/* ============================================================
   alexander-busch.eu — one stylesheet for the whole site
   ------------------------------------------------------------
   All colors and fonts are defined as variables in the three
   blocks below. The two dark blocks must stay identical: one
   applies when the visitor clicked the toggle, the other when
   their operating system prefers dark mode.
   ============================================================ */

:root {
  --bg:      #ffffff;
  --text:    #23282c;
  --muted:   #5d6871;
  --accent:  #176e4b;   /* deep green */
  --border:  #e3e7e5;
  --surface: #f5f7f6;   /* background of abstract / BibTeX boxes */

  --serif: Charter, "Bitstream Charter", "Iowan Old Style", "Sitka Text", Cambria, Georgia, serif;
  --sans:  system-ui, -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
  --mono:  ui-monospace, "Cascadia Code", Consolas, Menlo, monospace;
}

/* Dark theme, selected with the toggle button */
[data-theme="dark"] {
  --bg:      #15181a;
  --text:    #d8dcde;
  --muted:   #96a1a9;
  --accent:  #6cc59d;
  --border:  #2b3134;
  --surface: #1c2124;
}

/* Dark theme, following the operating system (toggle not used) */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg:      #15181a;
    --text:    #d8dcde;
    --muted:   #96a1a9;
    --accent:  #6cc59d;
    --border:  #2b3134;
    --surface: #1c2124;
  }
}

/* ---------- base ------------------------------------------- */

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0 auto;
  /* Width of the whole text column (1rem = 16px, so 50rem = 800px).
     Raise or lower this one value to make the site wider or narrower. */
  max-width: 50rem;
  padding: 0 1.25rem 3rem;
  font-family: var(--serif);
  font-size: 1.125rem;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}
a:hover { text-decoration-thickness: 2px; }

img { max-width: 100%; }

/* Anchor targets stop below the sticky header instead of underneath it */
section { scroll-margin-top: 4.5rem; }

h1, h2, h3 {
  font-family: var(--serif);
  line-height: 1.3;
  font-weight: 600;
}

h2 {
  font-size: 1.3rem;
  margin: 2.75rem 0 1.1rem;
  padding-bottom: 0.3rem;
  border-bottom: 1px solid var(--border);
}

/* Page title on the subpages (Media, Data, Impressum) */
.page-title { font-size: 1.3rem; margin: 0 0 0.4rem; }

h3 {
  font-family: var(--sans);
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--muted);
  text-transform: uppercase;
  margin: 1.9rem 0 0.9rem;
}

/* ---------- header ----------------------------------------- */

.site-header {
  position: sticky;   /* header stays visible while scrolling */
  top: 0;
  z-index: 50;
  background: var(--bg);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.45rem 0.9rem;
  padding: 1.05rem 0 0.85rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2rem;
}

.site-name {
  font-size: 1.35rem;
  font-weight: 600;
  margin: 0 auto 0 0;   /* pushes nav and buttons to the right */
}
.site-name a {
  color: var(--text);
  text-decoration: none;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem 1.05rem;
  font-family: var(--sans);
  font-size: 0.92rem;
}
.site-nav a {
  color: var(--muted);
  text-decoration: none;
}
.site-nav a:hover { color: var(--accent); }

#theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--muted);
  width: 1.85rem;
  height: 1.85rem;
  line-height: 1;
  font-size: 0.9rem;
  cursor: pointer;
  padding: 0;
}
#theme-toggle:hover { color: var(--accent); border-color: var(--accent); }

/* ☰ button; only shown on narrow screens (see media query below) */
.nav-burger {
  display: none;
  background: none;
  border: 1px solid var(--border);
  border-radius: 999px;
  width: 1.85rem;
  height: 1.85rem;
  padding: 0;
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 3px;
}
.nav-burger span {
  display: block;
  width: 0.9rem;
  height: 1.5px;
  background: var(--muted);
}
.nav-burger:hover { border-color: var(--accent); }
.nav-burger:hover span { background: var(--accent); }

/* Show ☾ in light mode, ☀ in dark mode */
#theme-toggle .sun  { display: none; }
[data-theme="dark"] #theme-toggle .moon { display: none; }
[data-theme="dark"] #theme-toggle .sun  { display: inline; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) #theme-toggle .moon { display: none; }
  :root:not([data-theme="light"]) #theme-toggle .sun  { display: inline; }
}

/* ---------- about ------------------------------------------ */

.about {
  display: flex;
  gap: 2rem;
  align-items: flex-start;
}
.about-text { flex: 1; }
.about-text p:first-child { margin-top: 0.2rem; }

.portrait {
  width: 158px;
  height: auto;      /* keeps the aspect ratio at every window size */
  border-radius: 6px;
  flex-shrink: 0;
  margin-top: 0.4rem;
}

.contact-links {
  font-family: var(--sans);
  font-size: 0.9rem;
  margin: 1.3rem 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem 0.65rem;
}
.contact-links a { text-decoration: none; }
.contact-links a:hover { text-decoration: underline; }
.contact-links .sep { color: var(--border); }

.edu {
  font-family: var(--sans);
  font-size: 0.88rem;
  color: var(--muted);
  list-style: none;
  padding: 0;
  margin: 0.2rem 0 0;   /* the "Education" heading above provides the spacing */
}
.edu li { margin: 0.15rem 0; }

.note {
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--muted);
}

/* ---------- publications ----------------------------------- */

.pub { margin: 0 0 1.9rem; }

.pub-title {
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.45;
  margin: 0;
}
.pub-title a { color: var(--text); }

.pub-authors {
  font-family: var(--sans);
  font-size: 0.88rem;
  color: var(--muted);
  margin: 0.1rem 0 0;
}

.pub-venue {
  font-style: italic;
  color: var(--muted);
  font-size: 0.95rem;
  margin: 0.1rem 0 0.25rem;
}

.pub-links,
.pub details {
  font-family: var(--sans);
  font-size: 0.88rem;
  margin: 0.15rem 0 0;
}
.pub-links { display: flex; flex-wrap: wrap; gap: 0.2rem 1rem; }

.pub summary {
  color: var(--accent);
  cursor: pointer;
  list-style: none;
  width: fit-content;
}
.pub summary::-webkit-details-marker { display: none; }
.pub summary::before { content: "▸ "; font-size: 0.75em; }
.pub details[open] > summary::before { content: "▾ "; }
.pub summary:hover { text-decoration: underline; }

.abstract-body {
  font-family: var(--serif);
  font-size: 0.95rem;
  margin: 0.5rem 0 0.25rem;
  padding: 0.55rem 0.9rem;
  border-left: 3px solid var(--accent);
  background: var(--surface);
}

.bibtex { position: relative; margin-top: 0.5rem; }
.bibtex pre {
  margin: 0;
  padding: 0.7rem 0.9rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 0.78rem;
  line-height: 1.55;
}
.copy-bib {
  position: absolute;
  top: 0.45rem;
  right: 0.45rem;
  font-family: var(--sans);
  font-size: 0.72rem;
  color: var(--muted);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 5px;
  padding: 0.15rem 0.5rem;
  cursor: pointer;
}
.copy-bib:hover { color: var(--accent); border-color: var(--accent); }

/* ---------- teaching --------------------------------------- */

.teach-list {
  list-style: none;
  padding: 0;
  margin: 0 0 1rem;
}
.teach-list li { margin: 0.25rem 0; }

/* ---------- media ------------------------------------------ */

.media-list {
  list-style: none;
  padding: 0;
  margin: 0;
}
.media-list li {
  display: grid;
  grid-template-columns: 5.6rem 1fr;
  gap: 1rem;
  margin: 0 0 0.95rem;
}
.media-date {
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--muted);
  padding-top: 0.15rem;
  white-space: nowrap;
}
.media-body { min-width: 0; }
.media-outlet { font-weight: 600; }
.media-links {
  font-family: var(--sans);
  font-size: 0.88rem;
}

/* ---------- data page -------------------------------------- */

.data-list {
  list-style: none;
  padding: 0;
  margin: 0 0 1.5rem;
}
.data-list li { margin: 0 0 0.85rem; }
.data-list .desc {
  display: block;
  font-size: 0.93rem;
  color: var(--muted);
}

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

.site-footer {
  margin-top: 3.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-family: var(--sans);
  font-size: 0.83rem;
  color: var(--muted);
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem 0.6rem;
}
.site-footer a { color: var(--muted); }
.site-footer a:hover { color: var(--accent); }

/* ---------- small screens ---------------------------------- */

/* Collapse the nav into the ☰ menu when it no longer fits on one line */
@media (max-width: 720px) {
  .nav-burger { display: flex; }
  .site-nav { display: none; }
  .site-header.nav-open .site-nav {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.6rem;
    width: 100%;
    order: 10;
    padding: 0.4rem 0 0.6rem;
  }
}

@media (max-width: 620px) {
  body { font-size: 1rem; }
  .about { flex-direction: column-reverse; gap: 1.1rem; }
  .portrait { width: 132px; }
  .media-list li {
    grid-template-columns: 1fr;
    gap: 0.05rem;
    margin-bottom: 1.1rem;
  }
}