* {
    margin: 0;
    padding: 0;
    font-family: "Calibri", sans-serif;
    box-sizing: border-box;
}

body {
    background-color: black;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.container {
    width: 100%;
    max-width: 400px;
    padding: 1em;
}

.calculator {
    background-color: black;
    border-radius: 15px;
    box-shadow: 0 0 10px rgba(255, 255, 255, 0.3);
    padding: 1em;
    width: 100%;
}

.display input {
    width: 100%;
    background-color: rgba(255, 255, 255, 0.1);
    color: white;
    font-size: 2em;
    padding: 0.5em;
    text-align: right;
    border: none;
    border-radius: 10px;
    margin-bottom: 1em;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.6em;
}

.buttons input {
    background-color: rgba(255, 255, 255, 0.1);
    border: none;
    border-radius: 50%;
    padding: 1em;
    font-size: 1.5em;
    color: white;
    transition: 0.2s;
}

.buttons input:hover {
    background-color: rgba(255, 255, 255, 0.2);
    cursor: pointer;
}

.operator {
    background-color: rgba(255, 255, 255, 0.2);
}

.equal {
    background-color: orangered;
    color: white;
    border-radius: 50%;
}

@media (max-width: 600px) {
    .buttons input {
        font-size: 1.2em;
        padding: 0.8em;
    }

    .display input {
        font-size: 1.5em;
    }
}