hover::after {
    opacity: 1;
}

/* Enhanced focus styles for all links */
a:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
    border-radius: 2px;
}

/* Improved touch targets for mobile */
@media (max-width: 768px) {
    .nav-link,
    .page-link,
    .category-link,
    .read-more {
        min-height: 44px;
        min-width: 44px;
        display: inline-flex;
        align-items: center;
        justify-content: center;
    }
    
    .article-title a {
        padding: 8px 0;
        display: block;
    }
}

/* Smooth scrolling for anchor links */
html {
    scroll-behavior: smooth;
}

/* Link click animations */
.link-clicked {
    animation: linkClick 0.3s ease;
}

@keyframes linkClick {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(0.95);
    }
    100% {
        transform: scale(1);
    }
}

/* Enhanced link states for better visual feedback */
a:active {
    opacity: 0.8;
    transition: opacity 0.1s ease;
}

/* Improved focus styles for all interactive elements */
button:focus,
.theme-toggle:focus,
.language-toggle:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
    border-radius: 3px;
}

/* Article Navigation Styles */
.article-navigation {
    background-color: var(--surface-color);
    border-top: 1px solid var(--border-color);
    padding: 40px 0;
    margin-top: 60px;
}

.nav-links {
    display: flex;
    justify-content: space-between;
    gap: 20px;
}

.nav-prev,
.nav-next {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--text-color);
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 20px;
    transition: all 0.3s ease;
    flex: 1;
    max-width: 45%;
    position: relative;
    overflow: hidden;
}

.nav-prev {
    justify-content: flex-start;
    text-align: left;
}

.nav-next {
    justify-content: flex-end;
    text-align: right;
}

.nav-prev:hover,
.nav-next:hover,
.nav-prev:focus,
.nav-next:focus {
    background-color: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(52, 152, 219, 0.3);
}

.nav-prev:focus,
.nav-next:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

.nav-arrow {
    font-size: 1.5rem;
    font-weight: bold;
    margin: 0 15px;
    transition: transform 0.3s ease;
}

.nav-prev:hover .nav-arrow {
    transform: translateX(-5px);
}

.nav-next:hover .nav-arrow {
    transform: translateX(5px);
}

.nav-content {
    flex: 1;
}

.nav-label {
    display: block;
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 5px;
    transition: color 0.3s ease;
}

.nav-prev:hover .nav-label,
.nav-next:hover .nav-label {
    color: rgba(255, 255, 255, 0.8);
}

.nav-title {
    display: block;
    font-size: 1.1rem;
    font-weight: 600;
    line-height: 1.4;
    transition: color 0.3s ease;
}

.nav-prev:hover .nav-title,
.nav-next:hover .nav-title {
    color: white;
}

/* Mobile styles for article navigation */
@media (max-width: 768px) {
    .nav-links {
        flex-direction: column;
        gap: 15px;
    }
    
    .nav-prev,
    .nav-next {
        max-width: 100%;
        min-height: 80px;
        margin-bottom: 0;
    }
    
    /* 移动端：上一篇在上，下一篇在下 */
    .nav-prev {
        order: 1;
    }
    
    .nav-next {
        order: 2;
    }
    
    .nav-arrow {
        margin: 0 10px;
    }
}

/* Footer */
.footer {
    background-color: var(--surface-color);
    padding: 30px 0;
    text-align: center;
    border-top: 1px solid var(--border-color);
}

.footer p {
    color: var(--text-secondary);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background-color: var(--surface-color);
        flex-direction: column;
        justify-content: flex-start;
        align-items: center;
        padding-top: 40px;
        transition: left 0.3s ease;
        gap: 20px;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .hero-content p {
        font-size: 1rem;
    }

    .hero-links {
        flex-direction: column;
        align-items: center;
    }

    .section-title,
    .page-title {
        font-size: 2rem;
    }

    .articles-grid {
        gap: 20px;
    }

    .article-card {
        padding: 20px;
    }

    .categories-grid {
        grid-template-columns: 1fr;
    }

    .contact-links {
        flex-direction: column;
        align-items: center;
    }

    .error-content h1 {
        font-size: 4rem;
    }

    .error-actions {
        flex-direction: column;
        align-items: center;
    }

    .timeline:before {
        left: 20px;
    }

    .timeline-item {
        padding-left: 60px;
    }

    .timeline-date {
        left: -10px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

    .nav-container {
        padding: 0 15px;
    }

    .hero {
        padding: 100px 0 60px;
    }

    .hero-content h1 {
        font-size: 1.8rem;
    }

    .main-content {
        padding: 40px 0;
    }
}

/* Dark mode specific adjustments */
body.dark-mode .article-card,
body.dark-mode .category-card,
body.dark-mode .timeline-content {
    background-color: var(--surface-color);
}

body.dark-mode .nav-link:hover,
body.dark-mode .nav-link.active {
    background-color: var(--secondary-color);
}

/* Smooth transitions for theme switching */
* {
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}