:root {
    --primary-color: #007BFF;
    --secondary-color: #6c757d;
    --background-color: #f8f9fa;
    --card-background: #fff;
    --border-color: #dee2e6;
    --text-color: #343a40;
    --label-color: #888;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

body {
    font-family: '微軟正黑體', 'Microsoft JhengHei', sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.registration-form {
    background-color: var(--card-background);
    padding: 40px;
    border-radius: 10px;
    box-shadow: var(--shadow);
    max-width: 600px;
    width: 100%;
}

.form-header {
    text-align: center;
    margin-bottom: 30px;
    color: var(--primary-color);
}

.form-group {
    margin-bottom: 20px;
}

.form-group-inline {
    display: flex;
    align-items: center;
    gap: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--label-color);
}

input[type="text"],
input[type="email"],
input[type="tel"],
input[type="password"],
select {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    box-sizing: border-box;
    font-size: 16px;
}

.input-inline {
    display: flex;
    align-items: center;
    gap: 10px;
}

.input-inline .input-field {
    flex-grow: 1;
}

.radio-group {
    display: flex;
    gap: 20px;
    align-items: center;
    margin-top: 10px;
}

.radio-group label {
    display: flex;
    align-items: center;
    gap: 5px;
    margin-bottom: 0;
    cursor: pointer;
}

.submit-btn {
    width: 100%;
    padding: 15px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 18px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.submit-btn:hover {
    background-color: #0056b3;
}

.error-message {
    color: red;
    font-size: 14px;
    text-align: left;
    margin-top: -5px;
    margin-bottom: 10px;
}