/* ============================================================
   RESET & BASE
   ============================================================ */

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

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

body {
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  color: #1a1a1a;
  background: #ffffff;
  line-height: 1.6;
}

img {
  max-width: 100%;
  display: block;
}

a {
  color: #1a1a1a;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* ============================================================
   LAYOUT UTILITIES
   ============================================================ */

.container {
  max-width: 820px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
}

.section-alt {
  background: #f8f8f7;
}

.section-title {
  font-size: 1.1rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #888;
  margin-bottom: 40px;
}

/* ============================================================
   NAVBAR
   ============================================================ */

.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: #ffffff;
  border-bottom: 1px solid #e8e8e8;
}

.nav-inner {
  max-width: 820px;
  margin: 0 auto;
  padding: 0 24px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 28px;
}

.nav-links a {
  font-size: 0.875rem;
  color: #555;
}

.nav-links a:hover {
  color: #1a1a1a;
  text-decoration: none;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.25rem;
  cursor: pointer;
  color: #1a1a1a;
  padding: 4px;
}

/* ============================================================
   ABOUT
   ============================================================ */

.about-section {
  padding-top: 88px;
  padding-bottom: 88px;
}

.about-grid {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 48px;
  align-items: start;
}

.about-text h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 6px;
}

.about-title {
  font-size: 1rem;
  color: #666;
  margin-bottom: 20px;
}

.about-bio {
  font-size: 0.975rem;
  color: #333;
  max-width: 520px;
  margin-bottom: 28px;
}

.about-links {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}

.about-links a {
  font-size: 0.875rem;
  font-weight: 500;
  border-bottom: 1px solid #1a1a1a;
  padding-bottom: 1px;
}

.about-links a:hover {
  text-decoration: none;
  color: #555;
  border-color: #555;
}

.about-photo img {
  width: 220px;
  height: 220px;
  border-radius: 50%;
  object-fit: cover;
  border: 1px solid #e8e8e8;
}

/* ============================================================
   EXPERIENCE
   ============================================================ */

.timeline {
  display: flex;
  flex-direction: column;
  gap: 36px;
}

.timeline-item {
  border-left: 2px solid #e8e8e8;
  padding-left: 20px;
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 2px;
}

.timeline-role {
  font-weight: 600;
  font-size: 0.975rem;
}

.timeline-date {
  font-size: 0.8125rem;
  color: #888;
  white-space: nowrap;
}

.timeline-company {
  font-size: 0.875rem;
  color: #666;
  margin-bottom: 8px;
}

.timeline-desc {
  font-size: 0.875rem;
  color: #444;
}

.timeline-desc ul {
  margin: 8px 0 0 0;
  padding-left: 1.2em;
  font-size: 0.875rem;
  color: #444;
  line-height: 1.6;
}

.timeline-desc ul li + li {
  margin-top: 4px;
}

/* ============================================================
   EDUCATION
   ============================================================ */

.edu-grid {
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.edu-item {
  display: grid;
  grid-template-columns: 1fr auto;
  grid-template-rows: auto auto;
  column-gap: 16px;
  align-items: baseline;
}

.edu-degree {
  font-weight: 600;
  font-size: 0.975rem;
}

.edu-school {
  font-size: 0.875rem;
  color: #666;
  grid-column: 1;
}

.edu-date {
  font-size: 0.8125rem;
  color: #888;
  grid-column: 2;
  grid-row: 1 / 3;
  align-self: center;
  white-space: nowrap;
}

.edu-thesis {
  grid-column: 1 / -1;
  font-size: 0.875rem;
  color: #555;
  margin-top: 10px;
  line-height: 1.6;
}

.edu-thesis-label {
  font-weight: 600;
  color: #1a1a1a;
}

/* ============================================================
   PUBLICATIONS
   ============================================================ */

.pub-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 28px;
  counter-reset: pub-counter;
}

.pub-item {
  counter-increment: pub-counter;
  display: grid;
  grid-template-columns: 20px 1fr;
  column-gap: 12px;
}

.pub-item::before {
  content: counter(pub-counter);
  font-size: 0.75rem;
  color: #bbb;
  font-weight: 600;
  padding-top: 3px;
  text-align: right;
}

.pub-title,
.pub-authors,
.pub-venue {
  grid-column: 2;
}

.pub-title {
  font-size: 0.975rem;
  font-weight: 500;
  margin-bottom: 4px;
}

.pub-title a:hover {
  text-decoration: underline;
}

.pub-authors {
  font-size: 0.8125rem;
  color: #555;
  margin-bottom: 2px;
}

.pub-venue {
  font-size: 0.8125rem;
  color: #888;
  font-style: italic;
}

/* ============================================================
   PROJECTS
   ============================================================ */

.card-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  max-width: 80%;
  margin: 0;
}

.card {
  display: flex;
  flex-direction: column;
  border: 1px solid #d4d4d4;
  border-radius: 20px;
  background: #ffffff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06);
  text-decoration: none;
  color: inherit;
}

.card:hover {
  text-decoration: none;
}

.card-preview-wrap {
  position: relative;
  overflow: hidden;
  border-radius: 19px 19px 0 0;
}

.card-preview {
  width: 100%;
  height: auto;
  display: block;
}

.card-gh-badge {
  position: absolute;
  top: 12px;
  right: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
  background: rgba(0, 0, 0, 0.65);
  color: #ffffff;
  font-size: 1rem;
  font-weight: 700;
  padding: 8px 16px;
  border-radius: 20px;
  backdrop-filter: blur(4px);
}

.card-gh-badge svg {
  width: 20px;
  height: 20px;
  fill: #ffffff;
  flex-shrink: 0;
}

.card-gh-arrow {
  font-size: 1rem;
  line-height: 1;
  color: #ffffff;
}

.card-body {
  display: flex;
  flex-direction: column;
  flex: 1;
  padding: 14px 16px;
}

.card-desc {
  flex: 1;
}

.card .card-tags {
  padding-top: 1em;
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 10px;
  gap: 12px;
}

.card-name {
  font-weight: 600;
  font-size: 0.925rem;
}

.card-link {
  font-size: 0.75rem;
  font-weight: 500;
  color: #fff;
  background: #1a1a1a;
  padding: 3px 10px;
  border-radius: 4px;
  white-space: nowrap;
  flex-shrink: 0;
}

.card-link:hover {
  background: #444;
  text-decoration: none;
  color: #fff;
}

.card-desc {
  font-size: 0.8125rem;
  color: #555;
  line-height: 1.55;
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  font-size: 0.875rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  padding: 6px 16px;
  border-radius: 6px;
  background: #475569;
  border: 1px solid #475569;
  color: #ffffff;
}

/* ============================================================
   SKILLS
   ============================================================ */

.skills-grid {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.skill-group {
  display: flex;
  align-items: baseline;
  gap: 16px;
}

.skill-group-name {
  font-size: 0.8125rem;
  font-weight: 600;
  color: #888;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  width: 110px;
  flex-shrink: 0;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

@media (max-width: 640px) {
  .skill-group {
    flex-direction: column;
    gap: 8px;
  }
}

/* ============================================================
   ONGOING RESEARCH
   ============================================================ */

.research-list {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.research-item {
  border-left: 2px solid #e8e8e8;
  padding-left: 20px;
}

.research-topic {
  font-weight: 600;
  font-size: 0.975rem;
  margin-bottom: 6px;
}

.research-desc {
  font-size: 0.875rem;
  color: #444;
}

/* ============================================================
   CERTIFICATIONS
   ============================================================ */

.cert-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.cert-card {
  display: flex;
  flex-direction: column;
  border: 1px solid #d4d4d4;
  border-radius: 20px;
  background: #ffffff;
  overflow: hidden;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06);
}

.cert-img {
  width: 100%;
  height: auto;
  display: block;
}

.cert-info {
  padding: 12px 16px;
  margin-top: auto;
}

.cert-name {
  font-weight: 600;
  font-size: 0.9rem;
  color: #1a1a1a;
}

.cert-issuer {
  font-size: 0.8125rem;
  color: #666;
  margin-top: 2px;
}

/* ============================================================
   CONTACT
   ============================================================ */

.contact-container {
  max-width: 500px;
}

.contact-sub {
  font-size: 0.875rem;
  color: #666;
  margin-bottom: 28px;
}

.contact-links {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.contact-item {
  display: flex;
  align-items: baseline;
  gap: 16px;
  font-size: 0.925rem;
}

.contact-item:hover {
  text-decoration: none;
}

.contact-item:hover .contact-value {
  text-decoration: underline;
}

.contact-label {
  font-weight: 600;
  width: 70px;
  flex-shrink: 0;
  color: #888;
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.contact-value {
  color: #1a1a1a;
}

/* ============================================================
   FOOTER
   ============================================================ */

.footer {
  border-top: 1px solid #e8e8e8;
  padding: 24px 0;
}

.footer p {
  font-size: 0.8125rem;
  color: #bbb;
}

/* ============================================================
   RESPONSIVE
   ============================================================ */

@media (max-width: 640px) {
  .section {
    padding: 56px 0;
  }

  .about-section {
    padding-top: 56px;
    padding-bottom: 56px;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .about-photo {
    order: -1;
  }

  .about-photo img {
    width: 100px;
    height: 100px;
  }

  .about-text h1 {
    font-size: 1.625rem;
  }

  .edu-item {
    grid-template-columns: 1fr;
    grid-template-rows: auto;
  }

  .edu-date {
    grid-column: 1;
    grid-row: auto;
    margin-top: 2px;
  }

  .timeline-header {
    flex-direction: column;
    gap: 2px;
  }

  .card-grid {
    grid-template-columns: 1fr;
    max-width: 100%;
  }

  .cert-grid {
    grid-template-columns: 1fr;
  }

  .card .tag {
    font-size: 0.75rem;
    padding: 4px 10px;
  }

  /* Mobile nav */
  .nav-toggle {
    display: block;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 56px;
    left: 0;
    right: 0;
    background: #ffffff;
    border-bottom: 1px solid #e8e8e8;
    flex-direction: column;
    gap: 0;
    padding: 8px 0;
  }

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

  .nav-links li a {
    display: block;
    padding: 10px 24px;
    font-size: 0.9375rem;
  }
}