.hp-calc-container {
    max-width: 450px;
    background: #fdfdfd;
    padding: 20px;
    margin: 30px auto;
    border-radius: 10px;
    box-shadow: 0 0 10px #ccc;
    font-family: Arial, sans-serif;
}
.hp-calc-container h3 {
    text-align: center;
}
.hp-calc-container label {
    display: block;
    margin-bottom: 10px;
}
.hp-calc-container input,
.hp-calc-container select {
    width: 100%;
    padding: 6px;
    margin-top: 5px;
}
.hp-calc-container button {
    width: 100%;
    padding: 10px;
    background: #007cba;
    color: white;
    border: none;
    margin-top: 10px;
    font-size: 16px;
    cursor: pointer;
}
.hp-calc-container button:hover {
    background: #005f8a;
}
#hp-calc-result {
    margin-top: 15px;
    padding: 10px;
    background: #eef;
    border-radius: 5px;
}
#hp-calc-result ul {
    padding-left: 20px;
}