/* CSS Custom Properties */
:root {
    --primary-bg: #0a0a0f;
    --secondary-bg: #141419;
    --card-bg: #1a1a24;
    --card-hover-bg: #22222e;
    --border-color: rgba(255, 255, 255, 0.1);

    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-gradient: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));

    --text-primary: #ffffff;
    --text-secondary: rgba(255, 255, 255, 0.7);
    --text-muted: rgba(255, 255, 255, 0.5);

    --success: #22c55e;
    --warning: #f59e0b;
    --error: #ef4444;

    --category-technology: #3b82f6;
    --category-business: #22c55e;
    --category-science: #f59e0b;
    --category-other: #8b5cf6;

    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;

    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;

    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
}

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

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

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

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

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

/* Firefox scrollbar */
* {
    scrollbar-width: thin;
    scrollbar-color: var(--border-color) var(--primary-bg);
}

/* Base */
html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--primary-bg);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

/* App Container */
.app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--secondary-bg);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    position: relative;
}

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

.header-center h1 {
    font-size: 1.5rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

/* Language Toggle */
.lang-toggle {
    display: flex;
    gap: 2px;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 2px;
}

.lang-btn {
    padding: 4px 12px;
    background: transparent;
    border: none;
    border-radius: var(--radius-sm);
    color: var(--text-muted);
    font-family: inherit;
    font-size: 0.8125rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-fast);
    letter-spacing: 0.5px;
}

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

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

.header-center h1 i {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

.back-btn {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    transition: var(--transition-fast);
}

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

/* Main Content */
.main {
    flex: 1;
    padding: var(--spacing-xl);
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition-fast);
    border: none;
    text-decoration: none;
}

.btn-primary {
    background: var(--accent-gradient);
    color: var(--text-primary);
}

.btn-primary:hover {
    opacity: 0.9;
    transform: translateY(-1px);
}

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

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

.btn-full {
    width: 100%;
}

.link-btn {
    background: none;
    border: none;
    color: var(--accent-primary);
    cursor: pointer;
    font-size: inherit;
    text-decoration: underline;
}

.link-btn:hover {
    color: var(--accent-secondary);
}

/* Featured Section */
.featured-section {
    margin-bottom: var(--spacing-2xl);
}

.featured-post {
    position: relative;
    background: var(--card-bg);
    border-radius: var(--radius-xl);
    overflow: hidden;
    border: 1px solid var(--border-color);
    cursor: pointer;
    transition: var(--transition-base);
}

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

.featured-image {
    width: 100%;
    height: 400px;
    object-fit: cover;
}

.featured-placeholder {
    width: 100%;
    height: 400px;
    background: var(--accent-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
}

.featured-placeholder i {
    font-size: 5rem;
    color: rgba(255, 255, 255, 0.3);
}

.featured-content {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    padding: var(--spacing-xl);
    background: linear-gradient(transparent, rgba(0, 0, 0, 0.9));
}

.featured-content .category-badge {
    margin-bottom: var(--spacing-md);
}

.featured-content h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    line-height: 1.3;
}

.featured-content .post-meta {
    color: var(--text-secondary);
}

/* News Section */
.news-section {
    margin-bottom: var(--spacing-2xl);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.section-header h2 {
    font-size: 1.5rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.section-header h2 i {
    color: var(--accent-primary);
}

.filters {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.filter-btn {
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 0.875rem;
    cursor: pointer;
    transition: var(--transition-fast);
}

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

.filter-btn.active {
    background: var(--accent-gradient);
    border-color: transparent;
    color: var(--text-primary);
}

/* News Grid */
.news-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

/* News Card */
.news-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--border-color);
    cursor: pointer;
    transition: var(--transition-base);
}

.news-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-primary);
}

.news-card-image {
    width: 100%;
    height: 180px;
    object-fit: cover;
}

.news-card-placeholder {
    width: 100%;
    height: 180px;
    background: linear-gradient(135deg, var(--secondary-bg), var(--card-bg));
    display: flex;
    align-items: center;
    justify-content: center;
}

.news-card-placeholder.technology {
    background: linear-gradient(135deg, #1e3a5f 0%, #3b82f6 100%);
}

.news-card-placeholder.business {
    background: linear-gradient(135deg, #14532d 0%, #22c55e 100%);
}

.news-card-placeholder.science {
    background: linear-gradient(135deg, #78350f 0%, #f59e0b 100%);
}

.news-card-placeholder.other {
    background: linear-gradient(135deg, #4c1d95 0%, #8b5cf6 100%);
}

.news-card-placeholder i {
    font-size: 3rem;
    color: rgba(255, 255, 255, 0.4);
}

.news-card-content {
    padding: var(--spacing-lg);
}

.category-badge {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-sm);
}

.category-badge.technology {
    background: rgba(59, 130, 246, 0.2);
    color: var(--category-technology);
}

.category-badge.business {
    background: rgba(34, 197, 94, 0.2);
    color: var(--category-business);
}

.category-badge.science {
    background: rgba(245, 158, 11, 0.2);
    color: var(--category-science);
}

.category-badge.other {
    background: rgba(139, 92, 246, 0.2);
    color: var(--category-other);
}

.news-card-content h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.news-card-content p {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-md);
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.post-meta {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    font-size: 0.75rem;
    color: var(--text-muted);
}

.post-meta span {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

/* Load More */
.load-more {
    text-align: center;
    margin-top: var(--spacing-xl);
    padding: var(--spacing-lg);
}

.load-more .loading-spinner {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    color: var(--text-muted);
    font-size: 1rem;
}

.load-more .loading-spinner i {
    font-size: 1.5rem;
    color: var(--accent-primary);
}

.load-more .loading-spinner .fa-spin {
    animation: fa-spin 1s infinite linear;
}

@keyframes fa-spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: var(--spacing-2xl);
    color: var(--text-muted);
}

.empty-state i {
    font-size: 4rem;
    margin-bottom: var(--spacing-lg);
    opacity: 0.5;
}

.empty-state h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
}

/* Modal */
.modal {
    position: fixed;
    inset: 0;
    z-index: 1000;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding: var(--spacing-xl);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-base);
    overflow-y: auto;
}

.modal.show {
    opacity: 1;
    visibility: visible;
}

.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(10, 10, 15, 0.95);
    backdrop-filter: blur(8px);
}

.modal-content {
    position: relative;
    background: var(--secondary-bg);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    width: 100%;
    max-width: 420px;
    margin: var(--spacing-xl) auto;
    border: 1px solid var(--border-color);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    transform: translateY(20px) scale(0.98);
    transition: var(--transition-base);
}

.modal.show .modal-content {
    transform: translateY(0) scale(1);
}

.modal-large {
    max-width: 680px;
    background: var(--primary-bg);
    border: none;
    box-shadow: none;
    padding: var(--spacing-lg) var(--spacing-xl) var(--spacing-2xl);
}

.modal-close {
    position: fixed;
    top: var(--spacing-lg);
    right: var(--spacing-lg);
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-fast);
    z-index: 1001;
    font-size: 1.125rem;
}

.modal-close:hover {
    background: var(--card-hover-bg);
    color: var(--text-primary);
    border-color: var(--text-muted);
    transform: scale(1.05);
}

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: var(--spacing-md);
    background: var(--secondary-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.9375rem;
    transition: var(--transition-fast);
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.form-group textarea {
    resize: vertical;
    min-height: 100px;
}

.form-group select {
    cursor: pointer;
}

.form-error {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid var(--error);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    color: var(--error);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-lg);
}

.form-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: flex-end;
    margin-top: var(--spacing-lg);
}

/* Post Detail */
.post-detail {
    max-width: 100%;
}

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

.post-detail-header .category-badge {
    margin-bottom: var(--spacing-md);
    display: inline-flex;
}

.post-detail-header h1 {
    font-size: 2rem;
    font-weight: 700;
    line-height: 1.25;
    margin-bottom: var(--spacing-md);
    letter-spacing: -0.02em;
}

.post-detail-header .post-meta {
    font-size: 0.875rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.post-detail-image {
    width: calc(100% + var(--spacing-xl) * 2);
    margin-left: calc(var(--spacing-xl) * -1);
    max-height: 380px;
    object-fit: cover;
    border-radius: 0;
    margin-bottom: var(--spacing-xl);
}

.post-detail-placeholder {
    width: calc(100% + var(--spacing-xl) * 2);
    margin-left: calc(var(--spacing-xl) * -1);
    height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-xl);
    background: linear-gradient(135deg, var(--secondary-bg), var(--card-bg));
}

.post-detail-placeholder.technology {
    background: linear-gradient(135deg, #1e3a5f 0%, #3b82f6 100%);
}

.post-detail-placeholder.business {
    background: linear-gradient(135deg, #14532d 0%, #22c55e 100%);
}

.post-detail-placeholder.science {
    background: linear-gradient(135deg, #78350f 0%, #f59e0b 100%);
}

.post-detail-placeholder.other {
    background: linear-gradient(135deg, #4c1d95 0%, #8b5cf6 100%);
}

.post-detail-placeholder i {
    font-size: 4rem;
    color: rgba(255, 255, 255, 0.3);
}

.post-detail-content {
    font-size: 1.0625rem;
    line-height: 1.85;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

.post-detail-content p {
    margin-bottom: var(--spacing-lg);
}

.post-detail-content p:last-child {
    margin-bottom: 0;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

/* Screen reader only - for accessibility */
.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;
}

/* Loading Spinner */
@keyframes spin {
    to { transform: rotate(360deg); }
}

.btn .fa-spinner {
    animation: spin 1s linear infinite;
}

/* Responsive */
@media (max-width: 768px) {
    .header {
        padding: var(--spacing-sm);
        gap: var(--spacing-sm);
    }

    .header-center {
        gap: var(--spacing-sm);
    }

    .header-center h1 {
        font-size: 1.25rem;
    }

    .lang-btn {
        padding: 4px 8px;
        font-size: 0.75rem;
    }

    /* Back button: icon only on mobile */
    .back-btn {
        width: 40px;
        height: 40px;
        padding: 0;
        justify-content: center;
        border-radius: var(--radius-md);
    }

    .back-btn-text {
        display: none;
    }

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

    .featured-image,
    .featured-placeholder {
        height: 250px;
    }

    .featured-content h2 {
        font-size: 1.25rem;
    }

    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }

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

    .modal {
        padding: 0;
    }

    .modal-content {
        padding: var(--spacing-md);
        width: 100%;
        border-radius: 0;
        margin: 0;
        min-height: 100vh;
    }

    .modal-large {
        padding: var(--spacing-md) var(--spacing-md) var(--spacing-2xl);
    }

    .modal-close {
        top: var(--spacing-md);
        right: var(--spacing-md);
        width: 40px;
        height: 40px;
    }

    .post-detail-header {
        padding-top: var(--spacing-xl);
    }

    .post-detail-header h1 {
        font-size: 1.5rem;
    }

    .post-detail-image {
        width: calc(100% + var(--spacing-md) * 2);
        margin-left: calc(var(--spacing-md) * -1);
        max-height: 240px;
    }

    .post-detail-content {
        font-size: 1rem;
    }

    .btn {
        padding: var(--spacing-sm) var(--spacing-md);
        font-size: 0.8125rem;
    }
}

@media (max-width: 480px) {
    .filters {
        width: 100%;
        justify-content: flex-start;
        overflow-x: auto;
        padding-bottom: var(--spacing-sm);
    }

    .filter-btn {
        flex-shrink: 0;
    }
}

/* Sources Section */
.sources-section {
    margin-top: var(--spacing-2xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--border-color);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.sources-section h4 {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: var(--spacing-md);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.sources-section h4 i {
    color: var(--accent-primary);
    font-size: 0.6875rem;
}

.sources-list {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.sources-list li {
    flex: 0 0 auto;
}

.sources-list a {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 14px;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 100px;
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.8125rem;
    transition: var(--transition-fast);
}

.sources-list a:hover {
    background: var(--card-bg);
    border-color: var(--accent-primary);
    color: var(--text-primary);
}

.sources-list a:hover i {
    color: var(--accent-primary);
}

.sources-list a i {
    font-size: 0.625rem;
    color: var(--text-muted);
    transition: var(--transition-fast);
}

.source-domain {
    font-weight: 500;
}

@media (max-width: 768px) {
    .sources-list {
        flex-direction: column;
    }

    .sources-list a {
        width: 100%;
        justify-content: center;
    }
}

/* Footer - SEO Content */
.footer {
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-xl) var(--spacing-lg);
    background: var(--secondary-bg);
    border-top: 1px solid var(--border-color);
    text-align: center;
}

.footer-content {
    max-width: 800px;
    margin: 0 auto;
}

.footer-content p {
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.footer-content strong {
    color: var(--text-primary);
}

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