:root {
    /* Design System Tokens - Semantic Colors */
    --surface-primary: 0 0% 100%;
    --surface-secondary: 210 40% 96.1%;
    --surface-tertiary: 210 40% 96.1%;
    --surface-inverse: 222.2 84% 4.9%;

    --content-primary: 222.2 84% 4.9%;
    --content-secondary: 215.4 16.3% 46.9%;
    --content-tertiary: 215.4 16.3% 46.9%;
    --content-inverse: 210 40% 98%;

    --border-primary: 214.3 31.8% 91.4%;
    --border-secondary: 214.3 31.8% 91.4%;
    --border-focus: 221.2 83.2% 53.3%;

    --action-primary: 221.2 83.2% 53.3%;
    --action-primary-hover: 221.2 83.2% 48.3%;
    --action-secondary: 210 40% 96.1%;
    --action-destructive: 0 84.2% 60.2%;

    --feedback-success: 142 76% 36%;
    --feedback-warning: 38 92% 50%;
    --feedback-error: 0 84.2% 60.2%;
    --feedback-info: 221.2 83.2% 53.3%;

    /* Spacing and Layout */
    --space-component-padding: 0.625rem 1.25rem;
    --space-component-gap: 0.5rem;
    --space-section-gap: 2rem;
    --radius-normal: 8px;
    --radius-large: 12px;
    --shadow-normal: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-pronounced: 0 4px 12px rgba(0, 0, 0, 0.15);
    --shadow-focus: 0 0 0 2px hsl(var(--border-focus) / 0.2);

    /* Typography Scale */
    --text-display: 3rem;
    --text-heading-1: 2.25rem;
    --text-heading-2: 1.875rem;
    --text-heading-3: 1.5rem;
    --text-body-large: 1.125rem;
    --text-body: 1rem;
    --text-body-small: 0.875rem;
    --text-caption: 0.75rem;

    /* Animation */
    --timing-fast: 150ms;
    --timing-normal: 250ms;
}

/* Dark Mode */
.dark {
    --surface-primary: 222.2 84% 4.9%;
    --surface-secondary: 217.2 32.6% 17.5%;
    --surface-tertiary: 217.2 32.6% 17.5%;
    --surface-inverse: 0 0% 100%;

    --content-primary: 210 40% 98%;
    --content-secondary: 215 20.2% 65.1%;
    --content-tertiary: 215 20.2% 65.1%;
    --content-inverse: 222.2 84% 4.9%;

    --border-primary: 217.2 32.6% 17.5%;
    --border-secondary: 217.2 32.6% 17.5%;
    --border-focus: 217.2 91.2% 59.8%;

    --action-primary: 217.2 91.2% 59.8%;
    --action-primary-hover: 217.2 91.2% 65.8%;
    --action-secondary: 217.2 32.6% 17.5%;
}

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

html,
body {
    overflow-x: hidden;
    max-width: 100%;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: hsl(var(--surface-primary));
    color: hsl(var(--content-primary));
    line-height: 1.6;
    transition: background-color var(--timing-normal), color var(--timing-normal);
}

/* Layout Container */
.dashboard-container {
    display: flex;
    min-height: 100vh;
    overflow-x: hidden;
    max-width: 100vw;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background: hsl(var(--surface-secondary));
    border-right: 1px solid hsl(var(--border-primary));
    padding: 2rem 1.5rem;
    position: fixed;
    height: 100vh;
    overflow-y: auto;
    transition: transform 0.3s ease;
}

.sidebar.collapsed {
    transform: translateX(-100%);
}

.sidebar-header {
    margin-bottom: 2rem;
}

.sidebar-logo {
    font-size: var(--text-heading-3);
    font-weight: 700;
    color: hsl(var(--action-primary));
    text-decoration: none;
    display: block;
    margin-bottom: 0.5rem;
}

.sidebar-subtitle {
    font-size: var(--text-body-small);
    color: hsl(var(--content-secondary));
}

.sidebar-nav {
    list-style: none;
}

.sidebar-nav-item {
    margin-bottom: 0.5rem;
}

.sidebar-nav-link {
    display: flex;
    align-items: center;
    padding: 0.75rem 1rem;
    color: hsl(var(--content-secondary));
    text-decoration: none;
    border-radius: var(--radius-normal);
    transition: all 0.2s;
    font-weight: 500;
}

.sidebar-nav-link:hover {
    background: hsl(var(--surface-tertiary));
    color: hsl(var(--content-primary));
}

.sidebar-nav-link.active {
    background: hsl(var(--action-primary));
    color: white;
}

.sidebar-icon {
    width: 20px;
    height: 20px;
    margin-right: 0.75rem;
}

/* Main Content */
.main-content {
    flex: 1;
    margin-left: 260px;
    transition: margin-left 0.3s ease;
    overflow-x: hidden;
    max-width: 100%;
}

.main-content.expanded {
    margin-left: 0;
}

/* Header */
.header {
    background: hsl(var(--surface-primary));
    border-bottom: 1px solid hsl(var(--border-primary));
    padding: 1.5rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 2rem;
}

.header-title-section {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.menu-toggle {
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: var(--radius-normal);
    color: hsl(var(--content-primary));
    display: none;
}

.menu-toggle:hover {
    background: hsl(var(--surface-secondary));
}

.page-title {
    font-size: var(--text-heading-2);
    font-weight: 600;
    color: hsl(var(--content-primary));
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.search-box {
    position: relative;
    width: 300px;
}

.search-icon {
    position: absolute;
    left: 12px;
    top: 50%;
    transform: translateY(-50%);
    color: hsl(var(--content-secondary));
}

.search-input {
    width: 100%;
    padding: 0.625rem 1rem 0.625rem 2.5rem;
    border: 1px solid hsl(var(--border-primary));
    border-radius: var(--radius-normal);
    background: hsl(var(--surface-primary));
    font-size: var(--text-body);
    transition: all var(--timing-fast) ease-out;
    color: hsl(var(--content-primary));
}

.search-input::placeholder {
    color: hsl(var(--content-tertiary));
}

.search-input:focus {
    outline: none;
    border-color: hsl(var(--action-primary));
    box-shadow: var(--shadow-focus);
}

/* Content Area */
.content {
    padding: 2rem;
}

/* Stats Bar */
.stats-bar {
    display: flex;
    gap: 2rem;
    padding: 1.5rem;
    background: hsl(var(--surface-secondary));
    border-radius: var(--radius-large);
    margin-bottom: var(--space-section-gap);
}

.stat-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.stat-value {
    font-size: var(--text-heading-2);
    font-weight: 700;
    color: hsl(var(--content-primary));
}

.stat-label {
    font-size: var(--text-body-small);
    color: hsl(var(--content-secondary));
}

/* Section Titles */
.section-title {
    font-size: var(--text-heading-3);
    font-weight: 600;
    color: hsl(var(--content-primary));
    margin-bottom: 1rem;
}

/* Featured Section */
.featured-section {
    margin-bottom: var(--space-section-gap);
}

.featured-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
}

.featured-card {
    background: linear-gradient(135deg, hsl(var(--action-primary)), hsl(var(--action-primary-hover)));
    border-radius: var(--radius-large);
    padding: 2rem;
    color: white;
    display: flex;
    flex-direction: column;
    min-height: 220px;
    transition: transform var(--timing-fast), box-shadow var(--timing-fast);
    cursor: pointer;
    text-decoration: none;
}

.featured-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-pronounced);
}

.featured-card .category-tag {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    padding: 0.375rem 0.75rem;
    border-radius: 9999px;
    font-size: var(--text-caption);
    font-weight: 500;
    width: fit-content;
    margin-bottom: 1rem;
}

.featured-card .card-title {
    font-size: var(--text-heading-3);
    font-weight: 600;
    margin-bottom: 0.5rem;
    line-height: 1.3;
}

.featured-card .card-excerpt {
    font-size: var(--text-body-small);
    opacity: 0.9;
    line-height: 1.5;
    flex: 1;
}

.featured-card .card-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-top: 1rem;
    font-size: var(--text-caption);
    opacity: 0.8;
}

/* Filters Bar */
.filters-bar {
    margin-bottom: 1.5rem;
}

.category-filters {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.category-btn {
    padding: 0.5rem 1rem;
    border: 1px solid hsl(var(--border-primary));
    border-radius: 9999px;
    background: hsl(var(--surface-primary));
    color: hsl(var(--content-secondary));
    font-size: var(--text-body-small);
    font-weight: 500;
    cursor: pointer;
    transition: all var(--timing-fast);
}

.category-btn:hover {
    border-color: hsl(var(--action-primary));
    color: hsl(var(--action-primary));
}

.category-btn.active {
    background: hsl(var(--action-primary));
    border-color: hsl(var(--action-primary));
    color: white;
}

/* Articles Section */
.articles-section {
    margin-bottom: var(--space-section-gap);
}

.articles-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

.article-card {
    background: hsl(var(--surface-primary));
    border: 1px solid hsl(var(--border-primary));
    border-radius: var(--radius-large);
    overflow: hidden;
    transition: transform var(--timing-fast), box-shadow var(--timing-fast);
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
}

.article-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-pronounced);
}

.article-card .card-image {
    height: 160px;
    background: linear-gradient(135deg, hsl(var(--surface-secondary)), hsl(var(--surface-tertiary)));
    display: flex;
    align-items: center;
    justify-content: center;
}

.article-card .card-image svg {
    width: 48px;
    height: 48px;
    color: hsl(var(--content-secondary));
    opacity: 0.5;
}

.article-card .card-content {
    padding: 1.25rem;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.article-card .category-tag {
    background: hsl(var(--action-primary) / 0.1);
    color: hsl(var(--action-primary));
    padding: 0.25rem 0.625rem;
    border-radius: 9999px;
    font-size: var(--text-caption);
    font-weight: 500;
    width: fit-content;
    margin-bottom: 0.75rem;
}

.article-card .card-title {
    font-size: var(--text-body-large);
    font-weight: 600;
    color: hsl(var(--content-primary));
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.article-card .card-excerpt {
    font-size: var(--text-body-small);
    color: hsl(var(--content-secondary));
    line-height: 1.5;
    flex: 1;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.article-card .card-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid hsl(var(--border-primary));
}

.article-card .author-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.article-card .author-avatar {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: hsl(var(--action-primary));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: var(--text-caption);
    font-weight: 600;
}

.article-card .author-name {
    font-size: var(--text-body-small);
    color: hsl(var(--content-primary));
    font-weight: 500;
}

.article-card .card-date {
    font-size: var(--text-caption);
    color: hsl(var(--content-tertiary));
}

/* Load More */
.load-more-section {
    display: flex;
    justify-content: center;
    padding: 2rem 0;
}

/* Buttons */
.btn {
    padding: var(--space-component-padding);
    border-radius: var(--radius-normal);
    font-weight: 500;
    font-size: var(--text-body);
    cursor: pointer;
    transition: all var(--timing-fast) ease-out;
    border: none;
    display: inline-flex;
    align-items: center;
    gap: var(--space-component-gap);
}

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

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

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

.btn-secondary:hover {
    background: hsl(var(--surface-tertiary));
}

/* Responsive */
@media (max-width: 1200px) {
    .articles-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 1024px) {
    .sidebar {
        transform: translateX(-100%);
        z-index: 200;
    }

    .sidebar.open {
        transform: translateX(0);
    }

    .main-content {
        margin-left: 0;
    }

    .menu-toggle {
        display: block;
    }

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

@media (max-width: 768px) {
    .header {
        padding: 1rem;
    }

    .header-content {
        flex-direction: column;
        align-items: stretch;
        gap: 1rem;
    }

    .search-box {
        width: 100%;
    }

    .content {
        padding: 1rem;
    }

    .stats-bar {
        flex-direction: column;
        gap: 1rem;
    }

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

    .category-filters {
        overflow-x: auto;
        flex-wrap: nowrap;
        padding-bottom: 0.5rem;
    }

    .category-btn {
        white-space: nowrap;
    }
}