body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background-color: #86afe7;
    font-family: 'Arial', sans-serif;
    margin: 0;
}

.calculator {
    width: 320px;
    background-color: #000000;
    border-radius: 30px;
    padding: 25px;
}

.display {
    background-color: #b7b4b2;
    border-radius: 15px;
    padding: 20px;
    margin-bottom: 25px;
    text-align: right;
    min-height: 60px;
}

.history {
    font-size: 14px;
    color: #777;
    height: 20px;
}

.main-display {
    font-size: 32px;
    font-weight: bold;
    color: #333;
    white-space: nowrap;
    overflow: hidden;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 15px;
}

button {
    border: none;
    background-color: #e0e5ec;
    padding: 20px 0;
    border-radius: 12px;
    font-size: 18px;
    font-weight: bold;
    cursor: pointer;
    transition: 0.2s;
}

button:active {
    box-shadow: inset -3px -3px 6px #ffffff;
}

.btn-c { color: #ff5e57; }
.btn-del { color: #1e90ff; }
.operator { color: #ffa502; }

.btn-zero {
    grid-column: span 4;
}

.btn-equals {
    grid-column: span 4;
    background-color: #4cd137;
    color: white;
    
}