/* ============================================
   KWC Motor — Design System (style.css)
   ============================================ */

/* --- CSS Custom Properties --- */
:root {
  /* Colors */
  --color-primary: #1E3A5F;
  --color-primary-light: #2563EB;
  --color-primary-dark: #0F1F3A;
  --color-accent: #00B4D8;
  --color-accent-glow: rgba(0, 180, 216, 0.15);
  --color-white: #FFFFFF;
  --color-bg: #F8FAFC;
  --color-bg-dark: #0B1120;
  --color-bg-card: #FFFFFF;
  --color-text: #1E293B;
  --color-text-light: #64748B;
  --color-text-muted: #94A3B8;
  --color-border: #E2E8F0;
  --color-border-light: #F1F5F9;
  --color-success: #10B981;
  --color-warning: #F59E0B;
  --color-danger: #EF4444;

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

  --fs-xs: 0.75rem;
  --fs-sm: 0.875rem;
  --fs-base: 1rem;
  --fs-lg: 1.125rem;
  --fs-xl: 1.25rem;
  --fs-2xl: 1.5rem;
  --fs-3xl: 1.875rem;
  --fs-4xl: 2.25rem;
  --fs-5xl: 3rem;
  --fs-6xl: 3.75rem;

  --fw-normal: 400;
  --fw-medium: 500;
  --fw-semibold: 600;
  --fw-bold: 700;
  --fw-extrabold: 800;

  --lh-tight: 1.2;
  --lh-normal: 1.5;
  --lh-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;

  /* Layout */
  --container-max: 1280px;
  --container-narrow: 960px;
  --header-height: 80px;
  --sidebar-width: 280px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.05);
  --shadow-glow: 0 0 20px rgba(37, 99, 235, 0.15);

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

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

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: var(--fs-base);
  font-weight: var(--fw-normal);
  line-height: var(--lh-normal);
  color: var(--color-text);
  background-color: var(--color-bg);
  overflow-x: hidden;
}

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

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

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

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-weight: var(--fw-bold);
  line-height: var(--lh-tight);
  color: var(--color-primary-dark);
}

h1 { font-size: var(--fs-5xl); }
h2 { font-size: var(--fs-4xl); }
h3 { font-size: var(--fs-2xl); }
h4 { font-size: var(--fs-xl); }
h5 { font-size: var(--fs-lg); }
h6 { font-size: var(--fs-base); }

p {
  margin-bottom: var(--space-4);
  color: var(--color-text-light);
  line-height: var(--lh-relaxed);
}

/* --- Layout Utilities --- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.container--narrow {
  max-width: var(--container-narrow);
}

.section {
  padding: var(--space-20) 0;
}

.section--dark {
  background-color: var(--color-bg-dark);
  color: var(--color-white);
}

.section--dark h2,
.section--dark h3,
.section--dark h4 {
  color: var(--color-white);
}

.section--dark p {
  color: rgba(255, 255, 255, 0.7);
}

.section--gray {
  background-color: var(--color-border-light);
}

.section__header {
  text-align: center;
  margin-bottom: var(--space-12);
}

.section__header h2 {
  margin-bottom: var(--space-4);
}

.section__subtitle {
  font-size: var(--fs-lg);
  color: var(--color-text-light);
  max-width: 640px;
  margin: 0 auto;
}

/* Flex utilities */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-wrap { flex-wrap: wrap; }
.items-center { align-items: center; }
.items-start { align-items: flex-start; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

/* Grid utilities */
.grid { display: grid; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-6 { grid-template-columns: repeat(6, 1fr); }

/* Text utilities */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }
.text-sm { font-size: var(--fs-sm); }
.text-lg { font-size: var(--fs-lg); }
.text-xl { font-size: var(--fs-xl); }
.text-muted { color: var(--color-text-muted); }
.text-primary { color: var(--color-primary-light); }
.text-white { color: var(--color-white); }
.font-medium { font-weight: var(--fw-medium); }
.font-semibold { font-weight: var(--fw-semibold); }
.font-bold { font-weight: var(--fw-bold); }

/* --- Gradient Text --- */
.gradient-text {
  background: linear-gradient(135deg, var(--color-primary-light), var(--color-accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* --- Responsive Breakpoints --- */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-6 { grid-template-columns: repeat(3, 1fr); }
  h1 { font-size: var(--fs-4xl); }
  h2 { font-size: var(--fs-3xl); }
}

@media (max-width: 768px) {
  :root {
    --header-height: 64px;
  }
  .container {
    padding: 0 var(--space-4);
  }
  .section {
    padding: var(--space-12) 0;
  }
  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }
  .grid-6 { grid-template-columns: repeat(2, 1fr); }
  h1 { font-size: var(--fs-3xl); }
  h2 { font-size: var(--fs-2xl); }
  h3 { font-size: var(--fs-xl); }
}

@media (max-width: 480px) {
  .grid-6 { grid-template-columns: 1fr; }
}

/* --- Scroll Animation --- */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

.fade-in-left {
  opacity: 0;
  transform: translateX(-30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in-left.visible {
  opacity: 1;
  transform: translateX(0);
}

.fade-in-right {
  opacity: 0;
  transform: translateX(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in-right.visible {
  opacity: 1;
  transform: translateX(0);
}

/* --- Stagger children animation --- */
.stagger-children > * {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

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

.stagger-children.visible > * {
  opacity: 1;
  transform: translateY(0);
}