:root {
  --bg: #ffffff;
  --bg-alt: #f6f7f9;
  --text: #16181d;
  --text-muted: #565c66;
  --accent: #2f6feb;
  --accent-2: #0b1f4d;
  --accent-contrast: #ffffff;
  --border: #e4e6ea;
  --card-bg: #ffffff;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --radius: 12px;
  --max-width: 960px;
  --gradient: linear-gradient(135deg, var(--accent), var(--accent-2));
  --gradient-wash: radial-gradient(1200px circle at 15% -10%, rgba(47,111,235,0.10), transparent 55%),
                   radial-gradient(1000px circle at 90% 10%, rgba(11,31,77,0.06), transparent 50%);
}

:root[data-theme="dark"] {
  --bg: #0f1115;
  --bg-alt: #161922;
  --text: #eceef1;
  --text-muted: #a3a9b3;
  --accent: #6d9bff;
  --accent-2: #2f57c9;
  --accent-contrast: #0f1115;
  --border: #262a33;
  --card-bg: #161922;
  --shadow: 0 1px 3px rgba(0,0,0,0.4), 0 1px 2px rgba(0,0,0,0.3);
  --gradient-wash: radial-gradient(1200px circle at 15% -10%, rgba(109,155,255,0.14), transparent 55%),
                   radial-gradient(1000px circle at 90% 10%, rgba(47,87,201,0.10), transparent 50%);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1115;
    --bg-alt: #161922;
    --text: #eceef1;
    --text-muted: #a3a9b3;
    --accent: #6d9bff;
    --accent-2: #2f57c9;
    --accent-contrast: #0f1115;
    --border: #262a33;
    --card-bg: #161922;
    --shadow: 0 1px 3px rgba(0,0,0,0.4), 0 1px 2px rgba(0,0,0,0.3);
    --gradient-wash: radial-gradient(1200px circle at 15% -10%, rgba(109,155,255,0.14), transparent 55%),
                     radial-gradient(1000px circle at 90% 10%, rgba(47,87,201,0.10), transparent 50%);
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--gradient-wash), var(--bg);
  background-attachment: fixed;
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.55;
  transition: background 0.2s ease, color 0.2s ease;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* Header / Nav */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: transparent;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  gap: 16px;
}

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

.nav-links {
  list-style: none;
  display: flex;
  gap: 20px;
  margin: 0;
  padding: 0;
  flex-wrap: wrap;
}

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

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

.nav-links a.active {
  color: var(--accent);
  font-weight: 600;
}

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  padding: 6px 10px;
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: border-color 0.15s ease, color 0.15s ease;
}

.nav-toggle {
  display: none;
  order: 2;
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  width: 36px;
  height: 32px;
  padding: 0;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
}

.nav-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--text);
  border-radius: 1px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.nav-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

.theme-toggle:hover {
  border-color: var(--accent);
}

.theme-toggle .icon-sun {
  display: none;
}

.theme-toggle.is-dark .icon-moon {
  display: none;
}

.theme-toggle.is-dark .icon-sun {
  display: block;
}

/* Hero */
.hero {
  padding: 12px 20px 24px;
  display: flex;
  align-items: stretch;
  justify-content: space-between;
  gap: 40px;
  flex-wrap: nowrap;
}

.hero-text {
  flex: 0 0 60%;
  min-width: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.hero-photo {
  flex: 0 0 40%;
  position: relative;
  width: 40%;
  height: auto;
  align-self: stretch;
}

.hero-photo::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 110%;
  height: 110%;
  background: var(--gradient);
  border-radius: 34px;
  filter: blur(40px);
  opacity: 0.4;
  z-index: 0;
  animation: heroGlowPulse 4s ease-in-out infinite;
}

.hero-photo img {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  border-radius: 30px;
  object-fit: cover;
  border: 3px solid rgba(47, 111, 235, 0.3);
}

@keyframes heroGlowPulse {
  0%, 100% { opacity: 0.3; transform: translate(-50%, -50%) scale(1); }
  50% { opacity: 0.55; transform: translate(-50%, -50%) scale(1.05); }
}

@media (max-width: 640px) {
  .hero {
    flex-direction: column-reverse;
    text-align: center;
  }

  .hero-actions {
    justify-content: center;
  }

  .hero-photo {
    flex-basis: auto;
    width: 200px;
    height: 200px;
    align-self: auto;
  }
}

.eyebrow {
  color: var(--accent);
  font-weight: 600;
  font-size: 0.9rem;
  letter-spacing: 0.02em;
  margin: 0 0 16px;
}

.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3rem);
  margin: 0 0 16px;
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-sub {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 640px;
  margin: 0 0 28px;
}

.text-accent {
  color: var(--accent);
  font-weight: 600;
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  position: relative;
  display: inline-block;
  padding: 10px 20px;
  border-radius: 8px;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  overflow: hidden;
  isolation: isolate;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

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

.btn::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(115deg, transparent 30%, rgba(255,255,255,0.35) 48%, transparent 66%);
  background-size: 220% 100%;
  background-position: 150% 0;
  transition: background-position 0.6s ease;
  pointer-events: none;
}

.btn:hover::after {
  background-position: -50% 0;
}

.btn-primary,
.btn-secondary {
  background: transparent;
  color: var(--accent);
  border-color: var(--accent);
}

.btn-primary:hover,
.btn-secondary:hover {
  background: rgba(47,111,235,0.08);
}

/* Sections */
.section {
  padding: 48px 20px;
  border-top: 1px solid var(--border);
}

#about.section {
  padding-top: 24px;
}

.section-title {
  font-size: 1.6rem;
  margin: 0 0 8px;
  display: inline-block;
  background: var(--gradient);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.section-lead {
  color: var(--text-muted);
  margin: 0 0 24px;
  max-width: 640px;
}

/* Timeline (horizontal on desktop, vertical on mobile — 3 milestones) */
.timeline-h {
  margin-top: 8px;
}

.timeline-h-track {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  align-items: stretch;
  position: relative;
}

.timeline-h-track::before {
  content: "";
  position: absolute;
  top: 10px;
  left: calc(100% / 6);
  right: calc(100% / 6);
  height: 2px;
  background: var(--gradient);
  z-index: 0;
}

.timeline-h-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  position: relative;
}

.timeline-h-dot {
  position: relative;
  z-index: 1;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--gradient);
  border: 3px solid var(--bg);
  box-shadow: 0 0 0 2px var(--border);
  margin-bottom: 16px;
}

.timeline-h-header {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
}

.timeline-h-card {
  width: 100%;
  flex: 1 1 auto;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px 20px;
}

.timeline-h-date {
  display: inline-block;
  padding: 3px 9px;
  background: rgba(47,111,235,0.1);
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--accent);
  margin-top: 2px;
}

.timeline-h-header h3 {
  margin: 0;
  font-size: 0.9rem;
}

.timeline-h-card .timeline-h-subtitle {
  color: var(--accent);
  font-weight: 700;
  font-size: 0.9rem;
  margin: 0 0 8px;
}

.timeline-h-card p {
  color: var(--text-muted);
  margin: 0;
  font-size: 0.85rem;
  line-height: 1.5;
}

@media (max-width: 700px) {
  .timeline-h-track {
    display: flex;
    flex-direction: column;
    gap: 32px;
    padding-left: 24px;
  }

  .timeline-h-track::before {
    top: 2px;
    bottom: 2px;
    left: 0;
    right: auto;
    width: 2px;
    height: auto;
    transform: none;
  }

  .timeline-h-item {
    align-items: flex-start;
  }

  .timeline-h-dot {
    position: absolute;
    left: -24px;
    top: 2px;
    margin-bottom: 0;
  }

  .timeline-h-header {
    align-items: flex-start;
    text-align: left;
    margin-bottom: 12px;
  }
}

/* Project rows */
.project-list {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.project-row {
  display: flex;
  align-items: center;
  gap: 28px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
}

.project-image {
  flex: 0 0 40%;
}

.project-image img {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
  border-radius: 12px;
  display: block;
  border: 1px solid var(--border);
}

.project-content {
  flex: 1;
  min-width: 0;
}

.project-content h3 {
  margin: 0 0 8px;
  font-size: 1.15rem;
}

.project-content p {
  color: var(--text-muted);
  margin: 0 0 14px;
  font-size: 0.95rem;
}

.project-content p a,
.project-content p a:visited {
  color: var(--accent);
  font-weight: 600;
}

.project-content p a:hover {
  text-decoration: none;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
}

.tag {
  display: inline-block;
  padding: 4px 10px;
  border: 1px solid var(--border);
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  color: var(--accent);
  background: rgba(47,111,235,0.08);
}

@media (max-width: 640px) {
  .project-row {
    flex-direction: column;
    align-items: stretch;
  }

  .project-image {
    flex: none;
  }
}

/* Cards */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}

.card h3 {
  margin: 0 0 8px;
  font-size: 1.05rem;
}

.card p {
  color: var(--text-muted);
  margin: 0;
  font-size: 0.95rem;
}

.card-placeholder {
  border-style: dashed;
}

.cert-card {
  text-decoration: none;
  color: inherit;
  display: block;
}

.cert-card:hover {
  border-color: var(--accent);
}

.cert-badge {
  width: 100%;
  max-width: 220px;
  border-radius: 8px;
  margin-bottom: 12px;
  display: block;
}

.card-links {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-top: 12px;
}

.card-link {
  display: inline-block;
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
}

.card-link-muted {
  color: var(--text-muted);
  font-style: italic;
  font-weight: 500;
}

/* Link lists (blog / certs) */
.link-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.link-list a {
  color: var(--text);
  text-decoration: none;
  font-weight: 500;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: 8px;
  display: block;
  background: var(--card-bg);
}

.link-list a:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* Contact page */
.contact-layout {
  display: flex;
  align-items: center;
  gap: 40px;
  flex-wrap: wrap;
  margin-top: 24px;
}

.contact-photo {
  flex: 0 0 auto;
  width: 160px;
  height: 160px;
}

.contact-photo img {
  width: 100%;
  height: 100%;
  border-radius: 30px;
  object-fit: cover;
  border: 3px solid rgba(47, 111, 235, 0.3);
}

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

.contact-row {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.05rem;
}

.contact-row a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
}

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

.copy-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 7px;
  color: var(--text-muted);
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease;
}

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

.copy-btn.is-copied {
  border-color: var(--accent);
  color: var(--accent);
}

@media (max-width: 640px) {
  .contact-layout {
    flex-direction: column;
    text-align: center;
  }

  .contact-row {
    justify-content: center;
  }
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 24px 20px;
  color: var(--text-muted);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-links {
  display: flex;
  align-items: center;
  gap: 16px;
}

.footer-links a {
  color: var(--text-muted);
  text-decoration: none;
}

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

.footer-icon {
  display: inline-flex;
  align-items: center;
}

@media (max-width: 640px) {
  .nav {
    flex-wrap: wrap;
    justify-content: flex-start;
  }

  .nav-toggle {
    display: flex;
    order: -1;
    margin-right: -10px;
  }

  .theme-toggle {
    order: 3;
    margin-left: auto;
  }

  .nav-links {
    order: 4;
    flex-basis: 100%;
    flex-direction: column;
    gap: 0;
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height 0.25s ease, opacity 0.2s ease;
  }

  .nav-links.is-open {
    max-height: 300px;
    opacity: 1;
    margin-top: 12px;
  }

  .nav-links li {
    width: 100%;
  }

  .nav-links a {
    display: block;
    padding: 10px 0;
    border-top: 1px solid var(--border);
  }

  .timeline-dates { margin-left: 0; }
}