/* ==========================================================================
   Luckywind.vn - Main Design System & Base Styles
   Theme: Crisp Light Theme (Default) with AI Tech Vibrant Accents
   Architecture Note: Built with Zero External Dependencies for Maximum Security & Performance.
   ========================================================================== */

:root {
  /* Brand Color Palette */
  --color-primary: #0284c7;
  --color-primary-light: #0ea5e9;
  --color-primary-dark: #0369a1;
  --color-accent: #06b6d4;
  --color-accent-emerald: #059669;
  --color-accent-purple: #7c3aed;

  /* Background & Surface Colors (Crisp Light Theme) */
  --bg-body: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-elevated: #ffffff;
  --bg-card: #ffffff;
  --bg-card-hover: #f1f5f9;
  --bg-card-subtle: #f8fafc;

  /* Border & Glassmorphism */
  --border-subtle: #e2e8f0;
  --border-medium: #cbd5e1;
  --border-glow: rgba(2, 132, 199, 0.25);
  --glass-blur: blur(16px);

  /* Typography Colors */
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --text-inverse: #ffffff;

  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #0284c7 0%, #06b6d4 50%, #059669 100%);
  --gradient-purple-blue: linear-gradient(135deg, #6366f1 0%, #0284c7 100%);
  --gradient-card: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
  --gradient-glow: radial-gradient(circle at 50% 0%, rgba(2, 132, 199, 0.08) 0%, transparent 70%);

  /* Spacing & Sizing */
  --container-max-width: 1240px;
  --header-height: 76px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-full: 9999px;

  /* Shadows (Light Theme) */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05), 0 1px 2px rgba(0, 0, 0, 0.03);
  --shadow-md: 0 6px 20px rgba(15, 23, 42, 0.07), 0 2px 6px rgba(15, 23, 42, 0.04);
  --shadow-lg: 0 16px 40px rgba(15, 23, 42, 0.08), 0 4px 12px rgba(15, 23, 42, 0.04);
  --shadow-glow: 0 10px 30px rgba(2, 132, 199, 0.16);

  /* Transitions */
  --transition-fast: 0.18s ease;
  --transition-normal: 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Optional Dark Theme Mode */
[data-theme="dark"] {
  --bg-body: #070b14;
  --bg-surface: #0f172a;
  --bg-surface-elevated: #1e293b;
  --bg-card: rgba(15, 23, 42, 0.75);
  --bg-card-hover: rgba(30, 41, 59, 0.85);
  --bg-card-subtle: rgba(15, 23, 42, 0.5);

  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-medium: rgba(255, 255, 255, 0.15);
  --border-glow: rgba(56, 189, 248, 0.35);

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --text-inverse: #020617;

  --gradient-primary: linear-gradient(135deg, #38bdf8 0%, #06b6d4 50%, #10b981 100%);
  --gradient-card: linear-gradient(180deg, rgba(30, 41, 59, 0.6) 0%, rgba(15, 23, 42, 0.8) 100%);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 40px rgba(56, 189, 248, 0.2);
}

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

html {
  scroll-behavior: smooth;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color-scheme: light dark;
}

body {
  background-color: var(--bg-body);
  color: var(--text-primary);
  line-height: 1.65;
  font-size: 16px;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* Subtle Ambient Background Light */
body::before {
  content: "";
  position: fixed;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 1100px;
  height: 650px;
  background: radial-gradient(circle, rgba(2, 132, 199, 0.05) 0%, rgba(6, 182, 212, 0.03) 40%, transparent 70%);
  pointer-events: none;
  z-index: 0;
}

/* Typography Base */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-primary);
  line-height: 1.25;
  font-weight: 700;
  letter-spacing: -0.02em;
}

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

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

button, input, textarea, select {
  font: inherit;
  color: inherit;
}

/* Containers & Grid */
.container {
  width: 100%;
  max-width: var(--container-max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
  position: relative;
  z-index: 1;
}

.section {
  padding-top: 100px;
  padding-bottom: 100px;
  position: relative;
}

.section-alt {
  background-color: #f8fafc;
}

[data-theme="dark"] .section-alt {
  background-color: rgba(15, 23, 42, 0.4);
}

.section-header {
  text-align: center;
  max-width: 760px;
  margin: 0 auto 56px auto;
}

.section-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: rgba(2, 132, 199, 0.08);
  border: 1px solid rgba(2, 132, 199, 0.2);
  border-radius: var(--radius-full);
  color: var(--color-primary);
  font-size: 13.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 16px;
}

.section-title {
  font-size: clamp(2rem, 3.8vw, 2.75rem);
  margin-bottom: 18px;
}

.section-description {
  color: var(--text-secondary);
  font-size: clamp(1.05rem, 1.5vw, 1.2rem);
  line-height: 1.6;
}

/* Gradient Text Helper */
.text-gradient {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  font-weight: 600;
  font-size: 15px;
  padding: 13px 26px;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-normal);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--gradient-primary);
  color: #ffffff;
  font-weight: 700;
  box-shadow: 0 4px 16px rgba(2, 132, 199, 0.28);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(2, 132, 199, 0.4);
  filter: brightness(1.05);
}

.btn-secondary {
  background: #ffffff;
  border: 1px solid var(--border-subtle);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
  background: #f8fafc;
  border-color: var(--border-medium);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 13.5px;
  border-radius: var(--radius-sm);
}

.btn-lg {
  padding: 16px 34px;
  font-size: 16.5px;
  border-radius: var(--radius-lg);
}

/* Responsive utilities */
@media (max-width: 768px) {
  .section {
    padding-top: 64px;
    padding-bottom: 64px;
  }
  .container {
    padding-left: 18px;
    padding-right: 18px;
  }
}