:root {
    --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    --font-serif: 'Georgia', 'Times New Roman', Times, serif;

    /* Light Mode Variables (Default) */
    --color-bg: #f9f9f9;
    --color-card-bg: #ffffff;
    --color-text: #111111;
    --color-text-light: #555555;
    --color-accent: #2c3e50; /* Dark Blue/Grey */
    --color-link: #2980b9;
    --color-border: #e0e0e0;
    --color-ad-bg: #f4f6f7;
    --color-ad-border: #cbd5e1;
    --shadow-subtle: 0 2px 4px rgba(0,0,0,0.02);
    --shadow-hover: 0 8px 16px rgba(0,0,0,0.05);

    --spacing-container: 1140px;
    --spacing-section: 4rem;
    --sidebar-width: 300px;
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --color-bg: #0f172a; /* Slate 900 */
    --color-card-bg: #1e293b; /* Slate 800 */
    --color-text: #e2e8f0; /* Slate 200 */
    --color-text-light: #94a3b8; /* Slate 400 */
    --color-accent: #f8fafc; /* Slate 50 */
    --color-link: #38bdf8; /* Sky 400 */
    --color-border: #334155; /* Slate 700 */
    --color-ad-bg: #1e293b;
    --color-ad-border: #475569;
    --shadow-subtle: 0 2px 4px rgba(0,0,0,0.2);
    --shadow-hover: 0 8px 16px rgba(0,0,0,0.3);
}

body {
    font-family: var(--font-serif);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.7;
    margin: 0;
    padding: 0;
    transition: background-color 0.3s, color 0.3s;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-sans);
    color: var(--color-accent);
    margin-top: 0;
    line-height: 1.2;
}

a {
    color: var(--color-link);
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    text-decoration: underline;
    color: var(--color-accent);
}

.container {
    max-width: var(--spacing-container);
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* Header Controls */
.header-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--color-border);
    border-radius: 50%;
    width: 36px;
    height: 36px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text);
    transition: all 0.2s;
}

.theme-toggle:hover {
    background: var(--color-bg);
    border-color: var(--color-text);
}

/* Layout Grid */
.layout-grid {
    display: grid;
    grid-template-columns: 1fr var(--sidebar-width);
    gap: 3rem;
    align-items: start;
}

/* Header */
header {
    background: var(--color-card-bg);
    border-bottom: 1px solid var(--color-border);
    padding: 1.5rem 0;
    margin-bottom: 3rem;
    box-shadow: var(--shadow-subtle);
    transition: background-color 0.3s, border-color 0.3s;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

nav ul {
    list-style: none;
    padding: 0;
    display: flex;
    gap: 2rem;
    font-family: var(--font-sans);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 600;
}

/* Main Content */
.news-feed {
    margin-bottom: 3rem;
}

.news-item {
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    padding: 2rem;
    margin-bottom: 2rem;
    border-radius: 4px;
    transition: background-color 0.3s, border-color 0.3s;
}

.news-meta {
    font-size: 0.85rem;
    color: var(--color-text-light);
    font-family: var(--font-sans);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Archive Grid (Within Main) */
.archive-list {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.archive-card {
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    padding: 2rem;
    border-radius: 4px;
    transition: transform 0.2s, box-shadow 0.2s, background-color 0.3s, border-color 0.3s;
    position: relative;
}

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

/* Badges */
.badge {
    display: inline-block;
    font-family: var(--font-sans);
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    margin-bottom: 0.5rem;
}

.badge-seminal {
    background-color: #e8f6f3;
    color: #16a085;
    border: 1px solid #a2d9ce;
}

[data-theme="dark"] .badge-seminal {
    background-color: #064e3b;
    color: #6ee7b7;
    border-color: #065f46;
}

.badge-new {
    background-color: #fef9e7;
    color: #f1c40f;
    border: 1px solid #f9e79f;
}

[data-theme="dark"] .badge-new {
    background-color: #422006;
    color: #fcd34d;
    border-color: #78350f;
}

/* Sidebar */
aside {
    position: sticky;
    top: 2rem;
}

.sidebar-widget {
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    padding: 1.5rem;
    border-radius: 4px;
    margin-bottom: 2rem;
    transition: background-color 0.3s, border-color 0.3s;
}

.sidebar-widget h3 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--color-accent);
}

/* AdSense */
.ad-container-leaderboard {
    background: var(--color-ad-bg);
    min-height: 100px;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 2rem 0;
    border: 1px dashed var(--color-ad-border);
    border-radius: 4px;
    transition: background-color 0.3s, border-color 0.3s;
}

.ad-sidebar {
    background: var(--color-ad-bg);
    min-height: 250px;
    display: flex;
    justify-content: center;
    align-items: center;
    border: 1px dashed var(--color-ad-border);
    border-radius: 4px;
    margin-bottom: 1rem;
    transition: background-color 0.3s, border-color 0.3s;
}

/* Buttons */
.btn-paypal {
    display: block;
    width: 100%;
    background-color: #0070ba;
    color: white;
    padding: 0.875rem;
    border-radius: 4px;
    font-family: var(--font-sans);
    font-weight: 700;
    text-align: center;
    text-decoration: none;
    margin-top: 1rem;
    transition: background-color 0.2s;
    border: none;
    cursor: pointer;
}

.btn-paypal:hover {
    background-color: #005ea6;
    text-decoration: none;
}

.btn-cite {
    background: transparent;
    border: 1px solid var(--color-border);
    padding: 0.5rem 1rem;
    font-family: var(--font-sans);
    font-size: 0.8rem;
    border-radius: 4px;
    cursor: pointer;
    color: var(--color-text-light);
    transition: all 0.2s;
    margin-top: 1rem;
}

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

/* Footer */
footer {
    background: var(--color-card-bg);
    border-top: 1px solid var(--color-border);
    padding: 3rem 0;
    margin-top: 5rem;
    font-size: 0.9rem;
    color: var(--color-text-light);
    text-align: center;
    transition: background-color 0.3s, border-color 0.3s;
}

.ymyl-disclaimer {
    font-size: 0.8rem;
    color: var(--color-text-light);
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--color-border);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

/* Mobile */
@media (max-width: 900px) {
    .layout-grid {
        grid-template-columns: 1fr;
    }

    .sidebar-widget {
        display: none; /* Hide sidebar on mobile or move below content */
    }

    aside {
        position: static;
    }

    nav {
        flex-direction: column;
        gap: 1rem;
    }

    nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: 1rem;
    }

    .header-controls {
        width: 100%;
        justify-content: flex-end;
    }
}