/* ==========================================
   Design System & CSS Custom Properties
   ========================================== */

:root {
  /* Colors */
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #818cf8;
  --secondary: #10b981;
  --secondary-dark: #059669;
  --accent: #f59e0b;

  /* Backgrounds */
  --bg-primary: #ffffff;
  --bg-secondary: #f9fafb;
  --bg-dark: #111827;

  /* Text Colors */
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-light: #9ca3af;
  --text-on-dark: #f9fafb;

  /* Borders */
  --border-color: #e5e7eb;

  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #6366f1 0%, #10b981 100%);
  --gradient-hero: linear-gradient(135deg, #667eea 0%, #764ba2 100%);

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);

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

  --text-xs: 0.75rem;
  --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;
  --text-6xl: 3.75rem;

  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;

  --leading-tight: 1.25;
  --leading-normal: 1.5;
  --leading-relaxed: 1.75;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Container */
  --container-max-width: 1280px;
  --container-padding: 2rem;

  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 400ms ease-in-out;
}

/* ==========================================
   CSS Reset & Base Styles
   ========================================== */

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

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--text-primary);
  background-color: var(--bg-primary);
  overflow-x: hidden;
}

/* ==========================================
   Typography
   ========================================== */

h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-semibold);
  line-height: var(--leading-tight);
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

h1 {
  font-size: var(--text-6xl);
  font-weight: var(--font-bold);
}

h2 {
  font-size: var(--text-4xl);
}

h3 {
  font-size: var(--text-2xl);
}

h4 {
  font-size: var(--text-xl);
}

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

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

a {
  color: var(--primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--primary-dark);
}

ul, ol {
  margin-bottom: var(--space-4);
  padding-left: var(--space-6);
}

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

strong {
  font-weight: var(--font-semibold);
  color: var(--text-primary);
}

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

.container {
  max-width: var(--container-max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--container-padding);
  padding-right: var(--container-padding);
}

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

.bg-alternate {
  background-color: var(--bg-secondary);
}

.bg-dark {
  background-color: var(--bg-dark);
  color: var(--text-on-dark);
}

.bg-dark h1, .bg-dark h2, .bg-dark h3, .bg-dark h4, .bg-dark h5, .bg-dark h6 {
  color: var(--text-on-dark);
}

.bg-dark p, .bg-dark .lead {
  color: rgba(249, 250, 251, 0.8);
}

/* Section Titles */
.section-title {
  text-align: center;
  margin-bottom: var(--space-3);
  position: relative;
}

.section-title::after {
  content: '';
  display: block;
  width: 60px;
  height: 4px;
  background: var(--gradient-primary);
  margin: var(--space-4) auto 0;
  border-radius: 2px;
}

.section-subtitle {
  text-align: center;
  font-size: var(--text-lg);
  color: var(--text-secondary);
  margin-bottom: var(--space-12);
}

.bg-dark .section-subtitle {
  color: rgba(249, 250, 251, 0.7);
}

/* ==========================================
   Buttons & CTAs
   ========================================== */

.btn-primary,
.btn-secondary {
  display: inline-block;
  padding: var(--space-3) var(--space-8);
  font-size: var(--text-base);
  font-weight: var(--font-medium);
  text-align: center;
  border-radius: 8px;
  transition: all var(--transition-base);
  cursor: pointer;
  border: 2px solid transparent;
  text-decoration: none;
}

.btn-primary {
  background: var(--gradient-primary);
  color: white;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: white;
}

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

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

/* ==========================================
   Tags & Labels
   ========================================== */

.tag {
  display: inline-block;
  padding: var(--space-1) var(--space-3);
  font-size: var(--text-xs);
  font-weight: var(--font-medium);
  background-color: var(--bg-secondary);
  color: var(--text-secondary);
  border-radius: 4px;
  margin-right: var(--space-2);
  margin-bottom: var(--space-2);
}

.tech-tag {
  display: inline-block;
  padding: var(--space-1) var(--space-3);
  font-size: var(--text-xs);
  font-weight: var(--font-medium);
  background-color: rgba(99, 102, 241, 0.1);
  color: var(--primary);
  border-radius: 4px;
  margin-right: var(--space-2);
  margin-bottom: var(--space-2);
  border: 1px solid rgba(99, 102, 241, 0.2);
}

/* ==========================================
   Cards
   ========================================== */

.card {
  background-color: var(--bg-primary);
  border-radius: 12px;
  padding: var(--space-8);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-base);
}

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

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

.main-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-sm);
  z-index: 1000;
  transition: transform var(--transition-base);
}

.main-nav.hidden {
  transform: translateY(-100%);
}

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

.nav-logo {
  font-size: var(--text-2xl);
  font-weight: var(--font-bold);
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-decoration: none;
}

.nav-menu {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: var(--space-8);
}

.nav-link {
  color: var(--text-primary);
  font-weight: var(--font-medium);
  text-decoration: none;
  transition: color var(--transition-fast);
  position: relative;
}

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

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

.nav-link:hover,
.nav-link.active {
  color: var(--primary);
}

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

.hamburger-line {
  width: 25px;
  height: 3px;
  background-color: var(--text-primary);
  transition: all var(--transition-base);
  border-radius: 2px;
}

.menu-toggle.active .hamburger-line:nth-child(1) {
  transform: rotate(45deg) translate(8px, 8px);
}

.menu-toggle.active .hamburger-line:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active .hamburger-line:nth-child(3) {
  transform: rotate(-45deg) translate(7px, -7px);
}

/* ==========================================
   Animations & Transitions
   ========================================== */

[data-animate] {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

[data-animate].animated {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger effect for multiple items */
[data-animate].animated:nth-child(1) {
  transition-delay: 0s;
}

[data-animate].animated:nth-child(2) {
  transition-delay: 0.1s;
}

[data-animate].animated:nth-child(3) {
  transition-delay: 0.2s;
}

[data-animate].animated:nth-child(4) {
  transition-delay: 0.3s;
}

[data-animate].animated:nth-child(5) {
  transition-delay: 0.4s;
}

[data-animate].animated:nth-child(6) {
  transition-delay: 0.5s;
}

/* ==========================================
   Utility Classes
   ========================================== */

.text-center {
  text-align: center;
}

.text-left {
  text-align: left;
}

.text-right {
  text-align: right;
}

.hidden {
  display: none !important;
}

.visible {
  display: block;
}

/* Smooth page transitions */
@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;
  }
}