/* ============================================================
   Seonghun Jung — researcher homepage
   Design system: "ink on technical paper".
   Single system typeface: Tahoma everywhere (display, prose, and
   metadata), differentiated by size, weight, and letter-spacing.
   Light theme only.
   ============================================================ */

:root {
  --bg:            #fcfcfd;   /* cool paper, deliberately not cream */
  --ink:           #16181d;   /* near-black with a cool undertone  */
  --muted:         #5b6472;   /* slate for secondary text          */
  --faint:         #98a1b0;   /* tertiary / metadata               */
  --rule:          #e7e9ee;   /* hairlines                         */
  --rule-strong:   #d4d8e0;
  --rule-heading:  #8b95a5;   /* darker rule under section titles  */
  --accent:        #2b41cc;   /* fountain-pen indigo               */
  --accent-strong: #1f2f9c;   /* hover / button                    */
  --accent-tint:   #eef1fe;   /* wash for current-nav, selection   */
  --edit:          #b7791f;   /* amber for editable placeholders   */
  --edit-bg:       #fdf6e7;

  --serif: Tahoma, Verdana, "Segoe UI", Geneva, sans-serif;
  --sans:  Tahoma, Verdana, "Segoe UI", Geneva, sans-serif;
  --mono:  Tahoma, Verdana, "Segoe UI", Geneva, sans-serif;

  --maxw: 780px;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.62;
  letter-spacing: -0.003em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

::selection { background: var(--accent-tint); }

a {
  color: var(--accent);
  text-decoration: none;
}
a:hover { color: var(--accent-strong); text-decoration: underline; text-underline-offset: 2px; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ---------- Shared metadata / mono treatment ---------- */
.mono,
.nav-links a,
.contact a,
.entry-date,
.entry-place,
.entry-tag {
  font-family: var(--mono);
  font-variant-ligatures: none;
}

/* small-caps mono label used for structure */
.label {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--faint);
}

/* ---------- Nav ---------- */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(252, 252, 253, 0.88);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(150%) blur(10px);
  border-bottom: 1px solid var(--rule);
}
.nav-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0.7rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}
.nav-brand {
  font-family: var(--serif);
  font-weight: 500;
  font-size: 1.02rem;
  color: var(--ink);
  letter-spacing: 0;
}
.nav-brand:hover { text-decoration: none; color: var(--accent); }
.nav-links {
  list-style: none;
  display: flex;
  gap: 1.15rem;
  margin: 0;
  padding: 0;
  flex-wrap: wrap;
}
.nav-links a {
  color: var(--faint);
  font-size: 0.74rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding-bottom: 2px;
  border-bottom: 1.5px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.nav-links a:hover { color: var(--ink); text-decoration: none; }
.nav-links a.is-current {
  color: var(--accent);
  border-color: var(--accent);
}

/* ---------- Layout ---------- */
.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 1.5rem 4.5rem;
}

/* ---------- Hero ---------- */
.hero {
  display: flex;
  gap: 2rem;
  align-items: center;
  padding: 1.5rem 0 0rem;
}
.hero-photo {
  width: 124px;
  height: 124px;
  border-radius: 18px;
  object-fit: cover;
  object-position: center top;
  flex-shrink: 0;
  border: 1px solid var(--rule-strong);
  box-shadow: 0 1px 0 #fff, 0 6px 22px -12px rgba(22, 24, 29, 0.35);
}
.hero-body { min-width: 0; }
.hero-name {
  font-family: var(--serif);
  font-size: clamp(2.1rem, 5vw, 2.7rem);
  line-height: 1.08;
  margin: 0 0 0.5rem;
  font-weight: 500;
  letter-spacing: -0.01em;
}
.hero-role {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--muted);
  margin: 0 0 0.75rem;
  letter-spacing: 0.01em;
}
.hero-thesis {
  font-family: var(--sans);
  font-size: 1.08rem;
  font-style: normal;
  line-height: 1.5;
  color: var(--ink);
  margin: 0 0 1.15rem;
  max-width: 52ch;
}

.contact {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0;
  margin: 0 0 1.25rem;
  padding: 0;
}
.contact a {
  color: var(--muted);
  font-size: 0.78rem;
  letter-spacing: 0.02em;
  padding: 0 0.85rem;
  border-right: 1px solid var(--rule-strong);
  transition: color 0.15s ease;
}
.contact li:first-child a { padding-left: 0; }
.contact li:last-child a { border-right: none; }
.contact a:hover { color: var(--accent); text-decoration: none; }

/* ---------- Sections ---------- */
.section {
  padding-top: 2.75rem;
  scroll-margin-top: 4.5rem;
}
.section > h2,
.section summary > h2 {
  font-family: var(--serif);
  font-size: 1.5rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  margin: 0 0 1.35rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--rule-heading);
}

/* Collapsible section (Other Projects): native <details>, no JS */
.collapsible summary {
  list-style: none;
  cursor: pointer;
}
.collapsible summary::-webkit-details-marker { display: none; }
.collapsible summary h2::after {
  content: "\25B8"; /* ▸ */
  float: right;
  color: var(--faint);
  font-size: 1.05rem;
}
.collapsible[open] summary h2::after { content: "\25BE"; /* ▾ */ }
.collapsible summary:hover h2 { color: var(--accent); }
.section h3 {
  font-family: var(--serif);
  font-size: 1.08rem;
  font-weight: 600;
  margin: 1.5rem 0 0.55rem;
}

/* ---------- Entries (education / experience / projects) ---------- */
/* Items are separated by a centered hairline at 90% width, lighter than
   the full-width rule under each section title so the two read as
   different levels. No divider above the first item. */
.entry,
.pub {
  position: relative;
  padding: 1rem 0;
}
.entry:not(:first-of-type)::after,
.pub:not(:first-child)::after {
  content: "";
  position: absolute;
  top: 0;
  left: 5%;
  width: 90%;
  height: 1px;
  background: var(--rule);
}
.entry:first-of-type,
.pub:first-child { padding-top: 0.25rem; }
.entry:last-child,
.pub:last-child { padding-bottom: 0.25rem; }
.entry-head,
.entry-sub {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 1rem;
}
.entry-head { margin-bottom: 0.1rem; }
.entry-title {
  font-weight: 600;
  font-size: 1.03rem;
  letter-spacing: -0.005em;
}
.entry-title a { color: var(--ink); }
.entry-title a:hover { color: var(--accent); }
.entry-role { color: var(--muted); font-weight: 500; }
.entry-date,
.entry-place {
  color: var(--faint);
  font-size: 0.74rem;
  letter-spacing: 0.01em;
  white-space: nowrap;
  flex-shrink: 0;
}
.entry-tag {
  display: inline-block;
  font-size: 0.64rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  background: #f1f3f6;
  padding: 0.12rem 0.45rem;
  border-radius: 4px;
  vertical-align: 0.12em;
  margin-left: 0.45rem;
  font-weight: 500;
  white-space: nowrap;
  flex-shrink: 0;
}
/* Date row: sits under the tag, right-aligned with it. */
.entry-dateline {
  display: flex;
  justify-content: flex-end;
  margin-top: 0.15rem;
}
.advisor {
  font-style: italic;
  color: var(--muted);
  font-size: 0.95rem;
  margin-left: 0.35rem;
}

.bullets {
  margin: 0.6rem 0 0;
  padding-left: 0;
  list-style: none;
}
.bullets li {
  position: relative;
  padding-left: 1.15rem;
  margin: 0.4rem 0;
}
.bullets li::before {
  content: "";
  position: absolute;
  left: 0.05rem;
  top: 0.72em;
  width: 5px;
  height: 5px;
  background: var(--rule-strong);
  border-radius: 1px;              /* tiny square — a "node", fits the systems theme */
}

/* ---------- Research interests ---------- */
.interests {
  margin: 0.5rem 0 0;
  padding-left: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}
.interests li {
  position: relative;
  padding-left: 1.5rem;
  color: var(--ink);
}
.interests li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--accent);
  font-family: var(--mono);
  font-size: 0.85rem;
}

/* ---------- Awards ---------- */
.award-group { margin-bottom: 1rem; }
.award-group h3 { margin: 1rem 0 0.4rem; }
.award-group .bullets { margin-top: 0.2rem; }

/* ---------- Publications ---------- */
.muted { color: var(--muted); }
#pub-empty {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--faint);
  padding: 0.85rem 1rem;
  border: 1px dashed var(--rule-strong);
  border-radius: 6px;
}
/* Numbers are drawn with a counter so they align with the dash at the left edge. */
.pub-list { list-style: none; counter-reset: pub; padding-left: 0; margin: 0; }
.pub { counter-increment: pub; padding-left: 1.5rem; }
.pub::before {
  content: counter(pub) ".";
  position: absolute;
  left: 0;
  top: 1rem;
  font-weight: 600;
  color: var(--muted);
}
.pub:first-child::before { top: 0.25rem; }
.pub-title { font-weight: 600; }
.pub-authors { font-size: 0.95rem; }
.pub-venue { font-family: var(--mono); color: var(--muted); font-size: 0.8rem; }
.pub-links { font-family: var(--mono); font-size: 0.78rem; margin-top: 0.2rem; }
/* Collapsed per-publication summary: native <details>, no JS */
.pub-details { margin-top: 0.4rem; }
.pub-details summary {
  list-style: none;
  cursor: pointer;
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--accent);
}
.pub-details summary::-webkit-details-marker { display: none; }
.pub-details summary::before { content: "\25B8  "; }
.pub-details[open] summary::before { content: "\25BE  "; }
.pub-details summary:hover { text-decoration: underline; }

.pub-summary { margin-top: 0.55rem; }
.pub-summary p { margin: 0.3rem 0; font-size: 0.95rem; }
.pub-label { font-weight: 600; }

/* ---------- Editable placeholders ---------- */
.placeholder {
  background: var(--edit-bg);
  border-left: 3px solid var(--edit);
  border-radius: 0 5px 5px 0;
  padding: 0.5rem 0.8rem;
  color: #7a5a12;
}
.placeholder::before {
  content: "✎ edit — ";
  font-family: var(--mono);
  font-size: 0.66rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--edit);
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--rule);
  padding: 1.75rem 1.5rem;
  text-align: center;
  color: var(--faint);
  font-family: var(--mono);
  font-size: 0.74rem;
  letter-spacing: 0.02em;
}
.site-footer a { color: var(--muted); }
.site-footer a:hover { color: var(--accent); }

/* ---------- Responsive ---------- */
@media (max-width: 600px) {
  body { font-size: 16px; }
  .hero {
    flex-direction: column;
    text-align: center;
    gap: 1.25rem;
    padding-top: 2.25rem;
  }
  .hero-thesis { max-width: none; }
  .contact { justify-content: center; }
  .contact li:first-child a { padding-left: 0.85rem; }
  .nav-brand { display: none; }
  .nav-inner { justify-content: center; }
  .entry-head,
  .entry-sub { flex-direction: column; gap: 0; }
  .entry-date,
  .entry-place { white-space: normal; margin-top: 0.05rem; }
  .entry-dateline { justify-content: flex-start; }
  .entry-head .entry-tag { margin-left: 0; margin-top: 0.1rem; }
}

/* ---------- Print (clean résumé-style output) ---------- */
@media print {
  .site-nav, .site-footer { display: none; }
  .placeholder { background: none; border: none; padding: 0; color: var(--muted); }
  .placeholder::before { content: none; }
  a { color: var(--ink); text-decoration: none; }
  body { font-size: 11pt; background: #fff; }
  .entry-tag { background: none; border: 1px solid var(--rule-strong); }
}