body {
    font-size: 16px;
    line-height: 1.6;
    font-family: Arial, sans-serif;
}

.container { 
    max-width: 600px; 
    margin: 20px auto;
    padding: 20px;
}

h1 {
    color: #2c3e50;
    text-align: center;
    margin-bottom: 25px;
}

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

.input-row { 
    display: flex; 
    gap: 10px; 
    margin-bottom: 10px;
}

select, input { 
    width: 100%; 
    padding: 10px;
    box-sizing: border-box;
    text-transform: uppercase;
    font-size: 16px;
}

label { 
    display: block; 
    margin-bottom: 8px; 
    font-weight: bold;
    font-size: 18px;
}

.counter { 
    color: #666; 
    font-size: 0.9em; 
    margin-left: 5px; 
}

.result { 
    font-size: 1.3em; 
    font-weight: bold;
    color: #2c3e50;
}

.reference {
    font-style: italic;
    color: #7f8c8d;
    margin: 15px 0;
    text-align: center;
}

.formula {
    background-color: #f8f9fa;
    padding: 15px;
    border-radius: 5px;
    margin: 25px 0;
    border-left: 4px solid #3498db;
}

.formula h3 {
    margin-top: 0;
    color: #2c3e50;
}