/* ==========================================================================
   Site theme — single-colour Material-style surface.
   Loaded on every page (see _includes/head/custom.html) so the landing page
   and the inner pages (course pages, /cv/, 404, ...) share one style.
   ========================================================================== */

:root {
  --bg: #f4f4f5;              /* single background colour */
  --surface: #ffffff;
  --primary: #111113;         /* accent: buttons, links, active nav */
  --primary-dark: #000000;
  --primary-soft: #ececee;
  --text: #111113;
  --muted: #5f5f66;
  --divider: rgba(17, 17, 19, 0.10);
  --chip: #f1f1f2;

  /* soft, layered shadows */
  --e1: 0 1px 2px rgba(17, 17, 19, 0.05), 0 2px 8px rgba(17, 17, 19, 0.06);
  --e2: 0 2px 6px rgba(17, 17, 19, 0.07), 0 8px 20px rgba(17, 17, 19, 0.08);
  --e4: 0 6px 14px rgba(17, 17, 19, 0.10), 0 18px 40px rgba(17, 17, 19, 0.14);
  --e-primary: 0 8px 20px rgba(17, 17, 19, 0.28);

  --radius: 18px;
  --radius-sm: 14px;

  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

html {
  scroll-behavior: smooth;
}

body {
  /* the theme's own body rules assume the old masthead; reset them */
  margin: 0;
  padding: 0;
  min-height: 100vh;
  background-color: var(--bg);
  background-image: url("/assets/images/pattern.svg");
  background-size: 165px 165px;
  background-attachment: fixed;
  color: var(--text);
  font-family: var(--font);
  -webkit-font-smoothing: antialiased;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.icon {
  width: 1em;
  height: 1em;
  vertical-align: -0.125em;
}

/* ==========================================================================
   Top app bar
   ========================================================================== */

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 1em;
  padding: 0 1.75em;
  height: 4rem;
  background: rgba(244, 244, 245, 0.82);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--divider);
}

.topbar__nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35em;
}

.topbar__nav a {
  padding: 0.5em 1em;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--muted);
  text-decoration: none;
  border-radius: 999px;
  transition: color 0.18s ease, background-color 0.18s ease;
}

.topbar__nav a:hover,
.topbar__nav a:focus,
.topbar__nav a.is-active {
  color: var(--primary);
  background: var(--primary-soft);
}

/* ==========================================================================
   Hero
   ========================================================================== */

.hero {
  max-width: 58em;
  margin: 0 auto;
  padding: 3em 1.5em 3.5em;
  text-align: center;
}

.hero__avatar {
  width: 168px;
  height: 168px;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--surface);
  box-shadow: var(--e2);
}

.hero__name {
  margin: 0.7em 0 0.3em;
  font-size: 2.6rem;
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.03em;
}

.hero__social {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.4em;
  margin: 0 0 1.5em;
  padding: 0;
  list-style: none;
}

.hero__social li {
  margin: 0;
}

.hero__social a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  font-size: 1.2rem;
  color: var(--muted);
  text-decoration: none;
  border-radius: 50%;
  transition: background-color 0.18s ease, color 0.18s ease, transform 0.18s ease;
}

.hero__social a:hover,
.hero__social a:focus {
  color: var(--primary);
  background: var(--primary-soft);
  transform: translateY(-2px);
}

.hero__buttons {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75em;
  margin-bottom: 2.2em;
}

.btn-pill {
  display: inline-block;
  padding: 0.6em 1.5em;
  font-size: 0.92rem;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: #fff;
  text-decoration: none;
  background-color: var(--primary);
  border: 0;
  border-radius: 999px;
  box-shadow: var(--e1);
  transition: transform 0.18s ease, box-shadow 0.18s ease, background-color 0.18s ease;
}

.btn-pill:hover,
.btn-pill:focus {
  color: #fff;
  background-color: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: var(--e-primary);
}

.btn-pill:active {
  transform: translateY(0);
  box-shadow: var(--e1);
}

.hero__bio {
  max-width: 54em;
  margin: 0 auto;
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--muted);
}

.hero__bio p {
  margin: 0 0 1em;
}

.hero__bio a,
.card__body a {
  color: var(--primary);
  text-decoration: underline;
}

/* ==========================================================================
   Sections (Teaching / Projects / Resume)
   ========================================================================== */

.section {
  max-width: 56em;
  margin: 0 auto;
  padding: 2.5em 1.5em;
  /* keep anchored headings clear of the sticky app bar */
  scroll-margin-top: 4rem;
}

.section__title {
  display: flex;
  align-items: center;
  gap: 0.45em;
  margin: 0 0 1.2em;
  font-size: 1.6rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
}

.section__title .icon {
  font-size: 0.8em;
  color: var(--primary);
}

.section__empty {
  color: var(--muted);
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(17em, 1fr));
  gap: 1em;
}

.card {
  padding: 1.5em 1.6em;
  background: var(--surface);
  border: 1px solid var(--divider);
  border-radius: var(--radius);
  box-shadow: var(--e1);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--e4);
}

.card__title {
  margin: 0 0 0.3em;
  font-size: 1.1rem;
  font-weight: 500;
  line-height: 1.3;
  color: var(--text);
}

.card__title a {
  color: var(--text);
  text-decoration: none;
}

.card__title a:hover,
.card__title a:focus {
  color: var(--primary);
  text-decoration: underline;
}

.card__meta {
  margin: 0 0 0.3em;
  font-size: 0.85rem;
  color: var(--muted);
}

.card__meta--muted {
  opacity: 0.85;
}

.card__sep {
  padding: 0 0.4em;
}

.card__body {
  margin: 0.6em 0 0.9em;
  font-size: 0.92rem;
  line-height: 1.6;
  color: var(--muted);
}

.card__link {
  display: inline-flex;
  align-items: center;
  gap: 0.4em;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--primary);
  text-decoration: none;
}

.card__link:hover,
.card__link:focus {
  color: var(--primary-dark);
  text-decoration: underline;
}

.card__link .icon {
  font-size: 0.85em;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4em;
  margin: 0.6em 0 0;
  padding: 0;
  list-style: none;
}

.tags li {
  margin: 0;
  padding: 0.3em 0.85em;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--primary-dark);
  background: var(--primary-soft);
  border-radius: 999px;
}

/* Publications */

.pubs {
  margin: 0;
  padding: 0;
  list-style: none;
}

.pub {
  position: relative;
  padding: 0 0 0 1.6em;
  margin-bottom: 1.3em;
}

.pub:last-child {
  margin-bottom: 0;
}

.pub::before {
  content: "";
  position: absolute;
  top: 0.5em;
  left: 0.15em;
  width: 0.5em;
  height: 0.5em;
  background: var(--primary);
}

.pub__title {
  margin: 0 0 0.3em;
  font-size: 1.02rem;
  font-weight: 600;
  line-height: 1.35;
  color: var(--text);
}

.pub__title a {
  color: var(--text);
  text-decoration: none;
}

.pub__title a:hover,
.pub__title a:focus {
  text-decoration: underline;
}

.pub__authors {
  margin: 0 0 0.25em;
  font-size: 0.9rem;
  line-height: 1.55;
  color: var(--muted);
}

.pub__authors strong {
  font-weight: 700;
  color: var(--text);
}

.pub__meta {
  margin: 0;
  font-size: 0.85rem;
  color: var(--muted);
}

/* Resume blocks */

.resume {
  display: grid;
  gap: 1em;
}

.timeline {
  margin: 0;
  padding: 0 0 0 1.1em;
  list-style: none;
  border-left: 2px solid var(--divider);
}

.timeline > li {
  position: relative;
  margin: 0 0 1.2em;
}

.timeline > li:last-child {
  margin-bottom: 0;
}

.timeline > li::before {
  content: "";
  position: absolute;
  top: 0.45em;
  left: -1.45em;
  width: 0.5em;
  height: 0.5em;
  background: var(--primary);
  border-radius: 50%;
}

.timeline__head {
  margin: 0;
  font-weight: 500;
}

.timeline__dates {
  margin: 0.1em 0 0;
  font-size: 0.82rem;
  color: var(--muted);
}

.timeline__details {
  margin: 0.4em 0 0;
  padding-left: 1.1em;
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--muted);
}

/* ==========================================================================
   Back-to-top button (Material FAB — round by convention)
   ========================================================================== */

.to-top {
  position: fixed;
  right: 1.5em;
  bottom: 1.5em;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 3rem;
  height: 3rem;
  padding: 0;
  font-size: 1rem;
  color: #fff;
  cursor: pointer;
  background: var(--primary);
  border: 0;
  border-radius: 50%;
  box-shadow: var(--e-primary);
  opacity: 0;
  transform: translateY(0.5em);
  transition: opacity 0.2s ease, transform 0.2s ease, background-color 0.18s ease, box-shadow 0.18s ease;
}

.to-top[hidden] {
  display: none;
}

.to-top.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.to-top:hover,
.to-top:focus {
  background: var(--primary-dark);
  transform: translateY(-3px);
  box-shadow: var(--e4), var(--e-primary);
}

/* ==========================================================================
   Inner pages — bring the old theme layouts in line with the new look
   ========================================================================== */

#main {
  max-width: 56em;
  margin: 0 auto;
  padding: 2.5em 1.5em 4em;
  float: none;
  clear: both;
}

.page,
.archive {
  width: 100%;
  float: none;
  padding: 0;
  margin: 0;
}

.page__inner-wrap {
  padding: 2em 2.2em;
  background: var(--surface);
  border: 1px solid var(--divider);
  border-radius: var(--radius);
  box-shadow: var(--e1);
}

.page__title,
.archive__subtitle {
  margin-top: 0;
  font-family: var(--font);
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
  border-bottom: 1px solid var(--divider);
}

.page__content,
.archive {
  color: var(--text);
  font-family: var(--font);
  line-height: 1.7;
}

.page__content h1,
.page__content h2,
.page__content h3,
.page__content h4 {
  font-family: var(--font);
  font-weight: 600;
  color: var(--text);
  border-bottom: 0;
}

.page__content h1 {
  font-size: 1.3rem;
  padding-bottom: 0.2em;
  border-bottom: 1px solid var(--divider);
}

.page__content a,
.archive a {
  color: var(--primary);
  text-decoration: underline;
}

.page__content code,
.page__content pre {
  background: var(--chip);
}

.page__meta,
.page__date {
  color: var(--muted);
}

/* the sidebar, share buttons and dark footer belong to the old look */
.sidebar,
.author__avatar,
.page__share,
.page__footer,
.page__meta-title,
.masthead {
  display: none;
}

.archive__item {
  padding: 1.4em 1.6em;
  margin-bottom: 1em;
  background: var(--surface);
  border: 1px solid var(--divider);
  border-radius: var(--radius);
  box-shadow: var(--e1);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.archive__item:hover {
  transform: translateY(-4px);
  box-shadow: var(--e4);
}

.archive__item-title {
  margin-top: 0;
  font-family: var(--font);
  font-weight: 500;
}

.archive__item-title a {
  color: var(--text);
  text-decoration: none;
}

.archive__item-title a:hover {
  color: var(--primary);
  text-decoration: underline;
}

/* ==========================================================================
   Small screens
   ========================================================================== */

@media (max-width: 37.5em) {
  .topbar {
    padding: 0 0.6em;
    height: 3.5rem;
  }

  .topbar__nav {
    gap: 0.15em;
  }

  .topbar__nav a {
    padding: 0.45em 0.7em;
    font-size: 0.85rem;
  }

  .hero {
    padding: 2em 1.25em 2.5em;
  }

  .hero__avatar {
    width: 128px;
    height: 128px;
  }

  .hero__name {
    font-size: 2rem;
  }

  .section {
    padding: 2em 1.25em;
  }

  .section__title {
    font-size: 1.35rem;
  }

  .page__inner-wrap {
    padding: 1.4em 1.2em;
  }

  .to-top {
    right: 1em;
    bottom: 1em;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .card,
  .to-top,
  .hero__social a,
  .btn-pill {
    transition: none;
  }
}