:root {
    --color-bg: #ffffff;
    --color-bg-secondary: #f8f9fa;
    --color-text: #1a1a1a;
    --color-text-secondary: #666666;
    --color-text-muted: #999999;
    --color-border: #eaeaea;
    --color-border-light: #f0f0f0;
    --color-primary: #e53935;
    --color-primary-hover: #c62828;
    --color-link: #1a1a1a;
    --color-link-hover: #e53935;
    --color-shadow: rgba(0, 0, 0, 0.08);
    --color-overlay: rgba(0, 0, 0, 0.5);
    --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    --font-mono: "SF Mono", "Fira Code", "Consolas", monospace;
    --header-height: 60px;
    --container-width: 720px;
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-full: 999px;
    --transition-fast: 0.15s ease;
    --transition-normal: 0.25s ease;
    --transition-slow: 0.4s ease;
}

[data-theme="dark"] {
    --color-bg: #1a1a1a;
    --color-bg-secondary: #242424;
    --color-text: #e8e8e8;
    --color-text-secondary: #a0a0a0;
    --color-text-muted: #707070;
    --color-border: #333333;
    --color-border-light: #2a2a2a;
    --color-link: #e8e8e8;
    --color-link-hover: #e53935;
    --color-shadow: rgba(0, 0, 0, 0.3);
    --color-overlay: rgba(0, 0, 0, 0.7);
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    min-height: 100vh;
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-bg);
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

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

a:hover {
    color: var(--color-link-hover);
}

img {
    display: block;
    max-width: 100%;
    height: auto;
}

button,
input,
textarea {
    font: inherit;
}

button {
    border: 0;
    background: none;
    cursor: pointer;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.header-inner {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    min-height: var(--header-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-md);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    min-width: 0;
    color: var(--color-text);
    font-size: 1.125rem;
    font-weight: 600;
}

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

.logo-img {
    width: auto;
    height: 32px;
}

.logo-text {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.nav {
    display: flex;
    flex: 1;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    min-width: 0;
}

.nav-item {
    position: relative;
}

.nav-link,
.nav-submenu-link {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    color: var(--color-text-secondary);
    white-space: nowrap;
}

.nav-link:hover,
.nav-link.active,
.nav-submenu-link:hover,
.nav-submenu-link.active {
    color: var(--color-text);
}

.nav-link.active,
.nav-submenu-link.active {
    font-weight: 500;
}

.nav-submenu {
    position: absolute;
    top: calc(100% + 8px);
    left: 50%;
    min-width: 160px;
    padding: var(--spacing-sm);
    display: flex;
    flex-direction: column;
    gap: 4px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background: var(--color-bg);
    box-shadow: 0 12px 32px var(--color-shadow);
    opacity: 0;
    visibility: hidden;
    transform: translate(-50%, -8px);
    transition: opacity var(--transition-fast), visibility var(--transition-fast), transform var(--transition-fast);
}

.nav-item--has-children:hover .nav-submenu,
.nav-item--has-children:focus-within .nav-submenu {
    opacity: 1;
    visibility: visible;
    transform: translate(-50%, 0);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.btn-icon {
    width: 36px;
    height: 36px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-secondary);
    border-radius: var(--radius-full);
    transition: color var(--transition-fast), background-color var(--transition-fast);
}

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

.icon {
    width: 20px;
    height: 20px;
}

#theme-toggle .icon-moon {
    display: none;
}

[data-theme="dark"] #theme-toggle .icon-sun {
    display: none;
}

[data-theme="dark"] #theme-toggle .icon-moon {
    display: block;
}

.mobile-menu-toggle {
    display: none;
}

.mobile-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    z-index: 99;
    display: none;
    flex-direction: column;
    gap: 4px;
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    box-shadow: 0 4px 12px var(--color-shadow);
}

.mobile-nav.active {
    display: flex;
}

.mobile-nav-link {
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-sm);
    color: var(--color-text-secondary);
}

.mobile-nav-link:hover,
.mobile-nav-link.active {
    color: var(--color-text);
    background-color: var(--color-bg-secondary);
}

.mobile-nav-link--child {
    padding-left: calc(var(--spacing-md) + 16px);
    font-size: 0.9375rem;
}

.search-modal {
    position: fixed;
    inset: 0;
    z-index: 200;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding-top: 120px;
    background-color: var(--color-overlay);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-normal), visibility var(--transition-normal);
}

.search-modal.active {
    opacity: 1;
    visibility: visible;
}

.search-modal-content {
    width: 100%;
    max-width: 560px;
    padding: 0 var(--spacing-lg);
    transform: translateY(-20px);
    transition: transform var(--transition-normal);
}

.search-modal.active .search-modal-content {
    transform: translateY(0);
}

.search-input-wrapper {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) var(--spacing-lg);
    background-color: var(--color-bg);
    border-radius: var(--radius-lg);
    box-shadow: 0 8px 32px var(--color-shadow);
}

.search-input {
    flex: 1;
    border: 0;
    outline: 0;
    background: transparent;
    color: var(--color-text);
    font-size: 1.125rem;
}

.search-input::placeholder {
    color: var(--color-text-muted);
}

.search-close {
    width: 32px;
    height: 32px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-full);
    color: var(--color-text-muted);
    font-size: 1.5rem;
}

.search-close:hover {
    color: var(--color-text);
    background-color: var(--color-bg-secondary);
}

.main {
    padding: var(--spacing-2xl) 0;
}

.post-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.post {
    padding: var(--spacing-xl);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    background-color: var(--color-bg);
    animation: fadeIn 0.4s ease forwards;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.post:hover {
    box-shadow: 0 4px 16px var(--color-shadow);
}

.post-title {
    margin-bottom: var(--spacing-sm);
    font-size: 1.25rem;
    line-height: 1.4;
    font-weight: 600;
}

.post-title a {
    color: var(--color-text);
}

.post-title a:hover {
    color: var(--color-primary);
}

.post-excerpt {
    margin-bottom: var(--spacing-md);
    color: var(--color-text-secondary);
    font-size: 0.9375rem;
    line-height: 1.8;
    display: -webkit-box;
    overflow: hidden;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
}

.post-meta,
.article-meta,
.related-post-card-meta {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--color-text-muted);
    font-size: 0.875rem;
}

.post-meta-sep,
.article-meta-sep {
    color: var(--color-border);
}

.post-category a,
.article-category a,
.related-post-card-meta a {
    color: inherit;
}

.category-header {
    margin-bottom: var(--spacing-2xl);
    text-align: center;
}

.category-title {
    font-size: 2rem;
    font-weight: 700;
}

.page-header {
    margin-bottom: var(--spacing-2xl);
    text-align: center;
}

.page-title {
    font-size: 2rem;
    font-weight: 700;
}

.article-detail {
    max-width: var(--container-width);
    margin: 0 auto;
}

.article-header {
    margin-bottom: var(--spacing-xl);
}

.article-title {
    margin-bottom: var(--spacing-md);
    font-size: 2rem;
    line-height: 1.3;
    font-weight: 700;
}

.article-content {
    line-height: 2;
    text-align: justify;
}

.article-content h1,
.article-content h2,
.article-content h3,
.article-content h4,
.article-content h5,
.article-content h6 {
    margin-top: var(--spacing-2xl);
    margin-bottom: var(--spacing-md);
    line-height: 1.4;
    font-weight: 600;
}

.article-content h2 {
    font-size: 1.5rem;
}

.article-content h3 {
    font-size: 1.25rem;
}

.article-content p,
.article-content ul,
.article-content ol,
.article-content blockquote,
.article-content pre {
    margin-bottom: var(--spacing-xl);
}

.article-content ul,
.article-content ol {
    padding-left: var(--spacing-lg);
}

.article-content li + li {
    margin-top: var(--spacing-sm);
}

.article-content blockquote {
    padding: var(--spacing-lg);
    background-color: var(--color-bg-secondary);
    border-left: 4px solid var(--color-primary);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

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

.article-content code {
    font-family: var(--font-mono);
    font-size: 0.9375rem;
}

.article-content p code,
.article-content li code {
    padding: 0.125rem 0.375rem;
    background-color: var(--color-bg-secondary);
    border-radius: var(--radius-sm);
}

.article-content img {
    margin: var(--spacing-md) 0;
    border-radius: var(--radius-md);
}

.article-nav {
    margin-top: var(--spacing-2xl);
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--spacing-lg);
}

.article-nav-item {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    padding: var(--spacing-lg);
    background-color: var(--color-bg-secondary);
    border-radius: var(--radius-md);
}

.article-nav-next {
    text-align: right;
}

.article-nav-label,
.article-nav-empty {
    color: var(--color-text-muted);
    font-size: 0.875rem;
}

.related-posts {
    margin-top: var(--spacing-2xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--color-border);
}

.related-posts-title {
    margin-bottom: var(--spacing-lg);
    font-size: 1.25rem;
    font-weight: 600;
}

.related-posts-list {
    display: grid;
    gap: var(--spacing-md);
}

.related-post-card {
    padding: var(--spacing-lg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    background-color: var(--color-bg);
    transition: box-shadow var(--transition-fast), border-color var(--transition-fast);
}

.related-post-card:hover {
    box-shadow: 0 4px 16px var(--color-shadow);
}

.related-post-card-title {
    margin-bottom: var(--spacing-sm);
    font-size: 1rem;
    font-weight: 600;
    line-height: 1.5;
}

.page-content {
    background-color: var(--color-bg);
}

.about-page {
    max-width: var(--container-width);
    margin: 0 auto;
}

.about-header {
    margin-bottom: var(--spacing-2xl);
    text-align: center;
}

.about-avatar {
    width: 120px;
    height: 120px;
    margin: 0 auto var(--spacing-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    border-radius: 50%;
    background-color: var(--color-bg-secondary);
    box-shadow: 0 4px 16px var(--color-shadow);
}

.about-avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.about-avatar-placeholder {
    color: var(--color-text-secondary);
    font-size: 2rem;
    font-weight: 700;
}

.about-name {
    margin-bottom: var(--spacing-sm);
    font-size: 1.75rem;
    font-weight: 700;
}

.about-bio {
    margin-bottom: var(--spacing-lg);
    color: var(--color-text-secondary);
    font-size: 1.0625rem;
}

.about-social {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-md);
}

.social-link {
    width: 40px;
    height: 40px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    background-color: var(--color-bg-secondary);
    color: var(--color-text-secondary);
    transition: color var(--transition-fast), background-color var(--transition-fast), transform var(--transition-fast);
}

.social-link:hover {
    color: var(--color-primary);
    background-color: rgba(229, 57, 53, 0.1);
    transform: translateY(-2px);
}

.social-link__text {
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
}

.no-results {
    padding: var(--spacing-2xl);
    text-align: center;
    color: var(--color-text-muted);
}

.error-page {
    min-height: 60vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-2xl) 0;
    text-align: center;
}

.error-code {
    margin-bottom: var(--spacing-md);
    color: var(--color-primary);
    font-size: 8rem;
    line-height: 1;
    font-weight: 700;
    text-shadow: 4px 4px 0 var(--color-border);
}

.error-title {
    margin-bottom: var(--spacing-md);
    font-size: 2rem;
    font-weight: 600;
}

.error-message {
    margin-bottom: var(--spacing-xl);
    color: var(--color-text-secondary);
}

.error-actions {
    display: flex;
    gap: var(--spacing-md);
}

.error-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-sm) var(--spacing-xl);
    border-radius: var(--radius-sm);
    background-color: var(--color-primary);
    color: #fff;
    transition: background-color var(--transition-fast), color var(--transition-fast);
}

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

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

.error-btn-secondary:hover {
    background-color: var(--color-border-light);
    color: var(--color-text);
}

.footer {
    padding: var(--spacing-xl) 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.footer-copyright {
    color: var(--color-text-muted);
    font-size: 0.8125rem;
}

.footer-theme {
    margin-top: var(--spacing-sm);
    color: var(--color-text-muted);
    font-size: 0.75rem;
}

.back-to-top {
    position: fixed;
    right: var(--spacing-lg);
    bottom: var(--spacing-lg);
    z-index: 50;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--color-border);
    border-radius: 50%;
    background-color: var(--color-bg);
    box-shadow: 0 2px 8px var(--color-shadow);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: opacity var(--transition-normal), visibility var(--transition-normal), transform var(--transition-normal);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top svg {
    width: 20px;
    height: 20px;
    color: var(--color-text-secondary);
}

.reading-progress {
    position: fixed;
    top: 0;
    left: 0;
    z-index: 101;
    width: 0;
    height: 3px;
    background: var(--color-primary);
    transition: width 0.1s linear;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 768px) {
    :root {
        --header-height: 56px;
    }

    .nav {
        display: none;
    }

    .mobile-menu-toggle {
        display: inline-flex;
    }

    .article-title,
    .category-title,
    .page-title {
        font-size: 1.5rem;
    }

    .article-nav {
        grid-template-columns: 1fr;
    }

    .article-nav-next {
        text-align: left;
    }

    .about-avatar {
        width: 100px;
        height: 100px;
    }

    .error-code {
        font-size: 5rem;
    }

    .error-title {
        font-size: 1.5rem;
    }

    .error-actions {
        width: 100%;
        flex-direction: column;
    }
}

@media (max-width: 480px) {
    .container,
    .header-inner {
        padding-left: var(--spacing-md);
        padding-right: var(--spacing-md);
    }

    .post {
        padding: var(--spacing-md);
    }

    .post-title {
        font-size: 1.125rem;
    }

    .article-title {
        font-size: 1.375rem;
    }

    .search-modal-content {
        padding: 0 var(--spacing-md);
    }

    .back-to-top {
        right: var(--spacing-md);
        bottom: var(--spacing-md);
        width: 40px;
        height: 40px;
    }
}

@media print {
    .header,
    .footer,
    .back-to-top,
    .search-modal,
    .mobile-nav,
    .article-nav,
    .related-posts,
    .reading-progress {
        display: none !important;
    }

    body {
        background: #fff;
        color: #000;
    }
}