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

:root {
  --bg:           #ffffff;
  --bg-alt:       #f7f8f9;
  --text:         #111827;
  --text-2:       #4b5563;
  --accent:       #0f766e;
  --accent-dim:   #e6f4f3;
  --border:       #e5e7eb;
  --mono:         'JetBrains Mono', 'Fira Mono', monospace;
  --sans:         'Inter', system-ui, -apple-system, sans-serif;
  --nav-h:        64px;
  --max-w:        1100px;
  --radius:       8px;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ===== Utilities ===== */
.mono { font-family: var(--mono); }

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ===== Navbar ===== */
#navbar {
  position: fixed;
  inset-block-start: 0;
  inset-inline: 0;
  height: var(--nav-h);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  transition: box-shadow 0.2s;
}

#navbar.scrolled {
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
}

.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 100%;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.nav-logo {
  font-family: var(--mono);
  font-weight: 500;
  font-size: 1rem;
  color: var(--accent);
  text-decoration: none;
  letter-spacing: 0.08em;
  flex-shrink: 0;
  padding: 0.25rem 0.5rem;
  border: 1px solid var(--accent-dim);
  border-radius: 4px;
  transition: background 0.15s;
}

.nav-logo:hover {
  background: var(--accent-dim);
}

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

.nav-links a {
  color: var(--text-2);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 500;
  transition: color 0.15s;
  white-space: nowrap;
}

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

.lang-switcher {
  display: flex;
  gap: 0.2rem;
  margin-inline-start: 1.5rem;
  flex-shrink: 0;
}

.lang-btn {
  background: none;
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0.2rem 0.45rem;
  font-family: var(--mono);
  font-size: 0.7rem;
  cursor: pointer;
  color: var(--text-2);
  transition: background 0.15s, border-color 0.15s, color 0.15s;
  line-height: 1.4;
}

.lang-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.lang-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.menu-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: all 0.2s;
}

/* ===== Sections ===== */
section {
  padding: 5rem 0;
}

#hero {
  padding-top: var(--nav-h);
}

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

.section-header {
  margin-bottom: 3rem;
}

.section-tag {
  display: block;
  font-size: 0.7rem;
  color: var(--accent);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 0.6rem;
}

.section-header h2 {
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.2;
}

/* ===== Hero ===== */
#hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
}

.hero-label {
  font-size: 0.8rem;
  color: var(--accent);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 0.75rem;
}

.hero-name {
  font-size: clamp(2.8rem, 7vw, 5rem);
  font-weight: 700;
  letter-spacing: -0.035em;
  line-height: 1.05;
  margin-bottom: 0.6rem;
}

.hero-title {
  font-size: clamp(1rem, 2.5vw, 1.3rem);
  font-weight: 400;
  color: var(--text-2);
  margin-bottom: 1.5rem;
}

.hero-tagline {
  font-size: 1.05rem;
  color: var(--text-2);
  max-width: 520px;
  line-height: 1.75;
  margin-bottom: 2.5rem;
}

.btn-primary {
  display: inline-block;
  padding: 0.7rem 2rem;
  background: var(--accent);
  color: #fff;
  border-radius: var(--radius);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.925rem;
  transition: opacity 0.15s, transform 0.15s;
}

.btn-primary:hover {
  opacity: 0.85;
  transform: translateY(-1px);
}

/* ===== About ===== */
.about-grid {
  display: grid;
  grid-template-columns: 190px 1fr;
  gap: 3.5rem;
  align-items: start;
}

.photo-placeholder {
  aspect-ratio: 1;
  background: var(--bg-alt);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-2);
  overflow: hidden;
}

.photo-placeholder svg {
  width: 65%;
  height: 65%;
}

.profile-photo {
  width: 100%;
  aspect-ratio: 1;
  border-radius: var(--radius);
  object-fit: cover;
  object-position: center top;
  border: 1px solid var(--border);
  display: block;
}

.about-text p {
  color: var(--text-2);
  margin-bottom: 1rem;
  line-height: 1.8;
}

.about-stats {
  display: flex;
  gap: 2.5rem;
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  flex-wrap: wrap;
}

.stat {
  display: flex;
  flex-direction: column;
}

.stat-num {
  font-size: 1.8rem;
  font-weight: 500;
  color: var(--accent);
  line-height: 1.1;
}

.stat-label {
  font-size: 0.78rem;
  color: var(--text-2);
  margin-top: 0.3rem;
  white-space: nowrap;
}

/* ===== Expertise ===== */
.expertise-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.expertise-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.expertise-card:hover {
  border-color: var(--accent);
  box-shadow: 0 4px 20px rgba(15, 118, 110, 0.07);
}

.card-icon {
  font-size: 0.72rem;
  color: var(--accent);
  letter-spacing: 0.06em;
  margin-bottom: 1rem;
}

.expertise-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  letter-spacing: -0.01em;
}

.expertise-card p {
  font-size: 0.88rem;
  color: var(--text-2);
  line-height: 1.7;
}

/* ===== Publications ===== */
.pub-list {
  list-style: none;
}

.pub-item {
  display: flex;
  gap: 2rem;
  padding: 1.25rem 0;
  border-bottom: 1px solid var(--border);
}

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

.pub-featured .pub-title {
  color: var(--accent);
}

.pub-featured .pub-year {
  color: var(--accent);
}

.pub-year {
  font-size: 0.78rem;
  color: var(--text-2);
  min-width: 3rem;
  flex-shrink: 0;
  padding-top: 0.2rem;
}

.pub-title {
  font-size: 0.94rem;
  font-weight: 500;
  margin-bottom: 0.3rem;
  line-height: 1.5;
}

.pub-venue {
  font-size: 0.81rem;
  color: var(--text-2);
}

.pub-links {
  margin-top: 2rem;
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.link-external {
  font-size: 0.875rem;
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
  transition: opacity 0.15s;
}

.link-external:hover {
  opacity: 0.7;
}

/* ===== Timeline ===== */
.timeline {
  list-style: none;
  position: relative;
  padding-inline-start: 1.5rem;
}

.timeline::before {
  content: '';
  position: absolute;
  inset-inline-start: 0;
  top: 0.5rem;
  bottom: 0.5rem;
  width: 1px;
  background: var(--border);
}

.timeline-item {
  position: relative;
  padding-inline-start: 1.5rem;
  padding-bottom: 2rem;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-marker {
  position: absolute;
  inset-inline-start: -4.5px;
  top: 0.45rem;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg-alt);
  box-shadow: 0 0 0 1px var(--accent);
}

.timeline-degree {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
  letter-spacing: -0.01em;
}

.timeline-inst {
  font-size: 0.875rem;
  color: var(--text-2);
}

/* ===== Contact ===== */
.contact-inner {
  max-width: 580px;
}

.contact-text {
  font-size: 1.05rem;
  color: var(--text-2);
  line-height: 1.75;
  margin-bottom: 2.5rem;
}

.contact-links {
  display: flex;
  flex-direction: column;
}

.contact-item {
  display: flex;
  align-items: baseline;
  gap: 1.25rem;
  text-decoration: none;
  color: var(--text);
  padding: 0.9rem 0;
  border-bottom: 1px solid var(--border);
  transition: color 0.15s;
}

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

.contact-item:hover {
  color: var(--accent);
}

.contact-item.no-link {
  cursor: default;
}

.contact-item.no-link:hover {
  color: var(--text);
}

.contact-label {
  font-size: 0.72rem;
  color: var(--text-2);
  min-width: 80px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  flex-shrink: 0;
}

/* ===== Footer ===== */
footer {
  padding: 1.75rem 0;
  border-top: 1px solid var(--border);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.footer-text {
  font-size: 0.8rem;
  color: var(--text-2);
  display: flex;
  gap: 0.4rem;
}

.footer-home {
  font-size: 0.75rem;
  color: var(--text-2);
  text-decoration: none;
  letter-spacing: 0.04em;
  transition: color 0.15s;
}

.footer-home:hover {
  color: var(--accent);
}

/* ===== RTL overrides ===== */
[dir="rtl"] .hero-tagline,
[dir="rtl"] .about-text p,
[dir="rtl"] .contact-text {
  text-align: start;
}

[dir="rtl"] .timeline::before {
  inset-inline-start: 0;
}

[dir="rtl"] .timeline-marker {
  inset-inline-start: -4.5px;
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .expertise-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: fixed;
    top: var(--nav-h);
    inset-inline: 0;
    background: var(--bg);
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border);
    gap: 1rem;
    z-index: 99;
    box-shadow: 0 8px 24px rgba(0,0,0,0.06);
  }

  .nav-links.open a {
    font-size: 1rem;
    padding: 0.25rem 0;
  }

  .lang-switcher {
    margin-inline-start: auto;
  }

  .menu-toggle {
    display: flex;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .about-photo {
    max-width: 130px;
  }

  .about-stats {
    gap: 1.5rem;
  }

  section {
    padding: 3.5rem 0;
  }

  #hero {
    min-height: auto;
    padding: calc(var(--nav-h) + 3.5rem) 0 3.5rem;
  }

  .pub-links {
    flex-direction: column;
    gap: 0.75rem;
  }

  .footer-inner {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }
}

@media (max-width: 480px) {
  .contact-label {
    min-width: 60px;
  }

  .pub-item {
    gap: 1rem;
  }

  .hero-name {
    font-size: 2.5rem;
  }
}