body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #f4f4f4;
}
.calculator {
    background-color: #fff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.1);
}
.display {
    width: 100%;
    height: 40px;
    text-align: right;
    margin-bottom: 10px;
    padding: 10px;
    font-size: 18px;
    border: 1px solid #ccc;
    border-radius: 5px;
    box-sizing: border-box;
}
.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}
.button {
    padding: 20px;
    font-size: 18px;
    border: none;
    border-radius: 5px;
    background-color: #f0f0f0;
    cursor: pointer;
    transition: background-color 0.3s;
}
.button:hover {
    background-color: #ddd;
}
.button.operator {
    background-color: #ff9500;
    color: white;
}
.button.operator:hover {
    background-color: #e08900;
}
.button.equal {
    background-color: #34c759;
    color: white;
}
.button.equal:hover {
    background-color: #2da94f;
}
.button.clear {
    background-color: #ff3b30;
    color: white;
}
.button.clear:hover {
    background-color: #e63329;
}
.info {
    color: gray;
}
table {
    border-collapse: collapse;
    width: 100%;
    margin-top: 20px;
}
th, td {
    border: 1px solid #ddd;
    padding: 8px;
    text-align: center;
}
th {
    background-color: #f8f9fa;
}
tr:nth-child(even) {
    background-color: #f2f2f2;
}
.error {
    color: red;
    margin-top: 10px;
}