/* ===================================================================
   Manh Hung Nguyen — Academic Page
   Inspired by Cecilia Baldoni's warm, organic aesthetic
   =================================================================== */

/* ---------- CSS Custom Properties ---------- */
:root {
  /* Warm earthy palette */
  --color-bg:        #FAF6F0;
  --color-bg-alt:    #F2EBE1;
  --color-text:      #3D3529;
  --color-text-light:#7A6F60;
  --color-heading:   #2C2418;
  --color-accent:    #8B7355;
  --color-accent-dk: #6B5740;
  --color-link:      #6B8F71;
  --color-link-hover:#4A6B4F;
  --color-highlight: #C4973B;
  --color-tag-bg:    #EDE7DD;
  --color-tag-text:  #6B5740;
  --color-card-bg:   #FFFFFF;
  --color-border:    #E0D5C7;
  --color-white:     #FFFFFF;
  --color-hero-bg:   #F5EDE2;

  /* Fonts */
  --font-serif: 'Crimson Pro', Georgia, 'Times New Roman', serif;
  --font-sans:  'DM Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  /* Spacing */
  --space-xs:  0.2rem;
  --space-sm:  0.4rem;
  --space-md:  0.75rem;
  --space-lg:  1.5rem;
  --space-xl:  2rem;
  --space-2xl: 3rem;
  --space-3xl: 2rem;

  /* Sizing */
  --max-width: 1100px;
  --nav-height: 56px;

  /* Transitions */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --transition: 0.3s var(--ease);
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4 {
  font-family: var(--font-serif);
  color: var(--color-heading);
  line-height: 1.2;
}

a {
  color: var(--color-link);
  text-decoration: none;
  transition: color var(--transition);
}
a:hover { color: var(--color-link-hover); }

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

.link {
  color: var(--color-link);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: var(--color-link);
  transition: all var(--transition);
}
.link:hover {
  color: var(--color-link-hover);
  text-decoration-color: var(--color-link-hover);
}

::selection {
  background: var(--color-accent);
  color: var(--color-white);
}

/* ---------- Container ---------- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* ---------- Section ---------- */
.section {
  padding: 1.2rem 0;
}
.section-alt {
  background-color: var(--color-bg-alt);
}

.section-header {
  margin-bottom: var(--space-lg);
}
.section-number {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-accent);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: var(--space-xs);
}
.section-header h2 {
  font-size: 2.4rem;
  font-weight: 600;
  position: relative;
  display: inline-block;
}
.section-header h2::after {
  content: '';
  position: absolute;
  bottom: -6px;
  left: 0;
  width: 50px;
  height: 3px;
  background: var(--color-accent);
  border-radius: 2px;
}

.section-intro {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  color: var(--color-text-light);
  max-width: 700px;
  margin-bottom: var(--space-lg);
  line-height: 1.8;
}

/* ---------- NAV ---------- */
#navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-lg);
  background: rgba(250, 246, 240, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition), box-shadow var(--transition);
}
#navbar.scrolled {
  border-bottom-color: var(--color-border);
  box-shadow: 0 2px 20px rgba(0,0,0,0.04);
}

.nav-logo {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--color-heading);
  text-decoration: none;
}
.nav-logo:hover { color: var(--color-accent); }

.nav-links {
  display: flex;
  gap: var(--space-lg);
}
.nav-links a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-light);
  text-decoration: none;
  position: relative;
  padding: var(--space-xs) 0;
  transition: color var(--transition);
}
.nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: width var(--transition);
}
.nav-links a:hover,
.nav-links a.active {
  color: var(--color-heading);
}
.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

#nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
#nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-heading);
  border-radius: 2px;
  transition: all var(--transition);
}

/* ---------- HERO ---------- */
.hero {
  min-height: auto;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding-top: var(--nav-height);
  padding-bottom: 2rem;
  background: var(--color-hero-bg);
  position: relative;
  overflow: hidden;
}

/* Subtle background texture */
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at 20% 80%, rgba(139, 115, 85, 0.08) 0%, transparent 60%),
    radial-gradient(ellipse at 80% 20%, rgba(107, 143, 113, 0.06) 0%, transparent 50%);
  pointer-events: none;
}

.hero-content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  display: grid;
  grid-template-columns: 160px auto 1fr;
  gap: var(--space-lg);
  align-items: center;
  justify-items: start;
  position: relative;
  z-index: 1;
}

.hero-greeting {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-style: italic;
  color: var(--color-accent);
  margin-bottom: var(--space-sm);
}

.hero h1 {
  font-size: 3.0rem;
  font-weight: 700;
  margin-bottom: var(--space-sm);
  letter-spacing: -0.02em;
}

.hero-tagline {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  line-height: 1.5;
  color: var(--color-text-light);
  margin-bottom: var(--space-md);
}

.hero-bio {
  font-size: 1.05rem;
  color: var(--color-text-light);
  max-width: 540px;
  margin-bottom: var(--space-lg);
  line-height: 1.8;
}
.hero-links {
  display: flex;
  gap: 0.2rem;
  flex-wrap: wrap;
}
.hero-links .btn {
  padding: 0.3rem 0.6rem;
  border-width: 1px;
  font-size: 0.8rem;
}


.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.4rem 0.9rem;
  border-radius: 8px;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  text-decoration: none;
  transition: all var(--transition);
  cursor: pointer;
  border: 2px solid transparent;
}
.btn-primary {
  background: var(--color-accent);
  color: var(--color-white);
  border-color: var(--color-accent);
}
.btn-primary:hover {
  background: var(--color-accent-dk);
  border-color: var(--color-accent-dk);
  color: var(--color-white);
}
.btn-outline {
  background: transparent;
  color: var(--color-accent);
  border-color: var(--color-accent);
}
.btn-outline:hover {
  background: var(--color-accent);
  color: var(--color-white);
}

/* Hero image */
.hero-image {
  display: flex;
  justify-content: center;
  align-items: start;
}
.hero-image-frame {
  width: 150px;
  height: 220px;
  border-radius: 16px;
  overflow: hidden;
  border: 4px solid var(--color-white);
  box-shadow: 0 20px 60px rgba(61, 53, 41, 0.12);
  position: relative;
  background: var(--color-bg-alt);
}
.hero-image-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.hero-image-placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--color-bg-alt) 0%, var(--color-border) 100%);
}
.hero-image-placeholder svg {
  width: 100px;
  height: 100px;
  opacity: 0.5;
}

/* Hero news */
.hero-news {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: var(--space-md);
  max-height: 220px;
  overflow-y: auto;
  width: 100%;
  scrollbar-width: thin;
  scrollbar-color: var(--color-border) transparent;
}
.hero-news::-webkit-scrollbar {
  width: 4px;
}
.hero-news::-webkit-scrollbar-track {
  background: transparent;
}
.hero-news::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: 4px;
}
.hero-news::-webkit-scrollbar-thumb:hover {
  background: var(--color-accent);
}
.hero-news h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
  color: var(--color-accent);
}
.hero-news ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}
.hero-news li {
  font-size: 0.85rem;
  line-height: 1.5;
}
.hero-news li strong {
  font-size: 0.9rem;
  color: var(--color-heading);
}

/* ---------- ABOUT ---------- */

.about-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-2xl);
}

.about-text p {
  margin-bottom: var(--space-sm);
  line-height: 1.8;
}
.about-text p:last-child { margin-bottom: 0; }

.about-details {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}
.detail-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: var(--space-md);
}
.detail-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
  color: var(--color-accent);
}
.detail-card ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}
.detail-card li {
  font-size: 0.9rem;
  line-height: 1.6;
}
.detail-card li strong {
  font-size: 0.95rem;
  color: var(--color-heading);
}
.detail-card li span {
  font-size: 0.85rem;
  color: var(--color-text-light);
}

/* ---------- RESEARCH ---------- */
.research-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.research-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: 16px;
  padding: var(--space-lg) var(--space-md);
  transition: all var(--transition);
  opacity: 0;
  transform: translateY(24px);
}
.research-card.visible {
  opacity: 1;
  transform: translateY(0);
}
.research-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(61, 53, 41, 0.1);
  border-color: var(--color-accent);
}

.research-icon {
  width: 48px;
  height: 48px;
  color: var(--color-accent);
  margin-bottom: var(--space-md);
}
.research-card h3 {
  font-size: 1.3rem;
  margin-bottom: var(--space-sm);
}
.research-card p {
  color: var(--color-text-light);
  font-size: 0.95rem;
  line-height: 1.7;
  margin-bottom: var(--space-md);
}

.research-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}
.tag {
  display: inline-block;
  padding: 4px 12px;
  font-size: 0.78rem;
  font-weight: 500;
  background: var(--color-tag-bg);
  color: var(--color-tag-text);
  border-radius: 20px;
  border: 1px solid var(--color-border);
}

/* ---------- PUBLICATIONS ---------- */
.publications-list {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.pub-item {
  display: grid;
  grid-template-columns: 60px 1fr;
  gap: var(--space-md);
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--color-border);
  opacity: 0;
  transform: translateY(16px);
  transition: all var(--transition);
}
.pub-item.visible {
  opacity: 1;
  transform: translateY(0);
}
.pub-item:first-child { border-top: 1px solid var(--color-border); }

.pub-year {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-accent);
  padding-top: 2px;
}

.pub-content h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 4px;
  line-height: 1.4;
}
.pub-authors {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin-bottom: 4px;
}
.pub-venue {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin-bottom: var(--space-sm);
}
.pub-highlight {
  color: var(--color-highlight);
  font-weight: 600;
}

.pub-links {
  display: inline-flex;
  gap: 6px;
  flex-shrink: 0;
  white-space: nowrap;
  vertical-align: middle;
  margin-left: 12px;
}
.pub-link {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--color-link);
  text-decoration: none;
  padding: 3px 10px;
  border: 1px solid var(--color-link);
  border-radius: 6px;
  transition: all var(--transition);
}
.pub-link:hover {
  background: var(--color-link);
  color: var(--color-white);
}

/* ---------- TEACHING & SERVICES ---------- */
.service-list {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.service-item {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: var(--space-md);
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--color-border);
  align-items: baseline;
}

.service-item:first-child { border-top: 1px solid var(--color-border); }

.service-label {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-heading);
  padding-top: 2px;
}

.service-content {
  font-size: 0.92rem;
  line-height: 1.7;
  color: var(--color-text);
}

/* ---------- CONTACT ---------- */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-2xl);
  align-items: start;
}
.contact-text p {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  color: var(--color-text-light);
  line-height: 1.8;
  margin-bottom: var(--space-lg);
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}
.contact-row {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  font-size: 0.95rem;
  color: var(--color-text);
}
.contact-row svg {
  flex-shrink: 0;
  color: var(--color-accent);
}
.contact-row a {
  color: var(--color-link);
}

.contact-socials {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}
.social-card {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-sm) var(--space-md);
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  text-decoration: none;
  color: var(--color-text);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
}
.social-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(61, 53, 41, 0.08);
  color: var(--color-heading);
}
.social-card svg {
  flex-shrink: 0;
  color: var(--color-accent);
}

/* ---------- FOOTER ---------- */
#footer {
  padding: var(--space-lg) 0;
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-text-light);
  border-top: 1px solid var(--color-border);
}
.footer-sub {
  margin-top: var(--space-xs);
  font-size: 0.78rem;
}

/* ---------- ANIMATIONS ---------- */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(24px); }
  to   { opacity: 1; transform: translateY(0); }
}

.hero-content > * {
  animation: fadeInUp 0.8s var(--ease) both;
}
.hero-content > :nth-child(2) {
  animation-delay: 0.15s;
}

/* ---------- RESPONSIVE ---------- */
@media (max-width: 960px) {
  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
  .hero-bio { margin-left: auto; margin-right: auto; }
  .hero-links { justify-content: center; }
  .hero-image { order: -1; }
  .hero-image-frame { width: 140px; height: 170px; }
  .hero-news {
    max-height: 200px;
    max-width: 400px;
    margin: var(--space-md) auto 0;
  }
  .hero h1 { font-size: 2.3rem; }
  .hero-tagline { font-size: 1.1rem; }

  .about-grid { grid-template-columns: 1fr; }
  .research-grid { grid-template-columns: 1fr; }
  .teaching-grid { grid-template-columns: 1fr; }
  .contact-grid { grid-template-columns: 1fr; }
  .contact-socials { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 640px) {
  :root { --space-3xl: 5rem; }

  .nav-links { display: none; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--color-bg);
    padding: var(--space-lg);
    border-bottom: 1px solid var(--color-border);
    gap: var(--space-md);
  }
  #nav-toggle { display: flex; }

  .hero h1 { font-size: 2.0rem; }
  .section-header h2 { font-size: 1.8rem; }

  .pub-item { grid-template-columns: 1fr; gap: var(--space-sm); }
  .talk-item { grid-template-columns: 1fr; gap: var(--space-xs); }

  .contact-socials { grid-template-columns: 1fr; }

}

/* ---------- Print ---------- */
@media print {
  #navbar, #nav-toggle { display: none; }
  .hero { min-height: auto; padding-top: 0; }
  .section { padding: 2rem 0; }
}