.flowrate-calculator {
    max-width: 500px;
    background: #fafafa;
    padding: 20px;
    margin: 30px auto;
    border-radius: 10px;
    box-shadow: 0 0 10px #ccc;
    font-family: Arial, sans-serif;
}
.flowrate-calculator h3 {
    text-align: center;
}
.flowrate-calculator label {
    display: block;
    margin-bottom: 12px;
}
.flowrate-calculator input,
.flowrate-calculator select {
    width: 100%;
    padding: 6px;
    margin-top: 5px;
}
.flowrate-calculator button {
    width: 100%;
    padding: 10px;
    background-color: #0073aa;
    color: #fff;
    border: none;
    margin-top: 10px;
    cursor: pointer;
}
.flowrate-calculator button:hover {
    background-color: #005f8a;
}
#flow-result {
    margin-top: 15px;
    padding: 10px;
    background-color: #eef;
    border-radius: 6px;
}