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

body {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #020024;
    background: linear-gradient(90deg, rgba(2, 0, 36, 1) 0%, rgba(9, 9, 121, 1) 35%, rgba(0, 212, 255, 1) 100%);
}


.calculator {
    background: #fff;
    border-radius: 16px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    padding: 20px;
    width: 460px;
    overflow: hidden;
}


.calculator-display {
    width: 100%;
    height: 80px;
    border: none;
    background: #f8f9fa;
    border-radius: 8px;
    text-align: right;
    padding: 0 15px;
    font-size: 2rem;
    margin-bottom: 20px;
    color: #333;
}

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

.btn {
    padding: 15px;
    font-size: 1.2rem;
    border: none;
    border-radius: 8px;
    background: #f8f9fa;
    cursor: pointer;
    transition: all 0.2s;
}

.btn:hover {
    background: #e9ecef;
}

.operator {
    background: #4dabf7;
    color: white;
}

.operator:hover {
    background: #339af0;
}

#equals {
    grid-column: span 1;
    background: #40c057;
    color: white;
}

#equals:hover {
    background: #37b24d;
}

#delete {
    background: #ffa94d;
    color: white;
}

#delete:hover {
    background: #ff922b;
}

.clear {
    background: #ff8787;
    color: white;
}

.clear:hover {
    background: #ff6b6b;
}

.mod {
    background: #4dabf7;
    color: white;
}

.mod:hover {
    background: #339af0;
}

.calculator-buttons button:last-child {
    grid-column: 3 / span 1;
}


@media screen and (max-width: 480px) {
    .calculator {
        width: 100%;
        padding: 10px;
        border-radius: 10px;
    }

    .calculator-display {
        height: 90px;
        font-size: 1.5rem;
        padding: 0 8px;

    }

    .btn {
        padding: 10px;
        font-size: 1rem;
        border-radius: 6px;
    }

    .calculator-buttons {
        gap: 6px;
    }
}