/* ==========================================================================
   Algorithmic Research Group — Startup Landing Page
   Midnight Lab · Inter · JetBrains Mono · Full-width sections
   ========================================================================== */

:root {
    --bg:            #111827;
    --surface:       #1F2937;
    --text:          #E8E6E3;
    --text-secondary:#9CA3AF;
    --accent:        #3B82F6;
    --accent-hover:  #60A5FA;
    --accent-alt:    #F97316;
    --border:        #2D3748;
    --code-bg:       #1A2332;
    --sans:          'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --mono:          'JetBrains Mono', 'Courier New', monospace;
    --content-max:   1200px;
    --content-narrow: 780px;
}

/* ---------- Reset ---------- */

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

/* ---------- Base ---------- */

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--sans);
    font-size: 17px;
    line-height: 1.7;
    color: var(--text);
    background: var(--bg);
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to   { opacity: 1; transform: translateY(0); }
}

::selection {
    background: var(--accent);
    color: #fff;
}

:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

/* ---------- Top accent line ---------- */

body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--accent);
    z-index: 1000;
}

/* ---------- Site nav ---------- */

.site-nav {
    position: sticky;
    top: 3px;
    z-index: 100;
    background: rgba(17, 24, 39, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    padding: 0 48px;
}

.site-nav .nav-inner {
    max-width: var(--content-max);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
}

.site-nav .nav-logo {
    text-decoration: none;
    display: flex;
    align-items: center;
}

.nav-logo-img {
    height: 28px;
    width: auto;
}

.site-nav .nav-links {
    display: flex;
    gap: 32px;
    list-style: none;
    font-family: var(--mono);
    font-size: 13px;
}

.site-nav .nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
    letter-spacing: 0.02em;
}

.site-nav .nav-links a:hover {
    color: var(--accent);
}

/* Hamburger toggle — hidden on desktop */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px 4px;
    z-index: 200;
}

.nav-toggle-bar {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text);
    margin: 5px 0;
    border-radius: 2px;
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.nav-toggle--open .nav-toggle-bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.nav-toggle--open .nav-toggle-bar:nth-child(2) {
    opacity: 0;
}

.nav-toggle--open .nav-toggle-bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ---------- Links (global) ---------- */

a {
    color: var(--accent);
    text-decoration: underline;
    text-decoration-color: rgba(59, 130, 246, 0.3);
    text-underline-offset: 3px;
    text-decoration-thickness: 1.5px;
    transition: color 0.2s ease, text-decoration-color 0.2s ease;
}

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

/* ---------- Section system ---------- */

.section {
    padding: 96px 48px;
}

.section--surface {
    background: var(--surface);
}

.section--bg {
    background: var(--bg);
}

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

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

/* ---------- Section labels ---------- */

.section-label {
    font-family: var(--mono);
    font-size: 13px;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--text-secondary);
    margin-bottom: 40px;
}

/* ---------- Hero ---------- */

.hero {
    padding: 120px 48px 96px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background-image: radial-gradient(circle, rgba(59, 130, 246, 0.08) 1px, transparent 1px);
    background-size: 24px 24px;
    pointer-events: none;
}

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

.hero-title {
    font-size: clamp(48px, 6vw, 80px);
    font-weight: 700;
    line-height: 1.05;
    letter-spacing: -2px;
    margin-bottom: 24px;
    background: linear-gradient(135deg, var(--text) 0%, var(--accent-hover) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-tagline {
    font-size: clamp(18px, 2vw, 22px);
    line-height: 1.6;
    color: var(--text-secondary);
    max-width: 640px;
}

/* ---------- Research grid ---------- */

.research-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.research-card {
    display: flex;
    flex-direction: column;
    padding: 28px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    text-decoration: none;
    transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.research-card:hover {
    transform: translateY(-2px);
    border-color: var(--accent);
    box-shadow: 0 4px 24px rgba(59, 130, 246, 0.12);
}

.research-card--featured {
    border-left: 3px solid var(--accent-alt);
}

.research-card-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 10px;
    line-height: 1.35;
}

.research-card:hover .research-card-title {
    color: var(--accent);
}

.research-card-summary {
    font-size: 14px;
    line-height: 1.6;
    color: var(--text-secondary);
    margin-bottom: 16px;
    flex: 1;
}

.research-card-tags {
    font-family: var(--mono);
    font-size: 11px;
    color: var(--accent);
    letter-spacing: 0.02em;
}

.research-section-footer {
    margin-top: 40px;
    text-align: center;
}

/* ---------- About ---------- */

.about-content {
    font-size: 18px;
    line-height: 1.8;
    max-width: 720px;
}

.about-content p {
    margin-bottom: 20px;
}

.about-content a {
    text-decoration-color: rgba(59, 130, 246, 0.3);
}

/* ---------- Contact ---------- */

.contact-subtitle {
    font-size: 18px;
    line-height: 1.6;
    color: var(--text-secondary);
    max-width: 560px;
    margin-bottom: 8px;
}

.calendly-embed {
    margin-top: 16px;
    border-radius: 8px;
    overflow: hidden;
}

/* ---------- Open Source hero ---------- */

.os-hero {
    background: var(--accent);
    padding: 96px 48px 72px;
}

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

.os-hero-title {
    font-size: clamp(40px, 5vw, 64px);
    font-weight: 700;
    line-height: 1.1;
    letter-spacing: -1.5px;
    color: #fff;
    margin-bottom: 24px;
}

.os-hero-desc {
    font-size: 18px;
    line-height: 1.7;
    color: rgba(255, 255, 255, 0.85);
    max-width: 720px;
    margin-bottom: 8px;
}

/* ---------- Artifact grid ---------- */

.artifact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.artifact-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 32px;
    display: flex;
    flex-direction: column;
}

.artifact-title {
    font-size: 20px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 12px;
    line-height: 1.3;
}

.artifact-desc {
    font-size: 15px;
    line-height: 1.65;
    color: var(--text-secondary);
    margin-bottom: 20px;
    flex: 1;
}

.artifact-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.artifact-links a {
    font-family: var(--mono);
    font-size: 13px;
    color: var(--accent);
    text-decoration: underline;
    text-decoration-color: rgba(59, 130, 246, 0.3);
    transition: color 0.2s ease;
}

.artifact-links a:hover {
    color: var(--accent-hover);
    text-decoration-color: var(--accent-hover);
}

/* ---------- Writing list ---------- */

.writing-list {
    list-style: none;
}

.writing-list li {
    padding: 16px 0;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: 24px;
}

.writing-list li:last-child {
    border-bottom: none;
}

.writing-list a {
    color: var(--text);
    text-decoration: none;
    font-size: 17px;
    font-weight: 500;
    transition: color 0.2s ease;
}

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

.writing-date {
    font-family: var(--mono);
    font-size: 13px;
    color: var(--text-secondary);
    white-space: nowrap;
    flex-shrink: 0;
}

.writing-section-footer {
    margin-top: 32px;
}

/* ---------- See-all link ---------- */

.see-all {
    display: inline-block;
    font-family: var(--mono);
    font-size: 14px;
    color: var(--accent);
    text-decoration: none;
    transition: color 0.2s ease;
}

.see-all:hover {
    color: var(--accent-hover);
}

/* ---------- Page header (blog, tags, categories, archives) ---------- */

.page-header {
    margin-bottom: 56px;
}

.page-title {
    font-size: 48px;
    font-weight: 700;
    line-height: 1.15;
    letter-spacing: -1px;
    margin-bottom: 12px;
    color: var(--text);
}

.page-nav {
    font-family: var(--mono);
    font-size: 14px;
}

.page-nav a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

.separator {
    margin: 0 10px;
    color: var(--border);
}

/* ---------- Blog listing ---------- */

.post-preview {
    margin-bottom: 48px;
    padding-bottom: 40px;
    border-bottom: 1px solid var(--border);
}

.post-preview:last-child {
    border-bottom: none;
}

.post-preview h2 {
    font-size: 28px;
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: 8px;
}

.post-preview h2 a {
    color: var(--text);
    text-decoration: none;
    transition: color 0.2s ease;
}

.post-preview h2 a:hover {
    color: var(--accent);
}

.post-meta {
    font-family: var(--mono);
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.post-tags a {
    color: var(--text-secondary);
    text-decoration: none;
    margin-left: 8px;
    transition: color 0.2s ease;
}

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

.post-summary {
    font-size: 16px;
    line-height: 1.65;
    color: var(--text);
    margin-bottom: 16px;
}

.post-date {
    font-family: var(--mono);
    font-size: 13px;
    color: var(--text-secondary);
    white-space: nowrap;
    flex-shrink: 0;
}

.read-more {
    font-family: var(--mono);
    font-size: 14px;
    color: var(--accent);
    text-decoration: none;
    transition: color 0.2s ease;
}

.read-more:hover {
    color: var(--accent-hover);
}

/* ---------- Post list (shared: tags, categories, archives) ---------- */

.post-list {
    list-style: none;
}

.post-list li {
    margin-bottom: 16px;
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: 16px;
}

.post-list a {
    color: var(--text);
    text-decoration: none;
    font-size: 18px;
    transition: color 0.2s ease;
}

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

/* ---------- Tags page ---------- */

.tag-group {
    margin-bottom: 40px;
}

.tag-group h2 {
    font-family: var(--mono);
    font-size: 16px;
    font-weight: 500;
    color: var(--accent);
    margin-bottom: 12px;
}

/* ---------- Categories page ---------- */

.category-group {
    margin-bottom: 40px;
}

.category-group h2 {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 12px;
}

/* ---------- Archives page ---------- */

.archive-entry {
    display: flex;
    align-items: baseline;
    gap: 20px;
    margin-bottom: 12px;
    font-size: 18px;
}

.archive-entry .post-date {
    min-width: 140px;
}

.archive-entry a {
    color: var(--text);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

/* ---------- Projects page grid ---------- */

.project-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.project-card {
    display: flex;
    flex-direction: column;
    padding: 28px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    text-decoration: none;
    transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.project-card:hover {
    transform: translateY(-2px);
    border-color: var(--accent);
    box-shadow: 0 4px 24px rgba(59, 130, 246, 0.12);
}

.project-card--featured {
    border-left: 3px solid var(--accent-alt);
}

.project-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 8px;
    line-height: 1.3;
}

.project-card:hover .project-title {
    color: var(--accent);
}

.project-desc {
    font-size: 14px;
    line-height: 1.55;
    color: var(--text-secondary);
    margin-bottom: 12px;
    flex: 1;
}

.project-meta {
    font-family: var(--mono);
    font-size: 11px;
    color: var(--accent);
    letter-spacing: 0.02em;
}

.project-card-image {
    margin: -28px -28px 16px -28px;
    border-radius: 7px 7px 0 0;
    overflow: hidden;
}

.project-card-image img {
    display: block;
    width: 100%;
    height: 160px;
    object-fit: cover;
}

/* ---------- Project detail page ---------- */

.project-hero {
    margin-bottom: 32px;
    border-radius: 6px;
    overflow: hidden;
    border: 1px solid var(--border);
}

.project-hero img {
    display: block;
    width: 100%;
    height: auto;
}

.project-links {
    display: flex;
    gap: 20px;
    margin-bottom: 16px;
}

.project-link {
    font-family: var(--mono);
    font-size: 14px;
    color: var(--accent);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

/* ---------- Article ---------- */

.full-article header {
    margin-bottom: 48px;
}

.breadcrumb {
    font-family: var(--mono);
    font-size: 13px;
    margin-bottom: 24px;
}

.breadcrumb a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

.breadcrumb .separator {
    margin: 0 6px;
    color: var(--border);
}

.article-title {
    font-size: 42px;
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.5px;
    margin-bottom: 16px;
    color: var(--text);
}

.article-meta {
    font-family: var(--mono);
    font-size: 13px;
    color: var(--text-secondary);
}

.article-content {
    font-size: 18px;
    line-height: 1.8;
}

.article-content h1 {
    font-size: 32px;
    font-weight: 700;
    margin: 48px 0 20px;
    letter-spacing: -0.3px;
}

.article-content h2 {
    font-size: 26px;
    font-weight: 600;
    margin: 40px 0 16px;
}

.article-content h3 {
    font-size: 21px;
    font-weight: 600;
    margin: 32px 0 12px;
}

.article-content p {
    margin-bottom: 20px;
}

.article-content ul, .article-content ol {
    margin: 20px 0 20px 32px;
}

.article-content li {
    margin-bottom: 8px;
}

.article-content blockquote {
    border-left: 3px solid var(--accent);
    padding-left: 24px;
    margin: 32px 0;
    font-style: italic;
    color: var(--text-secondary);
}

.article-content pre {
    background: var(--code-bg);
    padding: 20px 24px;
    border-radius: 6px;
    overflow-x: auto;
    margin: 28px 0;
    font-family: var(--mono);
    font-size: 14px;
    line-height: 1.6;
    border: 1px solid var(--border);
}

.article-content code {
    background: var(--code-bg);
    padding: 2px 6px;
    border-radius: 3px;
    font-family: var(--mono);
    font-size: 0.88em;
}

.article-content pre code {
    background: none;
    padding: 0;
    border-radius: 0;
    font-size: inherit;
}

.article-content img {
    max-width: 100%;
    height: auto;
    border-radius: 6px;
    margin: 28px 0;
}

.article-content hr {
    border: none;
    border-top: 1px solid var(--border);
    margin: 40px 0;
}

.article-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 28px 0;
    font-size: 15px;
}

.article-content th,
.article-content td {
    padding: 10px 14px;
    border: 1px solid var(--border);
    text-align: left;
}

.article-content th {
    background: var(--surface);
    font-weight: 600;
    font-size: 14px;
}

/* ---------- Article footer: prev/next ---------- */

.article-footer {
    margin-top: 56px;
    padding-top: 32px;
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    gap: 32px;
}

.article-footer .prev,
.article-footer .next {
    flex: 1;
}

.article-footer .next {
    text-align: right;
}

.article-footer .nav-label {
    font-family: var(--mono);
    font-size: 12px;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--text-secondary);
    display: block;
    margin-bottom: 4px;
}

.article-footer a {
    color: var(--text);
    text-decoration: none;
    font-size: 17px;
    transition: color 0.2s ease;
}

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

/* ---------- Inner page wrapper ---------- */

.inner-page {
    max-width: var(--content-narrow);
    margin: 0 auto;
    padding: 64px 40px 96px;
}

/* ---------- Site footer ---------- */

.site-footer {
    background: #0D1117;
    border-top: 1px solid var(--border);
}

.footer-mega {
    max-width: var(--content-max);
    margin: 0 auto;
    padding: 72px 48px 48px;
    display: grid;
    grid-template-columns: 1.2fr 2fr;
    gap: 64px;
}

.footer-brand {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.footer-logo {
    text-decoration: none;
    display: inline-block;
}

.footer-logo-img {
    height: 32px;
    width: auto;
}

.footer-tagline {
    font-size: 15px;
    line-height: 1.6;
    color: var(--text-secondary);
    max-width: 320px;
}

.footer-social {
    display: flex;
    gap: 16px;
    margin-top: 8px;
}

.footer-social a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

.footer-columns {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
}

.footer-col-title {
    font-family: var(--mono);
    font-size: 13px;
    font-weight: 600;
    color: var(--text);
    letter-spacing: 0.04em;
    margin-bottom: 16px;
}

.footer-col ul {
    list-style: none;
}

.footer-col li {
    margin-bottom: 10px;
}

.footer-col a {
    font-size: 14px;
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

.footer-bottom {
    max-width: var(--content-max);
    margin: 0 auto;
    padding: 24px 48px;
    border-top: 1px solid var(--border);
    font-family: var(--mono);
    font-size: 13px;
    color: var(--text-secondary);
}

/* ---------- Responsive: Tablet ---------- */

@media (max-width: 1024px) {
    .research-grid,
    .project-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .site-nav {
        padding: 0 24px;
    }

    .nav-toggle {
        display: block;
    }

    .nav-menu {
        position: fixed;
        top: 0;
        right: 0;
        width: 280px;
        height: 100vh;
        background: var(--surface);
        border-left: 1px solid var(--border);
        padding: 80px 32px 40px;
        transform: translateX(100%);
        transition: transform 0.3s ease;
        z-index: 150;
        overflow-y: auto;
    }

    .nav-menu--open {
        transform: translateX(0);
    }

    .site-nav .nav-links {
        flex-direction: column;
        gap: 0;
        font-size: 16px;
    }

    .site-nav .nav-links li {
        border-bottom: 1px solid var(--border);
    }

    .site-nav .nav-links a {
        display: block;
        padding: 16px 0;
        color: var(--text);
    }

    .hero {
        padding: 80px 24px 64px;
    }

    .hero-title {
        letter-spacing: -1px;
    }

    .section {
        padding: 64px 24px;
    }

    .os-hero {
        padding: 64px 24px 48px;
    }

    .artifact-grid {
        grid-template-columns: 1fr 1fr;
        gap: 16px;
    }

    .page-title {
        font-size: 36px;
    }

    .article-title {
        font-size: 32px;
    }

    .inner-page {
        padding: 48px 24px 72px;
    }

    .research-grid,
    .project-grid {
        grid-template-columns: 1fr 1fr;
        gap: 16px;
    }

    .writing-list li {
        flex-direction: column;
        gap: 4px;
    }

    .post-list li {
        flex-direction: column;
        gap: 4px;
    }

    .article-footer {
        flex-direction: column;
    }

    .article-footer .next {
        text-align: left;
    }

    .footer-mega {
        grid-template-columns: 1fr;
        gap: 40px;
        padding: 48px 24px 32px;
    }

    .footer-columns {
        grid-template-columns: repeat(3, 1fr);
        gap: 24px;
    }

    .footer-bottom {
        padding: 20px 24px;
    }
}

/* ---------- Responsive: Phone ---------- */

@media (max-width: 480px) {
    body {
        font-size: 16px;
    }

    .site-nav .nav-inner {
        height: 56px;
    }

    .site-nav .nav-links {
        gap: 14px;
    }

    .hero {
        padding: 64px 16px 48px;
    }

    .section {
        padding: 48px 16px;
    }

    .research-grid,
    .project-grid,
    .artifact-grid {
        grid-template-columns: 1fr;
    }

    .research-card,
    .project-card,
    .artifact-card {
        padding: 20px;
    }

    .os-hero {
        padding: 48px 16px 40px;
    }

    .page-title {
        font-size: 28px;
    }

    .article-title {
        font-size: 26px;
    }

    .article-content {
        font-size: 16px;
    }

    .inner-page {
        padding: 32px 16px 56px;
    }

    .archive-entry {
        flex-direction: column;
        gap: 2px;
    }

    .footer-mega {
        padding: 40px 16px 24px;
    }

    .footer-columns {
        grid-template-columns: 1fr 1fr;
        gap: 24px;
    }

    .footer-bottom {
        padding: 16px;
    }
}

/* ---------- Print ---------- */

@media print {
    .site-nav,
    .site-footer,
    .breadcrumb,
    .article-footer {
        display: none;
    }

    body {
        font-size: 12pt;
        color: #000;
        background: #fff;
    }

    body::before {
        display: none;
    }

    .inner-page {
        padding: 0;
        max-width: 100%;
    }

    a {
        color: #000;
        text-decoration: underline;
    }

    .article-content pre {
        border: 1px solid #ccc;
        page-break-inside: avoid;
    }
}