/* ========================================
   CSS Variables - Light Tech Theme
   ======================================== */
:root {
    --color-primary: #007bff;
    --color-primary-dark: #0056b3;
    --color-primary-light: #4dabf7;
    --color-secondary: #667eea;
    --color-accent: #ff6b6b;
    --color-success: #10b981;
    --color-warning: #f59e0b;
    
    --color-bg: #ffffff;
    --color-bg-secondary: #f8fafc;
    --color-bg-card: #ffffff;
    --color-bg-hover: #f1f5f9;
    --color-border: #e2e8f0;
    --color-border-light: #f1f5f9;
    
    --color-text-primary: #1e293b;
    --color-text-secondary: #64748b;
    --color-text-tertiary: #94a3b8;
    --color-text-inverse: #ffffff;
    
    --color-tag-bg: #e0f2fe;
    --color-tag-text: #0369a1;
    --color-tag-bg-secondary: #fce7f3;
    --color-tag-text-secondary: #be185d;
    --color-tag-bg-warning: #fef3c7;
    --color-tag-text-warning: #d97706;
    
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 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: 2rem;
    
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-full: 9999px;
    
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms ease;
    
    --max-width: 1200px;
    --header-height: 100px;
}

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

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background-color: var(--color-bg);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* ========================================
   Header
   ======================================== */
.header {
    background: linear-gradient(180deg, var(--color-bg-secondary) 0%, var(--color-bg) 100%);
    border-bottom: 1px solid var(--color-border);
    padding: var(--spacing-xl) var(--spacing-md);
    text-align: center;
    position: relative;
}

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

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
}

.logo-icon {
    width: 44px;
    height: 44px;
    color: var(--color-primary);
}

.logo-text {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    letter-spacing: -0.025em;
    color: var(--color-text-primary);
}

.header-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    font-weight: 400;
}

.lang-switch {
    display: flex;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-md);
    justify-content: center;
}

.lang-btn {
    padding: var(--spacing-xs) var(--spacing-md);
    border: 1px solid var(--color-border);
    background-color: transparent;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    font-weight: 500;
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-base);
}

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

.lang-btn.active {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--color-text-inverse);
}

/* ========================================
   Search Section
   ======================================== */
.search-section {
    background-color: var(--color-bg);
    padding: var(--spacing-lg) var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
}

.search-container {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
}

.search-box {
    position: relative;
    width: 100%;
    max-width: 600px;
}

.search-icon {
    position: absolute;
    left: var(--spacing-md);
    top: 50%;
    transform: translateY(-50%);
    width: 20px;
    height: 20px;
    color: var(--color-text-tertiary);
    transition: color var(--transition-base);
}

.search-input {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-xl);
    padding-left: calc(var(--spacing-md) + 28px);
    padding-right: calc(var(--spacing-md) + 28px);
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    color: var(--color-text-primary);
    font-size: var(--font-size-base);
    font-family: var(--font-family);
    transition: all var(--transition-base);
}

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

.search-input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.1);
}

.search-input:focus + .search-icon,
.search-box:hover .search-icon {
    color: var(--color-primary);
}

.search-clear {
    position: absolute;
    right: var(--spacing-md);
    top: 50%;
    transform: translateY(-50%);
    width: 20px;
    height: 20px;
    padding: 0;
    background: transparent;
    border: none;
    color: var(--color-text-tertiary);
    cursor: pointer;
    transition: color var(--transition-base);
    display: flex;
    align-items: center;
    justify-content: center;
}

.search-clear:hover {
    color: var(--color-primary);
}

.search-clear svg {
    width: 16px;
    height: 16px;
}

.search-stats {
    font-size: var(--font-size-sm);
    color: var(--color-text-tertiary);
    text-align: center;
}

.search-stats.has-results {
    color: var(--color-primary);
}

/* ========================================
   Tab Navigation
   ======================================== */
.tab-nav {
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.95);
}

.tab-container {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.tab-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    border: 1px solid transparent;
    background-color: transparent;
    color: var(--color-text-secondary);
    font-size: var(--font-size-base);
    font-weight: 500;
    cursor: pointer;
    border-radius: var(--radius-lg);
    transition: all var(--transition-base);
    white-space: nowrap;
    flex-shrink: 0;
}

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

.tab-btn.active {
    background-color: var(--color-primary);
    color: var(--color-text-inverse);
}

.tab-special {
    background: linear-gradient(135deg, var(--color-secondary) 0%, var(--color-primary) 100%);
    color: var(--color-text-inverse);
    font-weight: 600;
}

.tab-special:hover {
    opacity: 0.9;
    color: var(--color-text-inverse);
}

.tab-icon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
}

/* ========================================
   Filter Section
   ======================================== */
.filter-section {
    background-color: var(--color-bg-secondary);
    padding: var(--spacing-lg) var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
}

.filter-container {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.filter-label {
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-text-secondary);
    white-space: nowrap;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.filter-tags {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    flex: 1;
}

.filter-tag {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--color-border);
    background-color: var(--color-bg);
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    border-radius: var(--radius-full);
    cursor: pointer;
    transition: all var(--transition-base);
    white-space: nowrap;
}

.filter-tag:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.filter-tag.active {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--color-text-inverse);
}

/* ========================================
   Main Content
   ======================================== */
.main-content {
    flex: 1;
    padding: var(--spacing-xl) var(--spacing-md);
}

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

.cards-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
}

/* ========================================
   Card Styles - Grid Layout
   ======================================== */
.card {
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    transition: all var(--transition-base);
    cursor: pointer;
    position: relative;
}

.card:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

/* Avatar */
.card-avatar {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-secondary) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-inverse);
    font-size: var(--font-size-base);
    font-weight: 600;
    flex-shrink: 0;
    overflow: hidden;
}

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

/* Content Section */
.card-content {
    flex: 1;
    min-width: 0;
}

.card-header-row {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xs);
}

.card-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-text-primary);
    text-decoration: none;
    transition: color var(--transition-base);
}

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

.card-hot {
    padding: 2px 8px;
    background-color: var(--color-tag-bg-warning);
    color: var(--color-tag-text-warning);
    font-size: var(--font-size-xs);
    font-weight: 600;
    border-radius: var(--radius-full);
    white-space: nowrap;
}

.card-description {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    line-height: 1.5;
    margin-top: var(--spacing-xs);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* Stats Section */
.card-stats {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    flex-shrink: 0;
}

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

.stat-icon {
    width: 16px;
    height: 16px;
    color: var(--color-warning);
}

.stat-value {
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-text-primary);
}

.stat-change {
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-success);
}

/* ========================================
   Loading State
   ======================================== */
.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-2xl);
    color: var(--color-text-tertiary);
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 2px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: var(--spacing-md);
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* ========================================
   Empty State
   ======================================== */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-2xl);
    color: var(--color-text-tertiary);
}

.empty-icon {
    width: 64px;
    height: 64px;
    margin-bottom: var(--spacing-md);
    opacity: 0.5;
    color: var(--color-primary);
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background-color: var(--color-bg-secondary);
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-xl) var(--spacing-md);
    text-align: center;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

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

.footer-note {
    margin-top: var(--spacing-sm);
    color: var(--color-text-tertiary);
}

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 1023px) {
    .cards-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: var(--spacing-md);
    }
    
    .logo-text {
        font-size: var(--font-size-2xl);
    }
    
    .header-subtitle {
        font-size: var(--font-size-base);
    }
    
    .card-stats {
        gap: var(--spacing-md);
    }
}

@media (max-width: 767px) {
    .cards-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-md);
    }
    
    .tab-btn {
        padding: var(--spacing-sm) var(--spacing-md);
        font-size: var(--font-size-sm);
    }
    
    .tab-icon {
        width: 18px;
        height: 18px;
    }
    
    .filter-container {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .filter-label {
        margin-bottom: var(--spacing-sm);
    }
    
    .card {
        padding: var(--spacing-md);
    }
    
    .card-avatar {
        width: 40px;
        height: 40px;
        font-size: var(--font-size-sm);
    }
    
    .card-title {
        font-size: var(--font-size-base);
    }
    
    .card-stats {
        gap: var(--spacing-sm);
    }
}

@media (max-width: 639px) {
    :root {
        --font-size-3xl: 1.5rem;
        --font-size-2xl: 1.25rem;
    }
    
    .header {
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .logo-icon {
        width: 36px;
        height: 36px;
    }
    
    .logo-text {
        font-size: var(--font-size-xl);
    }
    
    .header-subtitle {
        font-size: var(--font-size-sm);
    }
    
    .tab-container {
        gap: 0;
        padding: var(--spacing-xs);
    }
    
    .tab-btn {
        flex: 1;
        justify-content: center;
        padding: var(--spacing-sm);
        font-size: var(--font-size-xs);
    }
    
    .tab-btn span {
        display: none;
    }
    
    .tab-icon {
        width: 24px;
        height: 24px;
    }
    
    .filter-section {
        padding: var(--spacing-md);
    }
    
    .filter-tag {
        padding: var(--spacing-xs) var(--spacing-sm);
        font-size: var(--font-size-xs);
    }
    
    .main-content {
        padding: var(--spacing-md);
    }
    
    .card {
        padding: var(--spacing-md);
        gap: var(--spacing-md);
    }
    
    .card-header-row {
        flex-wrap: wrap;
    }
    
    .card-hot {
        margin-top: var(--spacing-xs);
    }
    
    .card-description {
        font-size: var(--font-size-sm);
    }
    
    .card-stats {
        gap: var(--spacing-md);
    }
    
    .stat-value,
    .stat-change {
        font-size: var(--font-size-xs);
    }
}

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

.card {
    animation: fadeIn 0.3s ease forwards;
}

.card:nth-child(1) { animation-delay: 0.05s; }
.card:nth-child(2) { animation-delay: 0.1s; }
.card:nth-child(3) { animation-delay: 0.15s; }
.card:nth-child(4) { animation-delay: 0.2s; }
.card:nth-child(5) { animation-delay: 0.25s; }
.card:nth-child(6) { animation-delay: 0.3s; }
.card:nth-child(7) { animation-delay: 0.35s; }
.card:nth-child(8) { animation-delay: 0.4s; }

/* ========================================
   Accessibility
   ======================================== */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

.tab-btn:focus,
.filter-tag:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* ========================================
   Scrollbar Styling
   ======================================== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--color-bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-text-tertiary);
}

/* ========================================
   Selection Styling
   ======================================== */
::selection {
    background: rgba(0, 123, 255, 0.2);
    color: var(--color-text-primary);
}

/* ========================================
   Google AdSense Ad Slots
   ======================================== */
.ad-container {
    display: none;
    justify-content: center;
    padding: var(--spacing-lg) var(--spacing-md);
}

.ads-enabled .ad-container {
    display: flex;
}

.ad-slot {
    position: relative;
    background-color: var(--color-bg-card);
    border: 1px dashed var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.ad-label {
    position: absolute;
    top: 8px;
    left: 12px;
    font-size: 10px;
    color: var(--color-text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    z-index: 1;
}

.ad-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-tertiary);
    font-size: var(--font-size-sm);
}

.ad-top .ad-slot {
    width: 728px;
    height: 90px;
    max-width: 100%;
}

.ad-top .ad-placeholder::before {
    content: '728×90 Leaderboard Ad';
}

.ad-in-content .ad-slot {
    width: 336px;
    height: 280px;
}

.ad-in-content .ad-placeholder::before {
    content: '336×280 Large Rectangle Ad';
}

.ad-bottom .ad-slot {
    width: 728px;
    height: 90px;
    max-width: 100%;
}

.ad-bottom .ad-placeholder::before {
    content: '728×90 Leaderboard Ad';
}

@media (max-width: 767px) {
    .ad-top .ad-slot,
    .ad-bottom .ad-slot {
        width: 320px;
        height: 100px;
    }
    
    .ad-top .ad-placeholder::before,
    .ad-bottom .ad-placeholder::before {
        content: '320×100 Large Mobile Banner Ad';
    }
    
    .ad-in-content .ad-slot {
        width: 300px;
        height: 250px;
    }
    
    .ad-in-content .ad-placeholder::before {
        content: '300×250 Medium Rectangle Ad';
    }
}

@media (max-width: 360px) {
    .ad-top .ad-slot,
    .ad-bottom .ad-slot {
        width: 100%;
        height: 50px;
    }
    
    .ad-top .ad-placeholder::before,
    .ad-bottom .ad-placeholder::before {
        content: 'Mobile Banner Ad';
    }
}