/* ==========================================================================
   CSS Variables & Theme System
   ========================================================================== */

:root {
  /* Light theme (default) */
  --color-bg: #fafafa;
  --color-card: #ffffff;
  --color-primary: #1a1a2e;
  --color-accent: #e94560;
  --color-secondary: #0f3460;
  --color-text: #2d2d2d;
  --color-text-muted: #6b7280;
  --color-border: #e5e7eb;

  /* Fonts */
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  /* Spacing (8px grid) */
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-5: 40px;
  --space-6: 48px;
  --space-8: 64px;
  --space-10: 80px;
  --space-12: 96px;

  /* Border radius */
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;

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

  /* Nav height */
  --nav-height: 64px;
}

[data-theme="dark"] {
  --color-bg: #0f0f1a;
  --color-card: #1a1a2e;
  --color-primary: #e2e8f0;
  --color-accent: #e94560;
  --color-secondary: #60a5fa;
  --color-text: #d1d5db;
  --color-text-muted: #9ca3af;
  --color-border: #2d3748;
}

/* ==========================================================================
   Reset & Base
   ========================================================================== */

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  transition: background-color var(--transition-base), color var(--transition-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

ul {
  list-style: none;
}

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

/* Reduce motion for accessibility */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ==========================================================================
   Layout
   ========================================================================== */

.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 var(--space-3);
}

.section {
  padding: var(--space-10) 0;
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.section--alt {
  background-color: var(--color-card);
}

.section__header {
  text-align: center;
  margin-bottom: var(--space-6);
}

.section__title {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--space-1);
}

.section__subtitle {
  font-size: 1.125rem;
  color: var(--color-text-muted);
}

.section.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ==========================================================================
   Navigation
   ========================================================================== */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  z-index: 100;
  background: rgba(250, 250, 250, 0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: background-color var(--transition-base), border-color var(--transition-base);
}

[data-theme="dark"] .nav {
  background: rgba(15, 15, 26, 0.8);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.nav__logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary);
  z-index: 101;
}

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

.nav__link {
  position: relative;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-text-muted);
  transition: color var(--transition-fast);
  padding: var(--space-1) 0;
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-accent);
  transition: width var(--transition-base);
}

.nav__link:hover,
.nav__link:focus-visible {
  color: var(--color-primary);
}

.nav__link:hover::after,
.nav__link:focus-visible::after {
  width: 100%;
}

/* Theme toggle */
.nav__theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--color-text-muted);
  padding: var(--space-1);
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  transition: color var(--transition-fast), background-color var(--transition-fast);
  z-index: 101;
}

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

/* Show/hide sun/moon icons based on theme */
.icon-sun { display: none; }
.icon-moon { display: block; }

[data-theme="dark"] .icon-sun { display: block; }
[data-theme="dark"] .icon-moon { display: none; }

/* Hamburger button */
.nav__hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-1);
  z-index: 101;
}

.nav__hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background-color: var(--color-primary);
  border-radius: 2px;
  transition: transform var(--transition-base), opacity var(--transition-fast);
}

.nav__hamburger.active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav__hamburger.active span:nth-child(2) {
  opacity: 0;
}

.nav__hamburger.active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ==========================================================================
   Hero
   ========================================================================== */

.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: var(--nav-height);
  /* Hero is always visible, no scroll animation */
  opacity: 1;
  transform: none;
}

.hero__inner {
  max-width: 720px;
}

.hero__title {
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--space-2);
  line-height: 1.1;
}

.hero__subtitle {
  font-size: clamp(1.25rem, 3vw, 1.75rem);
  font-weight: 500;
  color: var(--color-accent);
  margin-bottom: var(--space-3);
  min-height: 2.5rem;
  font-family: var(--font-mono);
}

/* Typewriter cursor */
.hero__subtitle::after {
  content: '|';
  animation: blink 0.7s infinite;
  margin-left: 2px;
  color: var(--color-accent);
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

.hero__description {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-5);
  max-width: 560px;
  line-height: 1.7;
}

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

/* ==========================================================================
   Buttons
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 28px;
  font-family: var(--font-body);
  font-size: 0.9375rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  cursor: pointer;
  border: 2px solid transparent;
}

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

.btn--primary:hover {
  background-color: #d63451;
  border-color: #d63451;
  transform: translateY(-1px);
}

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

.btn--ghost:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-1px);
}

/* ==========================================================================
   About
   ========================================================================== */

.about__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
  align-items: start;
}

.about__text p {
  font-size: 1.0625rem;
  line-height: 1.8;
  color: var(--color-text);
  margin-bottom: var(--space-3);
}

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

.about__stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
}

.stat {
  text-align: center;
  padding: var(--space-3);
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
}

.stat__number {
  display: block;
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-accent);
  line-height: 1.2;
  margin-bottom: var(--space-1);
}

.stat__label {
  display: block;
  font-size: 0.875rem;
  color: var(--color-text-muted);
  font-weight: 500;
}

/* ==========================================================================
   Skills
   ========================================================================== */

.skills__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
}

.skills__category {
  padding: var(--space-4);
  background-color: var(--color-bg);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
}

[data-theme="dark"] .skills__category {
  background-color: var(--color-bg);
}

.skills__category-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: var(--space-2);
}

.skills__tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.tag {
  display: inline-block;
  padding: 4px 12px;
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-accent);
  background-color: rgba(233, 69, 96, 0.1);
  border-radius: var(--radius-sm);
  white-space: nowrap;
}

/* ==========================================================================
   Projects
   ========================================================================== */

.projects__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
}

.project-card {
  background-color: var(--color-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  transition: transform var(--transition-base), box-shadow var(--transition-base);
  overflow: hidden;
}

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.08);
}

[data-theme="dark"] .project-card:hover {
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.3);
}

.project-card__content {
  padding: var(--space-4);
}

.project-card__title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: var(--space-2);
}

.project-card__description {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  margin-bottom: var(--space-3);
}

.project-card__tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  margin-bottom: var(--space-3);
}

.project-card__link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--color-accent);
  transition: gap var(--transition-fast);
}

.project-card__link:hover {
  gap: 12px;
}

.project-card__link svg {
  transition: transform var(--transition-fast);
}

.project-card__link:hover svg {
  transform: translateX(2px);
}

/* ==========================================================================
   Contact
   ========================================================================== */

.contact__inner {
  max-width: 560px;
  margin: 0 auto;
  text-align: center;
}

.contact__description {
  font-size: 1.0625rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  margin-bottom: var(--space-5);
}

.contact__links {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  align-items: center;
}

.contact__link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-size: 1rem;
  color: var(--color-text);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.contact__link:hover {
  color: var(--color-accent);
  background-color: rgba(233, 69, 96, 0.05);
}

.contact__link svg {
  flex-shrink: 0;
  color: var(--color-text-muted);
  transition: color var(--transition-fast);
}

.contact__link:hover svg {
  color: var(--color-accent);
}

/* ==========================================================================
   Footer
   ========================================================================== */

.footer {
  padding: var(--space-4) 0;
  border-top: 1px solid var(--color-border);
}

.footer__text {
  text-align: center;
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

/* ==========================================================================
   Responsive — Mobile First
   ========================================================================== */

/* 640px+ */
@media (min-width: 640px) {
  .projects__grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* 768px+ */
@media (min-width: 768px) {
  .about__grid {
    grid-template-columns: 1.5fr 1fr;
  }

  .skills__grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .section {
    padding: var(--space-12) 0;
  }
}

/* 1024px+ */
@media (min-width: 1024px) {
  .hero__title {
    font-size: 4rem;
  }
}

/* Mobile nav (<768px) */
@media (max-width: 767px) {
  .nav__hamburger {
    display: flex;
  }

  .nav__menu {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-base), visibility var(--transition-base);
    z-index: 99;
  }

  .nav__menu.open {
    opacity: 1;
    visibility: visible;
  }

  .nav__list {
    flex-direction: column;
    align-items: center;
    gap: var(--space-5);
  }

  .nav__link {
    font-size: 1.25rem;
  }
}