/* Styling halaman */
 * {
    box-sizing: border-box;
}
body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    background: url(/Blackboard\ Writing\ PNG\ Picture\,\ Blackboard\ Writing\ In\ \ Industry\,\ Physics\,\ Mathematics\,\ Industry\ PNG\ Image\ For\ Free\ Download.jpeg);
    color: #333;
}
.container {
    background-color: #02b3c0;
    padding: 40px;
    border-radius: 12px;
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.3);
    width: 360px;
    text-align: center;
    transition: 0.4s;
}
.container:hover {
    transform: scale(1.05);
}
h1 {
    font-size: 26px;
    color: #283c86;
    margin-bottom: 30px;
    font-weight: bold;
}
label {
    font-size: 16px;
    color: #555;
    display: block;
    margin: 10px 0 5px;
}
input[type="number"] {
    width: 100%;
    padding: 12px;
    border: 2px solid #283c86;
    border-radius: 8px;
    font-size: 16px;
    margin-bottom: 20px;
    outline: none;
    transition: border-color 0.3s;
}
input[type="number"]:focus {
    border-color: #45a247;
}
button {
    background-color: #283c86;
    color: white;
    padding: 14px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    width: 100%;
    font-size: 18px;
    font-weight: bold;
    transition: 0.3s;
}
button:hover {
    background-color: #45a247;
}
.result {
    margin-top: 30px;
    font-size: 18px;
    color: #333;
}
.result p {
    margin: 10px 0;
}
.grade {
    font-size: 24px;
    font-weight: bold;
    color: #45a247;
}