/* ============================================
   BASE.CSS - Biến CSS, Reset, Typography
   VPBot - Dịch vụ thuê bot Messenger bảo vệ box FF
   ============================================ */

:root {
  /* Màu chính - xanh dương */
  --color-primary: #2563eb;
  --color-primary-light: #3b82f6;
  --color-primary-dark: #1d4ed8;
  --color-primary-rgb: 37, 99, 235;

  /* Gradient CTA */
  --gradient-cta: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
  --gradient-hero: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);

  /* Màu nền / bề mặt - light mode */
  --color-bg: #ffffff;
  --color-bg-alt: #f8fafc;
  --color-surface: #ffffff;
  --color-surface-alt: #f1f5f9;
  --color-border: #e2e8f0;

  /* Văn bản */
  --color-text: #0f172a;
  --color-text-muted: #64748b;
  --color-text-light: #94a3b8;
  --color-text-on-primary: #ffffff;

  /* Trạng thái */
  --color-success: #16a34a;
  --color-success-bg: #dcfce7;
  --color-danger: #dc2626;
  --color-danger-bg: #fee2e2;
  --color-warning: #d97706;
  --color-warning-bg: #fef3c7;
  --color-info: #0284c7;
  --color-info-bg: #e0f2fe;

  /* Glassmorphism */
  --glass-bg: rgba(255, 255, 255, 0.65);
  --glass-border: rgba(37, 99, 235, 0.18);
  --glass-blur: blur(12px);

  /* Bo góc */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Bóng đổ */
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 4px 12px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 10px 30px rgba(15, 23, 42, 0.12);
  --shadow-primary: 0 8px 24px rgba(37, 99, 235, 0.25);

  /* Khoảng cách */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 48px;
  --space-8: 64px;
  --space-9: 96px;

  /* Font */
  --font-family: 'Segoe UI', -apple-system, BlinkMacSystemFont, Roboto, Helvetica, Arial, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.5rem;
  --font-size-5xl: 3.25rem;

  /* Chuyển động */
  --transition-fast: 0.15s ease;
  --transition-base: 0.25s ease;
  --transition-slow: 0.4s ease;

  /* Container */
  --container-max: 1200px;
  --header-height: 72px;
}

/* Dark mode */
[data-theme="dark"] {
  --color-bg: #0b1220;
  --color-bg-alt: #0f172a;
  --color-surface: #111b2e;
  --color-surface-alt: #16213a;
  --color-border: #1e293b;

  --color-text: #f1f5f9;
  --color-text-muted: #94a3b8;
  --color-text-light: #64748b;

  --gradient-hero: linear-gradient(135deg, #0b1220 0%, #111b2e 100%);

  --glass-bg: rgba(17, 27, 46, 0.65);
  --glass-border: rgba(59, 130, 246, 0.25);

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.45);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--transition-base), color var(--transition-base);
  min-height: 100vh;
}

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

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

ul, ol {
  list-style: none;
}

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

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

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

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }

p { color: var(--color-text-muted); }

.text-gradient {
  background: var(--gradient-cta);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

/* Container & layout utils dùng chung */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-5);
}

.section {
  padding: var(--space-9) 0;
}

.text-center { text-align: center; }
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.justify-center { justify-content: center; }
.gap-2 { gap: var(--space-2); }
.gap-3 { gap: var(--space-3); }
.gap-4 { gap: var(--space-4); }
.gap-5 { gap: var(--space-5); }

.hidden { display: none !important; }

/* Scrollbar */
::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: var(--color-bg-alt); }
::-webkit-scrollbar-thumb { background: var(--color-border); border-radius: var(--radius-full); }
::-webkit-scrollbar-thumb:hover { background: var(--color-text-light); }

/* Animation scroll fade-in */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Responsive base */
@media (max-width: 768px) {
  h1 { font-size: var(--font-size-4xl); }
  h2 { font-size: var(--font-size-3xl); }
  h3 { font-size: var(--font-size-2xl); }
  .container { padding: 0 var(--space-4); }
  .section { padding: var(--space-7) 0; }
}