/* ============================================
   Portfolio Landing Page - Airbnb/Robinhood Inspired Design
   ============================================ */

/* ============================================
   1. CSS Custom Properties (Design Tokens)
   ============================================ */
:root {
  /* Colors - Light Mode (Default) */
  --color-bg-primary: #FFFFFF;
  --color-bg-secondary: #F7F7F7;
  --color-text-primary: #222222;
  --color-text-secondary: #717171;
  --color-accent: #0f35f5;
  --color-accent-hover: #0a28c7;

  /* Shadows - Light Mode */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
  --shadow-lg: 0 6px 16px rgba(0, 0, 0, 0.12);
  --shadow-xl: 0 12px 28px rgba(0, 0, 0, 0.15);
  --shadow-card: 0 6px 16px rgba(0, 0, 0, 0.12);
  --shadow-card-hover: 0 12px 28px rgba(0, 0, 0, 0.18);

  /* Spacing */
  --space-1: 0.25rem;   /* 4px */
  --space-2: 0.5rem;    /* 8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-5: 1.25rem;   /* 20px */
  --space-6: 1.5rem;    /* 24px */
  --space-8: 2rem;      /* 32px */
  --space-10: 2.5rem;   /* 40px */
  --space-12: 3rem;     /* 48px */
  --space-16: 4rem;     /* 64px */
  --space-20: 5rem;     /* 80px */
  --space-24: 6rem;     /* 96px */
  --space-32: 8rem;     /* 128px */

  /* Typography */
  --font-display: 'Playfair Display', Georgia, serif;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;

  --text-xs: 0.75rem;    /* 12px */
  --text-sm: 0.875rem;   /* 14px */
  --text-base: 1rem;     /* 16px */
  --text-lg: 1.125rem;   /* 18px */
  --text-xl: 1.25rem;    /* 20px */
  --text-2xl: 1.5rem;    /* 24px */
  --text-3xl: 1.875rem;  /* 30px */
  --text-4xl: 2.25rem;   /* 36px */
  --text-5xl: 3rem;      /* 48px */
  --text-6xl: 3.75rem;   /* 60px */
  --text-7xl: 4.5rem;    /* 72px */

  --leading-tight: 1.1;
  --leading-snug: 1.25;
  --leading-normal: 1.5;
  --leading-relaxed: 1.625;

  /* Border Radius */
  --radius-sm: 0.25rem;  /* 4px */
  --radius-md: 0.5rem;   /* 8px */
  --radius-lg: 0.75rem;  /* 12px */
  --radius-xl: 1rem;     /* 16px */
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;
  --transition-bounce: 300ms cubic-bezier(0.34, 1.56, 0.64, 1);

  /* Z-index */
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-modal: 300;
}

/* Dark Mode */
[data-theme="dark"] {
  --color-bg-primary: #0D0D0D;
  --color-bg-secondary: #1A1A1A;
  --color-text-primary: #FFFFFF;
  --color-text-secondary: #A3A3A3;
  --color-accent: #4F6EF7;
  --color-accent-hover: #6B84F9;

  /* Shadows - Dark Mode */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 6px 16px rgba(0, 0, 0, 0.5);
  --shadow-xl: 0 12px 28px rgba(0, 0, 0, 0.6);
  --shadow-card: 0 6px 16px rgba(0, 0, 0, 0.4);
  --shadow-card-hover: 0 12px 28px rgba(0, 0, 0, 0.5);
}

/* ============================================
   2. Base / Reset Styles
   ============================================ */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-slow), color var(--transition-slow);
}

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

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

/* ============================================
   3. Typography System
   ============================================ */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: var(--leading-tight);
  margin: 0;
}

.heading-display {
  font-family: var(--font-display);
}

.heading-1 {
  font-size: clamp(var(--text-4xl), 8vw, var(--text-7xl));
  line-height: 1.05;
  letter-spacing: -0.02em;
}

.heading-2 {
  font-size: clamp(var(--text-2xl), 5vw, var(--text-4xl));
}

.heading-3 {
  font-size: clamp(var(--text-xl), 3vw, var(--text-3xl));
}

.text-body {
  font-family: var(--font-body);
}

.text-lg {
  font-size: var(--text-lg);
  line-height: var(--leading-relaxed);
}

.text-xl {
  font-size: var(--text-xl);
  line-height: var(--leading-relaxed);
}

.text-2xl {
  font-size: var(--text-2xl);
  line-height: var(--leading-relaxed);
}

.text-secondary {
  color: var(--color-text-secondary);
}

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

.font-light {
  font-weight: 300;
}

.font-medium {
  font-weight: 500;
}

.font-semibold {
  font-weight: 600;
}

.font-bold {
  font-weight: 700;
}

.italic {
  font-style: italic;
}

/* Section Labels */
.section-label {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-6);
}

/* ============================================
   4. Layout Components
   ============================================ */
.container {
  width: 100%;
  max-width: 80rem; /* 1280px */
  margin: 0 auto;
  padding-left: var(--space-6);
  padding-right: var(--space-6);
}

.container-narrow {
  max-width: 64rem; /* 1024px */
}

.section {
  padding-top: var(--space-24);
  padding-bottom: var(--space-24);
}

.section-hero {
  padding-top: var(--space-32);
  padding-bottom: var(--space-24);
}

/* ============================================
   5. Navigation
   ============================================ */
.nav {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  background-color: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  transition: background-color var(--transition-slow), border-color var(--transition-slow);
}

[data-theme="dark"] .nav {
  background-color: rgba(13, 13, 13, 0.85);
  border-bottom-color: rgba(255, 255, 255, 0.06);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--space-6);
  max-width: 80rem;
  margin: 0 auto;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: -0.01em;
  text-transform: lowercase;
  transition: color var(--transition-fast);
}

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

.nav-logo-icon {
  color: var(--color-accent);
  font-size: 1.5rem;
}

.nav-links {
  display: none;
  align-items: center;
  gap: var(--space-6);
}

@media (min-width: 768px) {
  .nav-links {
    display: flex;
  }
}

.nav-link {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-primary);
  transition: color var(--transition-fast);
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-accent);
  transition: width var(--transition-base);
}

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

.nav-link:hover::after {
  width: 100%;
}

.nav-divider {
  color: var(--color-text-secondary);
  opacity: 0.3;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

/* ============================================
   6. Buttons
   ============================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-5);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
}

.btn-primary {
  background-color: var(--color-accent);
  color: #FFFFFF;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  background-color: var(--color-accent-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

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

.btn-secondary {
  background-color: transparent;
  color: var(--color-text-primary);
  border: 1px solid rgba(0, 0, 0, 0.15);
}

[data-theme="dark"] .btn-secondary {
  border-color: rgba(255, 255, 255, 0.15);
}

.btn-secondary:hover {
  background-color: var(--color-bg-secondary);
  transform: translateY(-2px);
}

/* ============================================
   7. Theme Toggle
   ============================================ */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 0;
  background: transparent;
  border: 1px solid rgba(0, 0, 0, 0.1);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

[data-theme="dark"] .theme-toggle {
  border-color: rgba(255, 255, 255, 0.1);
}

.theme-toggle:hover {
  background-color: var(--color-bg-secondary);
  transform: translateY(-2px);
}

.theme-toggle .icon-sun,
.theme-toggle .icon-moon {
  position: absolute;
  width: 20px;
  height: 20px;
  transition: all var(--transition-base);
}

.theme-toggle .icon-sun {
  color: #F59E0B;
  opacity: 1;
  transform: rotate(0deg) scale(1);
}

.theme-toggle .icon-moon {
  color: #6366F1;
  opacity: 0;
  transform: rotate(-90deg) scale(0.5);
}

[data-theme="dark"] .theme-toggle .icon-sun {
  opacity: 0;
  transform: rotate(90deg) scale(0.5);
}

[data-theme="dark"] .theme-toggle .icon-moon {
  opacity: 1;
  transform: rotate(0deg) scale(1);
}

/* ============================================
   8. Cards - Airbnb/Robinhood Style
   ============================================ */
.card {
  background-color: var(--color-bg-primary);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  box-shadow: var(--shadow-card);
  transition: all var(--transition-slow);
  position: relative;
  overflow: hidden;
}

.card:hover {
  box-shadow: var(--shadow-card-hover);
  transform: translateY(-4px);
}

.card-skill {
  padding: var(--space-10);
}

.card-skill .card-icon {
  margin-bottom: var(--space-6);
  transition: transform var(--transition-bounce);
}

.card-skill:hover .card-icon {
  transform: scale(1.1) rotate(5deg);
}

.card-skill .card-title {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  margin-bottom: var(--space-4);
}

.card-skill .card-description {
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}

/* Experience Cards */
.card-experience {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-height: 400px;
}

.card-experience::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--card-accent, var(--color-accent)), var(--card-accent-end, var(--color-accent)));
}

.card-experience[data-accent="blue"] {
  --card-accent: #3B82F6;
  --card-accent-end: #2563EB;
}

.card-experience[data-accent="red"] {
  --card-accent: #EF4444;
  --card-accent-end: #DC2626;
}

.card-experience[data-accent="indigo"] {
  --card-accent: #6366F1;
  --card-accent-end: #4F46E5;
}

.card-experience[data-accent="orange"] {
  --card-accent: #F97316;
  --card-accent-end: #EA580C;
}

.card-logo {
  width: 80px;
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg-primary);
  border: 1px solid rgba(0, 0, 0, 0.06);
  border-radius: var(--radius-lg);
  padding: var(--space-3);
}

[data-theme="dark"] .card-logo {
  background-color: var(--color-bg-secondary);
  border-color: rgba(255, 255, 255, 0.06);
}

.card-logo img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.card-badge {
  display: inline-flex;
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-xs);
  font-weight: 600;
  border-radius: var(--radius-full);
  background-color: var(--color-bg-secondary);
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-accent);
  transition: gap var(--transition-base);
}

.card-link:hover {
  gap: var(--space-4);
}

.card-link svg {
  width: 20px;
  height: 20px;
}

/* ============================================
   9. Grid Layouts
   ============================================ */
.grid-skills {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-8);
}

@media (min-width: 768px) {
  .grid-skills {
    grid-template-columns: repeat(3, 1fr);
  }
}

.grid-experience {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-8);
}

@media (min-width: 1024px) {
  .grid-experience {
    grid-template-columns: repeat(2, 1fr);
  }
}

.grid-contact {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-12);
}

@media (min-width: 768px) {
  .grid-contact {
    grid-template-columns: 1fr 1fr;
  }
}

/* ============================================
   10. Scroll Reveal Animations
   ============================================ */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.reveal.revealed {
  opacity: 1;
  transform: translateY(0);
}

.stagger-children > * {
  opacity: 0;
  transform: translateY(20px);
}

.stagger-children.revealed > * {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.5s ease-out, transform 0.5s ease-out;
}

.stagger-children.revealed > *:nth-child(1) { transition-delay: 0ms; }
.stagger-children.revealed > *:nth-child(2) { transition-delay: 100ms; }
.stagger-children.revealed > *:nth-child(3) { transition-delay: 200ms; }
.stagger-children.revealed > *:nth-child(4) { transition-delay: 300ms; }
.stagger-children.revealed > *:nth-child(5) { transition-delay: 400ms; }
.stagger-children.revealed > *:nth-child(6) { transition-delay: 500ms; }

@media (prefers-reduced-motion: reduce) {
  .reveal,
  .stagger-children > * {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* ============================================
   11. Hero Section
   ============================================ */
.hero-intro {
  max-width: 56rem;
}

.hero-title {
  font-size: clamp(2.5rem, 7vw, 4.5rem);
  line-height: 1.05;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-8);
}

.hero-title .highlight-gradient {
  background: linear-gradient(135deg, #3B82F6, #8B5CF6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: clamp(var(--text-lg), 2.5vw, var(--text-2xl));
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  font-weight: 300;
}

.hero-subtitle strong {
  color: var(--color-text-primary);
  font-weight: 600;
}

.hero-tech {
  font-size: var(--text-lg);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  font-weight: 300;
}

.hero-tech .tech-highlight {
  color: var(--color-accent);
  font-weight: 500;
  font-style: normal;
}

/* ============================================
   12. Contact Section
   ============================================ */
.contact-title {
  font-size: var(--text-2xl);
  font-weight: 700;
  margin-bottom: var(--space-6);
}

.contact-link {
  display: block;
  font-size: var(--text-xl);
  color: var(--color-accent);
  font-weight: 500;
  transition: color var(--transition-fast);
}

.contact-link:hover {
  text-decoration: underline;
}

.contact-phone {
  font-size: var(--text-xl);
  color: var(--color-text-secondary);
  font-weight: 500;
}

.social-links {
  display: flex;
  gap: var(--space-4);
  margin-top: var(--space-6);
}

.social-link {
  color: var(--color-text-secondary);
  transition: color var(--transition-fast);
}

.social-link:hover {
  color: var(--color-accent);
}

.social-link svg {
  width: 24px;
  height: 24px;
  fill: currentColor;
}

.contact-note {
  background-color: var(--color-bg-secondary);
  padding: var(--space-8);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: flex-start;
  gap: var(--space-3);
}

.contact-note-icon {
  color: var(--color-text-secondary);
  flex-shrink: 0;
  margin-top: 2px;
}

.contact-note p {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  font-style: italic;
}

/* ============================================
   13. Footer
   ============================================ */
.footer {
  border-top: 1px solid rgba(0, 0, 0, 0.06);
  padding: var(--space-10) var(--space-6);
  text-align: center;
}

[data-theme="dark"] .footer {
  border-top-color: rgba(255, 255, 255, 0.06);
}

.footer-text {
  font-size: var(--text-xs);
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

/* ============================================
   14. Utility Classes
   ============================================ */
.border-top {
  border-top: 1px solid rgba(0, 0, 0, 0.06);
}

[data-theme="dark"] .border-top {
  border-top-color: rgba(255, 255, 255, 0.06);
}

.mt-auto {
  margin-top: auto;
}

.mb-0 {
  margin-bottom: 0;
}

.mb-2 {
  margin-bottom: var(--space-2);
}

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

.mb-6 {
  margin-bottom: var(--space-6);
}

.mb-8 {
  margin-bottom: var(--space-8);
}

.mb-10 {
  margin-bottom: var(--space-10);
}

.pt-20 {
  padding-top: var(--space-20);
}

.pb-20 {
  padding-bottom: var(--space-20);
}

/* Focus States for Accessibility */
.btn:focus-visible,
.theme-toggle:focus-visible,
.nav-link:focus-visible,
.card-link:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* Hidden but accessible */
.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;
}