* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Times New Roman', Times, serif;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: linear-gradient(135deg, #00feba, #5b548a);
}

.calculator {
    background: rgba(255,255,255,0.3);
    backdrop-filter: blur(15px);
    border-radius: 20px;
    padding: 20px;
    max-width: 350px;
    width: 100%;
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}

.display input {
    width: 100%;
    padding: 15px;
    font-size: 2rem;
    border: none;
    border-radius: 10px;
    text-align: right;
    background: rgba(255,255,255,0.8);
    margin-bottom: 15px;
}

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

button {
    padding: 20px;
    font-size: 1.5rem;
    border-radius: 10px;
    border: none;
    cursor: pointer;
    background: #fff;
    color: #5b548a;
    font-weight: bold;
    transition: all 0.2s ease;
    white-space: nowrap;
}

button:hover {
    background: #00feba;
    color: #1f1f1f;
}

button.operator {
    background: #f7c59f;
}

button.equals {
    grid-column: span 2;
    background: #00feba;
    color: #fff;
}

button.clear {
    background: #ff6b6b;
    color: #fff;
}

button.erase {
    background: #ffa500;
    color: #fff;
}

button.toggle-sign {
    background: #7ecbff;
    color: #fff;
}

@media (max-width: 480px) {
    .display input {
        font-size: 1.5rem;
        padding: 12px;
    }

    button {
        padding: 15px;
        font-size: 1.2rem;
    }
}

button {
    border: none;
    outline: none;
    padding: 20px 25px;
    border-radius: 10px;
    background: #fff;
    color: #5b548a;
    font-weight: 600;
    font-size: 18px;
    cursor: pointer;
    transition: all 0.2s ease;
}

/* Hover effect for ALL buttons */
button:hover {
    background: #00feba;   /* Change to whatever highlight color you want */
    color: #1f1f1f;
    transform: translateY(-2px);
}

/* Optional: Active click effect */
button:active {
    transform: translateY(0);
}