/* ---------- Design tokens ---------- */
:root {
  --color-bg: #FFFFFF;
  --color-bg-alt: #F0FDFA;
  --color-accent-light: #99F6E4;
  --color-primary: #0D9488;
  --color-primary-dark: #115E59;
  --color-primary-hover: #0B4844;
  --color-text: #1E293B;
  --color-text-secondary: #64748B;
  --color-border: #E2E8F0;
  --color-danger: #B91C1C;

  --font-base: 'Inter', system-ui, -apple-system, sans-serif;

  --radius: 8px;
  --container-width: 1100px;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-base);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
}
img { max-width: 100%; display: block; }
a { color: var(--color-primary-dark); }
ul { list-style: none; margin: 0; padding: 0; }
h1, h2, h3 { line-height: 1.25; margin: 0 0 0.5em; }

/* ---------- Accessibility helpers ---------- */
.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap; border: 0;
}
.skip-link {
  position: absolute;
  left: 8px; top: -48px;
  background: var(--color-primary-dark);
  color: #fff;
  padding: 10px 16px;
  border-radius: var(--radius);
  z-index: 1000;
  transition: top 0.2s ease;
}
.skip-link:focus {
  top: 8px;
}
a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible {
  outline: 3px solid var(--color-primary-dark);
  outline-offset: 2px;
}

/* ---------- Layout helpers ---------- */
.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 24px;
}
.section {
  padding: 80px 0;
}
.section-alt {
  background: var(--color-bg-alt);
}
.section h2 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  padding: 12px 24px;
  border-radius: var(--radius);
  font-weight: 600;
  text-decoration: none;
  border: 2px solid transparent;
  cursor: pointer;
  font-size: 1rem;
  font-family: inherit;
  transition: background-color 0.2s ease, color 0.2s ease, transform 0.15s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn-primary {
  background: var(--color-primary-dark);
  color: #fff;
}
.btn-primary:hover { background: var(--color-primary-hover); }
.btn-secondary {
  background: transparent;
  color: var(--color-primary-dark);
  border-color: var(--color-primary);
}
.btn-secondary:hover { background: var(--color-accent-light); }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky;
  top: 0;
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(4px);
  border-bottom: 1px solid var(--color-border);
  z-index: 100;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}
.logo {
  font-weight: 700;
  font-size: 1.1rem;
  text-decoration: none;
  color: var(--color-text);
}
.primary-nav ul {
  display: flex;
  gap: 24px;
}
.primary-nav a {
  text-decoration: none;
  color: var(--color-text);
  font-weight: 500;
  padding: 4px 0;
  border-bottom: 2px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}
.primary-nav a:hover,
.primary-nav a.is-active {
  border-color: var(--color-primary);
  color: var(--color-primary-dark);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}
.nav-toggle-bar {
  width: 24px;
  height: 2px;
  background: var(--color-text);
}

@media (max-width: 768px) {
  .nav-toggle { display: flex; }
  .primary-nav {
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    display: none;
  }
  .primary-nav.is-open { display: block; }
  .primary-nav ul {
    flex-direction: column;
    padding: 16px 24px;
    gap: 16px;
  }
}

/* ---------- Hero ---------- */
.hero {
  padding: 120px 0 80px;
  background: linear-gradient(180deg, var(--color-bg-alt), var(--color-bg));
}
.eyebrow {
  color: var(--color-primary-dark);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-size: 0.85rem;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  max-width: 20ch;
}
.hero-lead {
  font-size: 1.15rem;
  color: var(--color-text-secondary);
  max-width: 55ch;
  margin-bottom: 2rem;
}
.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

/* ---------- About ---------- */
.about-content p {
  max-width: 70ch;
  margin-bottom: 1.2rem;
}

/* ---------- Skills ---------- */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 24px;
}
.skill-card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 24px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.skill-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(15, 23, 42, 0.08);
}
.skill-card h3 {
  color: var(--color-primary-dark);
  font-size: 1.1rem;
}
.skill-card li {
  padding: 6px 0;
  border-bottom: 1px solid var(--color-border);
}
.skill-card li:last-child { border-bottom: none; }

/* ---------- Projects ---------- */
.filters {
  display: flex;
  gap: 12px;
  margin-bottom: 32px;
  flex-wrap: wrap;
}
.filter-btn {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  padding: 8px 18px;
  cursor: pointer;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text);
}
.filter-btn {
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}
.filter-btn:hover { border-color: var(--color-primary); }
.filter-btn.is-active {
  background: var(--color-primary-dark);
  border-color: var(--color-primary-dark);
  color: #fff;
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}
.project-card {
  border: 1px solid var(--color-border);
  border-radius: 12px;
  overflow: hidden;
  background: #fff;
  display: flex;
  flex-direction: column;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.project-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.1);
}
.project-card[hidden] { display: none; }
.project-thumb {
  height: 140px;
  width: 100%;
  object-fit: cover;
  background: var(--color-primary-dark);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
}
.project-body { padding: 20px; }
.project-tag {
  color: var(--color-text-secondary);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin: 0 0 12px;
}
.tech-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 16px 0;
}
.tech-list li {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--color-bg-alt);
  color: var(--color-primary-dark);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 999px;
}
.project-links {
  display: flex;
  gap: 16px;
  font-weight: 600;
  font-size: 0.9rem;
}

.project-details {
  margin-top: 16px;
  border-top: 1px solid var(--color-border);
  padding-top: 12px;
}
.project-details summary {
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 600;
  font-size: 0.85rem;
  color: var(--color-primary-dark);
  background: transparent;
  border: 1px solid var(--color-primary);
  border-radius: 999px;
  padding: 8px 16px;
  transition: background-color 0.2s ease, color 0.2s ease;
}
.project-details summary:hover {
  background: var(--color-accent-light);
}
.project-details summary::-webkit-details-marker { display: none; }
.project-details summary::marker { content: ''; }
.project-details summary::before {
  content: '+';
  font-weight: 700;
}
.project-details[open] summary::before {
  content: '–';
}
.project-details dl {
  margin: 16px 0 0;
}
.project-details p {
  margin: 8px 0;
  font-size: 0.95rem;
}
.project-details p strong {
  color: var(--color-primary-dark);
}

/* ---------- Timeline ---------- */
.timeline {
  border-left: 3px solid var(--color-primary);
  padding-left: 24px;
}
.timeline li {
  margin-bottom: 24px;
}
.timeline h3 {
  color: var(--color-primary-dark);
  font-size: 1.1rem;
}

/* ---------- Contact ---------- */
.contact-lead {
  color: var(--color-text-secondary);
  margin-bottom: 32px;
}
.contact-grid {
  display: grid;
  gap: 40px;
}
.contact-form-full {
  max-width: 560px;
}
.form-field {
  margin-bottom: 20px;
}
.form-field label {
  display: block;
  font-weight: 600;
  margin-bottom: 6px;
}
.form-field input,
.form-field textarea {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 1rem;
}
.form-field input[aria-invalid="true"],
.form-field textarea[aria-invalid="true"] {
  border-color: var(--color-danger);
}
.field-error {
  color: var(--color-danger);
  font-size: 0.85rem;
  margin: 6px 0 0;
  min-height: 1em;
}
.form-success {
  color: var(--color-primary-dark);
  font-weight: 600;
  margin-top: 16px;
}
@media (max-width: 700px) {
  .contact-form-full { max-width: none; }
}

/* ---------- Reveal on scroll ---------- */
.reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
  }
  .reveal {
    opacity: 1;
    transform: none;
  }
}

/* ---------- Footer ---------- */
.site-footer {
  padding: 32px 0;
  color: var(--color-text-secondary);
  border-top: 1px solid var(--color-border);
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}
.footer-inner p { margin: 0; }
.footer-github {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}
.footer-github:hover {
  text-decoration: underline;
}
.footer-github i {
  font-size: 1.1rem;
}