:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --background-color: #f4f4f4;
    --card-color: #ffffff;
    --text-color: #333333;
}

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

body {
    font-family: 'Arial', sans-serif;
    background-color: var(--background-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    justify-content: center;
    align-items: center;
    line-height: 1.6;
}

.container {
    width: 100%;
    max-width: 500px;
    padding: 20px;
}

.calculator-card {
    background-color: var(--card-color);
    border-radius: 15px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    padding: 30px;
    text-align: center;
}

h1 {
    color: var(--primary-color);
    margin-bottom: 25px;
    font-size: 2rem;
}

.input-group {
    margin-bottom: 20px;
    text-align: left;
}

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

input[type="number"],
select {
    width: 100%;
    padding: 10px;
    border: 1px solid ;
}