@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

/* Global Design Tokens */
:root {
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --c-bg: #f5f7fa;
  --c-surface: rgba(255, 255, 255, 0.7);
  --c-surface-border: rgba(255, 255, 255, 0.5);
  --c-card-bg: #ffffff;
  --c-accent: #2563eb;
  --c-accent-hover: #1d4ed8;
  --c-text: #1f2937;
  --c-text-muted: #4b5563;
  --gap: 1.5rem;
  --radius: 0.75rem;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--c-bg);
  color: var(--c-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Layout Containers */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

section {
  padding: 3rem 0;
}

/* Header & Sticky Navigation */
.header-wrapper {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--c-surface);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--c-surface-border);
  transition: all 0.3s ease;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 4.5rem;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--c-text);
  text-decoration: none;
  letter-spacing: -0.025em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.logo span {
  font-weight: 300;
  color: var(--c-text-muted);
}

nav {
  display: flex;
  align-items: center;
  gap: 1rem;
}

nav a {
  font-size: 0.925rem;
  font-weight: 500;
  color: var(--c-text-muted);
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  transition: all 0.2s ease;
}

nav a:hover, nav a:focus {
  color: var(--c-accent);
  background-color: rgba(37, 99, 235, 0.08);
}

nav a.active {
  color: var(--c-accent);
  background-color: rgba(37, 99, 235, 0.1);
}

/* Hamburger Menu Button */
.hamburger-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--c-text);
}

.hamburger-btn svg {
  width: 1.5rem;
  height: 1.5rem;
}

@media (max-width: 768px) {
  .hamburger-btn {
    display: block;
  }
  
  nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background-color: #ffffff;
    border-bottom: 1px solid var(--c-surface-border);
    flex-direction: column;
    padding: 1.5rem;
    gap: 0.75rem;
    box-shadow: var(--shadow-lg);
  }
  
  nav.active {
    display: flex;
  }
  
  nav a {
    width: 100%;
    text-align: center;
  }
}

/* Typography & Titles */
h1, h2, h3, h4 {
  font-weight: 700;
  color: var(--c-text);
  line-height: 1.25;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }

p {
  color: var(--c-text-muted);
  margin-bottom: 1.5rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.925rem;
  font-weight: 600;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  border: none;
  cursor: pointer;
  transition: all 0.2s ease;
  text-decoration: none;
  gap: 0.5rem;
}

.btn-primary {
  background-color: var(--c-accent);
  color: #ffffff;
}

.btn-primary:hover, .btn-primary:focus {
  background-color: var(--c-accent-hover);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
}

.btn-secondary {
  background-color: var(--c-card-bg);
  border: 1px solid #d1d5db;
  color: var(--c-text);
}

.btn-secondary:hover, .btn-secondary:focus {
  background-color: #f3f4f6;
}

/* Cards & Layouts */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--gap);
  margin-top: var(--gap);
}

.card {
  background-color: var(--c-card-bg);
  border-radius: var(--radius);
  padding: 1.5rem;
  border: 1px solid #e5e7eb;
  box-shadow: var(--shadow-sm);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

/* Forms */
form {
  background-color: var(--c-card-bg);
  border-radius: var(--radius);
  padding: 2rem;
  border: 1px solid #e5e7eb;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.form-group label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--c-text);
}

input, textarea, select {
  font-family: inherit;
  font-size: 0.925rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius);
  border: 1px solid #d1d5db;
  background-color: #ffffff;
  color: var(--c-text);
  outline: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

input:focus, textarea:focus, select:focus {
  border-color: var(--c-accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

/* Accessibility Focus States */
a:focus-visible, button:focus-visible, input:focus-visible, textarea:focus-visible, select:focus-visible {
  outline: 2px solid var(--c-accent);
  outline-offset: 2px;
}

/* Footer */
footer {
  background-color: var(--c-card-bg);
  border-top: 1px solid #e5e7eb;
  padding: 3rem 0;
  margin-top: 4rem;
  text-align: center;
  color: var(--c-text-muted);
  font-size: 0.875rem;
}