body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #f4f4f4;
    font-family: Arial, sans-serif;
}

.calculator {
    background-color: #000;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.2);
    width: 320px;
}

#display {
    width: 100%;
    height: 50px;
    text-align: right;
    margin-bottom: 15px;
    font-size: 46px;
    color: white;
    background-color: black;
    border: none;
    padding: 10px;
    border-radius: 5px;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

button {
    padding: 20px;
    font-size: 24px;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    color: white;
}

button.operator {
    background-color: #ff9500;
    font-size: 28px;  /* Make symbols slightly larger */
    font-weight: bold;
}

button.equal {
    background-color: #007aff;  /* iPhone-like blue color for "=" */
    font-size: 28px;            /* Make the equals sign larger */
    color: white;
    border-radius: 50%;
    grid-column: span 1;        /* Ensures it only takes one grid space */
}

button.equal:hover {
    background-color: #005bb5;  /* Darken the blue on hover */
}

button.number {
    background-color: #333;
}

button.clear, button.plus-minus, button.percent {
    background-color: #a5a5a5;
    color: black;
}

button.blank {
    background-color: transparent;
    cursor: default;
}

button.dot {
    background-color: #333;
}

button:hover {
    opacity: 0.8;
}