:root {
  --primary-color: #4a90e2;
  --background-color: #f5f7fa;
  --input-bg: #ffffff;
  --input-border: #d1d9e6;
  --text-color: #333333;
  --border-radius: 8px;
  --shadow: rgba(0, 0, 0, 0.1);
}
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: 'Helvetica Neue', Arial, sans-serif;
  color: var(--text-color);
}
body {
  background-color: var(--background-color);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 20px;
}
.card {
  background: #fff;
  border-radius: var(--border-radius);
  box-shadow: 0 4px 12px var(--shadow);
  max-width: 500px;
  width: 100%;
  padding: 30px;
  transition: transform 0.3s ease;
}
.card:hover {
  transform: translateY(-5px);
}
.card h2 {
  margin-bottom: 20px;
  text-align: center;
  color: var(--primary-color);
}
.form-group {
  margin-bottom: 15px;
}
.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: bold;
}
.form-group input,
.form-group textarea {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--input-border);
  border-radius: var(--border-radius);
  background: var(--input-bg);
  transition: border-color 0.3s;
}
.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 5px rgba(74, 144, 226, 0.3);
}
.form-group textarea {
  resize: vertical;
  min-height: 120px;
}
.btn-submit {
  width: 100%;
  padding: 14px;
  background-color: var(--primary-color);
  border: none;
  color: #fff;
  font-size: 16px;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: background-color 0.3s, opacity 0.3s;
}
.btn-submit:hover {
  background-color: #357ab8;
}
.btn-submit:disabled {
  background-color: #a0c3e8;
  cursor: not-allowed;
}
.alert {
  text-align: center;
  margin-top: 10px;
  color: #e74c3c;
  display: none;
}