* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

h1 {
    font-size: 2rem;
    text-align: center;
    position:absolute;
    left: 50%;
    transform: translateX(-50%);
    top: 10px;
    color: #333;
}

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

.calculator {
    width: 300px;
    margin-top: 60px;
    border-radius: 20px;
    overflow: hidden;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    background-color: #000;
}

.display {
    padding: 20px;
    text-align: right;
    height: 120px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
}

.previous-operand {
    color: rgba(255, 255, 255, 0.7);
    font-size: 1.2rem;
    height: 24px;
    overflow: hidden;
}

.current-operand {
    color: white;
    font-size: 2.5rem;
    margin-top: 10px;
    overflow: hidden;
    text-overflow: ellipsis;
}

.buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1px;
    background-color: #333;
}

button {
    border: none;
    outline: none;
    padding: 20px;
    font-size: 1.5rem;
    cursor: pointer;
    background-color: #505050;
    color: white;
}

button:active {
    opacity: 0.8;
}

.operator {
    background-color: #FF9500;
}

.equals {
    background-color: #FF9500;
}

.span-two {
    grid-column: span 2;
}

[data-number] {
    background-color: #505050;
}

[data-action="clear"] {
    background-color: #a5a5a5;
    color: black;
}

[data-action="delete"] {
    background-color: #a5a5a5;
    color: black;
}