/* ============================================================
   Vo Thanh Nguyen — Academic research portfolio
   ============================================================ */

:root {
  --ink: #1a2230;            /* primary text, near-black navy */
  --ink-soft: #34404f;       /* secondary headings */
  --muted: #5c6773;          /* body-muted */
  --faint: #8b94a1;          /* faint meta */
  --accent: #2b4f8c;         /* deep academic blue */
  --accent-deep: #1f3a68;
  --accent-soft: #eef2f8;    /* accent tint */
  --border: #e2e6ec;         /* hairlines */
  --border-strong: #cfd6e0;
  --paper: #ffffff;
  --paper-soft: #f7f8fa;     /* alternate section */
  --paper-sunken: #f0f2f5;   /* image wells */
  --header-bg: rgba(255,255,255,.88);
  --shadow-soft: 0 1px 2px rgba(26,34,48,.05), 0 8px 24px rgba(26,34,48,.06);
  --shadow-lift: 0 2px 4px rgba(26,34,48,.06), 0 16px 40px rgba(26,34,48,.12);
  --radius: 6px;
  --max-width: 1080px;
  --font-serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
  --font-mono: "IBM Plex Mono", "SFMono-Regular", Consolas, monospace;
  color-scheme: light;
}

[data-theme="dark"] {
  --ink: #e8ebf0;
  --ink-soft: #c3cad4;
  --muted: #9aa4b1;
  --faint: #6d7684;
  --accent: #7fa3d8;
  --accent-deep: #a5c2ea;
  --accent-soft: rgba(127,163,216,.14);
  --border: #2a3340;
  --border-strong: #3b4656;
  --paper: #14181f;
  --paper-soft: #191e27;
  --paper-sunken: #0f131a;
  --header-bg: rgba(20,24,31,.88);
  --shadow-soft: 0 1px 2px rgba(0,0,0,.3), 0 8px 24px rgba(0,0,0,.25);
  --shadow-lift: 0 2px 4px rgba(0,0,0,.35), 0 16px 40px rgba(0,0,0,.45);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 84px; }
body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
::selection { background: var(--accent-soft); color: var(--ink); }

a { color: inherit; text-decoration: none; }
img { max-width: 100%; }
.container { width: min(calc(100% - 48px), var(--max-width)); margin-inline: auto; }

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

.site-header {
  position: sticky; top: 0; z-index: 100;
  background: var(--header-bg);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}
.theme-toggle {
  display: inline-flex; align-items: center; justify-content: center;
  width: 34px; height: 34px; padding: 0;
  color: var(--muted); background: transparent;
  border: 1px solid var(--border-strong); border-radius: 50%;
  font-size: 1rem; line-height: 1; cursor: pointer;
  transition: color .18s ease, border-color .18s ease, background .18s ease, transform .18s ease;
}
.theme-toggle:hover { color: var(--accent); border-color: var(--accent); background: var(--accent-soft); }
.theme-toggle:active { transform: scale(.94); }
.theme-toggle .icon-sun { display: none; }
.theme-toggle .icon-moon { display: block; }
[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }
.nav { display: flex; min-height: 68px; align-items: center; justify-content: space-between; gap: 24px; }
.name { display: flex; align-items: baseline; gap: 10px; font-weight: 600; font-size: 1.02rem; letter-spacing: .01em; }
.name::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: var(--accent); align-self: center; }
.name-short { display: none; }
.nav-links { display: flex; gap: 30px; color: var(--muted); font-size: .82rem; font-weight: 600; letter-spacing: .08em; text-transform: uppercase; }
.nav-links a { position: relative; padding: 4px 0; transition: color .18s ease; }
.nav-links a::after {
  content: ""; position: absolute; left: 0; bottom: -2px; width: 100%; height: 1.5px;
  background: var(--accent); transform: scaleX(0); transform-origin: left; transition: transform .22s ease;
}
.nav-links a:hover { color: var(--ink); }
.nav-links a:hover::after { transform: scaleX(1); }

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

.hero {
  display: grid; grid-template-columns: 1.4fr .6fr; gap: 64px;
  padding: 88px 0 40px; align-items: center;
}
.label {
  margin: 0 0 16px; color: var(--accent);
  font-family: var(--font-mono); font-size: .74rem; font-weight: 500;
  letter-spacing: .16em; text-transform: uppercase;
}
h1, h2, h3 { margin-top: 0; line-height: 1.15; text-wrap: balance; }
h1, h2 { font-family: var(--font-serif); font-weight: 600; }
h1 {
  margin-bottom: 26px; font-size: clamp(3.2rem, 6.5vw, 5.4rem);
  letter-spacing: -.03em; color: var(--ink);
}
.intro { max-width: 640px; margin: 0; color: var(--muted); font-size: 1.12rem; line-height: 1.75; }
.intro-mentor { margin-top: 18px; padding-top: 18px; border-top: 1px solid var(--border); font-size: .95rem; color: var(--muted); }
.hero-links { display: flex; margin-top: 34px; align-items: center; gap: 26px; font-size: .9rem; font-weight: 600; }
.hero-links a:not(.button) { color: var(--accent); border-bottom: 1px solid transparent; transition: border-color .18s ease, color .18s ease; }
.hero-links a:not(.button):hover { border-bottom-color: var(--accent); }
.button {
  padding: 11px 22px; color: #fff; background: var(--accent);
  border: 1px solid var(--accent); border-radius: var(--radius);
  box-shadow: 0 1px 2px rgba(43,79,140,.25);
  transition: background .18s ease, transform .18s ease, box-shadow .18s ease;
}
.button:hover { background: var(--accent-deep); transform: translateY(-1px); box-shadow: var(--shadow-lift); }
.button:active { transform: translateY(0); }

.hero-summary { padding-left: 30px; border-left: 1px solid var(--border); }
.profile-photo {
  display: block; width: 100%; aspect-ratio: 4 / 5; margin-bottom: 22px;
  object-fit: cover; border: 1px solid var(--border-strong); border-radius: var(--radius);
  box-shadow: var(--shadow-soft);
}
.hero-summary dl { margin: 0; }
.hero-summary dl div { padding: 15px 0; border-bottom: 1px solid var(--border); }
.hero-summary dl div:first-child { padding-top: 0; }
.hero-summary dl div:last-child { border-bottom: 0; }
.hero-summary dt {
  margin-bottom: 5px; color: var(--faint);
  font-family: var(--font-mono); font-size: .68rem; font-weight: 500;
  text-transform: uppercase; letter-spacing: .14em;
}
.hero-summary dd { margin: 0; font-size: .92rem; color: var(--ink-soft); }

/* ---------- Sections ---------- */

.section { padding-block: 84px; }
#research { padding-top: 40px; }
.section-gray { background: var(--paper-soft); border-block: 1px solid var(--border); }
.section-title { display: flex; gap: 18px; margin-bottom: 40px; align-items: baseline; }
.section-title .label { margin: 0; }
.section-title h2 { margin: 0; font-size: clamp(2rem, 3.4vw, 2.9rem); letter-spacing: -.02em; }

/* ---------- Projects / research entries ---------- */

.projects { border-top: 1px solid var(--border); }
.project { display: grid; grid-template-columns: 44px 1fr; gap: 24px; padding: 52px 0; border-bottom: 1px solid var(--border); }
.project-number {
  align-self: start; padding-top: 6px; color: var(--faint);
  font-family: var(--font-mono); font-size: .9rem; font-weight: 500; line-height: 1;
}
.project-content { width: 100%; }
.project-with-image { display: grid; grid-template-columns: minmax(0, .9fr) minmax(340px, 1.1fr); gap: 34px; align-items: start; }
.project-meta {
  margin: 0 0 14px; color: var(--accent);
  font-family: var(--font-mono); font-size: .72rem; font-weight: 500;
  text-transform: uppercase; letter-spacing: .12em;
}
.project h3 { margin: 0 0 16px; font-size: 1.55rem; letter-spacing: -.01em; color: var(--ink); }
.project-figure { align-self: center; margin: 0; }
.project-figure img {
  display: block; width: 100%; max-height: 520px; padding: 18px; object-fit: contain;
  background: var(--paper-sunken); border: 1px solid var(--border); border-radius: var(--radius);
  transition: transform .3s ease, box-shadow .3s ease, border-color .3s ease;
}
.project-figure:hover img { box-shadow: var(--shadow-lift); border-color: var(--border-strong); }
.project-figure img.project-photo { aspect-ratio: 4 / 3; padding: 0; object-fit: cover; }
.project-figure img.project-result { padding: 0; }
.project-figure img.forecast-gif { max-height: none; aspect-ratio: 16 / 9; padding: 0; object-fit: cover; background: #10161f; }
.project-figure img.qualification-gif { max-height: none; aspect-ratio: 16 / 9; padding: 0; object-fit: cover; background: #10161f; }

.forecast-comparison { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; align-items: start; }
.forecast-column { display: grid; gap: 12px; }
.forecast-label {
  color: var(--ink-soft); font-family: var(--font-mono); font-size: .68rem; font-weight: 500;
  letter-spacing: .14em; text-align: center; text-transform: uppercase;
}

.project-album { padding: 18px 14px 10px; }
.album-stack { position: relative; display: block; width: 100%; aspect-ratio: 3 / 2; padding: 0; background: transparent; border: 0; cursor: zoom-in; }
.project-figure .album-photo {
  position: absolute; inset: 0; max-height: none; aspect-ratio: 3 / 2; padding: 0; object-fit: cover;
  transition: transform .55s ease, opacity .55s ease;
  box-shadow: 0 10px 28px rgba(26,34,48,.22); pointer-events: none;
}
.album-photo[data-depth="0"] { z-index: 5; transform: translate(0, 0) rotate(0); opacity: 1; }
.album-photo[data-depth="1"] { z-index: 4; transform: translate(8px, -7px) rotate(1.8deg); opacity: .92; }
.album-photo[data-depth="2"] { z-index: 3; transform: translate(-7px, -12px) rotate(-2deg); opacity: .82; }
.album-photo[data-depth="3"] { z-index: 2; transform: translate(3px, -16px) rotate(.8deg); opacity: .7; }
.album-photo[data-depth="4"] { z-index: 1; transform: translate(-2px, -20px) rotate(1.2deg); opacity: .6; }
.album-stack:focus-visible { outline: 3px solid var(--accent); outline-offset: 6px; }
.album-controls { display: flex; align-items: center; justify-content: center; gap: 18px; margin-top: 14px; }
.album-nav {
  display: inline-flex; align-items: center; justify-content: center;
  width: 36px; height: 36px; padding: 0;
  color: var(--ink-soft); background: var(--paper);
  border: 1px solid var(--border-strong); border-radius: 50%;
  font-size: 1.4rem; line-height: 1; cursor: pointer;
  transition: color .18s ease, border-color .18s ease, background .18s ease, transform .18s ease;
}
.album-nav:hover { color: var(--accent); border-color: var(--accent); background: var(--accent-soft); }
.album-nav:active { transform: scale(.92); }
.album-counter {
  min-width: 44px; color: var(--faint); text-align: center;
  font-family: var(--font-mono); font-size: .78rem; font-weight: 500; letter-spacing: .08em;
}

.zoomable-media { cursor: zoom-in; }
.zoomable-media:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }

/* lightbox */
.media-lightbox {
  width: min(94vw, 1600px); max-width: none; max-height: 94vh; padding: 48px 16px 16px; overflow: auto;
  background: #0f141c; border: 0; border-radius: 10px; box-shadow: 0 32px 96px rgba(0,0,0,.5);
}
.media-lightbox::backdrop { background: rgba(10,14,20,.88); backdrop-filter: blur(4px); }
.media-lightbox-content { display: grid; place-items: center; }
.media-lightbox-content.is-gallery { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
.media-lightbox-content img { display: block; width: auto; max-width: 100%; height: auto; max-height: calc(94vh - 60px); margin: auto; object-fit: contain; border-radius: 2px; }
.media-lightbox-content.is-gallery img { width: 100%; max-height: none; }
.media-lightbox-close {
  position: absolute; top: 12px; right: 16px; padding: 6px 12px;
  color: #fff; background: transparent; border: 1px solid rgba(255,255,255,.4); border-radius: 4px;
  font-family: var(--font-mono); font-size: .75rem; letter-spacing: .08em; text-transform: uppercase; cursor: pointer;
  transition: background .18s ease;
}
.media-lightbox-close:hover { background: rgba(255,255,255,.14); }
body.lightbox-open { overflow: hidden; }

/* project prose + chips */
.project-content > p:not(.project-meta), .project-details > p:not(.project-meta) {
  max-width: 62ch; margin: 0; color: var(--muted); text-align: justify; hyphens: auto;
}
.project ul { display: flex; margin: 20px 0; padding: 0; flex-wrap: wrap; gap: 8px; list-style: none; }
.project li {
  padding: 5px 12px; color: var(--ink-soft);
  background: var(--paper); border: 1px solid var(--border-strong); border-radius: 999px;
  font-size: .8rem; font-weight: 500;
  transition: border-color .18s ease, color .18s ease, background .18s ease;
}
.project li:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }
.project-content > a, .project-details > a { color: var(--accent); font-size: .87rem; font-weight: 600; }
.project-links { display: flex; flex-wrap: wrap; gap: 8px 22px; }
.project-links a {
  color: var(--accent); font-size: 1rem; font-weight: 600;
  border-bottom: 1px solid transparent; transition: border-color .18s ease;
}
.project-links a:hover { border-bottom-color: var(--accent); }

/* ---------- Timeline ---------- */

.timeline { border-top: 1px solid var(--border); }
.timeline article {
  position: relative; display: grid; grid-template-columns: .75fr 1.2fr 1.4fr; gap: 36px;
  padding: 30px 0 30px 28px; border-bottom: 1px solid var(--border);
}
.timeline article::before {
  content: ""; position: absolute; left: 0; top: 0; bottom: 0;
  width: 1px; background: var(--border-strong);
}
.timeline article::after {
  content: ""; position: absolute; left: -4.5px; top: 36px;
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--paper); border: 2px solid var(--accent);
}
.timeline time {
  display: flex; align-items: center; color: var(--ink-soft);
  font-family: var(--font-mono); font-size: .8rem; font-weight: 500; letter-spacing: .04em;
}
.timeline h3 { margin-bottom: 6px; font-size: 1.02rem; letter-spacing: -.01em; }
.timeline p { margin: 0; color: var(--muted); font-size: .88rem; }

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

footer { padding: 40px 0; border-top: 1px solid var(--border); }
.footer-content { display: flex; align-items: center; justify-content: space-between; gap: 16px; color: var(--muted); font-size: .82rem; }
.footer-content div { display: flex; gap: 26px; }
.footer-content a { color: var(--muted); transition: color .18s ease; }
.footer-content a:hover { color: var(--accent); }

/* ---------- Focus & motion ---------- */

a:focus-visible, button:focus-visible, .button:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; border-radius: 2px; }

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

@media (max-width: 900px) {
  .hero { grid-template-columns: 1fr; gap: 44px; padding: 64px 0 32px; }
  .hero-summary { padding: 0; border: 0; }
  .profile-photo { width: min(260px, 70vw); }
  .project-with-image { grid-template-columns: 1fr; gap: 26px; }
  .timeline article { grid-template-columns: 1fr; gap: 10px; padding-left: 24px; }
  .timeline article::after { top: 30px; }
}

@media (max-width: 640px) {
  .name-full { display: none; } .name-short { display: inline; }
  .nav { min-height: 60px; } .nav-links { gap: 16px; } .nav-links a:nth-child(2) { display: none; }
  h1 { font-size: 3.2rem; }
  .hero-links { flex-wrap: wrap; gap: 18px; }
  .section { padding-block: 60px; } #research { padding-top: 32px; }
  .section-title { align-items: flex-start; flex-direction: column; gap: 8px; margin-bottom: 30px; }
  .project { grid-template-columns: 1fr; gap: 14px; padding: 40px 0; }
  .project-figure img { max-height: 340px; padding: 10px; }
  .intro, .project-content > p:not(.project-meta), .project-details > p:not(.project-meta) { text-align: left; hyphens: none; }
  .footer-content { align-items: flex-start; flex-direction: column; gap: 12px; }
  .media-lightbox-content.is-gallery { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
}