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

:root {
  --white:       #ffffff;
  --bg:          #fafafa;
  --text:        #1a1a1a;
  --text-muted:  #6b7280;
  --border:      #e5e7eb;
  --accent:      #111827;
  --radius:      12px;
  --shadow:      0 1px 3px rgba(0,0,0,.06), 0 4px 16px rgba(0,0,0,.04);
  --transition:  .2s ease;
  --content-pad: clamp(1.5rem, 4vw, 3rem);
  --content-max: 1000px;
  --nav-height:  60px;
}

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

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: var(--white);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  padding-top: var(--nav-height);
}

a { color: inherit; text-decoration: none; }
a:hover { opacity: .75; }
img { max-width: 100%; display: block; }
ul { list-style: none; }

/* ── Layout ───────────────────────────────────────────────── */

/* ── Top bar ──────────────────────────────────────────────── */
.topbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-height);
  background: rgba(255, 255, 255, .94);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  z-index: 200;
}

.topbar__inner {
  display: flex;
  align-items: center;
  height: 100%;
  width: 100%;
  padding: 0 clamp(1.5rem, 5vw, 4rem);
  gap: 1.5rem;
}

.topbar__brand {
  display: flex;
  align-items: center;
  gap: .625rem;
  flex-shrink: 0;
}

.topbar__brand:hover { opacity: 1; }

.topbar__avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  object-fit: cover;
  object-position: center top;
  border: 1px solid var(--border);
}

.topbar__name {
  font-size: .875rem;
  font-weight: 600;
  letter-spacing: -.02em;
  white-space: nowrap;
}

.topbar__nav {
  display: flex;
  align-items: center;
  gap: .25rem;
  flex: 1;
  overflow-x: auto;
  scrollbar-width: none;
}

.topbar__nav::-webkit-scrollbar { display: none; }

.nav__link {
  display: block;
  padding: .375rem .625rem;
  font-size: .8125rem;
  color: var(--text-muted);
  white-space: nowrap;
  border-radius: 6px;
  transition: color var(--transition), background var(--transition);
}

.nav__link:hover,
.nav__link.active {
  color: var(--text);
  background: var(--bg);
  opacity: 1;
}

.topbar__social {
  display: flex;
  align-items: center;
  gap: .75rem;
  flex-shrink: 0;
}

.social__link {
  font-size: .6875rem;
  color: var(--text-muted);
  font-weight: 500;
  letter-spacing: .02em;
  text-transform: uppercase;
  white-space: nowrap;
  transition: color var(--transition);
}

.social__link:hover { color: var(--text); opacity: 1; }

.menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: .5rem;
  flex-direction: column;
  gap: 5px;
  margin-left: auto;
}

.menu-btn span {
  display: block;
  width: 20px;
  height: 1.5px;
  background: var(--text);
  transition: var(--transition);
}

.menu-btn.open span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.menu-btn.open span:nth-child(2) { opacity: 0; }
.menu-btn.open span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* ── Main content ─────────────────────────────────────────── */
.main {
  width: 100%;
  padding: 0 clamp(1.5rem, 5vw, 4rem);
}

.section {
  padding: 5rem 0;
  max-width: var(--content-max);
  margin: 0 auto;
  width: 100%;
}

.section + .section {
  border-top: 1px solid var(--border);
}

.section__label {
  font-size: .75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--text-muted);
  margin-bottom: .75rem;
}

.section__title {
  font-size: 1.75rem;
  font-weight: 600;
  letter-spacing: -.03em;
  margin-bottom: 2rem;
  line-height: 1.3;
}

/* ── Hero ─────────────────────────────────────────────────── */
.hero {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: 3rem;
  padding: 5rem 0;
  max-width: var(--content-max);
  margin: 0 auto;
  width: 100%;
}

.hero__text {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.hero__greeting {
  font-size: .875rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
  font-weight: 400;
}

.hero__title {
  font-size: clamp(2.5rem, 4vw, 3.5rem);
  font-weight: 700;
  letter-spacing: -.04em;
  line-height: 1.1;
  margin-bottom: 1.5rem;
}

.hero__subtitle {
  font-size: 1.0625rem;
  color: var(--text-muted);
  line-height: 1.7;
}

.hero__gallery {
  position: relative;
  width: 100%;
  height: clamp(280px, 40vh, 480px);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  overflow: hidden;
}

.hero__image {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0;
  transition: opacity .6s ease;
}

.hero__image.active { opacity: 1; }

.hero__dots {
  position: absolute;
  bottom: 1rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: .5rem;
  z-index: 2;
}

.hero__dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  border: none;
  background: rgba(255, 255, 255, .5);
  cursor: pointer;
  padding: 0;
  transition: background var(--transition), transform var(--transition);
}

.hero__dot.active {
  background: #fff;
  transform: scale(1.2);
}

/* ── About ────────────────────────────────────────────────── */
.prose {
  columns: 2;
  column-gap: 3rem;
}

.prose p {
  color: var(--text-muted);
  margin-bottom: 1.25rem;
  font-size: .9375rem;
  break-inside: avoid;
}

.prose p:last-child { margin-bottom: 0; }

.prose strong { color: var(--text); font-weight: 500; }

/* ── Skills grid ──────────────────────────────────────────── */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1rem;
}

.skill-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  transition: box-shadow var(--transition);
}

.skill-card:hover { box-shadow: var(--shadow); }

.skill-card__title {
  font-size: .8125rem;
  font-weight: 600;
  margin-bottom: .5rem;
  letter-spacing: -.01em;
}

.skill-card__items {
  font-size: .8125rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ── Timeline (Experience) ────────────────────────────────── */
.timeline { display: flex; flex-direction: column; gap: 2.5rem; }

.timeline__item { position: relative; }

.timeline__header {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: .5rem 1rem;
  margin-bottom: .75rem;
}

.timeline__role {
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -.02em;
}

.timeline__company {
  font-size: .9375rem;
  color: var(--text-muted);
}

.timeline__company a {
  color: var(--text);
  border-bottom: 1px solid var(--border);
  transition: border-color var(--transition);
}

.timeline__company a:hover {
  border-color: var(--text);
  opacity: 1;
}

.timeline__date {
  font-size: .8125rem;
  color: var(--text-muted);
  margin-left: auto;
  white-space: nowrap;
}

.timeline__desc {
  font-size: .875rem;
  color: var(--text-muted);
  margin-bottom: .75rem;
  line-height: 1.7;
}

.timeline__bullets {
  padding-left: 1.25rem;
  list-style: disc;
}

.timeline__bullets li {
  font-size: .875rem;
  color: var(--text-muted);
  margin-bottom: .4rem;
  line-height: 1.6;
}

/* ── Education ────────────────────────────────────────────── */
.edu-list { display: flex; flex-direction: column; gap: 1.5rem; }

.edu-item {
  padding: 1.5rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.edu-item__degree {
  font-size: .9375rem;
  font-weight: 600;
  margin-bottom: .25rem;
}

.edu-item__school {
  font-size: .875rem;
  color: var(--text-muted);
  margin-bottom: .75rem;
}

.edu-item__desc {
  font-size: .875rem;
  color: var(--text-muted);
  line-height: 1.7;
}

.edu-item__badge {
  display: inline-block;
  font-size: .75rem;
  font-weight: 500;
  color: var(--text-muted);
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: .2rem .65rem;
  margin-top: .75rem;
}

/* ── Thesis highlight ─────────────────────────────────────── */
.thesis-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  margin-top: .5rem;
}

.thesis-card__title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: .75rem;
  letter-spacing: -.02em;
}

.thesis-card__meta {
  font-size: .8125rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.thesis-card__desc {
  font-size: .875rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: .75rem;
}

.thesis-card__tags {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  margin-top: 1rem;
}

.tag {
  font-size: .75rem;
  font-weight: 500;
  color: var(--text-muted);
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: .25rem .75rem;
}

/* ── Research ─────────────────────────────────────────────── */
.research-item {
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--border);
}

.research-item:last-child { border-bottom: none; }

.research-item__title {
  font-size: .9375rem;
  font-weight: 600;
  margin-bottom: .5rem;
}

.research-item__date {
  font-size: .8125rem;
  color: var(--text-muted);
  margin-bottom: .75rem;
}

.research-item__desc {
  font-size: .875rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: .75rem;
}

.research-item__links a {
  font-size: .875rem;
  color: var(--text);
  border-bottom: 1px solid var(--border);
  display: inline-block;
  margin-bottom: .35rem;
  transition: border-color var(--transition);
}

.research-item__links a:hover { border-color: var(--text); opacity: 1; }

/* ── Cards grid (certs, blogs) ────────────────────────────── */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 1.25rem;
}

.card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: box-shadow var(--transition);
  background: var(--white);
}

.card:hover { box-shadow: var(--shadow); }

.card__img {
  width: 100%;
  height: 160px;
  object-fit: cover;
  border-bottom: 1px solid var(--border);
}

.card__body { padding: 1.25rem; }

.card__meta {
  font-size: .75rem;
  color: var(--text-muted);
  margin-bottom: .5rem;
}

.card__title {
  font-size: .875rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: .5rem;
}

.card__title a { border-bottom: 1px solid transparent; transition: border-color var(--transition); }
.card__title a:hover { border-color: var(--text); opacity: 1; }

.card__desc {
  font-size: .8125rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ── Video ────────────────────────────────────────────────── */
.video-wrapper {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  margin-bottom: 1.5rem;
  background: #000;
}

.video-wrapper iframe {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  border: none;
}

.video-play {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  padding: 0;
  border: none;
  cursor: pointer;
  background: none;
}

.video-play img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.video-play__icon {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 64px;
  height: 64px;
  background: rgba(0, 0, 0, .7);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  padding-left: 4px;
  transition: background var(--transition), transform var(--transition);
}

.video-play:hover .video-play__icon {
  background: rgba(0, 0, 0, .85);
  transform: translate(-50%, -50%) scale(1.05);
}

/* ── Gallery ──────────────────────────────────────────────── */
.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1rem;
}

.gallery__item {
  position: relative;
  aspect-ratio: 4/3;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
}

.gallery__item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform .4s ease;
}

.gallery__item--contain {
  background: var(--bg);
}

.gallery__item--contain img {
  object-fit: contain;
}

.gallery__item:hover img { transform: scale(1.03); }

.gallery__caption {
  position: absolute;
  bottom: 0; left: 0; right: 0;
  padding: 2rem 1rem .875rem;
  background: linear-gradient(transparent, rgba(0,0,0,.55));
  color: #fff;
  font-size: .8125rem;
  font-weight: 500;
}

/* ── Footer ───────────────────────────────────────────────── */
.footer {
  padding: 2rem 0;
  border-top: 1px solid var(--border);
  font-size: .8125rem;
  color: var(--text-muted);
  max-width: var(--content-max);
  margin: 0 auto;
  width: 100%;
}

/* ── Responsive ───────────────────────────────────────────── */
@media (max-width: 1100px) {
  .topbar__social { display: none; }

  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
    padding-top: 4rem;
    padding-bottom: 4rem;
  }

  .prose { columns: 1; }
}

@media (max-width: 900px) {
  .menu-btn { display: flex; }

  .topbar__nav {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: .75rem 1.25rem 1.25rem;
    background: rgba(255, 255, 255, .98);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
    max-height: calc(100vh - var(--nav-height));
    overflow-y: auto;
  }

  .topbar__nav.open { display: flex; }

  .nav__link {
    padding: .625rem .75rem;
    border-radius: 8px;
  }

  .hero,
  .section { padding: 3rem 0; }

  .hero {
    min-height: auto;
    padding-top: 2rem;
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .footer { padding: 2rem 0; }

  .timeline__date { margin-left: 0; }

  .hero__gallery { height: 220px; }
}

@media (max-width: 480px) {
  .skills-grid { grid-template-columns: 1fr; }
  .card-grid { grid-template-columns: 1fr; }
  .gallery { grid-template-columns: 1fr 1fr; }
}

/* ── Fade-in animation ────────────────────────────────────── */
.fade-in {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity .5s ease, transform .5s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}