/* ============================================
   DEEPWATER DAILY - Modern Substack-Style CSS
   ============================================ */

/* CSS Variables */
:root {
    /* Colors - Light Mode */
    --color-primary: #0a2540;
    --color-primary-light: #1a4971;
    --color-accent: #0066cc;
    --color-accent-hover: #0052a3;
    --color-success: #28a745;
    --color-warning: #f5a623;
    --color-danger: #dc3545;
    
    /* Oil & Gas Theme Colors */
    --color-oil: #1a1a2e;
    --color-gas: #16537e;
    --color-deepwater: #0d3b66;
    --color-pipeline: #3a5a40;
    --color-crude: #6b4423;
    
    /* Background & Surface */
    --bg-primary: #ffffff;
    --bg-secondary: #f7f7f7;
    --bg-tertiary: #eef2f5;
    --bg-card: #ffffff;
    
    /* Text Colors */
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --text-tertiary: #999999;
    --text-inverse: #ffffff;
    
    /* Borders */
    --border-color: #e5e5e5;
    --border-radius: 8px;
    --border-radius-lg: 12px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-serif: 'Playfair Display', Georgia, serif;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms ease;
    
    /* Container */
    --container-max: 1200px;
    --content-max: 720px;
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --bg-primary: #0f0f0f;
    --bg-secondary: #1a1a1a;
    --bg-tertiary: #242424;
    --bg-card: #1a1a1a;
    
    --text-primary: #f5f5f5;
    --text-secondary: #a0a0a0;
    --text-tertiary: #707070;
    
    --border-color: #333333;
    
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.5);
}

/* Dark Mode Article Card Enhancements */
[data-theme="dark"] .article-card {
    background: var(--bg-card);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    margin-bottom: var(--spacing-md);
}

[data-theme="dark"] .article-card:last-child {
    margin-bottom: 0;
}

/* ============================================
   BASE STYLES
   ============================================ */

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 70px; /* account for sticky header height */
}

body {
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ============================================
   HEADER / NAVIGATION
   ============================================ */

.header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    backdrop-filter: blur(10px);
}

.header-container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: var(--spacing-md) var(--spacing-lg);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-lg);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 700;
    font-size: 1.25rem;
}

.logo-icon {
    font-size: 1.5rem;
}

.logo-text {
    font-family: var(--font-serif);
}

.nav {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    padding: var(--spacing-sm) 0;
    border-bottom: 2px solid transparent;
    transition: all var(--transition-base);
}

.nav-link:hover,
.nav-link.active {
    color: var(--text-primary);
    border-bottom-color: var(--color-accent);
}

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

.search-container {
    display: flex;
    align-items: center;
    background: var(--bg-secondary);
    border-radius: 100px;
    padding: var(--spacing-xs) var(--spacing-sm);
    border: 1px solid var(--border-color);
    transition: all var(--transition-base);
}

.search-container:focus-within {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(0, 102, 204, 0.1);
}

.search-input {
    border: none;
    background: transparent;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.9rem;
    width: 200px;
    color: var(--text-primary);
}

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

.search-input:focus {
    outline: none;
}

.search-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: var(--spacing-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color var(--transition-fast);
}

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

.theme-toggle {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-secondary);
    transition: all var(--transition-base);
}

.theme-toggle:hover {
    background: var(--bg-tertiary);
    color: var(--color-accent);
}

/* ============================================
   MAIN CONTENT
   ============================================ */

.main-content {
    min-height: calc(100vh - 200px);
}

.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* Hero Section */
.hero {
    text-align: center;
    padding: var(--spacing-2xl) 0;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: var(--spacing-xl);
}

.hero-title {
    font-family: var(--font-serif);
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.hero-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Filter Bar */
.filter-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--border-color);
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.filter-tabs {
    display: flex;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
}

.filter-tab {
    background: transparent;
    border: 1px solid var(--border-color);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: 100px;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-base);
    white-space: nowrap;
}

.filter-tab:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
}

.filter-tab.active {
    background: var(--color-accent);
    border-color: var(--color-accent);
    color: white;
}

.view-toggle {
    display: flex;
    gap: var(--spacing-xs);
}

.view-btn {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    width: 36px;
    height: 36px;
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-secondary);
    transition: all var(--transition-base);
}

.view-btn:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
}

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

/* ============================================
   ARTICLE STYLES (Substack-like)
   ============================================ */

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

.articles-container.grid-view {
    max-width: 100%;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-lg);
}

/* Article Card - List/Article View */
.article-card {
    background: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-xl);
    transition: all var(--transition-base);
}

.article-card:first-child {
    padding-top: 0;
}

.article-card:last-child {
    border-bottom: none;
}

.article-category {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--color-accent);
    margin-bottom: var(--spacing-sm);
}

.article-title {
    font-family: var(--font-serif);
    font-size: 1.5rem;
    font-weight: 600;
    line-height: 1.3;
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
    transition: color var(--transition-fast);
}

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

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

.article-excerpt {
    font-size: 1rem;
    line-height: 1.7;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.article-meta {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    font-size: 0.85rem;
    color: var(--text-tertiary);
}

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

.article-meta-item i {
    font-size: 0.9rem;
}

.article-source {
    padding: 2px 8px;
    background: var(--bg-tertiary);
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 500;
}

.read-more-link {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--color-accent);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9rem;
    margin-top: var(--spacing-md);
    transition: gap var(--transition-base);
}

.read-more-link:hover {
    gap: var(--spacing-sm);
}

/* Article Card - Grid View */
.grid-view .article-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
}

.grid-view .article-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.grid-view .article-title {
    font-size: 1.15rem;
}

.grid-view .article-excerpt {
    -webkit-line-clamp: 2;
}

/* ============================================
   LOADING & STATES
   ============================================ */

.loading-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-2xl);
    gap: var(--spacing-md);
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--color-accent);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

.no-results {
    text-align: center;
    padding: var(--spacing-2xl);
    color: var(--text-secondary);
}

.no-results i {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-tertiary);
}

.no-results h3 {
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

/* Load More */
.load-more-container {
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.load-more-btn {
    background: transparent;
    border: 2px solid var(--color-accent);
    color: var(--color-accent);
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: 100px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
}

.load-more-btn:hover {
    background: var(--color-accent);
    color: white;
}

/* ============================================
   ABOUT SECTION
   ============================================ */

.about-section {
    max-width: var(--content-max);
    margin: 0 auto;
    padding: var(--spacing-xl) 0;
}

.about-article {
    line-height: 1.8;
}

.about-article h1 {
    font-family: var(--font-serif);
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xl);
    color: var(--text-primary);
}

.about-article h2 {
    font-size: 1.35rem;
    font-weight: 600;
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.about-article p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

.about-article ul {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-xl);
}

.about-article li {
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
}

.about-article strong {
    color: var(--text-primary);
}

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

.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-xl) 0;
    margin-top: var(--spacing-2xl);
}

.footer-container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-lg);
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 600;
    color: var(--text-primary);
}

.footer-tagline {
    color: var(--text-tertiary);
    font-size: 0.85rem;
    font-weight: 400;
    margin-left: var(--spacing-md);
}

.footer-links {
    display: flex;
    gap: var(--spacing-lg);
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color var(--transition-fast);
}

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

.footer-info {
    text-align: right;
    font-size: 0.85rem;
    color: var(--text-tertiary);
}

.footer-info p {
    margin-bottom: var(--spacing-xs);
}

.last-updated {
    font-size: 0.8rem;
}

/* ============================================
   CATEGORY COLORS
   ============================================ */

.category-deepwater { color: var(--color-deepwater); }
.category-gulf { color: var(--color-gas); }
.category-crude { color: var(--color-crude); }
.category-gas { color: var(--color-pipeline); }
.category-pipeline { color: var(--color-pipeline); }
.category-lng { color: var(--color-gas); }

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

@media (max-width: 768px) {
    html {
        scroll-padding-top: 110px; /* taller header on mobile due to wrapped nav */
    }

    .header-container {
        flex-wrap: wrap;
        padding: var(--spacing-sm) var(--spacing-md);
    }

    .nav {
        order: 3;
        width: 100%;
        justify-content: center;
        padding-top: var(--spacing-sm);
        border-top: 1px solid var(--border-color);
        margin-top: var(--spacing-sm);
    }
    
    .header-actions {
        margin-left: auto;
    }

    .nav-link {
        padding: var(--spacing-xs) 0;
        font-size: 0.9rem;
    }

    .search-input {
        width: 150px;
    }
    
    .hero {
        padding: var(--spacing-xl) 0;
    }
    
    .hero-title {
        font-size: 1.75rem;
    }
    
    .filter-bar {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .filter-tabs {
        width: 100%;
        overflow-x: auto;
        padding-bottom: var(--spacing-sm);
        -webkit-overflow-scrolling: touch;
    }
    
    .articles-container.grid-view {
        grid-template-columns: 1fr;
    }
    
    .article-title {
        font-size: 1.25rem;
    }
    
    .footer-container {
        flex-direction: column;
        text-align: center;
    }
    
    .footer-info {
        text-align: center;
    }
    
    .footer-tagline {
        display: block;
        margin-left: 0;
        margin-top: var(--spacing-xs);
    }
}

@media (max-width: 480px) {
    .search-container {
        display: none;
    }
    
    .filter-tab {
        font-size: 0.8rem;
        padding: var(--spacing-xs) var(--spacing-sm);
    }
}

/* ============================================
   ANIMATIONS
   ============================================ */

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

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

/* Staggered animation for grid items */
.grid-view .article-card:nth-child(1) { animation-delay: 0.05s; }
.grid-view .article-card:nth-child(2) { animation-delay: 0.1s; }
.grid-view .article-card:nth-child(3) { animation-delay: 0.15s; }
.grid-view .article-card:nth-child(4) { animation-delay: 0.2s; }
.grid-view .article-card:nth-child(5) { animation-delay: 0.25s; }
.grid-view .article-card:nth-child(6) { animation-delay: 0.3s; }