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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: #f5f7fa;
  color: #1a1a2e;
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: 640px;
  margin: 0 auto;
  padding: 60px 24px;
}

.intro {
  text-align: center;
  margin-bottom: 48px;
}

.intro h1 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: #0f172a;
}

.intro p {
  font-size: 1rem;
  color: #475569;
  max-width: 520px;
  margin: 0 auto;
}

.form-section {
  background: #fff;
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  padding: 32px;
}

.form-section h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 24px;
  color: #0f172a;
}

.form-group {
  margin-bottom: 18px;
}

.form-group label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  margin-bottom: 6px;
  color: #334155;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 10px 14px;
  font-size: 0.9375rem;
  border: 1px solid #cbd5e1;
  border-radius: 8px;
  background: #f8fafc;
  color: #0f172a;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: #3b82f6;
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
  background: #fff;
}

.form-group input.invalid,
.form-group textarea.invalid {
  border-color: #ef4444;
}

.form-group .error {
  display: block;
  font-size: 0.8125rem;
  color: #ef4444;
  margin-top: 4px;
  min-height: 1.2em;
}

.form-group textarea {
  resize: vertical;
}

button[type="submit"] {
  width: 100%;
  padding: 12px;
  font-size: 1rem;
  font-weight: 600;
  color: #fff;
  background-color: #3b82f6;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.2s;
}

button[type="submit"]:hover {
  background-color: #2563eb;
}

button[type="submit"]:active {
  background-color: #1d4ed8;
}

.success-message {
  text-align: center;
  padding: 20px;
  margin-top: 20px;
  background: #f0fdf4;
  border: 1px solid #bbf7d0;
  border-radius: 8px;
  color: #166534;
  font-weight: 500;
}

.hidden {
  display: none;
}

@media (max-width: 480px) {
  .container {
    padding: 40px 16px;
  }

  .form-section {
    padding: 24px 20px;
  }
}