/* ==========================================================================
   mathbliss — main.css
   A well-organized notebook with some doodles in the margins
   ========================================================================== */

/* --------------------------------------------------------------------------
   Custom Properties
   -------------------------------------------------------------------------- */
:root {
    /* Colors - warm paper and ink */
    --color-bg: #faf8f4;
    --color-bg-subtle: #f4f1eb;
    --color-text: #2d2926;
    --color-text-secondary: #5c5652;
    --color-muted: #9a9490;
    --color-border: #e8e4dd;

    /* Accent - terracotta warmth */
    --color-accent: #c45d35;
    --color-accent-hover: #a84d2a;
    --color-accent-secondary: #5a7a64;

    /* Typography */
    --font-body: 'Crimson Pro', Georgia, 'Times New Roman', serif;
    --font-heading: 'Outfit', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;

    /* Scale - slightly larger for readability */
    --text-xs: 0.8125rem;
    --text-sm: 0.9375rem;
    --text-base: 1.125rem;
    --text-lg: 1.3125rem;
    --text-xl: 1.5rem;
    --text-2xl: 1.875rem;
    --text-3xl: 2.5rem;
    --text-4xl: 3.25rem;

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2.5rem;
    --space-2xl: 4rem;
    --space-3xl: 6rem;

    /* Layout */
    --max-width-content: 42rem;
    --max-width-wide: 64rem;

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

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

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

body {
    margin: 0;
    font-family: var(--font-body);
    font-size: var(--text-base);
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-bg);
    /* Subtle paper texture via noise */
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
    background-blend-mode: soft-light;
    background-size: 200px;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 600;
    line-height: 1.25;
    margin: 0;
    color: var(--color-text);
}

p {
    margin: 0;
}

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

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

/* --------------------------------------------------------------------------
   Site Header
   -------------------------------------------------------------------------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: var(--max-width-wide);
    margin: 0 auto;
    padding: var(--space-md) var(--space-lg);
}

.wordmark {
    font-family: var(--font-heading);
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--color-text);
    letter-spacing: -0.02em;
    text-decoration: none;
    position: relative;
}

.wordmark::after {
    content: '';
    position: absolute;
    bottom: 2px;
    left: 0;
    width: 100%;
    height: 3px;
    background: var(--color-accent);
    border-radius: 2px;
    transform: scaleX(0);
    transform-origin: right;
    transition: transform var(--transition-base);
}

.wordmark:hover {
    color: var(--color-text);
}

.wordmark:hover::after {
    transform: scaleX(1);
    transform-origin: left;
}

.main-nav {
    display: flex;
    gap: var(--space-lg);
}

.main-nav a {
    font-family: var(--font-heading);
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.04em;
    padding: var(--space-xs) 0;
    position: relative;
}

.main-nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--color-accent);
    transform: scaleX(0);
    transition: transform var(--transition-fast);
}

.main-nav a:hover {
    color: var(--color-text);
}

.main-nav a:hover::after {
    transform: scaleX(1);
}

/* Mobile nav toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 32px;
    height: 32px;
    padding: 4px;
    background: none;
    border: none;
    cursor: pointer;
}

.nav-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--color-text);
    border-radius: 1px;
    transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.nav-toggle.is-active span:first-child {
    transform: translateY(3.5px) rotate(45deg);
}

.nav-toggle.is-active span:last-child {
    transform: translateY(-3.5px) rotate(-45deg);
}

@media (max-width: 640px) {
    .nav-toggle {
        display: flex;
    }

    .main-nav {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        gap: 0;
        background: var(--color-bg);
        border-bottom: 1px solid var(--color-border);
        padding: 0 var(--space-lg);
        max-height: 0;
        overflow: hidden;
        transition: max-height var(--transition-base), padding var(--transition-base);
    }

    .main-nav.is-open {
        max-height: 200px;
        padding: var(--space-md) var(--space-lg);
    }

    .main-nav a {
        padding: var(--space-sm) 0;
    }
}

/* --------------------------------------------------------------------------
   Main Content
   -------------------------------------------------------------------------- */
.main-content {
    min-height: calc(100vh - 200px);
}

/* --------------------------------------------------------------------------
   Hero Section
   -------------------------------------------------------------------------- */
.hero {
    position: relative;
    max-width: var(--max-width-wide);
    margin: 0 auto;
    padding: var(--space-3xl) var(--space-lg);
    overflow: hidden;
}

.hero-inner {
    max-width: var(--max-width-content);
}

.hero-title {
    font-size: var(--text-3xl);
    font-weight: 700;
    margin-bottom: var(--space-lg);
    letter-spacing: -0.02em;
}

.hero-accent {
    color: var(--color-accent);
    position: relative;
}

.hero-subtitle {
    font-size: var(--text-lg);
    color: var(--color-text-secondary);
    max-width: 32rem;
    line-height: 1.6;
}

.hero-doodle {
    position: absolute;
    top: var(--space-2xl);
    right: var(--space-lg);
    width: 180px;
    height: 180px;
    opacity: 0.7;
    pointer-events: none;
}

@media (max-width: 900px) {
    .hero-doodle {
        display: none;
    }
}

@media (min-width: 768px) {
    .hero {
        padding: var(--space-3xl) var(--space-2xl);
    }

    .hero-title {
        font-size: var(--text-4xl);
    }
}

/* --------------------------------------------------------------------------
   Posts List
   -------------------------------------------------------------------------- */
.posts-section {
    max-width: var(--max-width-wide);
    margin: 0 auto;
    padding: 0 var(--space-lg) var(--space-3xl);
}

.section-title {
    font-size: var(--text-sm);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--color-muted);
    margin-bottom: var(--space-xl);
    padding-bottom: var(--space-sm);
    border-bottom: 1px solid var(--color-border);
}

.posts-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: grid;
    gap: var(--space-lg);
}

.post-item {
    margin: 0;
}

.post-link {
    display: block;
    text-decoration: none;
}

.post-card {
    padding: var(--space-lg);
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    transition: transform var(--transition-base), box-shadow var(--transition-base), border-color var(--transition-base);
}

.post-link:hover .post-card {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(45, 41, 38, 0.08);
    border-color: var(--color-accent);
}

.post-date {
    display: block;
    font-family: var(--font-heading);
    font-size: var(--text-xs);
    font-weight: 500;
    color: var(--color-muted);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: var(--space-sm);
}

.post-title {
    font-size: var(--text-xl);
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--space-sm);
    transition: color var(--transition-fast);
}

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

.post-excerpt {
    font-size: var(--text-base);
    color: var(--color-text-secondary);
    line-height: 1.6;
    margin-bottom: var(--space-md);
}

.post-read-more {
    font-family: var(--font-heading);
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-accent);
}

@media (min-width: 768px) {
    .posts-section {
        padding: 0 var(--space-2xl) var(--space-3xl);
    }

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

.posts-list--single {
    grid-template-columns: 1fr;
    max-width: var(--max-width-content);
}

/* --------------------------------------------------------------------------
   Category Page
   -------------------------------------------------------------------------- */
.category-header {
    max-width: var(--max-width-wide);
    margin: 0 auto;
    padding: var(--space-2xl) var(--space-lg) var(--space-xl);
}

.category-header-inner {
    max-width: var(--max-width-content);
}

.category-title {
    font-size: var(--text-3xl);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: var(--space-md);
}

.category-description {
    font-size: var(--text-lg);
    color: var(--color-text-secondary);
    line-height: 1.6;
}

.post-unit {
    display: inline-block;
    font-family: var(--font-heading);
    font-size: var(--text-xs);
    font-weight: 600;
    color: var(--color-accent);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    background: rgba(196, 93, 53, 0.1);
    padding: 0.25em 0.6em;
    border-radius: 4px;
    margin-bottom: var(--space-sm);
}

@media (min-width: 768px) {
    .category-header {
        padding: var(--space-3xl) var(--space-2xl) var(--space-xl);
    }

    .category-title {
        font-size: var(--text-4xl);
    }
}

/* --------------------------------------------------------------------------
   Article
   -------------------------------------------------------------------------- */
.article {
    max-width: var(--max-width-content);
    margin: 0 auto;
    padding: var(--space-2xl) var(--space-lg) var(--space-3xl);
}

.article-header {
    margin-bottom: var(--space-2xl);
    padding-bottom: var(--space-xl);
    border-bottom: 1px solid var(--color-border);
}

.article-date {
    display: block;
    font-family: var(--font-heading);
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-muted);
    text-transform: uppercase;
    letter-spacing: 0.04em;
    margin-bottom: var(--space-md);
}

.article-title {
    font-size: var(--text-3xl);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: var(--space-md);
}

.article-description {
    font-size: var(--text-lg);
    color: var(--color-text-secondary);
    font-style: italic;
}

.article-footer {
    margin-top: var(--space-2xl);
    padding-top: var(--space-xl);
    border-top: 1px solid var(--color-border);
}

.back-link {
    font-family: var(--font-heading);
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
}

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

.page-article .article-header {
    text-align: center;
    border-bottom: none;
    padding-bottom: var(--space-lg);
}

/* --------------------------------------------------------------------------
   Prose — Article Content Styling
   -------------------------------------------------------------------------- */
.prose {
    font-size: var(--text-base);
    line-height: 1.75;
}

.prose > * + * {
    margin-top: var(--space-lg);
}

.prose h2 {
    font-size: var(--text-2xl);
    margin-top: var(--space-2xl);
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-sm);
    border-bottom: 2px solid var(--color-border);
}

.prose h3 {
    font-size: var(--text-xl);
    margin-top: var(--space-xl);
    margin-bottom: var(--space-sm);
    color: var(--color-text);
}

.prose h4 {
    font-size: var(--text-lg);
    margin-top: var(--space-lg);
    margin-bottom: var(--space-sm);
}

.prose p {
    margin-top: var(--space-md);
}

.prose strong {
    font-weight: 600;
    color: var(--color-text);
}

.prose em {
    font-style: italic;
}

/* Links in prose */
.prose a {
    color: var(--color-accent);
    text-decoration: underline;
    text-decoration-thickness: 1px;
    text-underline-offset: 2px;
    transition: text-decoration-color var(--transition-fast);
}

.prose a:hover {
    text-decoration-color: transparent;
}

/* Lists */
.prose ul,
.prose ol {
    padding-left: var(--space-lg);
    margin-top: var(--space-md);
}

.prose li {
    margin-top: var(--space-sm);
    padding-left: var(--space-sm);
}

.prose li::marker {
    color: var(--color-accent);
}

.prose ol {
    list-style-type: decimal;
}

.prose ul {
    list-style-type: disc;
}

/* Blockquotes — margin note feel */
.prose blockquote {
    position: relative;
    margin: var(--space-xl) 0;
    padding: var(--space-lg) var(--space-xl);
    background: var(--color-bg-subtle);
    border-left: 4px solid var(--color-accent);
    border-radius: 0 8px 8px 0;
    font-style: italic;
}

.prose blockquote p {
    margin: 0;
    color: var(--color-text-secondary);
}

.prose blockquote p + p {
    margin-top: var(--space-md);
}

/* Code — inline */
.prose code {
    font-family: var(--font-mono);
    font-size: 0.9em;
    padding: 0.15em 0.4em;
    background: var(--color-bg-subtle);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    color: var(--color-accent-hover);
}

/* Code — blocks */
.prose pre {
    margin: var(--space-xl) 0;
    padding: var(--space-lg);
    background: #2d2926;
    border-radius: 8px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.prose pre code {
    font-size: var(--text-sm);
    padding: 0;
    background: none;
    border: none;
    border-radius: 0;
    color: #f4f1eb;
    line-height: 1.6;
}

/* Horizontal rule */
.prose hr {
    border: none;
    height: 1px;
    background: var(--color-border);
    margin: var(--space-2xl) 0;
}

/* Images */
.prose img {
    margin: var(--space-xl) auto;
    border-radius: 8px;
    box-shadow: 0 4px 16px rgba(45, 41, 38, 0.1);
}

/* Tables */
.prose table {
    width: 100%;
    margin: var(--space-xl) 0;
    border-collapse: collapse;
    font-size: var(--text-sm);
}

.prose th,
.prose td {
    padding: var(--space-sm) var(--space-md);
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}

.prose th {
    font-family: var(--font-heading);
    font-weight: 600;
    background: var(--color-bg-subtle);
}

.prose tr:hover td {
    background: var(--color-bg-subtle);
}

/* --------------------------------------------------------------------------
   Site Footer
   -------------------------------------------------------------------------- */
.site-footer {
    background: var(--color-bg-subtle);
    border-top: 1px solid var(--color-border);
    padding: var(--space-2xl) var(--space-lg);
    text-align: center;
}

.footer-inner {
    max-width: var(--max-width-content);
    margin: 0 auto;
}

.footer-doodle {
    width: 120px;
    margin: 0 auto var(--space-lg);
    color: var(--color-muted);
}

.footer-tagline {
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--space-sm);
}

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

.footer-meta a {
    color: var(--color-text-secondary);
    text-decoration: underline;
    text-underline-offset: 2px;
}

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

/* --------------------------------------------------------------------------
   Utilities
   -------------------------------------------------------------------------- */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Selection */
::selection {
    background: var(--color-accent);
    color: white;
}

/* Focus states */
:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Smooth scroll */
@media (prefers-reduced-motion: no-preference) {
    html {
        scroll-behavior: smooth;
    }
}

/* Print styles */
@media print {
    .site-header,
    .site-footer,
    .nav-toggle,
    .hero-doodle,
    .footer-doodle {
        display: none;
    }

    .article {
        max-width: none;
        padding: 0;
    }

    .prose a {
        color: var(--color-text);
    }

    .prose a::after {
        content: " (" attr(href) ")";
        font-size: var(--text-sm);
        color: var(--color-muted);
    }
}