/* =============================================================
   Zhuofu (Chester) Li — personal site
   A cinematic, deep-space portfolio. Single stylesheet, organised
   into: fonts · tokens · base · primitives · components · sections
   · motion · responsive · reduced-motion.
   ============================================================= */

/* ---------- Fonts ------------------------------------------------ */
@font-face {
  font-family: 'Space Grotesk';
  src: url('../fonts/space-grotesk.woff2') format('woff2');
  font-weight: 300 700;
  font-display: swap;
}
@font-face {
  font-family: 'Inter';
  src: url('../fonts/inter.woff2') format('woff2');
  font-weight: 100 900;
  font-display: swap;
}

/* ---------- Design tokens --------------------------------------- */
:root {
  /* Deep-space surfaces */
  --void: #05060d;
  --deep: #0a0c1a;
  --elevated: #11142a;
  --surface: rgba(20, 24, 48, 0.55);
  --surface-strong: rgba(24, 28, 56, 0.78);
  --hairline: rgba(255, 255, 255, 0.08);
  --hairline-strong: rgba(255, 255, 255, 0.16);

  /* Text */
  --text-bright: #f4f6ff;
  --text: #c7cce0;
  --text-dim: #8b91ad;

  /* Accents */
  --stellar: #6ea8ff;
  --nebula: #b388ff;
  --comet: #ffb86b;
  --grad-nebula: linear-gradient(135deg, #6ea8ff 0%, #b388ff 100%);
  --grad-aurora: linear-gradient(120deg, #6ea8ff 0%, #b388ff 55%, #ffb86b 100%);

  /* Type */
  --font-display: 'Space Grotesk', 'Segoe UI', system-ui, sans-serif;
  --font-body: 'Inter', system-ui, -apple-system, 'Segoe UI', sans-serif;
  --font-mono: ui-monospace, 'SF Mono', 'JetBrains Mono', 'Cascadia Code', Menlo, Consolas, monospace;

  --fs-body: clamp(1rem, 0.96rem + 0.2vw, 1.075rem);
  --fs-lead: clamp(1.1rem, 1rem + 0.55vw, 1.32rem);
  --fs-h3: clamp(1.2rem, 1.05rem + 0.7vw, 1.55rem);
  --fs-h2: clamp(1.95rem, 1.4rem + 2.3vw, 3.05rem);
  --fs-display: clamp(2.9rem, 1.5rem + 6vw, 6.1rem);

  /* Layout */
  --container: 1180px;
  --container-narrow: 760px;
  --gutter: clamp(1.25rem, 0.6rem + 3vw, 3rem);
  --space-section: clamp(4.5rem, 2.5rem + 9vw, 8.5rem);
  --header-h: 72px;

  /* Radii */
  --r-sm: 8px;
  --r: 14px;
  --r-lg: 24px;
  --r-pill: 999px;

  /* Elevation & glow */
  --shadow: 0 24px 60px -28px rgba(0, 0, 0, 0.85);
  --glow-stellar: 0 14px 44px -16px rgba(110, 168, 255, 0.45);
  --glow-nebula: 0 14px 44px -16px rgba(179, 136, 255, 0.4);

  /* Motion */
  --ease: cubic-bezier(0.16, 1, 0.3, 1);
  --dur-fast: 0.18s;
  --dur: 0.4s;
  --dur-slow: 0.8s;
}

/* ---------- Base ------------------------------------------------- */
*,
*::before,
*::after { box-sizing: border-box; }

* { margin: 0; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 1.5rem);
  -webkit-text-size-adjust: 100%;
}

body {
  min-height: 100vh;
  background: var(--void);
  color: var(--text);
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: 1.7;
  font-weight: 400;
  letter-spacing: 0.005em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

/* Two large, fixed nebula glows give the void depth behind the canvas. */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  z-index: -2;
  background:
    radial-gradient(46vw 46vw at 78% 8%, rgba(110, 168, 255, 0.16), transparent 70%),
    radial-gradient(50vw 50vw at 12% 82%, rgba(179, 136, 255, 0.15), transparent 72%),
    var(--void);
}

img { display: block; max-width: 100%; height: auto; }
svg { display: block; }

a {
  color: var(--stellar);
  text-decoration: none;
  transition: color var(--dur-fast) var(--ease);
}
a:hover { color: var(--nebula); }

ul, ol { list-style: none; padding: 0; }

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  cursor: pointer;
}

::selection {
  background: rgba(110, 168, 255, 0.32);
  color: var(--text-bright);
}

:focus-visible {
  outline: 2px solid var(--stellar);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ---------- Typography ------------------------------------------ */
h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--text-bright);
  line-height: 1.12;
  font-weight: 600;
  letter-spacing: -0.02em;
}

p { text-wrap: pretty; }

strong { color: var(--text-bright); font-weight: 600; }

.gradient-text {
  background: var(--grad-nebula);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

/* ---------- Layout primitives ----------------------------------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section {
  position: relative;
  padding-block: var(--space-section);
}

.section--tight { padding-block: clamp(3rem, 2rem + 5vw, 5rem); }

/* Hairline divider between stacked sections */
.section + .section::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: min(100% - 2 * var(--gutter), var(--container));
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--hairline-strong), transparent);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 500;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--stellar);
}
.eyebrow::before {
  content: '';
  width: 1.6rem;
  height: 1px;
  background: currentColor;
  opacity: 0.7;
}

.section-head {
  max-width: 640px;
  margin-bottom: clamp(2.5rem, 1.5rem + 3vw, 4rem);
}
.section-head--center {
  margin-inline: auto;
  text-align: center;
}
.section-head--center .eyebrow { justify-content: center; }
.section-head__title {
  font-size: var(--fs-h2);
  margin-top: 1.1rem;
}
.section-head__intro {
  margin-top: 1rem;
  font-size: var(--fs-lead);
  color: var(--text-dim);
}

.lead {
  font-size: var(--fs-lead);
  color: var(--text);
  line-height: 1.6;
}

/* ---------- Buttons --------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.85rem 1.5rem;
  border-radius: var(--r-pill);
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 500;
  letter-spacing: 0.01em;
  white-space: nowrap;
  transition: transform var(--dur-fast) var(--ease),
              box-shadow var(--dur) var(--ease),
              background var(--dur) var(--ease),
              border-color var(--dur) var(--ease);
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }
.btn .icon { width: 1.05rem; height: 1.05rem; }

.btn--primary {
  background: var(--grad-nebula);
  color: #0a0a18;
  font-weight: 600;
  box-shadow: var(--glow-stellar);
}
.btn--primary:hover {
  color: #0a0a18;
  box-shadow: 0 18px 54px -14px rgba(110, 168, 255, 0.6);
}

.btn--ghost {
  background: var(--surface);
  color: var(--text-bright);
  border: 1px solid var(--hairline-strong);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
}
.btn--ghost:hover {
  color: var(--text-bright);
  border-color: var(--stellar);
  box-shadow: var(--glow-stellar);
}

/* ---------- Chips & tags ---------------------------------------- */
.chips { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.chip {
  padding: 0.34rem 0.78rem;
  border-radius: var(--r-pill);
  background: rgba(110, 168, 255, 0.09);
  border: 1px solid var(--hairline);
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.02em;
  color: var(--text);
  transition: border-color var(--dur-fast) var(--ease),
              color var(--dur-fast) var(--ease);
}
.chip:hover { border-color: var(--stellar); color: var(--text-bright); }

/* ---------- Paper / citation link (reusable) -------------------- */
.paper-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 1.2rem;
  padding: 0.42rem 0.9rem;
  border-radius: var(--r-pill);
  background: rgba(110, 168, 255, 0.08);
  border: 1px solid rgba(110, 168, 255, 0.28);
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.02em;
  color: var(--stellar);
  transition: background var(--dur-fast) var(--ease),
              border-color var(--dur-fast) var(--ease),
              color var(--dur-fast) var(--ease);
}
.paper-link:hover {
  color: var(--text-bright);
  border-color: var(--stellar);
  background: rgba(110, 168, 255, 0.15);
}
.paper-link .icon { width: 0.85rem; height: 0.85rem; }

/* ---------- Icons (SVG sprite) ---------------------------------- */
.icon {
  width: 1.25rem;
  height: 1.25rem;
  flex: none;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.7;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* ---------- Decorative star canvas ------------------------------ */
.starfield {
  position: fixed;
  inset: 0;
  z-index: -1;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

/* ---------- Skip link ------------------------------------------- */
.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 200;
  padding: 0.7rem 1.1rem;
  border-radius: var(--r-sm);
  background: var(--elevated);
  color: var(--text-bright);
  border: 1px solid var(--stellar);
  transform: translateY(-160%);
  transition: transform var(--dur) var(--ease);
}
.skip-link:focus-visible { transform: translateY(0); }

/* ---------- Intro overlay --------------------------------------- */
.intro {
  position: fixed;
  inset: 0;
  z-index: 300;
  display: grid;
  place-items: center;
  background: var(--void);
  transition: opacity 0.55s var(--ease), visibility 0.55s;
  /* Failsafe: clears itself even if main.js never runs (delay only). */
  animation: intro-failsafe 0.4s var(--ease) 4s forwards;
}
.intro.is-done {
  opacity: 0;
  visibility: hidden;
}
.intro__mark {
  width: 76px;
  height: 76px;
  animation: intro-pulse 1.6s var(--ease) infinite;
}
.intro__bar {
  position: absolute;
  bottom: 28%;
  width: 132px;
  height: 2px;
  border-radius: 2px;
  background: var(--hairline-strong);
  overflow: hidden;
}
.intro__bar::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 2px;
  background: var(--grad-nebula);
  transform-origin: left;
  animation: intro-load 0.9s var(--ease) forwards;
}

/* ============================================================
   HEADER / NAVIGATION
   ============================================================ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-h);
  display: flex;
  align-items: center;
  transition: background var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              box-shadow var(--dur) var(--ease);
  border-bottom: 1px solid transparent;
}
.site-header.is-scrolled {
  background: rgba(8, 9, 20, 0.72);
  -webkit-backdrop-filter: blur(16px);
  backdrop-filter: blur(16px);
  border-bottom-color: var(--hairline);
  box-shadow: 0 10px 40px -24px rgba(0, 0, 0, 0.9);
}

.header-inner {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--text-bright);
  font-family: var(--font-display);
  font-weight: 600;
}
.brand:hover { color: var(--text-bright); }
.brand__mark { width: 30px; height: 30px; }
.brand__name { font-size: 1.02rem; letter-spacing: -0.01em; }
.brand__name span { color: var(--text-dim); font-weight: 400; }

.nav { display: flex; align-items: center; gap: 0.4rem; }
.nav__list { display: flex; align-items: center; gap: 0.2rem; }
.nav__link {
  position: relative;
  display: block;
  padding: 0.5rem 0.85rem;
  color: var(--text-dim);
  font-size: 0.92rem;
  border-radius: var(--r-sm);
  transition: color var(--dur-fast) var(--ease);
}
.nav__link::after {
  content: '';
  position: absolute;
  left: 0.85rem;
  right: 0.85rem;
  bottom: 0.15rem;
  height: 2px;
  border-radius: 2px;
  background: var(--grad-nebula);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--dur) var(--ease);
}
.nav__link:hover { color: var(--text-bright); }
.nav__link.is-active { color: var(--text-bright); }
.nav__link.is-active::after { transform: scaleX(1); }

.nav__cta { margin-left: 0.6rem; padding: 0.6rem 1.15rem; font-size: 0.9rem; }

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  border-radius: var(--r-sm);
  border: 1px solid var(--hairline-strong);
  position: relative;
}
.nav-toggle span,
.nav-toggle span::before,
.nav-toggle span::after {
  content: '';
  position: absolute;
  left: 50%;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: var(--text-bright);
  transition: transform var(--dur) var(--ease), opacity var(--dur-fast);
}
.nav-toggle span { top: 50%; transform: translate(-50%, -50%); }
.nav-toggle span::before { transform: translateX(-50%) translateY(-6px); }
.nav-toggle span::after { transform: translateX(-50%) translateY(6px); }
body.nav-open .nav-toggle span { background: transparent; }
body.nav-open .nav-toggle span::before { transform: translateX(-50%) rotate(45deg); }
body.nav-open .nav-toggle span::after { transform: translateX(-50%) rotate(-45deg); }

/* ============================================================
   HERO
   ============================================================ */
.hero {
  position: relative;
  min-height: 100vh;
  min-height: 100svh;
  display: flex;
  align-items: center;
  padding-top: calc(var(--header-h) + 2rem);
  padding-bottom: clamp(3rem, 6vw, 6rem);
}
.hero__inner {
  display: grid;
  gap: clamp(2.5rem, 5vw, 4.5rem);
  align-items: center;
}
.hero__eyebrow { margin-bottom: 1.5rem; }
.hero__title {
  font-size: var(--fs-display);
  font-weight: 600;
  letter-spacing: -0.035em;
  line-height: 1;
}
.hero__title .line { display: block; }
.hero__role {
  margin-top: 1.4rem;
  font-family: var(--font-display);
  font-size: clamp(1.05rem, 0.9rem + 0.7vw, 1.4rem);
  font-weight: 500;
  color: var(--text-bright);
}
.hero__lead {
  margin-top: 1.4rem;
  max-width: 46ch;
  font-size: var(--fs-lead);
  color: var(--text-dim);
}
.hero__actions {
  margin-top: 2.2rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
}
.hero__socials {
  margin-top: 2rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.icon-link {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: var(--r-pill);
  border: 1px solid var(--hairline);
  color: var(--text-dim);
  transition: color var(--dur-fast) var(--ease),
              border-color var(--dur-fast) var(--ease),
              transform var(--dur-fast) var(--ease);
}
.icon-link:hover {
  color: var(--text-bright);
  border-color: var(--stellar);
  transform: translateY(-2px);
}
.icon-link .icon { width: 1.15rem; height: 1.15rem; }

/* Portrait with orbital rings */
.hero__portrait {
  justify-self: center;
  position: relative;
  width: min(78vw, 380px);
  aspect-ratio: 1;
  display: grid;
  place-items: center;
}
.portrait {
  position: relative;
  z-index: 2;
  width: 68%;
  aspect-ratio: 1;
  border-radius: 50%;
  padding: 4px;
  background: var(--grad-nebula);
  box-shadow: var(--glow-stellar);
}
.portrait img {
  width: 100%;
  height: 100%;
  border-radius: 50%;
  object-fit: cover;
  background: var(--elevated);
}
.orbit-ring {
  position: absolute;
  border: 1px solid var(--hairline-strong);
  border-radius: 50%;
  animation: spin linear infinite;
}
.orbit-ring--1 { inset: 12%; animation-duration: 26s; }
.orbit-ring--2 { inset: 0; animation-duration: 40s; animation-direction: reverse; }
.orbit-ring__dot {
  position: absolute;
  top: -4px;
  left: 50%;
  width: 8px;
  height: 8px;
  margin-left: -4px;
  border-radius: 50%;
  background: var(--stellar);
  box-shadow: 0 0 12px 2px rgba(110, 168, 255, 0.7);
}
.orbit-ring--2 .orbit-ring__dot { background: var(--nebula); box-shadow: 0 0 12px 2px rgba(179, 136, 255, 0.7); }

.scroll-cue {
  position: absolute;
  left: 50%;
  bottom: 1.6rem;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--text-dim);
}
.scroll-cue__line {
  width: 1px;
  height: 38px;
  background: linear-gradient(var(--stellar), transparent);
  animation: cue-slide 2.2s var(--ease) infinite;
}

/* ============================================================
   ABOUT
   ============================================================ */
.about__grid {
  display: grid;
  gap: clamp(1.5rem, 3vw, 3rem);
}
.about__bio p + p { margin-top: 1.1rem; }
.about__bio .lead { margin-bottom: 1.3rem; }

.facts {
  align-self: start;
  padding: 1.8rem;
  border-radius: var(--r-lg);
  background: var(--surface);
  border: 1px solid var(--hairline);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
}
.facts__title {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--text-dim);
  margin-bottom: 1.1rem;
}
.facts__item {
  display: flex;
  gap: 0.85rem;
  padding-block: 0.8rem;
  border-top: 1px solid var(--hairline);
}
.facts__item:first-of-type { border-top: 0; padding-top: 0; }
.facts__item .icon {
  flex: none;
  width: 1.2rem;
  height: 1.2rem;
  margin-top: 0.15rem;
  color: var(--stellar);
}
.facts__label {
  display: block;
  font-size: 0.78rem;
  color: var(--text-dim);
}
.facts__value { color: var(--text-bright); font-weight: 500; }

/* Stat strip */
.stats {
  margin-top: clamp(2rem, 4vw, 3.2rem);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 1px;
  background: var(--hairline);
  border: 1px solid var(--hairline);
  border-radius: var(--r-lg);
  overflow: hidden;
}
.stat {
  padding: 1.6rem 1.4rem;
  background: var(--deep);
  text-align: center;
}
.stat__num {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 1.2rem + 1.8vw, 2.6rem);
  font-weight: 600;
  line-height: 1;
}
.stat__label {
  margin-top: 0.55rem;
  font-size: 0.84rem;
  color: var(--text-dim);
}

/* ============================================================
   RESEARCH — featured projects + interest grid
   ============================================================ */
.projects {
  display: flex;
  flex-direction: column;
  gap: 1.4rem;
}
.project {
  position: relative;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: clamp(1.2rem, 3vw, 2.6rem);
  padding: clamp(1.5rem, 1rem + 2vw, 2.4rem);
  border-radius: var(--r-lg);
  background: var(--surface);
  border: 1px solid var(--hairline);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  overflow: hidden;
  transition: transform var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              box-shadow var(--dur) var(--ease);
}
.project::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--grad-aurora);
  opacity: 0;
  transition: opacity var(--dur) var(--ease);
}
.project:hover {
  transform: translateY(-4px);
  border-color: var(--hairline-strong);
  box-shadow: var(--shadow);
}
.project:hover::before { opacity: 1; }

.project__index {
  font-family: var(--font-display);
  font-size: clamp(2rem, 1.4rem + 2vw, 3.1rem);
  font-weight: 600;
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1px var(--hairline-strong);
}
.project__head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.7rem 1rem;
}
.project__title {
  font-size: var(--fs-h3);
  flex: 1 1 14rem;
}
.project__status {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.28rem 0.7rem;
  border-radius: var(--r-pill);
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  border: 1px solid var(--hairline-strong);
  color: var(--text-dim);
}
.project__status .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--text-dim);
}
.project__status--active { color: var(--comet); border-color: rgba(255, 184, 107, 0.4); }
.project__status--active .dot {
  background: var(--comet);
  box-shadow: 0 0 8px 1px var(--comet);
  animation: blink 2.4s var(--ease) infinite;
}
.project__status--first { color: var(--stellar); border-color: rgba(110, 168, 255, 0.45); }
.project__status--first .dot {
  background: var(--stellar);
  box-shadow: 0 0 8px 1px var(--stellar);
  animation: blink 2.4s var(--ease) infinite;
}
.project__meta {
  margin-top: 0.7rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-dim);
}
.project__meta span { color: var(--stellar); }
.project__desc { margin-top: 1rem; }

.project__metrics {
  margin-top: 1.4rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 1rem;
  padding: 1.1rem 0;
  border-top: 1px solid var(--hairline);
  border-bottom: 1px solid var(--hairline);
}
.metric__value {
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--text-bright);
}
.metric__label {
  font-size: 0.78rem;
  color: var(--text-dim);
}
.project__tags { margin-top: 1.3rem; }

/* Research interests */
.subhead {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  margin-top: clamp(2.5rem, 5vw, 4rem);
  margin-bottom: 1.6rem;
  font-size: var(--fs-h3);
}
.subhead::before {
  content: '';
  width: 1.8rem;
  height: 2px;
  border-radius: 2px;
  background: var(--grad-nebula);
}
.subhead + .interests { margin-top: 0; }

.interests {
  margin-top: clamp(2.5rem, 5vw, 4rem);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(248px, 1fr));
  gap: 1.2rem;
}
.interest {
  padding: 1.7rem;
  border-radius: var(--r);
  background: var(--surface);
  border: 1px solid var(--hairline);
  transition: transform var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              background var(--dur) var(--ease);
}
.interest:hover {
  transform: translateY(-4px);
  border-color: var(--hairline-strong);
  background: var(--surface-strong);
}
.interest__icon {
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  border-radius: var(--r-sm);
  background: rgba(110, 168, 255, 0.1);
  border: 1px solid var(--hairline);
  color: var(--stellar);
  margin-bottom: 1.1rem;
}
.interest__icon .icon { width: 1.4rem; height: 1.4rem; }
.interest__title { font-size: 1.1rem; margin-bottom: 0.5rem; }
.interest__text { font-size: 0.94rem; color: var(--text-dim); }

/* ============================================================
   PUBLICATIONS
   ============================================================ */
.publications { display: flex; flex-direction: column; }
.pub {
  padding: 1.6rem 0;
  border-top: 1px solid var(--hairline);
}
.pub:first-child { border-top: 0; padding-top: 0; }
.pub__badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.3rem 0.7rem;
  border-radius: var(--r-pill);
  background: rgba(110, 168, 255, 0.12);
  border: 1px solid rgba(110, 168, 255, 0.42);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--stellar);
  margin-bottom: 0.8rem;
}
.pub__badge .icon { width: 0.85rem; height: 0.85rem; }
.pub__title {
  font-size: clamp(1.05rem, 0.95rem + 0.45vw, 1.2rem);
  line-height: 1.35;
  margin-bottom: 0.55rem;
  font-weight: 500;
}
.pub__title a {
  color: var(--text-bright);
  text-decoration: none;
  transition: color var(--dur-fast) var(--ease);
}
.pub__title a:hover {
  color: var(--stellar);
  text-decoration: underline;
  text-underline-offset: 0.25em;
}
.pub__title .icon {
  display: inline-block;
  width: 0.85rem;
  height: 0.85rem;
  margin-left: 0.35rem;
  vertical-align: -0.05em;
  color: var(--text-dim);
  transition: color var(--dur-fast) var(--ease);
}
.pub__title a:hover .icon { color: var(--stellar); }
.pub__authors {
  font-size: 0.94rem;
  color: var(--text-dim);
  margin-bottom: 0.4rem;
  line-height: 1.6;
}
.pub__authors strong { color: var(--text-bright); font-weight: 600; }
.pub__venue {
  font-size: 0.92rem;
  color: var(--text-dim);
}
.pub__venue .pub__journal { font-style: italic; color: var(--text); }
.pub__venue time { color: var(--stellar); }

/* ============================================================
   SKILLS
   ============================================================ */
.skills {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.2rem;
}
.skill-card {
  padding: 1.8rem;
  border-radius: var(--r-lg);
  background: var(--surface);
  border: 1px solid var(--hairline);
  transition: transform var(--dur) var(--ease),
              border-color var(--dur) var(--ease);
}
.skill-card:hover { transform: translateY(-4px); border-color: var(--hairline-strong); }
.skill-card__head {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  margin-bottom: 1.2rem;
}
.skill-card__icon {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  flex: none;
  border-radius: var(--r-sm);
  background: var(--grad-nebula);
  color: #0a0a18;
}
.skill-card__icon .icon { width: 1.35rem; height: 1.35rem; }
.skill-card__title { font-size: 1.12rem; }

/* ============================================================
   EDUCATION & HONORS TIMELINE
   ============================================================ */
.timeline {
  position: relative;
  margin-left: 0.5rem;
  padding-left: 2.2rem;
}
.timeline::before {
  content: '';
  position: absolute;
  left: 5px;
  top: 0.4rem;
  bottom: 0.4rem;
  width: 1px;
  background: linear-gradient(var(--stellar), var(--nebula), transparent);
}
.timeline__item {
  position: relative;
  padding-bottom: 2.2rem;
}
.timeline__item:last-child { padding-bottom: 0; }
.timeline__marker {
  position: absolute;
  left: calc(-2.2rem + 5px);
  top: 0.3rem;
  width: 12px;
  height: 12px;
  margin-left: -6px;
  border-radius: 50%;
  background: var(--void);
  border: 2px solid var(--stellar);
  box-shadow: 0 0 0 4px rgba(110, 168, 255, 0.12);
}
.timeline__date {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  color: var(--stellar);
}
.timeline__title { font-size: 1.16rem; margin-top: 0.35rem; }
.timeline__org { color: var(--text); font-weight: 500; margin-top: 0.2rem; }
.timeline__detail { font-size: 0.93rem; color: var(--text-dim); margin-top: 0.4rem; }

.awards {
  margin-top: 2.5rem;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
}
.award {
  display: flex;
  gap: 0.8rem;
  padding: 1.1rem 1.2rem;
  border-radius: var(--r);
  background: var(--surface);
  border: 1px solid var(--hairline);
}
.award .icon { flex: none; width: 1.3rem; height: 1.3rem; color: var(--comet); margin-top: 0.1rem; }
.award__title { color: var(--text-bright); font-weight: 500; font-size: 0.95rem; }
.award__year { font-family: var(--font-mono); font-size: 0.78rem; color: var(--text-dim); }

/* ============================================================
   ASTROPHOTOGRAPHY GALLERY
   ============================================================ */
/* Masonry via CSS columns — keeps each photo's native aspect ratio. */
.gallery { column-gap: clamp(0.7rem, 1.5vw, 1.1rem); }
@media (min-width: 600px) { .gallery { column-count: 2; } }
.gallery__item {
  position: relative;
  display: block;
  width: 100%;
  padding: 0;
  margin-bottom: clamp(0.7rem, 1.5vw, 1.1rem);
  break-inside: avoid;
  border-radius: var(--r);
  overflow: hidden;
  border: 1px solid var(--hairline);
  background: var(--elevated);
}
.gallery__item img {
  width: 100%;
  height: auto;
  transition: transform var(--dur-slow) var(--ease);
}
.gallery__item:hover img { transform: scale(1.06); }
.gallery__caption {
  position: absolute;
  inset: auto 0 0 0;
  padding: 1.6rem 1.1rem 0.9rem;
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 0.5rem;
  background: linear-gradient(transparent, rgba(5, 6, 13, 0.92));
  font-size: 0.88rem;
  color: var(--text-bright);
  opacity: 0;
  transform: translateY(8px);
  transition: opacity var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.gallery__item:hover .gallery__caption,
.gallery__item:focus-visible .gallery__caption { opacity: 1; transform: translateY(0); }
.gallery__caption .icon { width: 1.1rem; height: 1.1rem; color: var(--stellar); }

/* Lightbox */
.lightbox {
  position: fixed;
  inset: 0;
  z-index: 250;
  display: grid;
  place-items: center;
  padding: clamp(1rem, 4vw, 3rem);
  background: rgba(4, 5, 12, 0.92);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--dur) var(--ease), visibility var(--dur);
}
.lightbox.is-open { opacity: 1; visibility: visible; }
.lightbox__stage {
  max-width: 1100px;
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}
.lightbox__img {
  max-width: 100%;
  max-height: 76vh;
  width: auto;
  border-radius: var(--r);
  border: 1px solid var(--hairline-strong);
  box-shadow: var(--shadow);
}
.lightbox__caption {
  font-size: 0.92rem;
  color: var(--text-dim);
  text-align: center;
}
.lightbox__btn {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border-radius: var(--r-pill);
  background: var(--surface-strong);
  border: 1px solid var(--hairline-strong);
  color: var(--text-bright);
  transition: border-color var(--dur-fast) var(--ease),
              transform var(--dur-fast) var(--ease);
}
.lightbox__btn:hover { border-color: var(--stellar); transform: scale(1.06); }
.lightbox__btn .icon { width: 1.3rem; height: 1.3rem; }
.lightbox__close { position: absolute; top: 1.2rem; right: 1.2rem; }
.lightbox__nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
}
.lightbox__nav--prev { left: clamp(0.6rem, 2vw, 1.6rem); }
.lightbox__nav--next { right: clamp(0.6rem, 2vw, 1.6rem); }

/* ============================================================
   CONTACT
   ============================================================ */
.contact__panel {
  position: relative;
  padding: clamp(2.2rem, 1.5rem + 4vw, 4.2rem);
  border-radius: var(--r-lg);
  background:
    radial-gradient(120% 140% at 0% 0%, rgba(110, 168, 255, 0.16), transparent 55%),
    radial-gradient(120% 140% at 100% 100%, rgba(179, 136, 255, 0.16), transparent 55%),
    var(--surface-strong);
  border: 1px solid var(--hairline-strong);
  text-align: center;
  overflow: hidden;
}
.contact__title { font-size: var(--fs-h2); }
.contact__text {
  margin: 1rem auto 0;
  max-width: 48ch;
  font-size: var(--fs-lead);
  color: var(--text-dim);
}
.contact__email {
  margin-top: 2rem;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.65rem 0.65rem 0.65rem 1.3rem;
  border-radius: var(--r-pill);
  background: var(--deep);
  border: 1px solid var(--hairline-strong);
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--text-bright);
}
.copy-btn {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: var(--r-pill);
  background: var(--surface);
  border: 1px solid var(--hairline);
  color: var(--text-dim);
  transition: color var(--dur-fast) var(--ease),
              border-color var(--dur-fast) var(--ease);
}
.copy-btn:hover { color: var(--text-bright); border-color: var(--stellar); }
.copy-btn .icon { width: 1.05rem; height: 1.05rem; }
.copy-btn.is-copied { color: var(--comet); border-color: var(--comet); }

.contact__links {
  margin-top: 2.2rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.7rem;
}

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer {
  position: relative;
  border-top: 1px solid var(--hairline);
  padding-block: clamp(2.5rem, 4vw, 3.5rem);
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}
.footer__brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--text);
}
.footer__brand .brand__mark { width: 26px; height: 26px; }
.footer__nav { display: flex; flex-wrap: wrap; gap: 0.3rem 1.2rem; }
.footer__nav a { color: var(--text-dim); font-size: 0.9rem; }
.footer__nav a:hover { color: var(--text-bright); }
.footer__meta {
  width: 100%;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.6rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--hairline);
  font-size: 0.82rem;
  color: var(--text-dim);
}
/* Easter-egg trigger — a small, unobtrusive star */
.easter-star {
  color: var(--text-dim);
  padding: 0.2rem;
  line-height: 0;
  transition: color var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.easter-star:hover { color: var(--comet); transform: rotate(90deg) scale(1.2); }
.easter-star .icon { width: 1rem; height: 1rem; }

/* Supernova flash spawned by the easter egg */
.supernova {
  position: fixed;
  left: 50%;
  top: 50%;
  z-index: 400;
  width: 14px;
  height: 14px;
  margin: -7px 0 0 -7px;
  border-radius: 50%;
  background: #fff;
  pointer-events: none;
  animation: supernova 1.6s var(--ease) forwards;
}

/* ============================================================
   SCROLL REVEAL
   ============================================================ */
[data-reveal] {
  opacity: 0;
  transform: translateY(26px);
  transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
  transition-delay: var(--reveal-delay, 0s);
}
[data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

/* ============================================================
   KEYFRAMES
   ============================================================ */
@keyframes spin { to { transform: rotate(360deg); } }
@keyframes blink { 0%, 100% { opacity: 1; } 50% { opacity: 0.35; } }
@keyframes intro-pulse {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.12); opacity: 0.7; }
}
@keyframes intro-load { from { transform: scaleX(0); } to { transform: scaleX(1); } }
@keyframes intro-failsafe {
  to { opacity: 0; visibility: hidden; pointer-events: none; }
}
@keyframes cue-slide {
  0% { transform: scaleY(0); transform-origin: top; }
  45% { transform: scaleY(1); transform-origin: top; }
  55% { transform: scaleY(1); transform-origin: bottom; }
  100% { transform: scaleY(0); transform-origin: bottom; }
}
@keyframes supernova {
  0% { box-shadow: 0 0 0 0 rgba(255,255,255,0.9), 0 0 0 0 rgba(110,168,255,0.6); }
  60% { box-shadow: 0 0 80px 40px rgba(255,255,255,0.55), 0 0 200px 120px rgba(110,168,255,0.4); }
  100% {
    box-shadow: 0 0 0 2000px rgba(5,6,13,0), 0 0 300px 220px rgba(179,136,255,0);
    opacity: 0;
    transform: scale(2.4);
  }
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (min-width: 880px) {
  .hero__inner { grid-template-columns: 1.12fr 0.88fr; }
  .about__grid { grid-template-columns: 1.5fr 1fr; }
  .about__bio { padding-right: 1rem; }
}

@media (min-width: 980px) {
  .project { grid-template-columns: minmax(56px, auto) 1fr; }
}

/* Tablet & mobile navigation */
@media (max-width: 879px) {
  .nav-toggle { display: block; z-index: 110; }
  .nav {
    position: fixed;
    inset: 0;
    flex-direction: column;
    justify-content: center;
    gap: 0.6rem;
    padding: 2rem;
    background: rgba(8, 9, 20, 0.97);
    -webkit-backdrop-filter: blur(20px);
    backdrop-filter: blur(20px);
    transform: translateX(100%);
    visibility: hidden;
    transition: transform var(--dur-slow) var(--ease), visibility var(--dur-slow);
  }
  body.nav-open .nav { transform: translateX(0); visibility: visible; }
  .nav__list {
    flex-direction: column;
    gap: 0.4rem;
    width: min(100%, 320px);
  }
  .nav__link {
    text-align: center;
    font-size: 1.15rem;
    padding: 0.85rem;
  }
  .nav__link::after { display: none; }
  .nav__link.is-active { background: var(--surface); }
  .nav__cta {
    margin-left: 0;
    margin-top: 0.6rem;
    font-size: 1rem;
    padding: 0.8rem 1.6rem;
  }
  body.nav-open { overflow: hidden; }
}

@media (max-width: 620px) {
  .project { grid-template-columns: 1fr; gap: 0.4rem; }
  .project__index { font-size: 1.6rem; }
  .hero__actions .btn { flex: 1 1 auto; justify-content: center; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
  .lightbox__nav--prev { left: 0.5rem; }
  .lightbox__nav--next { right: 0.5rem; }
  .lightbox__btn { width: 42px; height: 42px; }
}

/* Graceful fallback where backdrop-filter is unsupported */
@supports not ((-webkit-backdrop-filter: blur(1px)) or (backdrop-filter: blur(1px))) {
  .site-header.is-scrolled,
  .facts, .project, .interest, .skill-card,
  .btn--ghost, .nav { background: var(--elevated); }
}

/* ============================================================
   REDUCED MOTION
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  [data-reveal] { opacity: 1; transform: none; }
  .orbit-ring { animation: none; }
  .scroll-cue { display: none; }
}