/* Base Styles and Core Variables */
:root {
    /* Color Palette - Premium Dark Theme Default */
    --bg-primary: #0f111a;
    /* Very dark slate blue/black */
    --bg-secondary: rgba(26, 29, 41, 0.7);
    /* Slightly lighter, translucent */
    --bg-card: rgba(30, 33, 48, 0.5);
    /* Card background, very translucent */
    --bg-card-hover: rgba(40, 44, 60, 0.8);

    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;

    /* Accents & Brand */
    --accent-primary: #6366f1;
    /* Indigo */
    --accent-primary-hover: #4f46e5;
    --accent-secondary: #ec4899;
    /* Pink */

    /* UI Elements */
    --border-color: rgba(255, 255, 255, 0.08);
    --border-highlight: rgba(255, 255, 255, 0.15);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.36);

    /* Gradients */
    --gradient-brand: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);

    /* Typography */
    --font-heading: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
    --font-body: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;

    /* Transitions */
    --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Mode - readable contrast on light backgrounds */
[data-theme="light"] {
    --bg-primary: #f1f5f9;
    --bg-secondary: rgba(255, 255, 255, 0.95);
    --bg-card: #ffffff;
    --bg-card-hover: #f8fafc;

    --text-primary: #0f172a;
    --text-secondary: #334155;
    --text-muted: #475569;

    --border-color: rgba(0, 0, 0, 0.12);
    --border-highlight: rgba(0, 0, 0, 0.2);
    --glass-shadow: 0 8px 32px 0 rgba(15, 23, 42, 0.08);
}

[data-theme="light"] .top-header {
    background: rgba(255, 255, 255, 0.9);
    border-bottom-color: rgba(0, 0, 0, 0.1);
}

[data-theme="light"] .feed-summary {
    color: var(--text-secondary);
}

[data-theme="light"] .feed-summary-filter-btn {
    background: #fff;
    color: var(--text-secondary);
    border-color: rgba(0, 0, 0, 0.18);
}

[data-theme="light"] .feed-summary-filter-btn:hover {
    color: var(--text-primary);
    border-color: var(--text-muted);
}

[data-theme="light"] .search-bar input:focus {
    background: #fff;
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

[data-theme="light"] body::before {
    background: radial-gradient(circle at 30% 30%, rgba(99, 102, 241, 0.04) 0%, transparent 50%),
        radial-gradient(circle at 70% 70%, rgba(236, 72, 153, 0.02) 0%, transparent 50%);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-body);
    line-height: 1.6;
    overflow: hidden;
    min-height: 100vh;
}

body.modal-open {
    overflow: hidden;
}

/* Skip link for keyboard / a11y */
.skip-link {
    position: absolute;
    top: -100px;
    left: 1rem;
    z-index: 9999;
    padding: 0.75rem 1rem;
    background: var(--accent-primary);
    color: #fff;
    font-weight: 600;
    font-size: 0.9rem;
    border-radius: 8px;
    text-decoration: none;
    transition: top 0.2s ease;
}

.skip-link:focus {
    top: 1rem;
    outline: 2px solid #fff;
    outline-offset: 2px;
}

/* Background Effect - subtle gradient mesh */
body::before {
    content: '';
    position: fixed;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 30%, rgba(99, 102, 241, 0.1) 0%, transparent 40%),
        radial-gradient(circle at 70% 70%, rgba(236, 72, 153, 0.05) 0%, transparent 40%);
    pointer-events: none;
    z-index: -1;
}

/* App Container Layout */
.app-container {
    display: flex;
    height: 100vh;
    width: 100vw;
}

/* Base Glassmorphism utility */
.glass {
    background: var(--bg-secondary);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-right: 1px solid var(--border-color);
}