:root {
  --primary: #0f172a;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --bg: #f8fafc;
  --surface: #ffffff;
  --text: #334155;
  --text-light: #64748b;
  --border: #e2e8f0;
  --radius: 10px;
  --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.02);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header & Nav */
header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 1rem 5%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--primary);
  text-decoration: none;
  letter-spacing: -0.5px;
}

nav {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

nav a {
  color: var(--text-light);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s ease;
}

nav a:hover, nav a.active {
  color: var(--accent);
  font-weight: 600;
}

/* Mobile Nav Toggle */
.mobile-toggle {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 24px;
  height: 18px;
  background: transparent;
  border: none;
  cursor: pointer;
}

.mobile-toggle .bar {
  height: 2px;
  width: 100%;
  background-color: var(--primary);
  border-radius: 2px;
}

/* Main Layout */
main {
  width: 100%;
  max-width: 1000px;
  margin: 2.5rem auto;
  padding: 0 1.5rem;
  flex: 1;
}

.card, .hero-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2.5rem;
  box-shadow: var(--shadow);
}

.hero-card {
  text-align: center;
  padding: 3.5rem 2rem;
  margin-bottom: 2rem;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

/* Typography */
h1 {
  font-size: 2.25rem;
  color: var(--primary);
  margin-bottom: 1rem;
  letter-spacing: -0.5px;
}

h3 {
  color: var(--primary);
  margin-bottom: 0.5rem;
}

p {
  color: var(--text-light);
  margin-bottom: 1.25rem;
  font-size: 1.05rem;
}

/* Form Controls */
.form-group {
  margin-bottom: 1.25rem;
}

label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--primary);
  font-size: 0.95rem;
}

input[type="text"], 
input[type="email"], 
textarea, 
input[type="file"] {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-size: 1rem;
  outline: none;
  transition: border-color 0.2s;
  background: var(--bg);
}

input:focus, textarea:focus {
  border-color: var(--accent);
  background: var(--surface);
}

textarea {
  resize: vertical;
  min-height: 130px;
}

/* Buttons */
.cta-group {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-block;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius);
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  border: none;
  transition: all 0.2s ease;
}

.btn-primary {
  background: var(--accent);
  color: white;
}

.btn-primary:hover {
  background: var(--accent-hover);
}

.btn-secondary {
  background: transparent;
  color: var(--primary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--border);
}

/* Footer */
footer {
  text-align: center;
  padding: 2rem 1.5rem;
  color: var(--text-light);
  font-size: 0.875rem;
  border-top: 1px solid var(--border);
  background: var(--surface);
}

/* Mobile Responsive Adjustments */
@media (max-width: 768px) {
  .mobile-toggle {
    display: flex;
  }

  nav {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--surface);
    flex-direction: column;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
    gap: 1rem;
  }

  nav.active {
    display: flex;
  }

  nav a {
    width: 100%;
    padding: 0.5rem 0;
  }

  .card, .hero-card {
    padding: 1.5rem;
  }

  h1 {
    font-size: 1.75rem;
  }

  .cta-group {
    flex-direction: column;
  }

  .btn {
    width: 100%;
    text-align: center;
  }
}