/* ==========================================================================
   nandan.dev — 2026 redesign
   Plain CSS, no build step. Custom properties drive light/dark theming.
   ========================================================================== */

:root {
  --bg: #faf8f5;
  --bg-alt: #f1ede7;
  --surface: #ffffff;
  --text: #1a1a1a;
  --text-muted: #5b5b5b;
  --border: #e4ded4;
  --accent: #e8720c;
  --accent-ink: #ffffff;
  --accent-soft: #fdece0;
  --shadow: 0 1px 2px rgba(20, 15, 5, 0.04), 0 8px 24px rgba(20, 15, 5, 0.06);
  --radius-sm: 8px;
  --radius: 14px;
  --radius-lg: 22px;
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono: "Space Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --container: 1120px;
}

:root[data-theme="dark"] {
  --bg: #121212;
  --bg-alt: #181818;
  --surface: #1b1b1b;
  --text: #f2efe9;
  --text-muted: #a8a29a;
  --border: #2d2b27;
  --accent: #ff9d3d;
  --accent-ink: #171008;
  --accent-soft: #2a1c0e;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 12px 28px rgba(0, 0, 0, 0.35);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #121212;
    --bg-alt: #181818;
    --surface: #1b1b1b;
    --text: #f2efe9;
    --text-muted: #a8a29a;
    --border: #2d2b27;
    --accent: #ff9d3d;
    --accent-ink: #171008;
    --accent-soft: #2a1c0e;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 12px 28px rgba(0, 0, 0, 0.35);
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; overflow-x: hidden; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  transition: background 0.25s ease, color 0.25s ease;
  overflow-x: hidden;
  max-width: 100%;
}

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

#skip-to-content {
  position: absolute;
  top: -100px;
  left: 12px;
  background: var(--accent);
  color: var(--accent-ink);
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 14px;
  z-index: 200;
  transition: top 0.2s ease;
}
#skip-to-content:focus { top: 12px; }

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

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.kicker {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 14px;
}

h1, h2, h3, h4 { font-weight: 700; line-height: 1.2; margin: 0 0 16px; }
h1 { font-size: clamp(2.2rem, 5vw, 3.4rem); letter-spacing: -0.02em; }
h2 { font-size: clamp(1.6rem, 3vw, 2.2rem); letter-spacing: -0.01em; }
h3 { font-size: 1.15rem; }
p { margin: 0 0 16px; color: var(--text-muted); }

section { padding: 88px 0; }
section + section { border-top: 1px solid var(--border); }
section.bg-alt { background: var(--bg-alt); }

.section-head { max-width: 640px; margin: 0 auto 56px; text-align: center; }
.section-head p { margin: 0; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 14.5px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease, border-color 0.15s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: var(--accent); color: var(--accent-ink); }
.btn-primary:hover { box-shadow: var(--shadow); }
.btn-ghost { background: transparent; color: var(--text); border-color: var(--border); }
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

/* ---------- Announcement bar ---------- */
.announce-bar {
  background: var(--accent);
  color: var(--accent-ink);
}
.announce-bar .container {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  padding: 10px 44px 10px 24px;
  position: relative;
  min-height: 40px;
}
.announce-bar p {
  margin: 0;
  color: var(--accent-ink);
  font-size: 14px;
  font-weight: 500;
  text-align: center;
}
.announce-bar a {
  color: var(--accent-ink);
  font-weight: 700;
  text-decoration: underline;
  text-decoration-color: color-mix(in srgb, var(--accent-ink) 50%, transparent);
  text-underline-offset: 2px;
  white-space: nowrap;
}
.announce-bar a:hover { text-decoration-color: var(--accent-ink); }
.announce-close {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  width: 26px;
  height: 26px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  color: var(--accent-ink);
  font-size: 20px;
  line-height: 1;
  cursor: pointer;
  opacity: 0.75;
  border-radius: 999px;
}
.announce-close:hover { opacity: 1; background: color-mix(in srgb, var(--accent-ink) 15%, transparent); }
.announce-bar.hidden { display: none; }
@media (max-width: 640px) {
  .announce-bar p { font-size: 13px; }
  .announce-bar .container { padding: 10px 40px 10px 16px; text-align: center; }
}

/* ---------- Nav ---------- */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}
.site-nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 66px;
}
.brand {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 17px;
  letter-spacing: -0.02em;
}
.brand span { color: var(--accent); }
.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 14.5px;
  font-weight: 500;
}
.nav-links a { padding: 8px 0; color: var(--text-muted); }
.nav-links a:hover, .nav-links .active > a { color: var(--text); }
.nav-item { position: relative; }
.nav-item > a { display: inline-flex; align-items: center; gap: 4px; }
.nav-item > a i { font-size: 10px; }
.nav-dropdown {
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 210px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow);
  padding: 8px;
  list-style: none;
  margin: 8px 0 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(4px);
  transition: opacity 0.15s ease, transform 0.15s ease, visibility 0.15s;
}
.nav-item:hover .nav-dropdown,
.nav-item:focus-within .nav-dropdown { opacity: 1; visibility: visible; transform: translateY(0); }
.nav-dropdown li a { display: block; padding: 8px 10px; border-radius: 6px; font-size: 14px; }
.nav-dropdown li a:hover { background: var(--bg-alt); color: var(--text); }
.nav-dropdown .sep { height: 1px; background: var(--border); margin: 6px 4px; }
.nav-right { display: flex; align-items: center; gap: 10px; }
.theme-toggle, .nav-burger {
  width: 38px; height: 38px;
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: 999px; border: 1px solid var(--border);
  background: var(--surface); color: var(--text);
  cursor: pointer; font-size: 15px;
}
.theme-toggle:hover, .nav-burger:hover { border-color: var(--accent); color: var(--accent); }
.icon-sun2, .theme-toggle .icon-moon2 { display: none; }
:root[data-theme="dark"] .theme-toggle .icon-sun2 { display: inline; }
:root[data-theme="dark"] .theme-toggle .icon-moon2 { display: none; }
.theme-toggle .icon-sun2 { display: none; }
.theme-toggle .icon-moon2 { display: inline; }

.nav-burger { display: none; flex-direction: column; gap: 5px; padding: 0; }
.nav-burger .bar {
  width: 17px; height: 2px; border-radius: 2px;
  background: var(--text);
  transition: transform 0.28s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.2s ease, background 0.2s ease;
}
.nav-burger:hover .bar { background: var(--accent); }
.nav-burger.open .bar:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-burger.open .bar:nth-child(2) { opacity: 0; transform: scaleX(0); }
.nav-burger.open .bar:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

html.nav-open { overflow: hidden; }

@media (max-width: 900px) {
  .nav-links {
    position: fixed;
    inset: 66px 0 0 0;
    background: var(--bg);
    flex-direction: column;
    align-items: stretch;
    padding: 14px 20px 40px;
    gap: 2px;
    overflow-y: auto;
    transform: translateY(-8px);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
  }
  .nav-links.open { opacity: 1; visibility: visible; transform: translateY(0); }

  .nav-links > li > a {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    padding: 15px 12px;
    border-radius: var(--radius-sm);
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text);
  }
  .nav-links > li > a:active { background: var(--bg-alt); }

  .nav-item { border-radius: var(--radius-sm); }
  .nav-item:first-of-type { border-top: 1px solid var(--border); margin-top: 10px; padding-top: 8px; }
  .nav-item.open > a { background: var(--bg-alt); }
  .nav-item > a i { font-size: 12px; color: var(--text-muted); transition: transform 0.2s ease; }
  .nav-item.open > a i { transform: rotate(180deg); }

  .nav-dropdown {
    position: static;
    opacity: 1; visibility: visible; transform: none; box-shadow: none;
    display: none;
    background: var(--bg-alt);
    border: none;
    border-radius: var(--radius-sm);
    padding: 6px;
    margin: 2px 0 10px;
  }
  .nav-item.open .nav-dropdown { display: block; }
  .nav-dropdown li a {
    padding: 11px 14px;
    border-radius: 8px;
    font-size: 14.5px;
    font-weight: 500;
  }
  .nav-dropdown li a:active { background: var(--surface); color: var(--text); }
  .nav-dropdown .sep { margin: 6px 10px; }

  .nav-burger { display: inline-flex; }
}

/* ---------- Hero ---------- */
.hero { padding: 96px 0 80px; border-top: none; }
.hero .container { display: flex; align-items: center; gap: 56px; }
.hero-copy { flex: 1.2; }
.hero-avatar {
  flex: 1;
  display: flex;
  justify-content: center;
}
.hero-avatar img {
  width: 260px; height: 260px;
  border-radius: 50%;
  object-fit: cover;
  border: 6px solid var(--surface);
  box-shadow: var(--shadow);
}
.hero h1 { margin-bottom: 10px; }
.hero .role { font-size: 1.15rem; color: var(--text-muted); margin-bottom: 20px; font-weight: 500; }
.hero .role a { color: var(--accent); font-weight: 600; text-decoration: underline; text-decoration-color: color-mix(in srgb, var(--accent) 40%, transparent); text-underline-offset: 3px; }
.hero .role a:hover { text-decoration-color: var(--accent); }
.hero .lede { max-width: 540px; font-size: 1.02rem; }
.hero .opportunity { max-width: 540px; font-size: 0.92rem; color: var(--text-muted); font-style: italic; margin: 0; }
.hero .opportunity a { color: var(--accent); font-weight: 600; text-decoration: underline; text-decoration-color: color-mix(in srgb, var(--accent) 40%, transparent); text-underline-offset: 3px; }
.hero .opportunity a:hover { text-decoration-color: var(--accent); }
.hero-cta { display: flex; flex-wrap: wrap; gap: 12px; margin: 26px 0; }
.social-row { display: flex; gap: 10px; list-style: none; padding: 0; margin: 0; }
.social-row a {
  width: 38px; height: 38px;
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: 999px; border: 1px solid var(--border);
  color: var(--text-muted);
}
.social-row a:hover { color: var(--accent); border-color: var(--accent); }

@media (max-width: 760px) {
  .hero .container { flex-direction: column-reverse; text-align: center; }
  .hero-avatar img { width: 180px; height: 180px; }
  .hero .lede { margin: 0 auto 16px; }
  .hero .opportunity { margin: 0 auto; }
  .hero-cta, .social-row { justify-content: center; }
}

/* ---------- About ---------- */
.about-grid { display: grid; grid-template-columns: 260px 1fr; gap: 48px; }
.about-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  height: fit-content;
}
.about-card dl { margin: 0; }
.about-card dt { font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--text-muted); margin-top: 16px; }
.about-card dt:first-child { margin-top: 0; }
.about-card dd { margin: 4px 0 0; font-weight: 600; }
.about-card dd a { color: var(--text); border-bottom: 1px solid var(--border); }
.about-card dd a:hover { color: var(--accent); border-color: var(--accent); }
.about-body p:last-of-type { margin-bottom: 22px; }
@media (max-width: 760px) { .about-grid { grid-template-columns: 1fr; } }

/* ---------- Experience ---------- */
.timeline { position: relative; max-width: 760px; margin: 0 auto; padding-left: 28px; border-left: 2px solid var(--border); }
.timeline-group-label {
  font-family: var(--font-mono);
  font-size: 12px; letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--accent); margin: 44px 0 20px -28px; padding-left: 28px;
}
.timeline-group-label:first-child { margin-top: 0; }
.tl-item { position: relative; padding-bottom: 32px; }
.tl-item:last-child { padding-bottom: 0; }
.tl-item::before {
  content: "";
  position: absolute; left: -34px; top: 4px;
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 4px var(--bg);
}
.tl-item h3 { margin-bottom: 2px; }
.tl-item .company { display: block; font-size: 14px; color: var(--text-muted); margin-bottom: 10px; }
.tl-item .company a { border-bottom: 1px solid var(--border); }
.tl-item .company a:hover { color: var(--accent); border-color: var(--accent); }
.tl-item p { margin: 0; font-size: 15px; }

/* ---------- Skills ---------- */
.skill-groups { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; max-width: 900px; margin: 0 auto; }
.skill-group h3 { font-size: 13px; text-transform: uppercase; letter-spacing: 0.08em; color: var(--text-muted); font-family: var(--font-mono); margin-bottom: 14px; }
.pill-row { display: flex; flex-wrap: wrap; gap: 8px; }
.pill {
  font-size: 13.5px; font-weight: 500;
  padding: 7px 14px; border-radius: 999px;
  background: var(--surface); border: 1px solid var(--border);
}
@media (max-width: 760px) { .skill-groups { grid-template-columns: 1fr; gap: 26px; } }

/* ---------- Press ---------- */
.press-strip { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; max-width: 880px; margin: 0 auto; }
.press-strip a {
  padding: 10px 18px; border: 1px solid var(--border); border-radius: 999px;
  font-size: 14px; font-weight: 600; color: var(--text-muted);
  background: var(--surface);
}
.press-strip a:hover { color: var(--accent); border-color: var(--accent); }
.press-more { text-align: center; margin-top: 22px; font-size: 14.5px; }
.press-more a { color: var(--accent); font-weight: 600; }
.press-more a:hover { text-decoration: underline; }

/* ---------- Blog ---------- */
.blog-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; margin-bottom: 40px; }
.blog-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex; flex-direction: column;
  box-shadow: var(--shadow);
}
.blog-card img { height: 180px; width: 100%; object-fit: cover; }
.blog-card .blog-body { padding: 20px 22px 22px; flex: 1; display: flex; flex-direction: column; }
.blog-card time { font-family: var(--font-mono); font-size: 12px; color: var(--text-muted); }
.blog-card h3 { margin: 8px 0 8px; font-size: 1.05rem; }
.blog-card p { font-size: 14.5px; flex: 1; }
.blog-card .read-more { font-size: 14px; font-weight: 600; color: var(--accent); }
@media (max-width: 760px) { .blog-grid { grid-template-columns: 1fr; } }

/* ---------- Resume CTA ---------- */
.resume-cta { text-align: center; background: var(--bg-alt); }
.resume-cta .kicker { display: block; }

/* ---------- Footer ---------- */
.site-footer { padding: 64px 0 32px; background: var(--bg-alt); border-top: 1px solid var(--border); }
.footer-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; margin-bottom: 48px; }
.footer-col h3 { font-size: 13px; text-transform: uppercase; letter-spacing: 0.08em; color: var(--text-muted); font-family: var(--font-mono); margin-bottom: 16px; }
.footer-col ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 10px; }
.footer-col a { color: var(--text); font-size: 14.5px; }
.footer-col a:hover { color: var(--accent); }
.footer-bottom { border-top: 1px solid var(--border); padding-top: 24px; font-size: 13.5px; color: var(--text-muted); text-align: center; }
.footer-bottom a { color: var(--text); font-weight: 600; }
@media (max-width: 760px) { .footer-grid { grid-template-columns: 1fr; gap: 28px; } }

/* ---------- Back to top ---------- */
.to-top {
  position: fixed; right: 22px; bottom: 22px;
  width: 44px; height: 44px; border-radius: 50%;
  background: var(--accent); color: var(--accent-ink);
  display: flex; align-items: center; justify-content: center;
  box-shadow: var(--shadow);
  opacity: 0; visibility: hidden; transform: translateY(8px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
  z-index: 90;
}
.to-top.visible { opacity: 1; visibility: visible; transform: translateY(0); }

/* ---------- Reveal on scroll ---------- */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity 0.5s ease, transform 0.5s ease; }
.reveal.in { opacity: 1; transform: translateY(0); }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
}

/* ==========================================================================
   Content pages (Jekyll layout: pages/blog posts/course notes)
   ========================================================================== */

.breadcrumb {
  font-family: var(--font-mono);
  font-size: 12.5px;
  color: var(--text-muted);
  padding: 18px 0 0;
  overflow-wrap: break-word;
  word-break: break-word;
}
.breadcrumb a { color: var(--text-muted); }
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb a:first-child { color: var(--text); font-weight: 600; }

.page-header { padding: 24px 0 8px; }
.page-header .kicker { display: block; margin: 0; }

.content-wrap { padding: 0 0 88px; }
.content {
  max-width: 760px;
  margin: 0 auto;
  font-size: 1.02rem;
  overflow-wrap: break-word;
  word-break: break-word;
}
.content h1, .content h2, .content h3, .content h4 { margin-top: 40px; scroll-margin-top: 90px; }
.content h1:first-child, .content h2:first-child { margin-top: 0; }
.content h2 { font-size: 1.6rem; }
.content h3 { font-size: 1.25rem; }
.content p, .content ul, .content ol, .content table, .content blockquote, .content pre { margin: 0 0 20px; }
.content ul, .content ol { padding-left: 1.3em; color: var(--text-muted); }
.content li { margin-bottom: 6px; }
.content a { color: var(--accent); text-decoration: underline; text-decoration-color: color-mix(in srgb, var(--accent) 40%, transparent); text-underline-offset: 2px; }
.content a:hover { text-decoration-color: var(--accent); }
.content img { border-radius: var(--radius-sm); margin: 8px 0 24px; }
.content mark { background: var(--accent-soft); color: var(--text); padding: 0 4px; border-radius: 4px; }
.content blockquote {
  margin-left: 0; padding: 4px 20px;
  border-left: 3px solid var(--accent);
  color: var(--text-muted);
  font-style: italic;
}
.content code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--bg-alt);
  padding: 2px 6px;
  border-radius: 4px;
}
.content pre {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px 18px;
  overflow-x: auto;
}
.content pre code { background: none; padding: 0; }
.content table { display: block; max-width: 100%; overflow-x: auto; width: 100%; border-collapse: collapse; font-size: 0.95rem; }
.content th, .content td { text-align: left; padding: 10px 14px; border: 1px solid var(--border); }
.content .katex-display { overflow-x: auto; overflow-y: hidden; max-width: 100%; padding: 4px 0; }
.content th { background: var(--bg-alt); font-weight: 600; }
.content hr { border: none; border-top: 1px solid var(--border); margin: 36px 0; }