/* =========================================================================
   Sandro Speth — personal academic website
   Design system + layout. No build step, no external dependencies.
   ========================================================================= */

/* ---- Design tokens ---------------------------------------------------- */
:root {
  /* Gropius blue: vivid #0083cc for graphics/buttons, #00639b for accessible text */
  --accent: #0083cc;
  --accent-strong: #00639b;
  --accent-soft: rgba(0, 131, 204, 0.10);
  --accent-ring: rgba(0, 131, 204, 0.28);

  --bg: #ffffff;
  --bg-alt: #f6f6f7;
  --surface: #ffffff;
  --surface-2: #ececee;
  --text: #3c3c43;
  --text-muted: #67676c;
  --heading: #1b1b1f;
  --border: #e2e2e3;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.04), 0 8px 24px rgba(16, 24, 40, 0.06);
  --shadow-sm: 0 1px 2px rgba(16, 24, 40, 0.05);

  --maxw: 1080px;
  --radius: 14px;
  --radius-sm: 9px;

  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Helvetica, Arial, sans-serif;
  --font-serif: "Newsreader", Georgia, "Times New Roman", serif;
}

:root[data-theme="dark"] {
  /* Gropius dark: bright sky-blue accent on near-black surfaces */
  --accent: #7cd0ff;
  --accent-strong: #9bdbff;
  --accent-soft: rgba(0, 131, 204, 0.24);
  --accent-ring: rgba(124, 208, 255, 0.30);

  --bg: #1b1b1f;
  --bg-alt: #161618;
  --surface: #202127;
  --surface-2: #2a2a31;
  --text: #dfdfd6;
  --text-muted: #98989f;
  --heading: #f4f4ee;
  --border: #3c3f44;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.32), 0 12px 32px rgba(0, 0, 0, 0.44);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.36);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 84px; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { animation: none !important; transition: none !important; }
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* ---- Typography ------------------------------------------------------- */
h1, h2, h3, h4 { color: var(--heading); line-height: 1.2; font-weight: 650; }
h2 { font-size: 1.7rem; letter-spacing: -0.01em; margin: 0 0 0.4rem; }
h3 { font-size: 1.15rem; margin: 0 0 0.3rem; }
p { margin: 0 0 1rem; }
a { color: var(--accent-strong); text-decoration: none; }
a:hover { text-decoration: underline; }

.section-eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 650;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--accent-strong);
  margin-bottom: 0.6rem;
}

/* ---- Layout ----------------------------------------------------------- */
.wrap { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

section { padding: 74px 0; border-top: 1px solid var(--border); }
section:first-of-type { border-top: none; }
.section-head { margin-bottom: 2.2rem; max-width: 640px; }
.section-head p { color: var(--text-muted); margin: 0; }

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

/* ---- Navigation ------------------------------------------------------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: saturate(1.4) blur(12px);
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  max-width: var(--maxw); margin: 0 auto; padding: 0 24px;
  height: 62px; display: flex; align-items: center; gap: 20px;
}
.nav-brand {
  font-weight: 700; color: var(--heading); font-size: 1.02rem;
  letter-spacing: -0.01em; margin-right: auto; display: flex; align-items: center; gap: 10px;
}
.nav-brand .dot { width: 10px; height: 10px; border-radius: 50%;
  background: var(--accent); box-shadow: 0 0 0 4px var(--accent-soft); }
.nav-links { display: flex; gap: 4px; align-items: center; }
.nav-links a {
  color: var(--text-muted); font-size: 0.93rem; font-weight: 500;
  padding: 8px 12px; border-radius: 8px; transition: color .15s, background .15s;
}
.nav-links a:hover { color: var(--heading); background: var(--surface-2); text-decoration: none; }
.theme-toggle {
  border: 1px solid var(--border); background: var(--surface);
  color: var(--text-muted); width: 38px; height: 38px; border-radius: 9px;
  cursor: pointer; display: grid; place-items: center; transition: all .15s;
}
.theme-toggle:hover { color: var(--heading); border-color: var(--accent-ring); }
.theme-toggle svg { width: 18px; height: 18px; }
.nav-burger { display: none; border: 1px solid var(--border); background: var(--surface);
  color: var(--heading); width: 38px; height: 38px; border-radius: 9px; cursor: pointer; }

/* ---- Hero ------------------------------------------------------------- */
.hero { padding: 68px 0 60px; border-top: none; }
.hero-grid {
  display: grid; grid-template-columns: 1fr 300px; gap: 56px; align-items: center;
}
.hero h1 {
  font-size: 2.9rem; letter-spacing: -0.02em; margin: 0 0 0.5rem; font-weight: 700;
}
.hero .role { font-size: 1.2rem; color: var(--text); margin: 0 0 0.2rem; font-weight: 550; }
.hero .affil { color: var(--text-muted); margin: 0 0 1.4rem; }
.hero .lead { font-size: 1.06rem; color: var(--text-muted); max-width: 52ch; margin-bottom: 1.6rem; }
.hero .lead strong { color: var(--text); font-weight: 600; }

.tag-row { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 1.7rem; }
.pill {
  font-size: 0.82rem; font-weight: 550; color: var(--accent-strong);
  background: var(--accent-soft); border: 1px solid var(--accent-ring);
  padding: 4px 12px; border-radius: 999px;
}

.hero-photo {
  position: relative; width: 100%; aspect-ratio: 1; border-radius: 20px;
  overflow: hidden; box-shadow: var(--shadow); border: 1px solid var(--border);
}
.hero-photo img { width: 100%; height: 100%; object-fit: cover; display: block; }
.hero-photo::after {
  content: ""; position: absolute; inset: 0;
  box-shadow: inset 0 0 0 1px rgba(255,255,255,0.06);
  border-radius: 20px; pointer-events: none;
}

/* ---- Social links ----------------------------------------------------- */
.socials { display: flex; flex-wrap: wrap; gap: 8px; }
.socials a {
  display: inline-flex; align-items: center; gap: 7px;
  font-size: 0.86rem; font-weight: 500; color: var(--text-muted);
  border: 1px solid var(--border); background: var(--surface);
  padding: 7px 13px; border-radius: 9px; transition: all .15s;
}
.socials a:hover { color: var(--heading); border-color: var(--accent-ring);
  background: var(--accent-soft); text-decoration: none; transform: translateY(-1px); }
.socials svg { width: 16px; height: 16px; flex: none; }

/* ---- Stat strip ------------------------------------------------------- */
.stats {
  display: grid; grid-template-columns: repeat(5, 1fr); gap: 16px;
  margin-top: 46px;
}
/* Below wide desktop, wrap the stat tiles to a 2-col grid (doctorate full-width) */
@media (max-width: 1000px) {
  .stats { grid-template-columns: repeat(2, 1fr); }
  .stat.stat-text { grid-column: 1 / -1; }
}
.stat {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 22px 20px; box-shadow: var(--shadow-sm);
}
.stat .num { font-size: 2rem; font-weight: 700; color: var(--heading); letter-spacing: -0.02em; }
.stat .num span { font-size: 1rem; color: var(--accent-strong); vertical-align: super; }
.stat .label { font-size: 0.85rem; color: var(--text-muted); margin-top: 2px; }
.stat .label em { font-style: italic; color: var(--accent-strong); font-weight: 600; }
.stat .sub { font-size: 0.74rem; color: var(--text-muted); opacity: .8; margin-top: 6px; }
.stat .sub a { font-weight: 600; }
.stat.stat-text .num { font-size: 1.35rem; line-height: 1.25; margin-bottom: 2px; }

/* ---- Cards / research ------------------------------------------------- */
.card-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 26px 26px 24px; box-shadow: var(--shadow-sm);
  transition: border-color .15s, transform .15s, box-shadow .15s;
}
.card:hover { border-color: var(--accent-ring); transform: translateY(-2px); box-shadow: var(--shadow); }
.card .ico {
  width: 42px; height: 42px; border-radius: 11px; display: grid; place-items: center;
  background: var(--accent-soft); color: var(--accent); margin-bottom: 14px;
}
.card .ico svg { width: 22px; height: 22px; }
.card p { color: var(--text-muted); margin: 0; font-size: 0.96rem; }

/* ---- News ------------------------------------------------------------- */
.news-list { display: flex; flex-direction: column; gap: 2px; max-width: 780px; }
.news-item {
  display: grid; grid-template-columns: 130px 1fr; gap: 20px;
  padding: 18px 0; border-bottom: 1px solid var(--border);
}
.news-item:last-child { border-bottom: none; }
.news-date { color: var(--accent-strong); font-weight: 600; font-size: 0.86rem; padding-top: 2px; }
.news-body { color: var(--text); font-size: 0.98rem; }
.news-body .tag {
  display: inline-block; font-size: 0.72rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.05em; color: var(--text-muted); background: var(--surface-2);
  border: 1px solid var(--border); padding: 1px 8px; border-radius: 6px; margin-right: 8px;
}

/* ---- Publications ----------------------------------------------------- */
.pub-toolbar {
  display: flex; flex-wrap: wrap; gap: 10px; align-items: center;
  margin-bottom: 26px;
}
.pub-search {
  flex: 1; min-width: 220px; position: relative;
}
.pub-search input {
  width: 100%; padding: 10px 14px 10px 38px; font-size: 0.92rem; font-family: inherit;
  color: var(--text); background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; transition: border-color .15s;
}
.pub-search input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.pub-search svg { position: absolute; left: 12px; top: 50%; transform: translateY(-50%);
  width: 16px; height: 16px; color: var(--text-muted); }

.filters { display: flex; flex-wrap: wrap; gap: 7px; }
.filter-btn {
  font-size: 0.83rem; font-weight: 500; font-family: inherit; cursor: pointer;
  color: var(--text-muted); background: var(--surface); border: 1px solid var(--border);
  padding: 7px 13px; border-radius: 999px; transition: all .15s;
}
.filter-btn:hover { color: var(--heading); border-color: var(--accent-ring); }
.filter-btn.active { color: #fff; background: var(--accent); border-color: var(--accent); }
:root[data-theme="dark"] .filter-btn.active { color: #1b1b1f; }

.pub-year-group { margin-bottom: 30px; }
.pub-year {
  font-family: var(--font-serif); font-size: 1.5rem; font-weight: 600; color: var(--heading);
  padding-bottom: 8px; margin-bottom: 12px; border-bottom: 2px solid var(--border);
}
.pub {
  display: flex; gap: 16px; padding: 15px 0; border-bottom: 1px solid var(--border);
}
.pub:last-child { border-bottom: none; }
.pub-mark {
  flex: none; width: 4px; border-radius: 3px; background: var(--border);
}
.pub.is-first .pub-mark { background: var(--accent); }
.pub-content { flex: 1; }
.pub-title { font-weight: 600; color: var(--heading); font-size: 1rem; line-height: 1.4; }
.pub-authors { font-size: 0.9rem; color: var(--text-muted); margin-top: 3px; }
.pub-authors strong { color: var(--text); font-weight: 650; }
.pub-meta { font-size: 0.86rem; color: var(--text-muted); margin-top: 5px; display: flex;
  flex-wrap: wrap; gap: 8px; align-items: center; }
.pub-venue { font-style: italic; }
.badge {
  font-size: 0.68rem; font-weight: 650; text-transform: uppercase; letter-spacing: 0.04em;
  padding: 1px 7px; border-radius: 5px; border: 1px solid var(--border); color: var(--text-muted);
}
.badge.journal { color: var(--accent-strong); border-color: var(--accent-ring); background: var(--accent-soft); }
.badge.first { color: #b26a00; border-color: rgba(178,106,0,.3); background: rgba(178,106,0,.08); }
:root[data-theme="dark"] .badge.first { color: #f0b866; border-color: rgba(240,184,102,.3); background: rgba(240,184,102,.10); }
.badge.note { color: #a3423b; border-color: rgba(163,66,59,.3); background: rgba(163,66,59,.07); }
:root[data-theme="dark"] .badge.note { color: #ef9a94; }
.pub-links a { font-size: 0.85rem; font-weight: 550; }
.pub-empty { color: var(--text-muted); padding: 30px 0; text-align: center; }

/* BibTeX toggle + panel */
.bib-btn {
  font-family: inherit; font-size: 0.85rem; font-weight: 550; cursor: pointer;
  color: var(--accent-strong); background: none; border: none; padding: 0;
}
.bib-btn:hover { text-decoration: underline; }
.bib-btn.active { color: var(--heading); }
.bibtex-box { margin-top: 12px; }
.bibtex-box pre {
  margin: 0; padding: 14px 16px; background: var(--surface-2);
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  font-family: "SFMono-Regular", ui-monospace, Menlo, Consolas, monospace;
  font-size: 0.8rem; line-height: 1.55; color: var(--text);
  overflow-x: auto; white-space: pre;
}
.bibtex-actions { display: flex; gap: 8px; margin-top: 8px; }
.mini-btn {
  font-family: inherit; font-size: 0.78rem; font-weight: 550; cursor: pointer;
  color: var(--text-muted); background: var(--surface); border: 1px solid var(--border);
  padding: 5px 12px; border-radius: 7px; transition: all .15s; text-decoration: none;
}
.mini-btn:hover { color: var(--heading); border-color: var(--accent-ring);
  background: var(--accent-soft); text-decoration: none; }

/* ---- Teaching / service lists ---------------------------------------- */
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 44px; }
.list-block h3 { margin-bottom: 14px; }
.tick-list { list-style: none; padding: 0; margin: 0; }
.tick-list li {
  position: relative; padding: 7px 0 7px 26px; color: var(--text);
  font-size: 0.96rem; border-bottom: 1px solid var(--border);
}
.tick-list li:last-child { border-bottom: none; }
.tick-list li::before {
  content: ""; position: absolute; left: 4px; top: 15px; width: 7px; height: 7px;
  border-radius: 50%; background: var(--accent);
}
.tick-list li .muted { color: var(--text-muted); font-size: 0.88rem; }

/* Timeline (experience & education) */
.timeline { display: flex; flex-direction: column; }
.tl-item {
  display: grid; grid-template-columns: 108px 1fr; gap: 16px;
  padding: 13px 0; border-bottom: 1px solid var(--border);
}
.tl-item:last-child { border-bottom: none; }
.tl-date { color: var(--accent-strong); font-weight: 600; font-size: 0.85rem; padding-top: 1px; }
.tl-role { color: var(--heading); font-weight: 600; font-size: 0.98rem; }
.tl-role em { font-style: italic; color: var(--accent-strong); font-weight: 600; }
.tl-place { color: var(--text-muted); font-size: 0.9rem; margin-top: 1px; }
@media (max-width: 560px) {
  .tl-item { grid-template-columns: 1fr; gap: 3px; }
  .tl-date { padding-top: 0; }
}

.project-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.project {
  display: block; text-decoration: none; color: inherit;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 22px; box-shadow: var(--shadow-sm); transition: all .15s;
}
.project:hover {
  border-color: var(--accent-ring); transform: translateY(-2px);
  box-shadow: var(--shadow); text-decoration: none;
}
.project h3 { display: flex; align-items: center; gap: 8px; color: var(--heading); }
.project:hover h3 { color: var(--accent-strong); }
.project .meta { font-size: 0.8rem; color: var(--accent-strong); font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.05em; margin-bottom: 8px; }
.project p { font-size: 0.92rem; color: var(--text-muted); margin: 0; }

/* ---- Contact ---------------------------------------------------------- */
.contact-grid { display: grid; grid-template-columns: 1.1fr 1fr; gap: 44px; align-items: start; }
.contact-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 28px; box-shadow: var(--shadow-sm);
}
.contact-row { display: flex; gap: 14px; padding: 12px 0; border-bottom: 1px solid var(--border); }
.contact-row:last-child { border-bottom: none; }
.contact-row .ci { flex: none; width: 34px; height: 34px; border-radius: 9px; display: grid;
  place-items: center; background: var(--accent-soft); color: var(--accent); }
.contact-row .ci svg { width: 17px; height: 17px; }
.contact-row .k { font-size: 0.78rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.04em; }
.contact-row .v { color: var(--text); font-size: 0.95rem; }

/* ---- Footer ----------------------------------------------------------- */
footer {
  border-top: 1px solid var(--border); padding: 34px 0; color: var(--text-muted);
  font-size: 0.88rem; background: var(--bg-alt);
}
.footer-inner { display: flex; justify-content: space-between; align-items: center; gap: 20px; flex-wrap: wrap; }
.footer-inner a { color: var(--text-muted); }
.footer-inner a:hover { color: var(--accent-strong); }

/* ---- Legal pages (Impressum / Datenschutz) --------------------------- */
.legal-nav { border-bottom: 1px solid var(--border); }
.legal-nav .nav-inner { justify-content: space-between; }
.legal-nav a.back { color: var(--text-muted); font-size: 0.93rem; font-weight: 500; display: inline-flex; gap: 6px; }
.legal-nav a.back:hover { color: var(--heading); text-decoration: none; }
.legal { max-width: 760px; margin: 0 auto; padding: 56px 24px 80px; }
.legal h1 { font-size: 2rem; letter-spacing: -0.01em; margin: 0 0 0.3rem; }
.legal .lead { color: var(--text-muted); margin: 0 0 2.4rem; }
.legal h2 { font-size: 1.2rem; margin: 2.2rem 0 0.6rem; }
.legal p { margin: 0 0 0.9rem; }
.legal address { font-style: normal; line-height: 1.7; }
.legal ul { padding-left: 20px; margin: 0 0 1rem; }
.legal li { margin-bottom: 4px; }
.legal .muted { color: var(--text-muted); }
.legal .note {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 14px 16px; font-size: 0.92rem;
  color: var(--text-muted); margin: 1.4rem 0;
}

/* ---- Responsive ------------------------------------------------------- */
/* Collapse the nav to a burger menu before the links crowd the brand. */
@media (max-width: 1000px) {
  .nav-links { display: none; }
  .nav-links.open {
    display: flex; position: absolute; top: 62px; left: 0; right: 0; flex-direction: column;
    background: var(--bg); border-bottom: 1px solid var(--border); padding: 12px 24px; gap: 2px;
  }
  .nav-links.open a { padding: 10px 12px; }
  .nav-burger { display: grid; place-items: center; }
}
@media (max-width: 860px) {
  .hero-grid { grid-template-columns: 1fr; gap: 34px; }
  .hero-photo { max-width: 220px; order: -1; justify-self: center; }
  .hero h1 { font-size: 2.3rem; }
  .card-grid, .project-grid { grid-template-columns: 1fr; }
  .two-col, .contact-grid { grid-template-columns: 1fr; gap: 34px; }
}
@media (max-width: 560px) {
  body { font-size: 16px; }
  section { padding: 56px 0; }
  .news-item { grid-template-columns: 1fr; gap: 4px; }
  .news-date { padding-top: 0; }
  .hero h1 { font-size: 2rem; }
  .hero .lead { font-size: 1rem; }

  /* Numeric metrics as a compact 2×2 grid; doctorate spans full width below */
  .stats { grid-template-columns: repeat(2, 1fr); gap: 10px; margin-top: 34px; }
  .stat { padding: 14px 10px; text-align: center; }
  .stat .num { font-size: 1.55rem; }
  .stat .num span { font-size: 0.8rem; }
  .stat .label { font-size: 0.72rem; line-height: 1.28; margin-top: 3px; }
  .stat .sub { display: none; }
  .stat.stat-text {
    grid-column: 1 / -1; text-align: left; padding: 16px;
    display: flex; align-items: baseline; gap: 6px 10px; flex-wrap: wrap;
  }
  .stat.stat-text .num { font-size: 1.15rem; }
  .stat.stat-text .label { font-size: 0.88rem; margin-top: 0; }
  .stat.stat-text .sub { display: block; width: 100%; margin-top: 4px; }
  .pub { gap: 12px; }
}

@media (max-width: 360px) {
  .stat .num { font-size: 1.35rem; }
  .stat .label { font-size: 0.68rem; }
}