* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body {
    background-color: #f7f7f7;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 88vh;
    margin: 0;
}

.calculator-wrapper {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    width: 100%;
    min-height: 50%;
    max-width: 400px;
    background-color: #000;
    margin-top: 50px;
    border-radius: 50px;
}

.input-display {
    width: 100%;
    height: 15vh;
    padding: 0 20px;
    color: #fff;
    font-size: 3rem;
    display: flex;
    justify-content: flex-end;
    align-items: flex-end;
    word-break: break-all;
}

.result-display {
    width: 100%;
    height: 15vh;
    padding: 0 20px;
    color: #fff;
    font-size: 4rem;
    display: flex;
    justify-content: flex-end;
    align-items: flex-start;
    word-break: break-all;
}

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

button {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background-color: #333;
    color: #fff;
    font-size: 2rem;
    border: none;
    cursor: pointer;
    transition: background-color 0.2s;
}

button:active {
    background-color: #555;
}

.button-gray {
    background-color: #A5A5A5;
    color: #000;
}

.button-gray:active {
    background-color: #C5C5C5;
}

.button-orange {
    background-color: #FF9500;
    color: #fff;
}

.button-orange:active {
    background-color: #FFB84D;
}

.button-zero {
    grid-column: span 2;
    width: 100%;
    border-radius: 40px;
    text-align: left;
    padding-left: 30px;
}