/* APIVerve Blog - Professional Stripe-inspired Design System */

:root {
    /* Colors - Light Mode */
    --color-background: #ffffff;
    --color-surface: #fafbfc;
    --color-surface-elevated: #ffffff;
    --color-border: #e6ebf1;
    --color-border-subtle: #f6f9fc;
    --color-text-primary: #0a2540;
    --color-text-secondary: #425466;
    --color-text-tertiary: #8792a2;
    --color-accent: #0066cc;
    --color-accent-light: #3385d6;
    --color-success: #00d924;
    --color-warning: #ff5722;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    
    /* Border radius */
    --radius-sm: 4px;
    --radius-md: 6px;
    --radius-lg: 8px;
    --radius-xl: 12px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(10, 37, 64, 0.05);
    --shadow-md: 0 2px 4px rgba(10, 37, 64, 0.07);
    --shadow-lg: 0 4px 8px rgba(10, 37, 64, 0.08);
}

[data-theme="dark"] {
    --color-background: #0d1117;
    --color-surface: #161b22;
    --color-surface-elevated: #21262d;
    --color-border: #30363d;
    --color-border-subtle: #21262d;
    --color-text-primary: #f0f6fc;
    --color-text-secondary: #b1bac4;
    --color-text-tertiary: #7d8590;
    --color-accent: #0066cc;
    --color-accent-light: #3385d6;
}

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.5;
    color: var(--color-text-primary);
    background: var(--color-background);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Header */
.header {
    background: var(--color-background);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 1001;
    backdrop-filter: blur(8px);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-xl);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-text-primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: var(--space-md);
    transition: opacity 0.2s ease;
}

.logo:hover {
    opacity: 0.8;
}

.logo-icon {
    width: 32px;
    height: 32px;
    object-fit: contain;
}

.logo-text {
    display: flex;
    flex-direction: column;
    line-height: 1.2;
}

.logo-name {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text-primary);
}

.logo-suffix {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-accent);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.theme-toggle {
    background: none;
    border: none;
    color: var(--color-text-secondary);
    cursor: pointer;
    padding: var(--space-sm);
    border-radius: var(--radius-md);
    transition: all 0.15s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
}

.theme-toggle:hover {
    color: var(--color-text-primary);
    background: var(--color-surface);
}

.theme-toggle svg {
    width: 20px;
    height: 20px;
}

.sun-icon {
    display: none;
}

[data-theme="light"] .sun-icon {
    display: block;
}

[data-theme="light"] .moon-icon {
    display: none;
}

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

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

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    font-weight: 500;
    text-decoration: none;
    transition: all 0.15s ease;
    border: 1px solid transparent;
    cursor: pointer;
    white-space: nowrap;
}

.btn-primary {
    background: var(--color-accent);
    color: #ffffff;
    border-color: var(--color-accent);
}

.btn-primary:hover {
    background: var(--color-accent-light);
    border-color: var(--color-accent-light);
    transform: translateY(-1px);
}

.btn-secondary {
    background: transparent;
    color: var(--color-text-secondary);
    border-color: var(--color-border);
}

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

/* Navigation Menu */
.nav-menu {
    display: flex;
    flex: 1;
    justify-content: center;
}

/* Desktop: Always show menu normally */
@media (min-width: 769px) {
    .nav-menu {
        transform: none !important;
        visibility: visible !important;
        position: static !important;
        height: auto !important;
        background: none !important;
        padding: 0 !important;
        border: none !important;
    }
}

.nav-list {
    display: flex;
    list-style: none;
    gap: var(--space-2xl);
    align-items: center;
    margin: 0;
    padding: 0;
}

.nav-item {
    margin: 0;
}

.nav-link {
    text-decoration: none;
    color: var(--color-text-secondary);
    font-weight: 500;
    font-size: var(--font-size-sm);
    transition: color 0.15s ease;
    padding: var(--space-sm) 0;
}

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

.nav-link.active {
    color: var(--color-accent);
}

.mobile-only-menu-item {
    display: none;
}

/* Mobile Menu Overlay */
.mobile-menu-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 998;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
    display: none;
}

.mobile-menu-overlay.active {
    opacity: 1;
    visibility: visible;
    display: block;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-sm);
    flex-direction: column;
    gap: 4px;
    width: 36px;
    height: 36px;
    justify-content: center;
    align-items: center;
    border-radius: var(--radius-md);
    transition: background 0.15s ease;
    z-index: 1000;
    position: relative;
}

.mobile-menu-toggle:hover {
    background: var(--color-surface);
}

.hamburger-line {
    width: 20px;
    height: 2px;
    background: var(--color-text-primary);
    transition: all 0.3s ease;
    border-radius: 2px;
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle[aria-expanded="true"] .hamburger-line:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .nav-container {
        padding: 0 var(--space-md);
    }

    .mobile-menu-toggle {
        display: flex !important;
        order: -1;
    }

    .mobile-menu-overlay {
        display: block;
    }

    .nav-menu {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        bottom: 0;
        width: 100%;
        height: calc(100vh - 70px);
        background: var(--color-background);
        padding: var(--space-xl);
        z-index: 999;
        overflow-y: auto;
        transform: translateX(-100%);
        transition: transform 0.3s ease;
        visibility: hidden;
        border-top: 1px solid var(--color-border);
        display: block;
    }

    .nav-menu[aria-hidden="true"] {
        transform: translateX(-100%) !important;
        visibility: hidden !important;
    }

    .nav-menu[aria-hidden="false"] {
        transform: translateX(0);
        visibility: visible;
    }

    .nav-list {
        flex-direction: column;
        gap: 0;
        width: 100%;
        display: flex !important;
    }

    .nav-item {
        width: 100%;
        border-bottom: 1px solid var(--color-border);
    }

    .nav-item:last-child {
        border-bottom: none;
    }

    .nav-link {
        display: block;
        padding: var(--space-md) 0;
        font-size: var(--font-size-base);
    }

    .mobile-only-menu-item {
        display: block !important;
    }

    .nav-actions .btn-secondary,
    .nav-actions .btn-primary {
        display: none !important;
    }

    .theme-toggle {
        order: 1;
    }
}

@media (min-width: 769px) and (max-width: 1024px) {
    .nav-list {
        gap: var(--space-lg);
    }

    .btn {
        padding: 0.5rem 0.75rem;
        font-size: 0.8125rem;
    }
}

/* Main Content */
.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--space-3xl) var(--space-xl);
}

.content-layout {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: var(--space-2xl);
    align-items: start;
}

/* Typography */
.page-title {
    font-size: var(--font-size-4xl);
    font-weight: 600;
    margin-bottom: var(--space-lg);
    line-height: 1.25;
    letter-spacing: -0.025em;
    color: var(--color-text-primary);
}

.section-title {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    margin-bottom: var(--space-2xl);
    color: var(--color-text-primary);
    letter-spacing: -0.025em;
}

.page-description {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-2xl);
    line-height: 1.6;
}

/* Cards */
.card {
    background: var(--color-surface-elevated);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border);
    transition: all 0.2s ease;
}

.card:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.post-card {
    background: var(--color-surface-elevated);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border);
    transition: all 0.2s ease;
    text-decoration: none;
    color: inherit;
}

.post-card:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.post-image {
    aspect-ratio: 16/9;
    background: var(--color-surface);
    overflow: hidden;
}

.post-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.post-content {
    padding: var(--space-lg);
}

.post-meta {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    margin-bottom: var(--space-sm);
    font-size: var(--font-size-xs);
    color: var(--color-text-tertiary);
}

.category-badge {
    padding: 2px var(--space-sm);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-xs);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border: 1px solid;
    text-decoration: none;
}

.post-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-bottom: var(--space-sm);
    line-height: 1.4;
    color: var(--color-text-primary);
}

.post-title a {
    color: inherit;
    text-decoration: none;
}

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

.post-excerpt {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    line-height: 1.5;
    margin-bottom: var(--space-md);
}

.post-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--font-size-xs);
    color: var(--color-text-tertiary);
}

.post-reading-time {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
}

/* Grids */
.posts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--space-lg);
    margin-bottom: var(--space-2xl);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--radius-md);
    text-decoration: none;
    font-weight: 500;
    font-size: var(--font-size-sm);
    transition: all 0.15s ease;
    border: 1px solid var(--color-border);
    cursor: pointer;
}

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

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

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

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

/* Sidebar */
.sidebar {
    background: var(--color-surface-elevated);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border);
    height: fit-content;
}

.sidebar h3 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-bottom: var(--space-lg);
    color: var(--color-text-primary);
}

.category-list {
    list-style: none;
}

.category-item {
    margin-bottom: var(--space-xs);
}

.category-link {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--radius-md);
    text-decoration: none;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    transition: all 0.15s ease;
}

.category-link:hover {
    background: var(--color-surface);
    color: var(--color-text-primary);
}

.category-count {
    font-size: var(--font-size-xs);
    background: var(--color-surface);
    color: var(--color-text-tertiary);
    padding: 2px var(--space-sm);
    border-radius: var(--radius-sm);
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--space-sm);
    margin: var(--space-2xl) 0;
}

.pagination a {
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--radius-md);
    text-decoration: none;
    color: var(--color-text-secondary);
    font-weight: 500;
    font-size: var(--font-size-sm);
    transition: all 0.15s ease;
    border: 1px solid var(--color-border);
    background: var(--color-background);
}

.pagination a:hover {
    background: var(--color-accent);
    color: white;
    border-color: var(--color-accent);
}

.pagination .current {
    background: var(--color-accent);
    color: white;
    border-color: var(--color-accent);
}

/* Footer */
.footer {
    background: var(--color-text-primary);
    color: var(--color-background);
    padding: var(--space-2xl) 0 var(--space-xl);
    margin-top: var(--space-3xl);
    border-top: 1px solid var(--color-border);
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-xl);
    text-align: center;
}

.footer-logo {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--space-md);
    color: #ffffff;
    text-decoration: none;
    transition: opacity 0.15s ease;
}

.footer-logo:hover {
    opacity: 0.8;
}

.footer-logo-img {
    width: 32px;
    height: 32px;
    object-fit: contain;
}

.footer-description {
    font-size: var(--font-size-sm);
    color: var(--color-text-tertiary);
    margin-bottom: var(--space-xl);
    max-width: 400px;
    margin-left: auto;
    margin-right: auto;
    line-height: 1.5;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: var(--space-xl);
    margin-bottom: var(--space-xl);
}

.footer-links a {
    color: var(--color-text-tertiary);
    text-decoration: none;
    font-size: var(--font-size-sm);
    transition: color 0.15s ease;
}

.footer-links a:hover {
    color: var(--color-background);
}

.footer-bottom {
    padding-top: var(--space-lg);
    border-top: 1px solid var(--color-border);
    color: var(--color-text-tertiary);
    font-size: var(--font-size-xs);
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: var(--space-3xl) var(--space-xl);
    color: var(--color-text-tertiary);
}

.empty-state i {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--space-lg);
    opacity: 0.3;
}

.empty-state h3 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--space-sm);
    color: var(--color-text-primary);
}

/* Article Styles */
.article-header {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-3xl) 0;
    text-align: center;
}

.article-header-content {
    max-width: 680px;
    margin: 0 auto;
    padding: 0 var(--space-xl);
}

.article-title {
    font-size: var(--font-size-4xl);
    font-weight: 600;
    margin-bottom: var(--space-lg);
    line-height: 1.25;
    letter-spacing: -0.025em;
    color: var(--color-text-primary);
}

.article-excerpt {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    line-height: 1.6;
    margin-bottom: var(--space-xl);
}

.article-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 var(--space-xl) var(--space-3xl);
}

.article-body {
    font-size: var(--font-size-lg);
    line-height: 1.7;
    color: var(--color-text-primary);
}

.article-body h1, .article-body h2, .article-body h3, .article-body h4 {
    color: var(--color-text-primary);
    font-weight: 600;
    margin: var(--space-2xl) 0 var(--space-lg);
    line-height: 1.3;
}

.article-body h2 { font-size: var(--font-size-2xl); }
.article-body h3 { font-size: var(--font-size-xl); }
.article-body h4 { font-size: var(--font-size-lg); }

.article-body p {
    margin-bottom: var(--space-lg);
}

.article-body a {
    color: var(--color-accent);
    text-decoration: underline;
    text-decoration-thickness: 1px;
    text-underline-offset: 2px;
}

.article-body a:hover {
    color: var(--color-accent-light);
}

.article-body pre {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    margin: var(--space-xl) 0;
    overflow-x: auto;
    font-size: var(--font-size-sm);
}

.article-body code {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    padding: 2px var(--space-xs);
    border-radius: var(--radius-sm);
    font-size: 0.9em;
    font-family: 'Courier New', monospace;
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .nav-container {
        padding: 0 var(--space-md);
    }
    
    .nav-links {
        gap: var(--space-lg);
    }
    
    .main-content {
        padding: var(--space-xl) var(--space-md);
    }
    
    .content-layout {
        grid-template-columns: 1fr;
        gap: var(--space-xl);
    }
    
    .posts-grid {
        grid-template-columns: 1fr;
    }
    
    .page-title {
        font-size: var(--font-size-3xl);
    }
    
    .article-title {
        font-size: var(--font-size-3xl);
    }
    
    .footer-links {
        flex-direction: column;
        gap: var(--space-md);
    }
    
    .sidebar {
        order: -1;
    }
}