:root {
  --bg: #050914;
  --bg-alt: #0d1224;
  --bg-card: #10172b;
  --accent: #5ac8fa;
  --accent-soft: rgba(90, 200, 250, 0.15);
  --text: #e6edf7;
  --muted: #a4acc4;
  --border-subtle: #1f2940;
  --font-sans: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --max-width: 1000px;
}

/* Reset-ish */

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

html, body {
  height: 100%;
}

body {
  font-family: var(--font-sans);
  color: var(--text);
  line-height: 1.6;
  position: relative;
  min-height: 100vh;
  margin: 0;
  background-image: url("img/astro_topology_minimal.png"); 
  background-size: cover;
  background-position: center;
  background-attachment: fixed; /* nice parallax feel on desktop */
}

/* Layered background: soft “orbits” + starfield-style speckles */
body::before {
  content: "";
  position: fixed;
  inset: -12vh -12vw; /* bleed a bit outside to avoid edges */
  background:
    /* bright top-left blob */
    radial-gradient(circle at 10% 5%, rgba(90, 200, 250, 0.35), transparent 55%),
    /* magenta/purple top-right blob */
    radial-gradient(circle at 85% 0%, rgba(140, 92, 255, 0.32), transparent 60%),
    /* teal glow coming from bottom */
    radial-gradient(circle at 50% 115%, rgba(0, 255, 190, 0.18), transparent 60%),
    /* subtle left “orbit” */
    radial-gradient(circle at 0% 70%, rgba(255, 255, 255, 0.06), transparent 55%),
    /* subtle right “orbit” */
    radial-gradient(circle at 100% 60%, rgba(255, 255, 255, 0.05), transparent 55%),
    /* tiny speckles to suggest stars / points */
    radial-gradient(circle at 20% 20%, rgba(255, 255, 255, 0.12), transparent 40%) repeat,
    radial-gradient(circle at 80% 80%, rgba(255, 255, 255, 0.09), transparent 45%) repeat,
    /* base vignette */
    radial-gradient(circle at 50% -20%, #141c3b, transparent 70%);
  background-size:
    55% 55%,   /* bright top-left */
    55% 55%,   /* top-right */
    80% 80%,   /* bottom glow */
    80% 80%,   /* left orbit */
    80% 80%,   /* right orbit */
    240px 240px, /* speckles field 1 */
    260px 260px, /* speckles field 2 */
    100% 100%; /* base vignette */
  opacity: 0.9;
  z-index: -1;
  pointer-events: none;
}

/* Dark vignette on top to keep text readable */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(circle at 50% 0%, rgba(0, 0, 0, 0.4), transparent 55%),
    radial-gradient(circle at 50% 100%, rgba(0, 0, 0, 0.65), transparent 70%);
  mix-blend-mode: multiply;
  opacity: 0.9;
  z-index: -1;
  pointer-events: none;
}


/* Global elements */

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

a:hover {
  text-decoration: underline;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.6rem;
}

/* Header / Navigation */

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(5, 9, 20, 0.93);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.03);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 3.5rem;
}

.brand {
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-size: 0.85rem;
  color: var(--text);
}

.brand:hover {
  text-decoration: none;
}

.site-nav {
  display: flex;
  gap: 0.9rem;
  flex-wrap: wrap;
}

.nav-link {
  font-size: 0.9rem;
  color: var(--muted);
  padding: 0.25rem 0.4rem;
  border-radius: 999px;
}

.nav-link:hover {
  color: var(--accent);
  background: rgba(255, 255, 255, 0.02);
  text-decoration: none;
}

.nav-link.active {
  color: #02030a;
  background: var(--accent);
  font-weight: 600;
}

/* Layout */

main {
  padding: 2.3rem 0 3.5rem;
}

.page-header {
  margin-bottom: 1.6rem;
}

.page-kicker {
  text-transform: uppercase;
  letter-spacing: 0.18em;
  font-size: 0.68rem;
  color: var(--accent);
  margin-bottom: 0.6rem;
}

.page-title {
  font-size: 1.9rem;
  margin-bottom: 0.2rem;
}

.page-subtitle {
  font-size: 0.98rem;
  color: var(--muted);
  max-width: 40rem;
}

/* Sections */

.section {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255, 255, 255, 0.03);
}

.section:first-of-type {
  margin-top: 1.5rem;
}

.section-title {
  font-size: 1.25rem;
  margin-bottom: 0.4rem;
}

.section-intro {
  font-size: 0.95rem;
  color: var(--muted);
  max-width: 44rem;
}

/* Hero (home only) */

.hero {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.hero-heading {
  font-size: 2.2rem;
  line-height: 1.15;
}

.hero-tagline {
  font-size: 1rem;
  color: var(--muted);
  max-width: 40rem;
}

.hero-meta {
  font-size: 0.9rem;
  color: var(--muted);
}

.hero-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 0.3rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.55rem 1.25rem;
  border-radius: 999px;
  border: 1px solid transparent;
  font-size: 0.9rem;
  cursor: pointer;
  text-decoration: none;
}

.btn-primary {
  background: var(--accent);
  color: #02030a;
  font-weight: 600;
}

.btn-outline {
  border-color: var(--accent-soft);
  background: var(--accent-soft);
  color: var(--accent);
}

/* Cards & grids */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
  margin-top: 0.8rem;
}

.card {
  background: rgba(16, 23, 43, 0.92);
  border-radius: 1.1rem;
  padding: 1rem 1.1rem;
  border: 1px solid var(--border-subtle);
  box-shadow: 0 16px 45px rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(6px);
  transition: transform 0.15s ease-out, box-shadow 0.15s ease-out, border-color 0.15s ease-out;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.45);
  border-color: var(--accent-soft);
}

.card-title {
  font-size: 1.02rem;
  margin-bottom: 0.3rem;
}

.card-meta {
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.25rem;
}

.card-body {
  font-size: 0.9rem;
  color: var(--muted);
}

.card-links {
  margin-top: 0.5rem;
  font-size: 0.85rem;
}

.card-links span {
  margin: 0 0.3rem;
}

/* Two-column layout */

.two-column {
  display: grid;
  grid-template-columns: 2.2fr 1.4fr;
  gap: 1.8rem;
  margin-top: 0.8rem;
}

@media (max-width: 820px) {
  .two-column {
    grid-template-columns: 1fr;
  }
}

/* Lists */

.item-list {
  list-style: none;
  margin-top: 0.8rem;
}

.item-list li {
  margin-bottom: 0.6rem;
  font-size: 0.92rem;
  color: var(--muted);
}

.item-list li strong {
  color: var(--text);
}

/* Timeline-style (talks, publications) */

.timeline {
  margin-top: 0.8rem;
  border-left: 1px solid rgba(255, 255, 255, 0.06);
  padding-left: 1.1rem;
}

.timeline-item {
  margin-bottom: 1rem;
  position: relative;
}

.timeline-item::before {
  content: "";
  position: absolute;
  left: -1.55rem;
  top: 0.3rem;
  width: 8px;
  height: 8px;
  border-radius: 999px;
  background: var(--accent);
}

.timeline-title {
  font-size: 0.96rem;
  margin-bottom: 0.15rem;
}

.timeline-meta {
  font-size: 0.8rem;
  color: var(--muted);
  margin-bottom: 0.15rem;
}

.timeline-desc {
  font-size: 0.88rem;
  color: var(--muted);
}

/* Tag pills */

.pills {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin-top: 0.4rem;
}

.pill {
  padding: 0.25rem 0.7rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.78rem;
}

/* Footer */

.site-footer {
  border-top: 1px solid rgba(255, 255, 255, 0.03);
  padding: 1.2rem 0 1.8rem;
  background: #02030a;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.6rem;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  font-size: 0.8rem;
  color: var(--muted);
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.footer-links a {
  font-size: 0.8rem;
}

/* Responsiveness */

@media (max-width: 720px) {
  .nav-container {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.35rem;
    height: auto;
    padding: 0.5rem 0;
  }

  .site-nav {
    justify-content: flex-start;
  }

  .hero-heading {
    font-size: 1.9rem;
  }
}