/* ============================================================
   Design Tokens
   ============================================================ */
:root {
  /* Colors — dark theme (default) */
  --color-bg:           #0f0f0f;
  --color-surface:      #1a1a1a;
  --color-surface-2:    #222222;
  --color-border:       #2e2e2e;
  --color-primary:      #6ee7b7;
  --color-primary-hover:#34d399;
  --color-text:         #e5e7eb;
  --color-muted:        #9ca3af;
  --color-heading:      #f9fafb;

  /* Typography */
  --font-sans:  'Inter', system-ui, -apple-system, sans-serif;
  --font-mono:  'JetBrains Mono', 'Courier New', monospace;

  --text-sm:   0.875rem;
  --text-base: 1rem;
  --text-lg:   1.125rem;
  --text-xl:   1.25rem;
  --text-2xl:  1.5rem;
  --text-3xl:  1.875rem;
  --text-4xl:  2.25rem;
  --text-5xl:  3rem;

  --leading-tight:  1.2;
  --leading-normal: 1.6;

  /* Spacing */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-24: 6rem;

  /* Radii */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 16px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
}

[data-theme="light"] {
  --color-bg:           #f9fafb;
  --color-surface:      #ffffff;
  --color-surface-2:    #f3f4f6;
  --color-border:       #e5e7eb;
  --color-primary:      #059669;
  --color-primary-hover:#047857;
  --color-text:         #111827;
  --color-muted:        #6b7280;
  --color-heading:      #111827;
}

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

html {
  font-size: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  background-color: var(--color-bg);
  color: var(--color-text);
  transition: background-color var(--transition-base), color var(--transition-base);
}

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

ul,
ol {
  list-style: none;
}

a {
  color: inherit;
  text-decoration: none;
}

/* ============================================================
   Accessibility
   ============================================================ */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-4);
  background: var(--color-primary);
  color: #000;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-sm);
  font-weight: 600;
  z-index: 1000;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: var(--space-4);
}

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
}

/* ============================================================
   Layout
   ============================================================ */
.container {
  width: min(90%, 72rem);
  margin-inline: auto;
}

section {
  padding-block: var(--space-24);
}

/* ============================================================
   Typography
   ============================================================ */
.section__heading {
  font-size: var(--text-3xl);
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: var(--space-12);
  position: relative;
}

.section__heading::after {
  content: '';
  display: block;
  width: 2.5rem;
  height: 3px;
  background: var(--color-primary);
  margin-top: var(--space-3);
  border-radius: 2px;
}

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-block;
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-md);
  font-size: var(--text-base);
  font-weight: 600;
  cursor: pointer;
  transition:
    background-color var(--transition-fast),
    color var(--transition-fast),
    border-color var(--transition-fast),
    transform var(--transition-fast);
}

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

.btn:active {
  transform: translateY(0);
}

.btn--primary {
  background-color: var(--color-primary);
  color: #000;
  border: 2px solid var(--color-primary);
}

.btn--primary:hover {
  background-color: var(--color-primary-hover);
  border-color: var(--color-primary-hover);
}

.btn--outline {
  background-color: transparent;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
}

.btn--outline:hover {
  background-color: var(--color-primary);
  color: #000;
}

/* ============================================================
   Header & Nav
   ============================================================ */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: background-color var(--transition-base), border-color var(--transition-base);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-block: var(--space-4);
  gap: var(--space-4);
  position: relative;
}

.header__logo {
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: 0.05em;
  font-family: var(--font-mono);
}

.nav__menu {
  display: flex;
  gap: var(--space-6);
  align-items: center;
}

.nav__link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-muted);
  padding-block: var(--space-1);
  border-bottom: 2px solid transparent;
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

.nav__link:hover,
.nav__link[aria-current="true"] {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-2);
}

.nav__toggle-bar {
  display: block;
  width: 22px;
  height: 2px;
  background-color: var(--color-text);
  border-radius: 2px;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.theme-toggle {
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-2) var(--space-3);
  cursor: pointer;
  font-size: var(--text-base);
  line-height: 1;
  color: var(--color-text);
  transition: border-color var(--transition-fast), color var(--transition-fast);
}

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

.theme-toggle__icon {
  display: none;
}

[data-theme="dark"] .theme-toggle__icon--dark {
  display: inline;
}

[data-theme="light"] .theme-toggle__icon--light {
  display: inline;
}

/* ============================================================
   Hero
   ============================================================ */
.hero {
  min-height: calc(100vh - 65px);
  display: flex;
  align-items: center;
  padding-block: var(--space-24);
}

.hero__inner {
  max-width: 42rem;
}

.hero__eyebrow {
  font-size: var(--text-base);
  color: var(--color-primary);
  font-weight: 500;
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
}

.hero__heading {
  font-size: clamp(var(--text-4xl), 8vw, var(--text-5xl));
  font-weight: 700;
  color: var(--color-heading);
  line-height: var(--leading-tight);
  margin-bottom: var(--space-4);
}

.hero__tagline {
  font-size: var(--text-xl);
  color: var(--color-primary);
  font-weight: 600;
  margin-bottom: var(--space-4);
}

.hero__summary {
  font-size: var(--text-lg);
  color: var(--color-muted);
  margin-bottom: var(--space-8);
  max-width: 36rem;
}

.hero__cta {
  display: flex;
  gap: var(--space-4);
  flex-wrap: wrap;
}

/* ============================================================
   About
   ============================================================ */
.about {
  background-color: var(--color-surface);
}

.about__text p {
  font-size: var(--text-lg);
  color: var(--color-text);
  margin-bottom: var(--space-4);
  max-width: 60rem;
}

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

.about__text strong {
  color: var(--color-primary);
  font-weight: 600;
}

/* ============================================================
   Skills
   ============================================================ */
.skills__list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(20rem, 1fr));
  gap: var(--space-6);
}

.skills__group {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: border-color var(--transition-base);
}

.skills__group:hover {
  border-color: var(--color-primary);
}

.skills__category {
  display: block;
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-4);
  font-family: var(--font-mono);
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.skill-tag {
  background-color: var(--color-surface-2);
  color: var(--color-text);
  font-size: var(--text-sm);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  font-family: var(--font-mono);
}

/* ============================================================
   Experience / Timeline
   ============================================================ */
.experience {
  background-color: var(--color-surface);
}

.timeline {
  position: relative;
  padding-left: var(--space-8);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--color-border);
}

.timeline__item {
  position: relative;
  margin-bottom: var(--space-12);
}

.timeline__item:last-child {
  margin-bottom: 0;
}

.timeline__marker {
  position: absolute;
  left: calc(-1 * var(--space-8) + 2px);
  top: 1.4rem;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background-color: var(--color-primary);
  border: 2px solid var(--color-bg);
  box-shadow: 0 0 0 2px var(--color-primary);
}

.timeline__content {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: border-color var(--transition-base);
}

.timeline__content:hover {
  border-color: var(--color-primary);
}

.timeline__header {
  margin-bottom: var(--space-4);
}

.timeline__title {
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: var(--space-1);
}

.timeline__company {
  font-size: var(--text-base);
  color: var(--color-primary);
  font-weight: 600;
  margin-bottom: var(--space-1);
}

.timeline__period {
  display: block;
  font-size: var(--text-sm);
  color: var(--color-muted);
  font-family: var(--font-mono);
}

.timeline__bullets {
  list-style: disc;
  padding-left: var(--space-4);
}

.timeline__bullets li {
  color: var(--color-text);
  font-size: var(--text-base);
  margin-bottom: var(--space-2);
}

.timeline__bullets li:last-child {
  margin-bottom: 0;
}

/* ============================================================
   Certifications
   ============================================================ */
.cert-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(18rem, 1fr));
  gap: var(--space-4);
}

.cert-card {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-4) var(--space-6);
  transition: border-color var(--transition-base), transform var(--transition-fast);
}

.cert-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

.cert-card__badge {
  display: block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background-color: var(--color-primary);
  flex-shrink: 0;
}

.cert-card__name {
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--color-text);
}

/* ============================================================
   Contact
   ============================================================ */
.contact {
  background-color: var(--color-surface);
  text-align: center;
}

.contact__inner {
  margin-inline: auto;
  max-width: 40rem;
}

.contact__intro {
  font-size: var(--text-lg);
  color: var(--color-muted);
  margin-bottom: var(--space-8);
}

.contact__links {
  display: flex;
  justify-content: center;
  gap: var(--space-4);
  flex-wrap: wrap;
}

/* ============================================================
   Footer
   ============================================================ */
.footer {
  background-color: var(--color-bg);
  border-top: 1px solid var(--color-border);
  padding-block: var(--space-8);
}

.footer__inner {
  display: flex;
  justify-content: center;
  align-items: center;
}

.footer__copy {
  font-size: var(--text-sm);
  color: var(--color-muted);
}

/* ============================================================
   Scroll Reveal
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================================
   Responsive — Mobile
   ============================================================ */
@media (max-width: 768px) {
  section {
    padding-block: var(--space-16);
  }

  .nav__menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: flex-start;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-4) var(--space-8);
    gap: var(--space-4);
  }

  .nav__menu.is-open {
    display: flex;
  }

  .nav__toggle {
    display: flex;
  }

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

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

  .timeline {
    padding-left: var(--space-6);
  }

  .timeline__marker {
    left: calc(-1 * var(--space-6) + 2px);
  }
}

/* ============================================================
   Reduced Motion
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }

  html {
    scroll-behavior: auto;
  }
}