*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --bg: #f7f7f5;
  --surface: #fff;
  --text: #1c1c1e;
  --text-2: #48484a;
  --text-3: #8e8e93;
  --border: #e5e5e3;
  --serif: 'Cormorant Garamond', 'Noto Serif KR', Georgia, serif;
  --sans-kr: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --sans-en: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --content: 720px;
  --page: 960px;
  --gutter: clamp(1.25rem, 5vw, 2rem);
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--sans-kr);
  color: var(--text);
  background: var(--bg);
  line-height: 1.8;
  letter-spacing: -0.01em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body.en {
  font-family: var(--sans-en);
  letter-spacing: 0;
  line-height: 1.7;
}

a {
  color: inherit;
  text-decoration: none;
}

/* ── Navigation ── */

.nav {
  padding: 2rem var(--gutter);
}

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

.nav-logo {
  font-family: var(--sans-en);
  font-size: 0.875rem;
  font-weight: 500;
  letter-spacing: 0.25em;
}

.nav-lang {
  font-size: 0.8125rem;
  color: var(--text-3);
  letter-spacing: 0.08em;
  transition: color 0.2s ease;
}

.nav-lang:hover {
  color: var(--text);
}

/* ── Hero ── */

.hero {
  padding: 6rem var(--gutter) 5rem;
  text-align: center;
}

.hero-mark {
  font-family: var(--sans-en);
  font-size: clamp(2.5rem, 8vw, 4.5rem);
  font-weight: 300;
  letter-spacing: 0.3em;
  margin-right: -0.3em;
  line-height: 1;
  animation: fadeUp 0.8s ease both;
}

.hero-dot {
  color: var(--text-3);
}

.hero-subtitle {
  font-family: var(--serif);
  font-size: clamp(1.0625rem, 2.5vw, 1.3125rem);
  font-weight: 400;
  color: var(--text-2);
  margin-top: 2rem;
  line-height: 1.8;
  letter-spacing: 0.02em;
  animation: fadeUp 0.8s ease 0.15s both;
}

.hero-tagline {
  font-size: 0.9375rem;
  font-weight: 300;
  color: var(--text-3);
  margin-top: 2rem;
  line-height: 1.9;
  animation: fadeUp 0.8s ease 0.3s both;
}

/* ── Sections ── */

.section {
  padding: 5rem var(--gutter);
}

.section--alt {
  background: var(--surface);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.container {
  max-width: var(--content);
  margin: 0 auto;
}

.container--wide {
  max-width: var(--page);
}

.section-title {
  font-family: var(--serif);
  font-size: 1.375rem;
  font-weight: 400;
  letter-spacing: 0.02em;
  margin-bottom: 2.5rem;
  color: var(--text);
}

/* ── About ── */

.lead {
  font-size: 1.0625rem;
  line-height: 1.9;
  margin-bottom: 1.5rem;
  color: var(--text);
}

.section-content p {
  font-size: 0.9375rem;
  line-height: 1.9;
  color: var(--text-2);
  margin-bottom: 1rem;
}

.section-content p:last-child {
  margin-bottom: 0;
}

/* ── Research ── */

.research-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 3rem;
}

.research-icon {
  width: 36px;
  height: 36px;
  color: var(--text-3);
  margin-bottom: 1.25rem;
}

.research-label {
  font-family: var(--sans-en);
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--text-3);
  letter-spacing: 0.06em;
  margin-bottom: 0.375rem;
  text-transform: uppercase;
}

.research-item h3 {
  font-family: var(--serif);
  font-size: 1.125rem;
  font-weight: 500;
  letter-spacing: 0.01em;
  margin-bottom: 0.75rem;
  color: var(--text);
}

.research-item p {
  font-size: 0.875rem;
  line-height: 1.85;
  color: var(--text-2);
}

/* ── Contact ── */

.contact-text {
  font-size: 0.9375rem;
  color: var(--text-2);
  margin-bottom: 1.25rem;
}

.contact-email {
  font-family: var(--sans-en);
  font-size: 0.9375rem;
  letter-spacing: 0.02em;
  color: var(--text);
  border-bottom: 1px solid var(--border);
  padding-bottom: 2px;
  transition: border-color 0.2s ease;
  display: inline-block;
}

.contact-email:hover {
  border-color: var(--text);
}

/* ── Footer ── */

.footer {
  padding: 3rem var(--gutter);
  border-top: 1px solid var(--border);
}

.footer p {
  font-size: 0.75rem;
  color: var(--text-3);
  letter-spacing: 0.04em;
}

/* ── Animations ── */

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Responsive ── */

@media (min-width: 640px) {
  .hero {
    padding: 8rem var(--gutter) 6rem;
  }

  .section {
    padding: 6rem var(--gutter);
  }

  .research-grid {
    grid-template-columns: 1fr 1fr;
    gap: 3.5rem 3rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

@media print {
  .nav-lang {
    display: none;
  }

  .fade-in {
    opacity: 1;
    transform: none;
  }
}