/* ===== CSS Variables & Theme ===== */
:root {
    /* Color Palette - Cool, crisp with indigo accents */
    --bg-primary: #FDFDFE;
    --bg-secondary: #F4F4F8;
    --bg-tertiary: #EAEAF0;

    --text-primary: #12121A;
    --text-secondary: #4E4E5E;
    --text-muted: #85859A;

    --accent: #4338CA;
    --accent-secondary: #0D9488;
    --accent-tertiary: #6366F1;

    --border-color: #DDDDE6;
    --border-light: #EEEEF4;

    /* Typography Scale */
    --font-display: 'Newsreader', Georgia, serif;
    --font-body: 'Inter', -apple-system, sans-serif;
    --font-mono: 'IBM Plex Mono', 'SF Mono', monospace;

    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 2rem;
    --text-4xl: 2.75rem;
    --text-5xl: 3.5rem;

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    --space-4xl: 6rem;

    /* Layout */
    --max-width: 1200px;
    --content-width: 720px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;
}

/* Dark mode */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #0B0B0F;
        --bg-secondary: #131318;
        --bg-tertiary: #1E1E28;

        --text-primary: #E8E8F0;
        --text-secondary: #A0A0B8;
        --text-muted: #5C5C74;

        --accent: #818CF8;
        --accent-secondary: #2DD4BF;
        --accent-tertiary: #A5B4FC;

        --border-color: #24242E;
        --border-light: #1A1A22;
    }
}

/* ===== Reset & Base ===== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-body);
    font-size: var(--text-base);
    font-weight: 400;
    line-height: 1.7;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    min-height: 100vh;
    position: relative;
}

/* Grain overlay (disabled) */
.grain-overlay {
    display: none;
}

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

img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* ===== Header & Navigation ===== */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-light);
    backdrop-filter: blur(12px);
    background: rgba(253, 253, 254, 0.85);
}

@media (prefers-color-scheme: dark) {
    .site-header {
        background: rgba(11, 11, 15, 0.85);
    }
}

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

.logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-family: var(--font-display);
    font-size: var(--text-xl);
    font-weight: 500;
    letter-spacing: -0.02em;
    transition: opacity var(--transition-fast);
}

.logo:hover {
    opacity: 0.7;
}

.logo-symbol {
    font-size: var(--text-2xl);
    color: var(--accent);
    font-weight: 400;
}

.nav-links {
    display: flex;
    gap: var(--space-xl);
}

.nav-link {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--text-secondary);
    letter-spacing: 0.02em;
    text-transform: uppercase;
    position: relative;
    padding: var(--space-xs) 0;
    transition: color var(--transition-fast);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--accent);
    transition: width var(--transition-base);
}

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

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

/* ===== Main Content ===== */
.main-content {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--space-3xl) var(--space-xl);
}

/* ===== Hero Section ===== */
.hero {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: var(--space-3xl);
    align-items: center;
    padding-bottom: var(--space-4xl);
    border-bottom: 1px solid var(--border-light);
    margin-bottom: var(--space-4xl);
}

.hero-tagline {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--accent);
    margin-bottom: var(--space-sm);
    animation: fadeInUp 0.6s ease forwards;
    opacity: 0;
}

.hero-title {
    font-family: var(--font-display);
    font-size: var(--text-5xl);
    font-weight: 500;
    line-height: 1.1;
    letter-spacing: -0.03em;
    margin-bottom: var(--space-lg);
    animation: fadeInUp 0.6s ease 0.1s forwards;
    opacity: 0;
}

.hero-accent {
    font-style: italic;
    font-weight: 400;
    color: var(--accent);
}

.hero-description {
    font-size: var(--text-lg);
    color: var(--text-secondary);
    max-width: 480px;
    line-height: 1.8;
    animation: fadeInUp 0.6s ease 0.2s forwards;
    opacity: 0;
}

.hero-decoration {
    width: 200px;
    height: 200px;
    animation: fadeIn 1s ease 0.4s forwards, rotate 60s linear infinite;
    opacity: 0;
}

.hero-svg {
    width: 100%;
    height: 100%;
}

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

@keyframes fadeIn {
    to {
        opacity: 1;
    }
}

@keyframes rotate {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

/* ===== Section Headers ===== */
.section-header {
    display: flex;
    align-items: center;
    gap: var(--space-lg);
    margin-bottom: var(--space-2xl);
}

.section-title {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--text-muted);
    white-space: nowrap;
}

.section-line {
    flex: 1;
    height: 1px;
    background: var(--border-color);
}

/* ===== Posts Section ===== */
.posts-section {
    margin-bottom: var(--space-4xl);
}

.post-card {
    padding: var(--space-xl) 0;
    border-bottom: 1px solid var(--border-light);
    transition: transform var(--transition-base);
}

.post-card.featured {
    padding: var(--space-2xl);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    margin-bottom: var(--space-xl);
}

.post-card:hover {
    transform: translateX(4px);
}

.post-card.featured:hover {
    transform: translateY(-2px);
}

.post-meta {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    margin-bottom: var(--space-sm);
}

.post-date {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    color: var(--text-muted);
    letter-spacing: 0.05em;
}

.post-category {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.post-title {
    font-family: var(--font-display);
    font-size: var(--text-2xl);
    font-weight: 500;
    line-height: 1.3;
    margin-bottom: var(--space-sm);
}

.post-title a {
    transition: color var(--transition-fast);
}

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

.post-card.featured .post-title {
    font-size: var(--text-3xl);
}

.post-excerpt {
    font-size: var(--text-base);
    color: var(--text-secondary);
    line-height: 1.7;
    max-width: 640px;
}

.post-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-sm);
    margin-top: var(--space-md);
}

.tag {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    color: var(--text-muted);
    padding: var(--space-xs) var(--space-sm);
    background: var(--bg-tertiary);
    border-radius: 2px;
    letter-spacing: 0.02em;
}

.posts-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0 var(--space-2xl);
}

.view-all {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    margin-top: var(--space-xl);
    font-family: var(--font-mono);
    font-size: var(--text-sm);
    color: var(--accent);
    transition: gap var(--transition-fast);
}

.view-all:hover {
    gap: var(--space-md);
}

/* ===== Topics Section ===== */
.topics-section {
    margin-bottom: var(--space-4xl);
}

.topics-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-md);
}

.topic-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--space-xl);
    background: var(--bg-secondary);
    border: 1px solid var(--border-light);
    border-radius: 4px;
    text-align: center;
    transition: all var(--transition-base);
}

.topic-card:hover {
    border-color: var(--accent);
    transform: translateY(-2px);
}

.topic-icon {
    font-size: var(--text-2xl);
    margin-bottom: var(--space-sm);
    color: var(--accent);
}

.topic-name {
    font-family: var(--font-display);
    font-size: var(--text-lg);
    font-weight: 500;
    margin-bottom: var(--space-xs);
}

.topic-count {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    color: var(--text-muted);
}

/* ===== Footer ===== */
.site-footer {
    border-top: 1px solid var(--border-color);
    margin-top: var(--space-4xl);
}

.footer-content {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--space-2xl) var(--space-xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-copyright {
    font-family: var(--font-mono);
    font-size: var(--text-sm);
    color: var(--text-muted);
}

.footer-note {
    font-size: var(--text-sm);
    color: var(--text-muted);
    font-style: italic;
    margin-top: var(--space-xs);
}

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

.footer-link {
    font-family: var(--font-mono);
    font-size: var(--text-sm);
    color: var(--text-secondary);
    transition: color var(--transition-fast);
}

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

/* ===== Responsive Design ===== */
@media (max-width: 900px) {
    .hero {
        grid-template-columns: 1fr;
    }

    .hero-decoration {
        display: none;
    }

    .posts-grid {
        grid-template-columns: 1fr;
    }

    .topics-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 600px) {
    :root {
        --text-5xl: 2.5rem;
        --text-4xl: 2rem;
        --text-3xl: 1.75rem;
    }

    .nav-container {
        padding: var(--space-md);
    }

    .nav-links {
        gap: var(--space-md);
    }

    .main-content {
        padding: var(--space-xl) var(--space-md);
    }

    .post-card.featured {
        padding: var(--space-lg);
    }

    .topics-grid {
        grid-template-columns: 1fr;
    }

    .footer-content {
        flex-direction: column;
        gap: var(--space-lg);
        text-align: center;
    }
}