/* ============================================================
   Vy Tuong Phan — Personal Website
   Theme: Deep Navy / Blue
   ============================================================ */

:root {
  --navy-deep:    #07101f;
  --navy-mid:     #0d1b38;
  --glass-bg:     rgba(9, 18, 40, 0.84);
  --glass-light:  rgba(14, 26, 56, 0.70);
  --glass-border: rgba(90, 155, 220, 0.20);
  --accent:       #5b9bd5;
  --accent-hover: #88c0f0;
  --text-primary: #dde6f4;
  --text-secondary: #7a9ec4;
  --text-muted:   #3f5f84;
  --nav-height:   62px;
}

/* ---- Reset ---- */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: 19px; }

body {
  min-height: 100vh;
  font-family: 'Crimson Pro', 'Georgia', 'Times New Roman', serif;
  font-size: 20px;
  line-height: 1.75;
  color: var(--text-primary);
  background: var(--navy-deep);
  -webkit-font-smoothing: antialiased;
}

/* ---- Background canvas (fixed, below everything) ---- */
#bg-canvas {
  position: fixed;
  top: 0; left: 0;
  width: 100vw; height: 100vh;
  z-index: 0;
  pointer-events: none;
}

/* ---- Site wrapper ---- */
.site-wrapper {
  position: relative;
  z-index: 1;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ============================================================
   NAVIGATION
   ============================================================ */
nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-height);
  z-index: 100;
  background: rgba(7, 16, 31, 0.90);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--glass-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2.5rem;
}

.nav-brand {
  font-family: 'Inter', 'Helvetica Neue', sans-serif;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--text-primary);
  text-decoration: none;
  transition: color 0.2s;
}
.nav-brand:hover { color: var(--accent-hover); }

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav-links a {
  font-family: 'Inter', 'Helvetica Neue', sans-serif;
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.2s;
  padding: 4px 0;
  border-bottom: 2px solid transparent;
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--accent-hover);
  border-bottom-color: var(--accent);
}

/* ---- Hamburger (mobile) ---- */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 22px; height: 2px;
  background: var(--text-secondary);
  border-radius: 2px;
  transition: 0.3s;
}

/* ============================================================
   MAIN CONTENT
   ============================================================ */
main {
  flex: 1;
  padding-top: var(--nav-height);
}

/* ---- Generic section ---- */
.section {
  max-width: 860px;
  margin: 0 auto;
  padding: 5rem 2rem 3rem;
}

.section-label {
  font-family: 'Inter', sans-serif;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.6rem;
}

h1 {
  font-size: 2.6rem;
  font-weight: 400;
  color: #fff;
  line-height: 1.2;
  margin-bottom: 1.2rem;
}
h2 {
  font-size: 1.5rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.8rem;
  margin-top: 2.4rem;
}
h3 {
  font-size: 1.1rem;
  font-weight: 600;
  font-family: 'Inter', sans-serif;
  color: var(--accent);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: 0.6rem;
  margin-top: 2rem;
}

p { margin-bottom: 1rem; }

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s;
}
a:hover { color: var(--accent-hover); text-decoration: underline; }

/* ---- Glass card ---- */
.glass-card {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  padding: 2.2rem 2.4rem;
  margin-bottom: 1.8rem;
}

/* ---- Divider ---- */
hr {
  border: none;
  border-top: 1px solid var(--glass-border);
  margin: 2.5rem 0;
}

/* ============================================================
   HOME PAGE
   ============================================================ */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 0 2rem;
  max-width: 860px;
  margin: 0 auto;
}

.hero {
  flex-direction: row !important;
  align-items: center;
  gap: 3rem;
}

.hero-text {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.hero-avatar-wrap {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero-avatar {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  object-fit: cover;
  object-position: center top;
  border: 2px solid var(--glass-border);
  mix-blend-mode: luminosity;
  opacity: 0.92;
  transition: opacity 0.3s, mix-blend-mode 0.3s;
}
.hero-avatar:hover {
  opacity: 1;
  mix-blend-mode: normal;
}

[data-theme="light"] .hero-avatar {
  mix-blend-mode: multiply;
}
[data-theme="light"] .hero-avatar:hover {
  mix-blend-mode: normal;
}

.hero-greeting {
  font-family: 'Inter', sans-serif;
  font-size: 0.85rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1rem;
}

.hero-name {
  font-size: clamp(2.4rem, 6vw, 4rem);
  font-weight: 400;
  color: #fff;
  line-height: 1.1;
  margin-bottom: 1.4rem;
}

.hero-tagline {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin-bottom: 2.4rem;
}

.hero-links {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  font-family: 'Inter', sans-serif;
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.55rem 1.4rem;
  border-radius: 6px;
  transition: all 0.2s;
  text-decoration: none;
}
.btn-outline {
  border: 1px solid var(--accent);
  color: var(--accent);
  background: transparent;
}
.btn-outline:hover {
  background: var(--accent);
  color: #fff;
  text-decoration: none;
}

/* Research interests blurb */
.home-bio {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 2rem 4rem;
}

/* Passions row */
.passions-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-top: 1.2rem;
}

.passion-card {
  border-radius: 10px;
  overflow: hidden;
  position: relative;
  aspect-ratio: 1 / 1;
}

.passion-card img {
  width: 100%; height: 100%;
  object-fit: cover;
  display: block;
  transition: transform 0.4s;
}
.passion-card:hover img { transform: scale(1.05); }

.passion-label {
  position: absolute;
  bottom: 0; left: 0; right: 0;
  background: linear-gradient(transparent, rgba(7,16,31,0.85));
  color: #fff;
  font-family: 'Inter', sans-serif;
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  text-align: center;
  padding: 0.8rem 0.4rem 0.6rem;
}

/* ============================================================
   RESEARCH PAGE
   ============================================================ */
.paper-entry {
  padding: 1.4rem 0;
  border-bottom: 1px solid var(--glass-border);
}
.paper-entry:last-child { border-bottom: none; }

.paper-title {
  font-size: 1.05rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.3rem;
  line-height: 1.5;
}
.paper-title a { color: var(--text-primary); }
.paper-title a:hover { color: var(--accent-hover); }

.paper-meta {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-bottom: 0.2rem;
}

.paper-tag {
  display: inline-block;
  font-family: 'Inter', sans-serif;
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 4px;
  background: rgba(91, 155, 213, 0.15);
  color: var(--accent);
  border: 1px solid rgba(91, 155, 213, 0.3);
  margin-bottom: 0.5rem;
}

/* Horizontal image scroller */
.image-scroll {
  display: flex;
  gap: 0.8rem;
  overflow-x: auto;
  padding: 1rem 0 0.5rem;
  scrollbar-width: thin;
  scrollbar-color: var(--accent) var(--navy-mid);
}
.image-scroll::-webkit-scrollbar { height: 4px; }
.image-scroll::-webkit-scrollbar-track { background: var(--navy-mid); }
.image-scroll::-webkit-scrollbar-thumb { background: var(--accent); border-radius: 2px; }

.image-scroll img {
  height: 180px;
  width: auto;
  border-radius: 8px;
  object-fit: cover;
  flex-shrink: 0;
  border: 1px solid var(--glass-border);
  transition: transform 0.3s;
}
.image-scroll img:hover { transform: scale(1.03); }

.project-tasks {
  margin: 0.6rem 0 0 1rem;
  color: var(--text-secondary);
  font-size: 0.92rem;
}
.project-tasks li { margin-bottom: 0.2rem; }

/* ============================================================
   CV PAGE
   ============================================================ */
.cv-section { margin-bottom: 2.4rem; }

.cv-entry {
  display: grid;
  grid-template-columns: 130px 1fr;
  gap: 0 1.4rem;
  padding: 1rem 0;
  border-bottom: 1px solid rgba(90,155,220,0.1);
}
.cv-entry:last-child { border-bottom: none; }

.cv-date {
  font-family: 'Inter', sans-serif;
  font-size: 0.8rem;
  color: var(--text-muted);
  padding-top: 0.15rem;
  line-height: 1.5;
}

.cv-content { }
.cv-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.2rem;
}
.cv-subtitle {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.4rem;
}
.cv-detail {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.6;
}
.cv-bullets {
  font-size: 0.88rem;
  color: var(--text-secondary);
  padding-left: 1rem;
  margin-top: 0.3rem;
}
.cv-bullets li { margin-bottom: 0.2rem; }

.cv-pdf-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: 'Inter', sans-serif;
  font-size: 0.82rem;
  margin-bottom: 2rem;
}

/* ============================================================
   NOTES PAGE
   ============================================================ */
.notes-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.2rem;
  margin-top: 1.4rem;
}

.note-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 10px;
  padding: 1.4rem 1.6rem;
  text-decoration: none;
  color: var(--text-primary);
  transition: border-color 0.2s, transform 0.2s;
  display: block;
}
.note-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  text-decoration: none;
  color: var(--text-primary);
}

.note-card-label {
  font-family: 'Inter', sans-serif;
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.5rem;
}
.note-card-title {
  font-size: 1rem;
  font-weight: 500;
  line-height: 1.4;
  margin-bottom: 0.4rem;
}
.note-card-source {
  font-size: 0.82rem;
  color: var(--text-secondary);
}
.note-card.coming-soon {
  opacity: 0.55;
  cursor: default;
}
.note-card.coming-soon:hover { transform: none; }
.note-card.coming-soon a { pointer-events: auto; cursor: pointer; }

/* Notes content (math page) */
.notes-content {
  max-width: 780px;
  margin: 0 auto;
  padding: 4rem 2rem;
}

.notes-content h1 { margin-bottom: 0.6rem; }
.notes-content h2 {
  font-size: 1.4rem;
  color: var(--text-primary);
  border-bottom: 1px solid var(--glass-border);
  padding-bottom: 0.4rem;
  margin-top: 3rem;
}
.notes-content h3 {
  font-size: 1.05rem;
  color: var(--accent);
  text-transform: none;
  letter-spacing: 0;
  margin-top: 2rem;
}
.notes-content h4 {
  font-family: 'Inter', sans-serif;
  font-size: 0.9rem;
  color: var(--text-secondary);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: 1.5rem;
  margin-bottom: 0.5rem;
}
.notes-content p { margin-bottom: 0.8rem; }
.notes-content ul, .notes-content ol {
  padding-left: 1.6rem;
  margin-bottom: 0.8rem;
}
.notes-content li { margin-bottom: 0.2rem; }

.notes-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0 1.4rem;
  font-size: 0.9rem;
}
.notes-content th {
  background: rgba(91,155,213,0.15);
  color: var(--accent);
  font-family: 'Inter', sans-serif;
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.5rem 0.8rem;
  text-align: left;
  border-bottom: 1px solid var(--glass-border);
}
.notes-content td {
  padding: 0.45rem 0.8rem;
  border-bottom: 1px solid rgba(90,155,220,0.08);
  color: var(--text-secondary);
}
.notes-content tr:last-child td { border-bottom: none; }

.notes-content code {
  font-family: 'Fira Code', 'Cascadia Code', monospace;
  font-size: 0.85em;
  background: rgba(91,155,213,0.12);
  border: 1px solid rgba(91,155,213,0.2);
  padding: 0.1em 0.4em;
  border-radius: 4px;
  color: var(--accent-hover);
}

.notes-content blockquote {
  border-left: 3px solid var(--accent);
  padding: 0.4rem 1rem;
  margin: 1rem 0;
  color: var(--text-secondary);
  font-style: italic;
}

/* KaTeX overrides */
.katex { font-size: 1em !important; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 0.5rem 0; }

/* Loading indicator */
.loading {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4rem;
  color: var(--text-secondary);
  font-family: 'Inter', sans-serif;
  gap: 0.8rem;
}
.spinner {
  width: 18px; height: 18px;
  border: 2px solid var(--glass-border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ============================================================
   BOOKSHELF PAGE
   ============================================================ */
.shelf-genre {
  margin-bottom: 2.8rem;
}

.shelf-genre-title {
  font-family: 'Inter', sans-serif;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--glass-border);
}

.book-list {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 0.6rem;
}

.book-item {
  padding: 0.7rem 1rem;
  background: var(--glass-light);
  border: 1px solid rgba(90,155,220,0.1);
  border-radius: 8px;
  transition: border-color 0.2s;
}
.book-item:hover { border-color: var(--accent); }

.book-title {
  font-size: 0.9rem;
  color: var(--text-primary);
  line-height: 1.4;
}
.book-link {
  display: block;
  text-decoration: none;
  color: inherit;
}
.book-item:has(.book-link):hover { border-color: var(--accent); }
.book-link:hover .book-title { color: var(--accent); text-decoration: none; }
.book-link:hover { text-decoration: none; }

.book-author {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 0.15rem;
  font-family: 'Inter', sans-serif;
}

/* ============================================================
   FOOTER
   ============================================================ */
footer {
  text-align: center;
  padding: 2.5rem 1rem;
  font-family: 'Inter', sans-serif;
  font-size: 0.78rem;
  color: var(--text-muted);
  letter-spacing: 0.06em;
  border-top: 1px solid var(--glass-border);
}

/* ============================================================
   LIGHTBOX
   ============================================================ */
#lightbox-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 1000;
  background: rgba(0, 0, 0, 0.88);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  align-items: center;
  justify-content: center;
  cursor: zoom-out;
}
#lightbox-overlay.active {
  display: flex;
}
#lightbox-img {
  max-width: 80vw;
  max-height: 90vh;
  object-fit: contain;
  border-radius: 6px;
  box-shadow: 0 8px 40px rgba(0,0,0,0.6);
  cursor: default;
}

#lightbox-prev,
#lightbox-next {
  background: rgba(255,255,255,0.12);
  border: 1px solid rgba(255,255,255,0.25);
  border-radius: 50%;
  color: #fff;
  cursor: pointer;
  font-size: 1.4rem;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: background 0.2s;
}
#lightbox-prev:hover,
#lightbox-next:hover {
  background: rgba(255,255,255,0.28);
}

/* ============================================================
   NAV RIGHT GROUP + THEME TOGGLE
   ============================================================ */
.nav-right {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.theme-toggle {
  background: none;
  border: 1px solid var(--glass-border);
  border-radius: 6px;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 1rem;
  line-height: 1;
  padding: 4px 7px;
  transition: border-color 0.2s, color 0.2s;
}
.theme-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* ============================================================
   LIGHT MODE
   ============================================================ */
[data-theme="light"] {
  --navy-deep:      #f0f4fb;
  --navy-mid:       #e2ecf7;
  --glass-bg:       rgba(255, 255, 255, 0.82);
  --glass-light:    rgba(240, 246, 255, 0.72);
  --glass-border:   rgba(91, 155, 213, 0.22);
  --accent:         #2563a8;
  --accent-hover:   #1a4f8c;
  --text-primary:   #0d1b38;
  --text-secondary: #3d5a80;
  --text-muted:     #7a9ec4;
}

[data-theme="light"] body {
  background: var(--navy-deep);
  color: var(--text-primary);
}

[data-theme="light"] nav {
  background: rgba(240, 244, 251, 0.92);
}

[data-theme="light"] h1,
[data-theme="light"] .hero-name {
  color: var(--text-primary);
}

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 700px) {
  body { font-size: 18px; }

  nav { padding: 0 1.2rem; }

  .nav-links {
    display: none;
    position: fixed;
    top: var(--nav-height);
    left: 0; right: 0;
    background: rgba(7,16,31,0.97);
    backdrop-filter: blur(20px);
    flex-direction: column;
    gap: 0;
    border-bottom: 1px solid var(--glass-border);
  }
  .nav-links.open { display: flex; }
  [data-theme="light"] .nav-links { background: rgba(240, 244, 251, 0.97); }
  .nav-links li { border-bottom: 1px solid rgba(90,155,220,0.08); }
  .nav-links a {
    display: block;
    padding: 1rem 1.4rem;
    font-size: 0.9rem;
  }

  .nav-toggle { display: flex; }

  .hero { padding: 0 1.2rem; flex-direction: column !important; text-align: center; }
  .hero-avatar-wrap { order: -1; }
  .hero-avatar { width: 130px; height: 130px; }
  .hero-name { font-size: 2.2rem; }

  .section { padding: 3rem 1.2rem 2rem; }

  .passions-grid { grid-template-columns: repeat(3, 1fr); gap: 0.5rem; }

  .cv-entry { grid-template-columns: 1fr; gap: 0.2rem; }
  .cv-date { font-size: 0.75rem; }

  h1 { font-size: 2rem; }
}