:root {
  --primary: #0056b3;
  --secondary: #f0f8ff;
  --border: #d0e3ff;
  --text: #333;
  --light-bg: #f9f9f9;
  --error: #d9534f;
  --error-bg: #f8d7da;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Arial', sans-serif;
}

body {
  line-height: 1.5;
  color: var(--text);
  background: var(--light-bg);
  padding: 15px;
}

.container {
  max-width: 900px;
  margin: 0 auto;
  background: white;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

h1 {
  text-align: center;
  color: var(--primary);
  font-size: 1.5rem;
  margin-bottom: 20px;
}

.error {
  color: var(--error);
  background: var(--error-bg);
  padding: 8px 12px;
  border-radius: 4px;
  margin-bottom: 15px;
  font-size: 0.9rem;
  border: 1px solid var(--error);
}

.calculator {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
}

@media (min-width: 768px) {
  .calculator {
    grid-template-columns: 1fr 1fr;
  }
}

.calculator-form {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.form-group {
  margin-bottom: 12px;
}

label {
  display: block;
  margin-bottom: 5px;
  font-size: 0.9rem;
  
}

input, select {
  width: 100%;
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 4px;
  font-size: 0.9rem;
}

.radio-group {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
  gap: 8px;
}

.radio-option input {
  display: none;
}

.radio-option label {
  padding: 8px;
  background: #f5f5f5;
  border-radius: 4px;
  text-align: center;
  cursor: pointer;
  font-size: 0.85rem;
  transition: all 0.2s;
}

.radio-option input:checked + label {
  background: var(--primary);
  color: white;
}

.checkbox-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.checkbox-option {
  display: flex;
  align-items: center;
  font-size: 0.9rem;
}

.checkbox-option input {
  width: auto;
  margin-right: 8px;
}

.optional-group {
  margin-top: 8px;
  padding-left: 12px;
  border-left: 2px solid var(--primary);
  font-size: 0.85rem;
}

.result {
  background: var(--secondary);
  padding: 15px;
  border-radius: 8px;
  border: 1px solid var(--border);
}

.price-details {
  margin-bottom: 15px;
  font-size: 0.9rem;
}

.price-row {
  display: flex;
  justify-content: space-between;
  margin-bottom: 8px;
  padding-bottom: 8px;
  border-bottom: 1px dashed #ccc;
}

.total {
  font-size: 1.2rem;
  font-weight: bold;
  color: var(--primary);
  margin-top: 15px;
  padding-top: 15px;
  border-top: 2px solid var(--primary);
}

.btn {
  display: inline-block;
  padding: 10px 15px;
  background: #25D366;
  color: white;
  border: none;
  border-radius: 4px;
  font-size: 0.9rem;
  font-weight: bold;
  cursor: pointer;
  text-align: center;
  text-decoration: none;
  transition: background 0.2s;
  margin-top: 15px;
  width: 100%;
}

.btn:hover {
  background: #128C7E;
}

.btn i {
  margin-right: 5px;
}

@media (max-width: 480px) {
  .radio-group {
    grid-template-columns: 1fr 1fr;
  }
  input, select, .btn {
    padding: 8px;
  }
}