:root {
    /* Base colors - Light Mode */
    --bg-color: #f6f8fa;
    --surface-color: #ffffff;
    --text-primary: #111827;
    --text-secondary: #4b5563;
    --border-color: #e5e7eb;
    --accent-color: #3b82f6;
    --accent-hover: #2563eb;
    --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
    --card-hover-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -2px rgba(0, 0, 0, 0.04);
    --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    /* Dark Mode */
    --bg-color: #0d1117;
    --surface-color: #161b22;
    --text-primary: #f0f6fc;
    --text-secondary: #8b949e;
    --border-color: #30363d;
    --accent-color: #58a6ff;
    --accent-hover: #79c0ff;
    --card-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -1px rgba(0, 0, 0, 0.15);
    --card-hover-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.2);
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 60px 24px;
    width: 100%;
}

/* Header & Controls */
header {
    margin-bottom: 60px;
    animation: fadeInDown 0.6s ease-out forwards;
}

.controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 50px;
}

.lang-selector {
    display: flex;
    background: var(--surface-color);
    border-radius: 24px;
    padding: 4px;
    box-shadow: var(--card-shadow);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.lang-btn {
    background: none;
    border: none;
    padding: 8px 16px;
    border-radius: 20px;
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
    letter-spacing: 0.5px;
}

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

.lang-btn.active {
    background: var(--accent-color);
    color: #ffffff;
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.3);
}

.theme-toggle {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    width: 44px;
    height: 44px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: var(--card-shadow);
    transition: var(--transition);
}

.theme-toggle:hover {
    color: var(--accent-color);
    transform: translateY(-2px);
    box-shadow: var(--card-hover-shadow);
}

/* Typography */
h1 {
    font-size: 2.8rem;
    font-weight: 700;
    letter-spacing: -0.03em;
    margin-bottom: 20px;
    color: var(--text-primary);
    line-height: 1.2;
}

.subtitle {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 650px;
    font-weight: 400;
}

h2 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 24px;
    text-transform: uppercase;
    letter-spacing: 1.5px;
}

/* Sections */
section {
    margin-bottom: 60px;
    animation: fadeInUp 0.6s ease-out forwards;
    opacity: 0;
}

.links-section { animation-delay: 0.1s; }
.articles-section { animation-delay: 0.2s; }

/* Link Cards */
.social-links {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 16px;
}

.link-card {
    display: flex;
    align-items: center;
    padding: 16px 20px;
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    box-shadow: var(--card-shadow);
    transition: var(--transition);
}

.link-card .icon {
    font-size: 1.25rem;
    margin-right: 14px;
    display: inline-flex;
}

.link-card:not(.disabled):hover {
    transform: translateY(-3px);
    box-shadow: var(--card-hover-shadow);
    border-color: var(--accent-hover);
    color: var(--accent-color);
}

.link-card.disabled {
    opacity: 0.5;
    cursor: not-allowed;
    background: var(--bg-color);
}

/* Article Cards */
.article-card {
    background: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 28px;
    margin-bottom: 24px;
    box-shadow: var(--card-shadow);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.article-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background-color: var(--accent-color);
    opacity: 0;
    transition: var(--transition);
}

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

.article-card:hover::before {
    opacity: 1;
}

.article-link {
    color: var(--text-primary);
    text-decoration: none;
    font-size: 1.3rem;
    font-weight: 600;
    display: inline-block;
    margin-bottom: 12px;
    transition: color 0.2s;
}

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

.article-desc {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.5;
}

/* Footer */
footer {
    text-align: center;
    margin-top: auto;
    padding-top: 60px;
    padding-bottom: 20px;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 600px) {
    h1 { font-size: 2.2rem; }
    .controls { 
        flex-direction: column; 
        gap: 24px; 
    }
    .lang-selector {
        width: 100%;
        justify-content: space-between;
    }
    .lang-btn {
        flex: 1;
        text-align: center;
        padding: 10px 0;
    }
    .theme-toggle { 
        align-self: flex-end; 
        margin-top: -68px; 
    }
    .container {
        padding: 40px 20px;
    }
}