/* ========================================
   CSS Variables & Theme
======================================== */
:root {
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-tertiary: #f1f5f9;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --border: #e2e8f0;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: 0.2s ease;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #0f172a;
        --bg-secondary: #1e293b;
        --bg-tertiary: #334155;
        --text-primary: #f1f5f9;
        --text-secondary: #cbd5e1;
        --text-muted: #64748b;
        --border: #334155;
        --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
        --shadow-lg: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    }
}

/* ========================================
   Base Styles
======================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

a {
    color: inherit;
    text-decoration: none;
}

/* ========================================
   Header
======================================== */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 24px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 32px;
}

.logo {
    font-size: 14px;
    font-weight: 700;
    letter-spacing: 2px;
}

.sort-tabs {
    display: flex;
    gap: 8px;
}

.sort-tab {
    background: rgba(255, 255, 255, 0.15);
    border: none;
    color: rgba(255, 255, 255, 0.8);
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

.sort-tab:hover {
    background: rgba(255, 255, 255, 0.25);
    color: white;
}

.sort-tab.active {
    background: white;
    color: #667eea;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 16px;
}

.last-refresh {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    font-size: 12px;
}

.refresh-label {
    opacity: 0.7;
    font-size: 10px;
    letter-spacing: 1px;
}

.refresh-time {
    font-weight: 600;
}

/* ========================================
   Search
======================================== */
.search-container {
    padding: 20px 24px;
    background: var(--bg-primary);
}

.search-wrapper {
    position: relative;
    max-width: 100%;
}

.search-icon {
    position: absolute;
    left: 16px;
    top: 50%;
    transform: translateY(-50%);
    width: 20px;
    height: 20px;
    color: var(--text-muted);
}

.search-input {
    width: 100%;
    padding: 14px 16px 14px 48px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 15px;
    transition: var(--transition);
}

.search-input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

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

/* ========================================
   Top Signals Carousel
======================================== */
.top-signals {
    padding: 0 24px 24px;
}

.section-title {
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 1px;
    color: var(--text-muted);
    margin-bottom: 16px;
}

.signals-carousel {
    display: flex;
    gap: 16px;
    overflow-x: auto;
    padding-bottom: 8px;
    scroll-snap-type: x mandatory;
    -webkit-overflow-scrolling: touch;
}

.signals-carousel::-webkit-scrollbar {
    height: 6px;
}

.signals-carousel::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
    border-radius: 3px;
}

.signals-carousel::-webkit-scrollbar-thumb {
    background: var(--text-muted);
    border-radius: 3px;
}

.signal-card {
    flex: 0 0 300px;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-tertiary) 100%);
    border-radius: var(--radius);
    padding: 20px;
    scroll-snap-align: start;
    border: 1px solid var(--border);
    transition: var(--transition);
    cursor: pointer;
}

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

.signal-source {
    font-size: 11px;
    font-weight: 600;
    color: var(--accent);
    letter-spacing: 0.5px;
    margin-bottom: 8px;
}

.signal-title {
    font-size: 16px;
    font-weight: 600;
    line-height: 1.4;
    margin-bottom: 12px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.signal-meta {
    display: flex;
    gap: 16px;
    font-size: 13px;
    color: var(--text-secondary);
}

.signal-meta span {
    display: flex;
    align-items: center;
    gap: 4px;
}

/* ========================================
   Main Grid
======================================== */
.main-grid {
    display: grid;
    grid-template-columns: 1fr 1.5fr 1fr;
    gap: 24px;
    padding: 0 24px 24px;
}

.main-grid.three-cols {
    grid-template-columns: repeat(3, 1fr);
}

@media (max-width: 1200px) {
    .main-grid {
        grid-template-columns: 1fr 1fr;
    }

    .main-grid.three-cols {
        grid-template-columns: 1fr 1fr;
    }

    .column-wide {
        grid-column: span 2;
    }
}

@media (max-width: 768px) {
    .main-grid,
    .main-grid.three-cols {
        grid-template-columns: 1fr;
    }

    .column-wide {
        grid-column: span 1;
    }
}

/* ========================================
   Columns
======================================== */
.column {
    background: var(--bg-secondary);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    overflow: hidden;
}

.column-header {
    padding: 16px 20px;
    border-bottom: 1px solid var(--border);
    position: relative;
}

.column-title {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    font-weight: 600;
    letter-spacing: 0.5px;
    cursor: pointer;
    user-select: none;
}

.dropdown-icon {
    width: 16px;
    height: 16px;
    color: var(--text-muted);
    transition: var(--transition);
}

.column-title:hover .dropdown-icon {
    color: var(--text-primary);
}

.source-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-lg);
    z-index: 50;
    margin-top: 4px;
}

.source-menu.open {
    display: block;
}

.source-option {
    display: block;
    width: 100%;
    padding: 12px 20px;
    border: none;
    background: none;
    color: var(--text-primary);
    font-size: 14px;
    text-align: left;
    cursor: pointer;
    transition: var(--transition);
}

.source-option:hover {
    background: var(--bg-tertiary);
}

.source-option.active {
    color: var(--accent);
    font-weight: 500;
}

.column-content {
    max-height: 800px;
    overflow-y: auto;
}

.column-content::-webkit-scrollbar {
    width: 6px;
}

.column-content::-webkit-scrollbar-track {
    background: transparent;
}

.column-content::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

/* ========================================
   List Items (HN, LessWrong, GitHub)
======================================== */
.list-item {
    display: flex;
    gap: 16px;
    padding: 16px 20px;
    border-bottom: 1px solid var(--border);
    transition: var(--transition);
    cursor: pointer;
}

.list-item:hover {
    background: var(--bg-tertiary);
}

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

.item-rank {
    flex: 0 0 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-tertiary);
    border-radius: 50%;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-secondary);
}

.item-content {
    flex: 1;
    min-width: 0;
}

.item-title {
    font-size: 14px;
    font-weight: 500;
    line-height: 1.4;
    margin-bottom: 4px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.item-title-original {
    font-size: 12px;
    color: var(--text-muted);
    margin-bottom: 8px;
    display: -webkit-box;
    -webkit-line-clamp: 1;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.item-source {
    font-size: 11px;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.item-meta {
    display: flex;
    gap: 12px;
    font-size: 12px;
    color: var(--text-secondary);
}

.item-meta span {
    display: flex;
    align-items: center;
    gap: 4px;
}

.item-bookmark {
    flex: 0 0 auto;
    padding: 8px;
    border: none;
    background: none;
    color: var(--text-muted);
    cursor: pointer;
    transition: var(--transition);
    border-radius: var(--radius-sm);
}

.item-bookmark:hover {
    background: var(--bg-tertiary);
    color: var(--accent);
}

.item-bookmark.saved {
    color: var(--accent);
}

/* ========================================
   Grid Layout (Midjourney)
======================================== */
.grid-layout {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    padding: 12px;
}

.grid-item {
    position: relative;
    aspect-ratio: 1;
    border-radius: var(--radius-sm);
    overflow: hidden;
    cursor: pointer;
}

.grid-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s ease;
}

.grid-item:hover img {
    transform: scale(1.05);
}

.grid-item-overlay {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    padding: 12px;
    background: linear-gradient(transparent, rgba(0, 0, 0, 0.8));
    color: white;
    opacity: 0;
    transition: var(--transition);
}

.grid-item:hover .grid-item-overlay {
    opacity: 1;
}

.grid-item-prompt {
    font-size: 11px;
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.grid-item-like {
    position: absolute;
    top: 8px;
    right: 8px;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.9);
    border-radius: 50%;
    color: var(--text-secondary);
    opacity: 0;
    transition: var(--transition);
    cursor: pointer;
}

.grid-item:hover .grid-item-like {
    opacity: 1;
}

.grid-item-like:hover {
    background: white;
    color: #ef4444;
}

.grid-item-like.liked {
    opacity: 1;
    color: #ef4444;
}

/* ========================================
   Loading States
======================================== */
.loading-placeholder {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 12px;
    padding: 48px;
    color: var(--text-muted);
}

.loading-spinner {
    width: 32px;
    height: 32px;
    border: 3px solid var(--border);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* ========================================
   Footer
======================================== */
.footer {
    padding: 24px;
    text-align: center;
    font-size: 13px;
    color: var(--text-muted);
    border-top: 1px solid var(--border);
}

/* ========================================
   Responsive
======================================== */
@media (max-width: 768px) {
    .header {
        flex-direction: column;
        gap: 16px;
    }

    .header-left {
        flex-direction: column;
        gap: 16px;
    }

    .sort-tabs {
        flex-wrap: wrap;
        justify-content: center;
    }

    .signal-card {
        flex: 0 0 260px;
    }
}