:root {
  --bg: #faf9f6;
  --surface: #ffffff;
  --ink: #1c1917;
  --ink-soft: #57534e;
  --border: #e7e4de;
  --accent: #0d9488;
  --accent-ink: #ffffff;

  --font-display: 'Sora', sans-serif;
  --font-body: 'Inter', sans-serif;
  --font-mono: 'IBM Plex Mono', monospace;

  --max-width: 1080px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  line-height: 1.6;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  line-height: 1.25;
  margin: 0 0 0.5em;
}

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

p { margin: 0 0 1em; }

.section {
  scroll-margin-top: 80px;
  padding: 3rem 1.5rem;
  max-width: var(--max-width);
  margin: 0 auto;
}

.section-error {
  color: #b91c1c;
  font-family: var(--font-mono);
  font-size: 0.9rem;
}

.section-label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.75rem;
}

.section-intro {
  color: var(--ink-soft);
  max-width: 640px;
}

/* ---------- Header / Nav ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250, 249, 246, 0.9);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}

.nav {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  display: flex;
  align-items: center;
}

.nav-brand img {
  height: 28px;
  width: auto;
  display: block;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 1.75rem;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--ink-soft);
  font-size: 0.92rem;
  font-weight: 500;
  transition: color 0.15s ease;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--accent);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.25rem;
}

.nav-toggle span {
  width: 22px;
  height: 2px;
  background: var(--ink);
}

/* ---------- Hero ---------- */

#hero.section {
  padding-top: 1rem;
  padding-bottom: 1.5rem;
}

#news.section {
  padding-top: 2rem;
}

.hero {
  padding-top: 0.5rem;
  padding-bottom: 1rem;
  text-align: center;
}

.hero-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  margin-bottom: 1rem;
}

.hero h1 {
  margin: 0 0 0.5rem;
}

.hero-wordmark {
  display: block;
  width: 100%;
  max-width: 640px;
  height: auto;
  margin: 0 auto;
}

.hero-tagline {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--ink);
  letter-spacing: 0.02em;
  margin: 0 0 2rem;
}

.hero-sub {
  font-size: 1.1rem;
  color: var(--ink-soft);
  max-width: 760px;
  margin-left: auto;
  margin-right: auto;
}

.hero-highlight {
  color: var(--accent);
  font-weight: 600;
}

.hero-cta {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-top: 1.5rem;
}

.btn {
  display: inline-block;
  padding: 0.7rem 1.4rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid var(--border);
}

.btn-primary {
  background: var(--accent);
  color: var(--accent-ink);
  border-color: var(--accent);
}

.btn-secondary {
  background: transparent;
  color: var(--ink);
}

/* ---------- Card grid (News) ---------- */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
  margin-top: 2rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
}

.card-image {
  display: block;
  width: calc(100% + 3rem);
  height: 160px;
  object-fit: cover;
  margin: -1.5rem -1.5rem 1rem;
  border-radius: 12px 12px 0 0;
}

.card-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  background: rgba(13, 148, 136, 0.1);
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
  margin-bottom: 0.75rem;
}

.card-date {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-soft);
}

.card h3 {
  font-size: 1.05rem;
  margin-top: 0.4rem;
}

/* ---------- Research list ---------- */

.research-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-top: 2rem;
}

.research-item {
  display: flex;
  gap: 1.75rem;
  align-items: flex-start;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.25rem 1.75rem;
  cursor: pointer;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.research-item:hover,
.research-item:focus-visible {
  border-color: var(--accent);
  box-shadow: 0 2px 10px rgba(13, 148, 136, 0.12);
  outline: none;
}

.research-index {
  font-family: var(--font-mono);
  font-size: 1.6rem;
  font-weight: 500;
  color: var(--accent);
  line-height: 1;
  flex-shrink: 0;
  min-width: 2.5rem;
}

.research-body h3 {
  font-size: 1.15rem;
  margin: 0 0 0.35rem;
}

.research-oneliner {
  font-size: 0.85rem;
  color: var(--ink-soft);
  margin: 0 0 0.85rem;
}

/* 카드에는 안 보이고, 클릭 시 모달 내용으로만 쓰인다 */
.research-desc {
  display: none;
}

.research-topics {
  display: grid;
  grid-template-columns: repeat(var(--topic-count, 1), 1fr);
  gap: 0.6rem;
}

.research-topic {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.55rem 0.75rem;
  background: var(--bg);
}

.research-topic-name {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--ink);
}

.research-topic-detail {
  font-size: 0.76rem;
  color: var(--ink-soft);
  margin-top: 0.2rem;
}

/* ---------- Publications ---------- */

.pub-tabs {
  display: flex;
  gap: 1.5rem;
  margin-top: 2rem;
  border-bottom: 1px solid var(--border);
}

.pub-tab {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--ink-soft);
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.6rem 0.25rem;
  margin-bottom: -1px;
  border-bottom: 2px solid transparent;
}

.pub-tab:hover {
  color: var(--ink);
}

.pub-tab.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.pub-panel {
  margin-top: 0.5rem;
}

.pub-empty {
  color: var(--ink-soft);
  font-size: 0.9rem;
  padding: 1.5rem 0;
}

.pub-item {
  padding: 1.1rem 0;
  border-bottom: 1px solid var(--border);
}

.pub-item .pub-title {
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.pub-meta {
  font-size: 0.85rem;
  color: var(--ink-soft);
}

.pub-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent);
}

.pub-batch {
  display: inline-block;
  margin-left: 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--accent);
  background: rgba(13, 148, 136, 0.1);
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
}

/* ---------- Members ---------- */

.pi-card {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1.5rem;
  align-items: start;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.75rem;
  margin-top: 2rem;
}

.pi-photo {
  width: 96px;
  height: 96px;
  border-radius: 50%;
  object-fit: cover;
  flex-shrink: 0;
}

.pi-role {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent);
  text-transform: uppercase;
}

.pi-bio {
  font-size: 0.85rem;
  color: var(--ink-soft);
}

.pi-divider {
  border-top: 1px solid var(--border);
  margin: 1.25rem 0;
}

.pi-section-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-soft);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin: 0 0 0.6rem;
}

.pi-edu-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.pi-edu-list li {
  font-size: 0.85rem;
  color: var(--ink-soft);
}

.pi-edu-year {
  font-family: var(--font-mono);
  color: var(--ink);
  font-weight: 600;
  margin-right: 0.6rem;
}

.member-group {
  margin-top: 2.5rem;
}

.member-group-title {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--ink-soft);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin: 0 0 1rem;
}

.member-recruit {
  border: 1px dashed var(--border);
  border-radius: 10px;
  padding: 1.1rem 1.5rem;
  color: var(--ink-soft);
  font-size: 0.9rem;
}

.member-recruit a {
  color: var(--accent);
  font-weight: 600;
}

.member-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  gap: 1rem;
}

.member-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0 0 1rem;
  text-align: center;
  overflow: hidden;
}

.member-card h4 {
  font-size: 0.92rem;
  font-weight: 600;
  margin: 0;
  padding: 0 0.75rem;
}

.member-photo {
  width: 100%;
  height: 140px;
  object-fit: contain;
  background: var(--surface);
  display: block;
  margin: 0 0 0.75rem;
}

.member-photo-empty {
  background: var(--border);
}

.member-dept {
  font-size: 0.78rem;
  color: var(--ink-soft);
  margin: 0.2rem 0 0;
  padding: 0 0.75rem;
}

.member-tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.4rem;
  margin-top: 0.6rem;
  padding: 0 0.75rem;
}

.member-tags span {
  font-size: 0.72rem;
  background: rgba(13, 148, 136, 0.08);
  color: var(--accent);
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
}

/* ---------- Projects / Honors (timeline-ish) ---------- */

.timeline-item {
  border-left: 2px solid var(--border);
  padding: 0 0 1.75rem 1.25rem;
  position: relative;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -5px;
  top: 4px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-soft);
}

.timeline-content {
  display: flex;
  gap: 1.5rem;
  align-items: flex-start;
  flex-wrap: wrap;
}

.timeline-text {
  flex: 1;
  min-width: 220px;
}

.timeline-photo {
  width: 160px;
  height: auto;
  border-radius: 8px;
  border: 1px solid var(--border);
  box-shadow: 0 2px 8px rgba(28, 25, 23, 0.08);
  flex-shrink: 0;
}

/* ---------- Gallery ---------- */

.gallery-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  gap: 0.6rem;
  margin-top: 2rem;
}

.gallery-grid img {
  width: 100%;
  height: 120px;
  object-fit: cover;
  border-radius: 10px;
  border: 1px solid var(--border);
}

.gallery-empty {
  color: var(--ink-soft);
  font-size: 0.9rem;
  border: 1px dashed var(--border);
  border-radius: 10px;
  padding: 2rem;
  text-align: center;
  margin-top: 2rem;
}

/* ---------- Contact ---------- */

.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.25rem;
  margin-top: 2rem;
}

.contact-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem 1.75rem;
}

.contact-card h3 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--ink-soft);
  font-family: var(--font-mono);
  font-weight: 500;
  margin: 0 0 1rem;
}

.contact-address {
  margin-bottom: 1rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border);
}

.contact-pi {
  margin: 0;
}

.recruit-item {
  margin-bottom: 1rem;
}

.recruit-item:last-child {
  margin-bottom: 0;
}

.recruit-title {
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.recruit-item p {
  font-size: 0.9rem;
  color: var(--ink-soft);
  margin: 0;
}

/* ---------- Research modal ---------- */

.modal {
  position: fixed;
  inset: 0;
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
}

.modal[hidden] {
  display: none;
}

.modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(28, 25, 23, 0.45);
  opacity: 0;
  transition: opacity 0.15s ease;
}

.modal-box {
  position: relative;
  background: var(--surface);
  border-radius: 14px;
  padding: 2rem;
  max-width: 480px;
  width: 100%;
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.15s ease, transform 0.15s ease;
}

.modal.open .modal-backdrop {
  opacity: 1;
}

.modal.open .modal-box {
  opacity: 1;
  transform: translateY(0);
}

.modal-close {
  position: absolute;
  top: 0.75rem;
  right: 0.75rem;
  width: 32px;
  height: 32px;
  border: none;
  background: none;
  font-size: 1.5rem;
  line-height: 1;
  color: var(--ink-soft);
  cursor: pointer;
}

.modal-close:hover {
  color: var(--ink);
}

.modal-index {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  margin-bottom: 0.5rem;
}

.modal-box h3 {
  font-size: 1.3rem;
  margin: 0 0 0.85rem;
}

.modal-box p {
  font-size: 0.95rem;
  color: var(--ink-soft);
  margin: 0;
}

/* ---------- Footer ---------- */

.site-footer {
  border-top: 1px solid var(--border);
  padding: 2rem 1.5rem;
  text-align: center;
  font-size: 0.82rem;
  color: var(--ink-soft);
}

/* ---------- Responsive ---------- */

@media (max-width: 720px) {
  .nav-toggle {
    display: flex;
  }

  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    gap: 0;
    padding: 0.5rem 0;
    display: none;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links li {
    width: 100%;
  }

  .nav-links a {
    display: block;
    padding: 0.85rem 1.5rem;
  }

  .pi-card {
    grid-template-columns: 1fr;
  }

  .research-item {
    flex-direction: column;
    gap: 0.5rem;
  }

  .research-topics {
    grid-template-columns: 1fr;
  }
}