/* ============================================================
   CUSTOM PROPERTIES (Design Tokens)
   ============================================================ */
:root {
  /* Palette */
  --color-dark:              #0A0F1E;
  --color-dark-elevated:     #131929;
  --color-white:             #FFFFFF;
  --color-bg:                #FFFFFF;
  --color-surface:           #F8FAFC;
  --color-text-primary:      #0F172A;
  --color-text-secondary:    #64748B;
  --color-text-on-dark:      #F1F5F9;
  --color-text-muted-dark:   #94A3B8;
  --color-accent:            #2563EB;
  --color-accent-hover:      #1D4ED8;
  --color-accent-light:      #60A5FA;
  --color-accent-subtle:     #EFF6FF;
  --color-border:            #E2E8F0;
  --color-border-dark:       rgba(255, 255, 255, 0.08);

  /* Typography */
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;

  /* Spacing scale (8px base) */
  --sp-1:   4px;
  --sp-2:   8px;
  --sp-3:  12px;
  --sp-4:  16px;
  --sp-5:  24px;
  --sp-6:  32px;
  --sp-7:  48px;
  --sp-8:  64px;
  --sp-9:  96px;
  --sp-10: 128px;

  /* Layout */
  --max-width:  960px;
  --nav-height: 64px;

  /* Borders */
  --radius-sm:   4px;
  --radius-md:   8px;
  --radius-lg:  12px;
  --radius-xl:  16px;
  --radius-pill: 9999px;

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

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.625;
  color: var(--color-text-primary);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

ul, ol {
  list-style: none;
}

strong {
  font-weight: 600;
}

/* ============================================================
   SKIP LINK
   ============================================================ */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--sp-4);
  background: var(--color-accent);
  color: var(--color-white);
  padding: var(--sp-2) var(--sp-4);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 600;
  z-index: 9999;
  transition: top var(--t-fast);
}

.skip-link:focus {
  top: var(--sp-2);
}

/* ============================================================
   BASE TYPOGRAPHY
   ============================================================ */
h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

/* ============================================================
   LAYOUT PRIMITIVES
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--sp-5);
}

.section {
  padding: var(--sp-9) 0;
}

/* ============================================================
   NAVIGATION
   ============================================================ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-height);
  transition: background var(--t-base), box-shadow var(--t-base);
}

.site-header.is-scrolled {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  box-shadow: 0 1px 0 var(--color-border);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--nav-height);
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--sp-5);
}

.nav-wordmark {
  font-size: 0.9375rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--color-white);
  transition: color var(--t-fast);
}

.site-header.is-scrolled .nav-wordmark {
  color: var(--color-text-primary);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: var(--sp-5);
}

.nav-link {
  font-size: 0.9rem;
  font-weight: 500;
  color: rgba(255, 255, 255, 0.75);
  transition: color var(--t-fast);
  padding: var(--sp-1) 0;
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 1px;
  background: var(--color-accent-light);
  transform: scaleX(0);
  transition: transform var(--t-fast);
  transform-origin: left;
}

.nav-link:hover,
.nav-link[aria-current="true"] {
  color: var(--color-white);
}

.nav-link:hover::after,
.nav-link[aria-current="true"]::after {
  transform: scaleX(1);
}

.site-header.is-scrolled .nav-link {
  color: var(--color-text-secondary);
}

.site-header.is-scrolled .nav-link:hover,
.site-header.is-scrolled .nav-link[aria-current="true"] {
  color: var(--color-text-primary);
}

.site-header.is-scrolled .nav-link::after {
  background: var(--color-accent);
}

/* Resume CTA in nav */
.nav-link--cta {
  color: var(--color-accent-light) !important;
}

.site-header.is-scrolled .nav-link--cta {
  color: var(--color-accent) !important;
}

.nav-link--cta::after {
  display: none;
}

/* Hamburger (hidden on desktop) */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--sp-2);
  position: relative;
  z-index: 10;
}

.nav-toggle-bar {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--color-white);
  border-radius: 1px;
  transition: background var(--t-fast), transform var(--t-base), opacity var(--t-fast);
}

.site-header.is-scrolled .nav-toggle-bar {
  background: var(--color-text-primary);
}

/* Animated hamburger → close */
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) {
  opacity: 0;
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.6875rem 1.5rem;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  cursor: pointer;
  transition: background var(--t-fast), border-color var(--t-fast), color var(--t-fast);
  white-space: nowrap;
}

/* On dark background */
.btn--primary {
  background: var(--color-accent);
  color: var(--color-white);
  border-color: var(--color-accent);
}

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

.btn--secondary {
  background: transparent;
  color: rgba(255, 255, 255, 0.85);
  border-color: rgba(255, 255, 255, 0.25);
}

.btn--secondary:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.45);
  color: var(--color-white);
}

/* On dark background (contact section) */
.btn--light {
  background: var(--color-white);
  color: var(--color-accent);
  border-color: var(--color-white);
}

.btn--light:hover {
  background: var(--color-accent-subtle);
  border-color: var(--color-accent-subtle);
}

/* ============================================================
   SECTION COMMON
   ============================================================ */
.section-header {
  margin-bottom: var(--sp-7);
}

.section-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: var(--sp-2);
}

.section-label--light {
  color: var(--color-accent-light);
}

.section-heading {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  color: var(--color-text-primary);
  letter-spacing: -0.03em;
}

/* ============================================================
   HERO
   ============================================================ */
.hero {
  min-height: 100vh;
  background-color: var(--color-dark);
  background-image:
    radial-gradient(ellipse 60% 50% at 80% 10%, rgba(37, 99, 235, 0.18) 0%, transparent 100%);
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding-top: calc(var(--nav-height) + var(--sp-8));
  padding-bottom: var(--sp-8);
  position: relative;
}

.hero__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-8);
}

.hero__content {
  flex: 1;
  min-width: 0;
}

.hero__overline {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-accent-light);
  letter-spacing: 0.04em;
  margin-bottom: var(--sp-4);
}

.hero__name {
  font-size: clamp(3.5rem, 9vw, 6rem);
  font-weight: 800;
  color: var(--color-white);
  line-height: 0.92;
  letter-spacing: -0.04em;
  margin-bottom: var(--sp-6);
}

.hero__tagline {
  font-size: clamp(1rem, 2.2vw, 1.125rem);
  color: var(--color-text-muted-dark);
  line-height: 1.75;
  margin-bottom: var(--sp-6);
  max-width: 420px;
}

.hero__actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--sp-3);
  margin-bottom: var(--sp-6);
}

.hero__meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--sp-2);
  font-size: 0.875rem;
  color: var(--color-text-muted-dark);
}

.hero__meta a {
  color: var(--color-text-muted-dark);
  transition: color var(--t-fast);
}

.hero__meta a:hover {
  color: var(--color-white);
}

.hero__meta-sep {
  opacity: 0.35;
}

/* Photo */
.hero__photo-wrap {
  flex: 0 0 auto;
}

.hero__photo {
  width: 300px;
  height: 300px;
  object-fit: cover;
  object-position: center top;
  border-radius: var(--radius-xl);
  border: 1px solid var(--color-border-dark);
  /* Subtle desaturated treatment in case photo is color */
  filter: grayscale(15%);
}

/* Scroll cue */
.hero__scroll-cue {
  position: absolute;
  bottom: var(--sp-6);
  left: 50%;
  transform: translateX(-50%);
}

.hero__scroll-line {
  display: block;
  width: 1px;
  height: 48px;
  background: linear-gradient(to bottom, rgba(255, 255, 255, 0.35), transparent);
  animation: scrollPulse 2.5s ease-in-out infinite;
}

/* ============================================================
   ABOUT
   ============================================================ */
.about {
  background: var(--color-bg);
}

.about__body {
  max-width: 680px;
}

.about__text {
  font-size: 1.0625rem;
  line-height: 1.8;
  color: var(--color-text-primary);
  margin-bottom: var(--sp-5);
}

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

.about__text strong {
  color: var(--color-text-primary);
}

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

.experience__list {
  display: flex;
  flex-direction: column;
  gap: var(--sp-4);
}

.role-card {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--sp-6);
  transition: box-shadow var(--t-base), border-color var(--t-base), transform var(--t-base);
}

.role-card:hover {
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.07);
  border-color: #CBD5E1;
  transform: translateY(-1px);
}

.role-card__header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--sp-4);
  margin-bottom: var(--sp-5);
}

.role-card__company {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text-primary);
  letter-spacing: -0.02em;
  margin-bottom: var(--sp-1);
}

.role-card__title {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-accent);
}

.role-card__meta {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: var(--sp-1);
  flex-shrink: 0;
}

.role-card__period {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.role-card__location {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
}

.role-card__bullets {
  margin-bottom: var(--sp-5);
}

.role-card__bullets li {
  position: relative;
  padding-left: 1.125rem;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--color-text-primary);
  margin-bottom: var(--sp-2);
}

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

.role-card__bullets li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.65em;
  width: 5px;
  height: 5px;
  background: var(--color-accent);
  border-radius: 50%;
  flex-shrink: 0;
}

.role-card__bullets li strong {
  color: var(--color-text-primary);
}

.role-card__tech {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
}

.tech-tag {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 400;
  color: var(--color-text-secondary);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  padding: 3px 9px;
  border-radius: var(--radius-sm);
  white-space: nowrap;
}

/* Condensed card for earlier roles */
.role-card--condensed {
  border-style: dashed;
  border-color: var(--color-border);
}

.role-card--condensed .role-card__company {
  color: var(--color-text-secondary);
}

/* ============================================================
   SKILLS
   ============================================================ */
.skills {
  background: var(--color-bg);
}

.skills__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-7) var(--sp-8);
}

.skill-cluster__label {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  margin-bottom: var(--sp-3);
}

.skill-cluster__badges {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
}

.badge {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-accent);
  background: var(--color-accent-subtle);
  padding: 5px 13px;
  border-radius: var(--radius-pill);
  white-space: nowrap;
  transition: background var(--t-fast), color var(--t-fast);
}

.badge:hover {
  background: #DBEAFE;
}

/* ============================================================
   EDUCATION
   ============================================================ */
.education {
  background: var(--color-surface);
}

.education__list {
  border-top: 1px solid var(--color-border);
}

.education__item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--sp-5) 0;
  border-bottom: 1px solid var(--color-border);
  gap: var(--sp-5);
}

.education__degree {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.education__credential {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text-primary);
}

.education__detail {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-accent);
}

.education__institution {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 3px;
  flex-shrink: 0;
}

.education__school {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-text-secondary);
}

.education__year {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
}

/* ============================================================
   CONTACT
   ============================================================ */
.contact {
  background: var(--color-dark);
  background-image:
    radial-gradient(ellipse 70% 60% at 0% 100%, rgba(37, 99, 235, 0.15) 0%, transparent 100%);
}

.contact__inner {
  max-width: 600px;
}

.contact__heading {
  font-size: clamp(2.25rem, 6vw, 3.5rem);
  color: var(--color-white);
  letter-spacing: -0.04em;
  line-height: 1.0;
  margin-bottom: var(--sp-5);
  margin-top: var(--sp-3);
}

.contact__sub {
  font-size: 1.0625rem;
  color: var(--color-text-muted-dark);
  line-height: 1.7;
  margin-bottom: var(--sp-7);
}

.contact__links {
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  margin-bottom: var(--sp-7);
}

.contact__link {
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  padding: var(--sp-4) var(--sp-5);
  border: 1px solid var(--color-border-dark);
  border-radius: var(--radius-md);
  transition: background var(--t-fast), border-color var(--t-fast);
}

.contact__link:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: rgba(255, 255, 255, 0.18);
}

.contact__link--primary {
  border-color: rgba(96, 165, 250, 0.25);
}

.contact__link--primary:hover {
  border-color: rgba(96, 165, 250, 0.45);
  background: rgba(96, 165, 250, 0.06);
}

.contact__link-label {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-accent-light);
  min-width: 76px;
  flex-shrink: 0;
}

.contact__link-value {
  font-size: 0.9375rem;
  color: var(--color-text-on-dark);
}

/* ============================================================
   FOOTER
   ============================================================ */
.footer {
  background: var(--color-dark);
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  padding: var(--sp-5) 0;
}

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

.footer__copy {
  font-size: 0.8125rem;
  color: rgba(255, 255, 255, 0.25);
}

/* ============================================================
   ANIMATIONS
   ============================================================ */
@keyframes heroFadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes scrollPulse {
  0%, 100% { opacity: 0.3; transform: scaleY(0.9); }
  50%       { opacity: 0.7; transform: scaleY(1); }
}

.hero__content {
  animation: heroFadeIn 0.7s cubic-bezier(0.16, 1, 0.3, 1) both;
}

.hero__photo-wrap {
  animation: heroFadeIn 0.7s 0.12s cubic-bezier(0.16, 1, 0.3, 1) both;
}

/* Section reveal (driven by IntersectionObserver in JS) */
.reveal-section,
.reveal-item {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.55s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.55s cubic-bezier(0.16, 1, 0.3, 1);
}

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

/* Staggered reveal for items within a section */
.reveal-item:nth-child(2) { transition-delay: 0.07s; }
.reveal-item:nth-child(3) { transition-delay: 0.14s; }
.reveal-item:nth-child(4) { transition-delay: 0.21s; }
.reveal-item:nth-child(5) { transition-delay: 0.28s; }

/* ============================================================
   RESPONSIVE — Mobile first breakpoint at 768px
   ============================================================ */
@media (max-width: 768px) {
  :root {
    --nav-height: 56px;
  }

  .section {
    padding: var(--sp-8) 0;
  }

  /* --- Nav --- */
  .nav-toggle {
    display: flex;
  }

  .nav-menu {
    display: none;
    position: fixed;
    inset: 0;
    background: var(--color-dark);
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: var(--sp-7);
    z-index: 5;
  }

  .nav-menu.is-open {
    display: flex;
  }

  .nav-menu .nav-link {
    font-size: 1.5rem;
    color: var(--color-text-on-dark) !important;
  }

  .nav-menu .nav-link:hover {
    color: var(--color-white) !important;
  }

  .nav-menu .nav-link::after {
    display: none;
  }

  /* --- Hero --- */
  .hero {
    min-height: 100svh;
    padding-top: calc(var(--nav-height) + var(--sp-5));
    padding-bottom: var(--sp-7);
  }

  .hero__inner {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--sp-6);
  }

  .hero__photo-wrap {
    order: -1;
  }

  .hero__photo {
    width: 120px;
    height: 120px;
    border-radius: var(--radius-lg);
  }

  .hero__name {
    font-size: clamp(3rem, 15vw, 4.5rem);
  }

  .hero__tagline {
    max-width: 100%;
  }

  .hero__scroll-cue {
    display: none;
  }

  /* --- Experience cards --- */
  .role-card__header {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--sp-2);
  }

  .role-card__meta {
    align-items: flex-start;
    flex-direction: row;
    gap: var(--sp-3);
  }

  /* --- Skills --- */
  .skills__grid {
    grid-template-columns: 1fr;
    gap: var(--sp-6);
  }

  /* --- Education --- */
  .education__item {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--sp-2);
  }

  .education__institution {
    align-items: flex-start;
    flex-direction: row;
    gap: var(--sp-3);
  }

  /* --- Contact --- */
  .contact__links {
    gap: var(--sp-2);
  }

  .contact__link {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--sp-1);
  }

  .contact__link-label {
    min-width: unset;
  }
}

/* ============================================================
   REDUCED MOTION
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .hero__content,
  .hero__photo-wrap {
    animation: none;
  }

  .reveal-section,
  .reveal-item {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .hero__scroll-line {
    animation: none;
  }

  .role-card {
    transition: box-shadow var(--t-base);
    transform: none !important;
  }
}