/* ===========================
   CSS Variables
   =========================== */
:root {
  --color-primary: #1a56db;
  --color-primary-light: #3b82f6;
  --color-primary-dark: #1e40af;
  --color-secondary: #0891b2;
  --color-secondary-light: #22d3ee;
  --color-accent: #059669;
  --color-accent-light: #10b981;
  --color-bg: #ffffff;
  --color-bg-alt: #f8fafc;
  --color-bg-card: #ffffff;
  --color-bg-card-hover: #f1f5f9;
  --color-border: #e2e8f0;
  --color-border-light: #cbd5e1;
  --color-text: #1e293b;
  --color-text-secondary: #64748b;
  --color-text-muted: #94a3b8;
  --color-gradient-1: linear-gradient(135deg, #1a56db, #0891b2);
  --color-gradient-2: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
  --font-heading: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
  --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 25px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 50px -12px rgba(0, 0, 0, 0.12);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --nav-height: 72px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

ul {
  list-style: none;
}

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

/* ===========================
   Typography
   =========================== */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text);
}

h1 { font-size: 3rem; letter-spacing: -1.5px; }
h2 { font-size: 2.25rem; letter-spacing: -0.5px; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

/* ===========================
   Container
   =========================== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===========================
   Buttons
   =========================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  transition: var(--transition);
  cursor: pointer;
  border: none;
  text-decoration: none;
}

.btn-primary {
  background: var(--color-gradient-1);
  color: #ffffff;
  box-shadow: 0 4px 16px rgba(26, 86, 219, 0.25);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(26, 86, 219, 0.35);
}

.btn-outline {
  background: transparent;
  color: var(--color-text);
  border: 2px solid var(--color-border-light);
}

.btn-outline:hover {
  background: var(--color-bg-alt);
  border-color: var(--color-primary);
  color: var(--color-primary);
}

/* ===========================
   Section Base
   =========================== */
.section {
  padding: 100px 0;
  position: relative;
}

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

.section-header {
  text-align: center;
  margin-bottom: 56px;
}

.section-title {
  font-size: 2.25rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  margin-bottom: 16px;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: '';
  display: block;
  width: 48px;
  height: 3px;
  background: var(--color-gradient-1);
  margin: 16px auto 0;
  border-radius: 2px;
}

.section-subtitle {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.7;
}

.about-subsection-title {
  font-size: 1.6rem;
  font-weight: 700;
  margin-top: 64px;
  margin-bottom: 32px;
  color: var(--color-text);
  position: relative;
  padding-bottom: 12px;
  text-align: center;
}

.about-subsection-title::after {
  content: '';
  display: block;
  width: 36px;
  height: 3px;
  background: var(--color-secondary);
  border-radius: 2px;
  margin: 8px auto 0;
}

/* ===========================
   Animations
   =========================== */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ===========================
   Utility
   =========================== */
.text-gradient {
  background: var(--color-gradient-1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}