:root {
    /* Monochrome Color System */
    --color-black: #000000;
    --color-white: #ffffff;
    --color-gray-50: #fafafa;
    --color-gray-100: #f5f5f5;
    --color-gray-200: #e5e5e5;
    --color-gray-300: #d4d4d4;
    --color-gray-400: #a3a3a3;
    --color-gray-500: #737373;
    --color-gray-600: #525252;
    --color-gray-700: #404040;
    --color-gray-800: #262626;
    --color-gray-900: #171717;
    
    /* Light Theme (Default) */
    --bg-primary: var(--color-white);
    --bg-secondary: var(--color-gray-50);
    --bg-tertiary: var(--color-gray-100);
    --text-primary: var(--color-gray-900);
    --text-secondary: var(--color-gray-600);
    --text-tertiary: var(--color-gray-500);
    --border-color: var(--color-gray-200);
    --border-hover: var(--color-gray-300);
    --accent-bg: var(--color-gray-900);
    --accent-text: var(--color-white);
    --link-color: var(--color-gray-900);
    --link-hover: var(--color-gray-600);
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

/* Dark Theme */
[data-theme="dark"] {
    --bg-primary: var(--color-gray-900);
    --bg-secondary: var(--color-gray-800);
    --bg-tertiary: var(--color-gray-700);
    --text-primary: var(--color-gray-100);
    --text-secondary: var(--color-gray-400);
    --text-tertiary: var(--color-gray-500);
    --border-color: var(--color-gray-700);
    --border-hover: var(--color-gray-600);
    --accent-bg: var(--color-gray-100);
    --accent-text: var(--color-gray-900);
    --link-color: var(--color-gray-100);
    --link-hover: var(--color-gray-400);
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
}

/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Header */
.header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
}

.logo {
    font-size: 20px;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    letter-spacing: -0.5px;
    transition: color 0.3s ease;
}

/* Desktop Navigation */
.nav-desktop {
    display: flex;
    align-items: center;
    gap: 8px;
    flex: 1;
    justify-content: center;
}

.nav-link {
    padding: 8px 16px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
    border-radius: 6px;
    transition: all 0.2s ease;
}

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

/* Header Actions */
.header-actions {
    display: flex;
    align-items: center;
    gap: 8px;
}

.icon-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
}

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

/* Theme Toggle */
.theme-toggle {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    position: relative;
    overflow: hidden;
}

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

.theme-icon {
    position: absolute;
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.light-icon {
    opacity: 1;
    transform: translateY(0);
}

.dark-icon {
    opacity: 0;
    transform: translateY(20px);
}

[data-theme="dark"] .light-icon {
    opacity: 0;
    transform: translateY(-20px);
}

[data-theme="dark"] .dark-icon {
    opacity: 1;
    transform: translateY(0);
}

/* Hamburger Menu */
.hamburger {
    display: none;
    width: 40px;
    height: 40px;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.hamburger span {
    display: block;
    width: 18px;
    height: 2px;
    background-color: var(--text-primary);
    border-radius: 2px;
    transition: all 0.3s ease;
}

.hamburger:hover {
    background-color: var(--bg-secondary);
    border-color: var(--border-hover);
}

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

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

.hamburger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* Mobile Navigation */
.mobile-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 101;
}

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

.nav-mobile {
    position: fixed;
    top: 0;
    right: -100%;
    width: 320px;
    max-width: 90%;
    height: 100vh;
    background-color: var(--bg-primary);
    border-left: 1px solid var(--border-color);
    z-index: 102;
    transition: right 0.3s ease;
    overflow-y: auto;
}

.nav-mobile.active {
    right: 0;
}

.nav-mobile-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
}

.nav-mobile-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
}

.nav-mobile-close {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: 6px;
    transition: all 0.2s ease;
}

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

.nav-mobile-links {
    padding: 16px;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.nav-mobile-link {
    padding: 12px 16px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 15px;
    font-weight: 500;
    border-radius: 8px;
    transition: all 0.2s ease;
}

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

/* Main Content */
.main-content {
    min-height: calc(100vh - 64px - 300px);
}

/* Centered View */
.centered-view {
    max-width: 900px;
    margin: 0 auto;
    padding: 48px 24px;
}

/* ============================================
   HOME VIEW STYLES
   ============================================ */

.hero-section {
    text-align: center;
    padding: 64px 20px;
    margin-bottom: 48px;
}

.hero-section h1 {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--text-primary);
    letter-spacing: -1px;
}

.hero-section .lead {
    font-size: 20px;
    color: var(--text-secondary);
    margin-bottom: 32px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.cta-button {
    display: inline-block;
    padding: 14px 32px;
    background-color: var(--accent-bg);
    color: var(--accent-text);
    text-decoration: none;
    font-weight: 600;
    border-radius: 8px;
    transition: all 0.2s ease;
}

.cta-button:hover {
    opacity: 0.9;
    transform: translateY(-2px);
}

.featured-categories {
    margin-bottom: 64px;
}

.featured-categories h2 {
    font-size: 28px;
    font-weight: 600;
    margin-bottom: 32px;
    color: var(--text-primary);
    text-align: center;
}

.view-all {
    text-align: center;
    margin-top: 32px;
}

.link-button {
    display: inline-block;
    color: var(--link-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
}

.link-button:hover {
    color: var(--link-hover);
}

/* ============================================
   CATEGORY GRID STYLES
   ============================================ */

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 20px;
}

.category-grid.full {
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
}

.category-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 32px 24px;
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    text-decoration: none;
    transition: all 0.2s ease;
    text-align: center;
}

.category-card:hover {
    background-color: var(--bg-tertiary);
    border-color: var(--border-hover);
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.category-icon {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--bg-primary);
    border-radius: 12px;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.category-card h3 {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.category-card p {
    font-size: 14px;
    color: var(--text-tertiary);
    margin: 0;
}

/* ============================================
   PAGE HEADER STYLES
   ============================================ */

.page-header {
    text-align: center;
    margin-bottom: 40px;
}

.page-header h1 {
    font-size: 36px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 12px;
    letter-spacing: -0.5px;
}

.page-header .lead {
    font-size: 18px;
    color: var(--text-secondary);
    margin: 0;
}

.back-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 14px;
    margin-bottom: 16px;
    transition: color 0.2s ease;
}

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

/* ============================================
   ITEMS LIST STYLES (Simplified)
   ============================================ */

.items-list {
    display: flex;
    flex-direction: column;
}

.item-row {
    display: flex;
    align-items: baseline;
    gap: 8px;
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
}

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

.item-bullet {
    color: var(--text-tertiary);
    font-size: 14px;
    flex-shrink: 0;
}

.item-icon-small {
    width: 16px;
    height: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-tertiary);
    flex-shrink: 0;
}

.item-content {
    flex: 1;
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    gap: 6px;
    min-width: 0;
}

.item-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-primary);
}

.item-separator {
    color: var(--text-tertiary);
    font-size: 14px;
}

.item-description {
    font-size: 14px;
    color: var(--text-secondary);
}

.item-url {
    font-size: 13px;
    color: var(--text-tertiary);
    text-decoration: none;
    transition: color 0.2s ease;
}

.item-url:hover {
    color: var(--text-primary);
    text-decoration: underline;
}

.item-category {
    font-size: 12px;
    color: var(--text-tertiary);
    font-style: italic;
}

/* ============================================
   PAGE VIEW STYLES (About, Contact)
   ============================================ */

.page-view .page-header {
    text-align: center;
}

.page-view .content-article {
    max-width: 700px;
    margin: 0 auto;
}

.page-view .content-article h2 {
    font-size: 24px;
    font-weight: 600;
    margin-top: 32px;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.page-view .content-article p {
    font-size: 16px;
    line-height: 1.7;
    margin-bottom: 16px;
    color: var(--text-secondary);
}

.page-view .content-article ul {
    margin: 16px 0;
    padding-left: 24px;
}

.page-view .content-article li {
    margin-bottom: 8px;
    color: var(--text-secondary);
    line-height: 1.6;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin-top: 32px;
}

.contact-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 20px;
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.2s ease;
}

.contact-link:hover {
    background-color: var(--bg-tertiary);
    border-color: var(--border-hover);
}

/* ============================================
   SEARCH RESULTS STYLES
   ============================================ */

.search-results-view .page-header {
    text-align: center;
}

.no-results {
    text-align: center;
    padding: 64px 20px;
    color: var(--text-secondary);
}

.error-view {
    text-align: center;
    padding: 80px 20px;
}

.error-view h1 {
    font-size: 28px;
    color: var(--text-primary);
    margin-bottom: 16px;
}

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

/* ============================================
   FOOTER STYLES
   ============================================ */

.footer {
    background-color: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    margin-top: auto;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 64px 24px 32px;
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 64px;
    margin-bottom: 48px;
}

.footer-brand {
    max-width: 300px;
}

.footer-logo {
    font-size: 24px;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.5px;
}

.footer-tagline {
    margin-top: 12px;
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.6;
}

.footer-links {
    display: flex;
    gap: 64px;
}

.footer-group {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-group h4 {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.footer-group a {
    font-size: 14px;
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
}

.footer-group a:hover {
    color: var(--text-primary);
}

.footer-bottom {
    padding-top: 32px;
    border-top: 1px solid var(--border-color);
    text-align: center;
}

.footer-bottom p {
    font-size: 14px;
    color: var(--text-tertiary);
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

@media (max-width: 1024px) {
    .nav-desktop {
        display: none;
    }
    
    .hamburger {
        display: flex;
    }
    
    .hero-section h1 {
        font-size: 40px;
    }
    
    .category-grid {
        grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 48px;
    }
    
    .footer-links {
        gap: 48px;
    }
}

@media (max-width: 640px) {
    .header-container {
        padding: 0 16px;
    }
    
    .centered-view {
        padding: 32px 16px;
    }
    
    .hero-section {
        padding: 40px 16px;
    }
    
    .hero-section h1 {
        font-size: 32px;
    }
    
    .hero-section .lead {
        font-size: 18px;
    }
    
    .category-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }
    
    .category-grid.full {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .category-card {
        padding: 24px 16px;
    }
    
    .category-icon {
        width: 40px;
        height: 40px;
    }
    
    .page-header h1 {
        font-size: 28px;
    }
    
    .item-content {
        flex-direction: column;
        gap: 2px;
    }
    
    .item-separator {
        display: none;
    }
    
    .item-description {
        font-size: 13px;
    }
    
    .contact-links {
        flex-direction: column;
        align-items: center;
    }
    
    .footer-links {
        flex-direction: column;
        gap: 32px;
    }
}