/* General Background */
body {
    background-color: #121212; /* Deep dark theme */
    padding: 20px;
    border: 20px;
    box-shadow: 0px 10px 30px rgba(0,0,0,0.5);
    width: 320px;
}
#display{
    width: 100%;
    height: 60px;
    font-size: 2rem;
    text-align: right;
    margin-bottom: 20px;
    background: transparent;
    border: none;
    color: #00ff88;
    padding-right: 10px;
    box-sizing: border-box;
}
.buttons{
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

button{
    padding: 15px;
    font-size: 1.1rem;
    border: none;
    border-radius: 10px;
    background-color: #333;
    color: white;
    cursor: pointer;
    transition: 0.2s;
}
button:hover {
    background-color: #444;
}
.btn-op { color: #ff9500; }
.btn-func { background-color: #ff3b30; }
.btn-sci { color: #007aff; }
.btn-equal{
    background-color: #00ff88;
    color: black;
    grid-column: span 1;
}
educes space between buttons */
    }
}