/* Minimal academic personal website for Sippengg.github.io */

:root {
  --bg: #f7f5ef;
  --surface: #ffffff;
  --surface-2: #fbfaf6;
  --text: #1f2933;
  --muted: #667085;
  --line: #e4dfd5;
  --accent: #243b53;
  --accent-2: #486581;
  --accent-soft: #e8eef3;
  --shadow: 0 24px 70px rgba(31, 41, 51, 0.08);
  --radius: 24px;
  --max-width: 1120px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(72, 101, 129, 0.12), transparent 32rem),
    linear-gradient(180deg, var(--bg), #fffaf0 100%);
  line-height: 1.65;
}

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

a:hover {
  color: var(--accent-2);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(18px);
  background: rgba(247, 245, 239, 0.78);
  border-bottom: 1px solid rgba(228, 223, 213, 0.7);
}

.nav {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-no-brand {
  justify-content: flex-end;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand-mark {
  width: 40px;
  height: 40px;
  border-radius: 14px;
  display: grid;
  place-items: center;
  color: #fff;
  background: var(--accent);
  font-size: 0.85rem;
  letter-spacing: 0.04em;
}

.brand-text {
  font-size: 1rem;
}

.nav-links {
  display: flex;
  gap: 24px;
  align-items: center;
  font-size: 0.95rem;
  color: var(--muted);
}

.nav-links a {
  padding: 6px 0;
  border-bottom: 1px solid transparent;
}

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

.nav-toggle {
  display: none;
  border: 0;
  background: transparent;
  padding: 8px;
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  margin: 5px 0;
  background: var(--accent);
  border-radius: 2px;
}

.section {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 92px 24px;
}

.section.narrow {
  max-width: 860px;
}

.hero {
  padding-top: 96px;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) 360px;
  gap: 48px;
  align-items: center;
}

.eyebrow {
  margin: 0 0 14px;
  color: var(--accent-2);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  margin: 0;
  line-height: 1.16;
  color: var(--text);
}

h1 {
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(3.4rem, 8vw, 6.9rem);
  font-weight: 500;
  letter-spacing: -0.07em;
}

h2 {
  font-size: clamp(2rem, 4vw, 3.2rem);
  letter-spacing: -0.045em;
}

h3 {
  font-size: 1.08rem;
  letter-spacing: -0.02em;
}

.hero-text {
  margin: 24px 0 0;
  max-width: 680px;
  color: var(--muted);
  font-size: clamp(1.05rem, 1.8vw, 1.24rem);
}

.hero-actions {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 34px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 18px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.72);
  color: var(--accent);
  font-weight: 700;
  box-shadow: 0 8px 24px rgba(31, 41, 51, 0.05);
}

.button.primary {
  color: #fff;
  background: var(--accent);
  border-color: var(--accent);
}

.button:hover {
  transform: translateY(-1px);
}

.profile-card {
  padding: 30px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.78);
  box-shadow: var(--shadow);
}

.avatar {
  width: 108px;
  height: 108px;
  border-radius: 32px;
  display: grid;
  place-items: center;
  background: linear-gradient(145deg, var(--accent), #102a43);
  color: #fff;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 2rem;
  letter-spacing: -0.04em;
  margin-bottom: 24px;
}

.photo-avatar {
  width: 300px;
  height: 300px;
  overflow: hidden;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: #f0f0f0;
}

.photo-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.profile-card h2 {
  font-size: 1.6rem;
  margin-bottom: 10px;
}

.profile-card p {
  margin: 6px 0;
  color: var(--muted);
}

.profile-meta {
  display: grid;
  gap: 10px;
  margin-top: 22px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--accent);
}

.section-heading {
  margin-bottom: 34px;
}

.prose {
  font-size: 1.05rem;
  color: var(--muted);
}

.prose p {
  margin: 0 0 18px;
}

.note {
  padding: 18px 20px;
  border-left: 4px solid var(--accent);
  border-radius: 16px;
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 700;
}

.cards {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.research-cards {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.card {
  padding: 24px;
  min-height: 180px;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: rgba(255, 255, 255, 0.72);
  box-shadow: 0 16px 40px rgba(31, 41, 51, 0.05);
}

.card p {
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 0.96rem;
}

.publication-list {
  display: grid;
  gap: 18px;
}

.publication {
  display: grid;
  grid-template-columns: 78px minmax(0, 1fr);
  gap: 20px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: rgba(255, 255, 255, 0.78);
}

.pub-year {
  color: var(--accent);
  font-weight: 800;
  font-size: 0.95rem;
}

.pub-body h3 {
  margin-bottom: 10px;
}

.authors,
.venue {
  margin: 4px 0;
  color: var(--muted);
}

.venue {
  color: var(--accent-2);
  font-weight: 700;
}

.contact-section {
  padding-bottom: 70px;
}

.contact-card {
  display: flex;
  justify-content: space-between;
  gap: 30px;
  padding: 36px;
  border-radius: var(--radius);
  background: var(--accent);
  color: #fff;
  box-shadow: var(--shadow);
}

.contact-card h2,
.contact-card p,
.contact-card .eyebrow {
  color: #fff;
}

.contact-card p {
  max-width: 600px;
  opacity: 0.82;
}

.contact-links {
  min-width: 250px;
  display: grid;
  align-content: center;
  gap: 12px;
}

.contact-links a {
  padding: 14px 16px;
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.08);
  font-weight: 700;
}

.contact-links a:hover {
  color: #fff;
  background: rgba(255, 255, 255, 0.14);
}

.footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 24px;
  color: var(--muted);
  font-size: 0.92rem;
  border-top: 1px solid var(--line);
}

@media (max-width: 960px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }

  .profile-card {
    max-width: 440px;
  }

  .cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .research-cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .contact-card {
    flex-direction: column;
  }
}

@media (max-width: 720px) {
  .section {
    padding: 70px 20px;
  }

  .nav {
    padding: 14px 20px;
  }

  .nav-no-brand {
    justify-content: space-between;
  }

  .nav-toggle {
    display: block;
  }

  .nav-links {
    position: absolute;
    left: 20px;
    right: 20px;
    top: 72px;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 10px;
    padding: 16px;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: rgba(255, 255, 255, 0.96);
    box-shadow: var(--shadow);
  }

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

  .cards {
    grid-template-columns: 1fr;
  }

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

  .publication {
    grid-template-columns: 1fr;
  }

  .pub-year {
    margin-bottom: -8px;
  }

  h1 {
    font-size: 4rem;
  }

  .photo-avatar {
    width: 100%;
    max-width: 300px;
    height: auto;
    aspect-ratio: 1 / 1;
  }
}

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

  .button:hover {
    transform: none;
  }
}