:root {
  --bg: #f5f7fb;
  --bg-alt: #ffffff;
  --text: #222222;
  --muted: #666666;
  --accent: #0066cc;
  --accent-soft: #e1efff;
  --border: #e1e4ec;
  --shadow-soft: 0 10px 30px rgba(15, 23, 42, 0.06);
  --radius-lg: 1.5rem;
  --radius-md: 1rem;
  --radius-sm: 0.75rem;
}

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

html,
body {
  scroll-behavior: smooth;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

/* Utility containers */
.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header / Nav */
.site-header {
  position: relative;
  top: 0;
  z-index: 100;
  background: rgba(245, 247, 251, 0.96);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(225, 228, 236, 0.8);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 0;
}

.logo a {
  text-decoration: none;
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: 0.04em;
  color: var(--text);
}

.logo span {
  color: var(--accent);
}

.nav {
  display: flex;
  align-items: center;
}

.nav-toggle {
  display: none;
  border: none;
  background: none;
  font-size: 1.4rem;
  cursor: pointer;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 1.5rem;
}

.nav-links a {
  text-decoration: none;
  color: var(--muted);
  font-size: 0.95rem;
  font-weight: 500;
  position: relative;
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -0.25rem;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width 0.2s ease;
}

.nav-links a:hover {
  color: var(--accent);
}

.nav-links a:hover::after {
  width: 100%;
}

/* ===== HERO SECTION ===== */
.hero-section {
  position: relative;
  padding: 6rem 0 4rem;
  min-height: 60vh;         /* Full viewport height hero */
  overflow: hidden;          /* Hide video overflow */
  display: flex;
  align-items: center;
}

/* Hero grid (text + photo) */
.hero-container {
  position: relative;
  z-index: 2;                /* Above video + overlay */
  display: grid;
  grid-template-columns: minmax(0, 2fr) minmax(0, 1.3fr);
  gap: 2.5rem;
  align-items: center;
}

.hero-eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.75rem;
  color: red;
  margin-bottom: 0.5rem;
}

.hero-section h1 {
  font-size: clamp(2.1rem, 3vw, 2.7rem);
  line-height: 1.15;
  margin-bottom: 1rem;
}

.hero-section h1 span {
  color: blue;
}

.hero-subtitle {
  color: #f2f4f7;   /* soft white, not harsh */
  font-size: 0.98rem;
  max-width: 34rem;
  margin-bottom: 1.5rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* ===== True Halo / Glow Without Changing Text Color ===== */
.hero-section h1,
.hero-section h1 span,
.hero-subtitle {
  text-shadow:
    0 0 8px rgba(255, 255, 255, 0.55),
    0 0 14px rgba(255, 255, 255, 0.35),
    0 0 22px rgba(255, 255, 255, 0.25);
}

/* Slightly stronger glow for the main heading */
.hero-section h1 {
  text-shadow:
    0 0 10px rgba(255, 255, 255, 0.65),
    0 0 18px rgba(255, 255, 255, 0.45),
    0 0 28px rgba(255, 255, 255, 0.30);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.6rem 1.4rem;
  border-radius: 999px;
  font-size: 0.95rem;
  font-weight: 500;
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: transform 0.1s ease, box-shadow 0.1s ease, background 0.15s ease;
}

.primary-btn {
  background: var(--accent);
  color: #ffffff;
  box-shadow: var(--shadow-soft);
}

.primary-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 12px 35px rgba(0, 102, 204, 0.25);
}

.secondary-btn {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: rgba(0, 102, 204, 0.1);
}

.secondary-btn:hover {
  transform: translateY(-1px);
}

/* Hero card */
.hero-card {
  background: var(--bg-alt);
  border-radius: var(--radius-lg);
  padding: 1.75rem 1.5rem;
  box-shadow: var(--shadow-soft);
  border: 1px solid var(--border);
}

.hero-photo {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  object-fit: cover;
  margin-bottom: 1rem;
  border: 3px solid var(--accent-soft);
}

.hero-card-title {
  font-weight: 600;
  margin-bottom: 0.4rem;
}

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

/* Sections */
.section {
  padding: 3.5rem 0;
}

.section-alt {
  background: var(--bg-alt);
}

.section-title {
  font-size: 1.5rem;
  margin-bottom: 1.5rem;
}

.section-intro {
  max-width: 34rem;
  color: var(--muted);
  margin-bottom: 1.5rem;
}

/* Grids */
.grid {
  display: grid;
  gap: 1.75rem;
}

.two-col {
  grid-template-columns: minmax(0, 1.6fr) minmax(0, 1.1fr);
}

.three-col {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

/* About */
.about-highlight {
  background: var(--accent-soft);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.3rem;
  border: 1px solid rgba(0, 102, 204, 0.15);
}

.about-highlight h3 {
  font-size: 1.05rem;
  margin-bottom: 0.5rem;
}

.about-highlight ul {
  list-style: none;
  font-size: 0.9rem;
  color: var(--muted);
}

.about-highlight li::before {
  content: "• ";
  color: var(--accent);
}

/* Cards */
.cards .card {
  background: var(--bg);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.25rem;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-soft);
}

.cards .card h3 {
  font-size: 1.05rem;
  margin-bottom: 0.5rem;
}

/* Publications */
.pub-list {
  list-style: none;
  display: grid;
  gap: 1rem;
}

.pub-year {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--accent);
  min-width: 3rem;
}

.pub-details {
  flex: 1;
}

.pub-title {
  font-weight: 500;
}

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

.pub-doi {
  font-family: "Courier New", monospace;
  font-size: 0.88rem;
}

/* Layout for each publication */
.pub-list li {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
}

/* Contact */
.contact-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1.3fr);
  gap: 2rem;
  margin-top: 1.5rem;
}

.contact-list {
  list-style: none;
  font-size: 0.95rem;
}

.contact-list li + li {
  margin-top: 0.35rem;
}

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

.contact-list a:hover {
  text-decoration: underline;
}

.contact-form {
  background: var(--bg-alt);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  padding: 1.5rem;
  box-shadow: var(--shadow-soft);
}

.contact-form label {
  display: block;
  font-size: 0.9rem;
  margin-bottom: 0.75rem;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  margin-top: 0.25rem;
  padding: 0.5rem 0.65rem;
  border-radius: 0.5rem;
  border: 1px solid var(--border);
  font-family: inherit;
  font-size: 0.9rem;
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: 2px solid var(--accent-soft);
  border-color: var(--accent);
}

.form-note {
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 0.5rem;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.75rem 0;
  background: #f3f4f8;
}

.footer-container {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  font-size: 0.85rem;
  color: var(--muted);
  flex-wrap: wrap;
}

.footer-small {
  opacity: 0.9;
}

/* Responsive base layout */
@media (max-width: 900px) {
  .hero-container {
    grid-template-columns: minmax(0, 1fr);
  }

  .two-col,
  .three-col,
  .contact-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .cards .card {
    background: var(--bg-alt);
  }
}

/* Mobile nav + hero spacing */
@media (max-width: 720px) {
  .nav-toggle {
    display: block;
  }

  .nav-links {
    position: absolute;
    right: 1.5rem;
    top: 3.1rem;
    flex-direction: column;
    background: #ffffff;
    padding: 0.75rem 1rem;
    border-radius: 0.75rem;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-soft);
    display: none;
  }

  .nav-links.nav-open {
    display: flex;
  }

  .hero-section {
    padding-top: 3.25rem;
  }
}

/* ===== Video Background (only in hero) ===== */
.video-container {
  position: absolute;
  inset: 0;              /* top:0; right:0; bottom:0; left:0; */
  width: 100%;
  height: 100%;
  z-index: 0;            /* lowest in hero stack */
  overflow: hidden;
}

#bg-video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: brightness(60%);
}

/* Dark overlay over video for text readability */
.hero-section::before {
  content: "";
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.25);
  z-index: 1;           /* above video, below content */
}

/* Ensure hero content is above video + overlay */
.hero-container {
  position: relative;
  z-index: 2;
}

/* ===== Social PNG Icons Section ===== */
.social-section {
  padding: 2rem 0;
  text-align: center;
}

.social-container {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 4.5rem;
  flex-wrap: wrap;         /* allow icons to wrap onto new lines */
}

.social-icon {
  width: 70px;
  height: 70px;
  object-fit: contain;
  filter: brightness(90%);
  transition: transform 0.2s ease, filter 0.2s ease;
}

.social-icon:hover {
  transform: scale(1.15);
  filter: brightness(120%);
}

/* Make icons smaller & tighter on mobile */
@media (max-width: 600px) {
  .social-container {
    gap: 1.5rem;
  }

  .social-icon {
    width: 48px;
    height: 48px;
  }
}


/* ===== Membership Grid (3 logos row) ===== */
.membership-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  justify-items: center;
  align-items: start;
  gap: 2rem;
  margin-top: 2rem;
}

.membership-block {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.membership-logo {
  max-width: 440px;      /* limit how wide any logo can be */
  max-height: 240px;     /* shared height box for all logos */
  width: auto;
  height: auto;
  object-fit: contain;
  display: block;
  margin: 0 auto 0.75rem;  /* center the image */
}

.membership-caption {
  font-size: 1rem;
  font-weight: 600;
  margin-top: 0.25rem;
  line-height: 1.3;
}

/* Responsive membership grid */
@media (max-width: 768px) {
  .membership-grid {
    grid-template-columns: 1fr;
  }

  .membership-logo {
    width: 180px;
  }
}

/* ===== Certificate Slider (certifications.html) ===== */

.cert-slider-wrapper {
  margin-top: 2rem;
  display: flex;
  justify-content: center;
}

.cert-slider {
  position: relative;
  max-width: 1000px;     /* adjust if you want wider/narrower */
  width: 100%;
  margin: 0 auto;
  overflow: hidden;
  border-radius: 0.75rem;
}

.cert-slide {
  display: none;
}

.cert-slide.active {
  display: block;
}

.cert-slide img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 80vh;      /* keep it within viewport height */
  object-fit: contain;
}

/* Arrows overlay */
.cert-arrow {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  border: none;
  background: transparent;
  color: #ffffff;
  font-size: 2.5rem;
  cursor: pointer;
  padding: 0.25rem 0.5rem;
  opacity: 0;
  transition: opacity 0.2s ease, transform 0.15s ease;
  pointer-events: none; /* disabled by default, enabled on hover below */
}

.cert-arrow-left {
  left: 1rem;
}

.cert-arrow-right {
  right: 1rem;
}

/* Show arrows only when hovering the slider */
.cert-slider:hover .cert-arrow {
  opacity: 0.9;
  pointer-events: auto;
}

.cert-arrow:hover {
  transform: translateY(-50%) scale(1.05);
}

/* Smaller arrows on mobile */
@media (max-width: 600px) {
  .cert-arrow {
    font-size: 2rem;
  }
}

/* ===== Download CV Button ===== */
.about-actions {
  margin-top: 2rem;
  display: flex;
  justify-content: flex-end; /* moves to right side */
}

.btn-download {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--accent);
  color: #fff;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  text-decoration: none;
  font-weight: 600;
  box-shadow: var(--shadow-soft);
  transition: 0.3s ease;
}

.btn-download:hover {
  background: #004c99;
  transform: translateY(-2px);
}

.btn-download .icon {
  font-size: 1.2rem;
  line-height: 1;
}

/* ===== Contact Page Layout ===== (extended) */

.contact-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(0, 1.2fr);
  gap: 2rem;
  align-items: flex-start;
  margin-top: 2rem;
}

@media (max-width: 768px) {
  .contact-grid {
    grid-template-columns: 1fr;
  }
}

.contact-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.contact-list li {
  margin-bottom: 0.75rem;
  font-size: 0.95rem;
}

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

.contact-list a:hover {
  text-decoration: underline;
}

.contact-form {
  background: var(--bg-alt);
  padding: 2rem;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
}

.contact-form label {
  display: block;
  font-weight: 500;
  margin-bottom: 0.25rem;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  padding: 0.8rem;
  margin-bottom: 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  font-family: inherit;
}

.contact-form textarea {
  resize: vertical;
  min-height: 150px;
}

.contact-form .btn {
  display: inline-block;
  background: var(--accent);
  color: #ffffff;
  padding: 0.8rem 1.6rem;
  border: none;
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}

.contact-form .btn:hover {
  background: #004c99; /* slightly darker than --accent */
  transform: translateY(-1px);
  box-shadow: var(--shadow-soft);
}

.map-container {
  margin-top: 2rem;
}

.map-container iframe {
  width: 100%;
  height: 280px;
  border: 0;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
}

/* ===== Album Tabs & Panels ===== */

.album-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin: 2rem 0 1rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.5rem;
}

.album-tab {
  border: 1px solid var(--border);
  background: var(--bg-alt);
  padding: 0.4rem 0.9rem;
  border-radius: 999px;
  font-size: 0.9rem;
  cursor: pointer;
  transition: background 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
}

.album-tab.active {
  background: var(--accent);
  color: #fff;
  box-shadow: var(--shadow-soft);
  transform: translateY(-1px);
}

.album-panel {
  display: none;
  margin-top: 1.5rem;
}

.album-panel.active {
  display: block;
}

.album-heading {
  font-size: 1.4rem;
  margin-bottom: 0.3rem;
}

.album-text {
  font-size: 0.95rem;
  color: var(--muted);
  margin-bottom: 1rem;
}

/* ===== Photo Grid ===== */

.photo-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 0.9rem;
}

.photo-card {
  background: var(--bg-alt);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-soft);
}

.photo-card img {
  width: 100%;
  height: 160px;
  object-fit: cover;
  display: block;
  transition: transform 0.25s ease;
}

.photo-card:hover img {
  transform: scale(1.05);
}

@media (min-width: 1024px) {
  .photo-card img {
    height: 190px;
  }
}