body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: linear-gradient(135deg, #1e1f21 0%, #c3cfe2 100%);
    margin: 0;
}

.content {
    width: 320px;
    margin-bottom: 20px;
}

#displayArea {
    width: 100%;
    height: 60px;
    font-size: 2em;
    text-align: right;
    padding: 10px 20px;
    border: none;
    border-bottom: 2px solid #888;
    color: #000;
    background-color: #fff;
    box-shadow: 0px 4px 8px rgba(0, 0, 0, 0.1);
    direction: rtl;
    text-overflow: ellipsis;
    overflow: hidden;
    white-space: nowrap;
    font-family: 'Courier New', Courier, monospace;
    margin-bottom: 20px;
}

#buttonArea {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    padding-left: 20px;
}

button {
    width: 100%;
    height: 60px;
    font-size: 1.5em;
    border: none;
    background-color: #E0E0E0;
    color: #000;
    box-shadow: 0px 4px 6px rgba(0, 0, 0, 0.1);
    cursor: pointer;
    transition: background-color 0.2s;
}

button:hover {
    background-color: #D3D3D3;
}

button:active {
    background-color: #B0B0B0;
}

button:nth-child(4n) {
    background-color: #FF9500;
    color: #fff;
}

button:nth-child(4n):hover {
    background-color: #E58C00;
}

button:nth-child(4n):active {
    background-color: #CC7A00;
}

/* Media query for tablet and mobile devices */
@media (max-width: 1024px) {
    body {
        display: flex;
        justify-content: center;
        align-items: center; 
        flex-direction: column;
        height: 100vh;
        margin: 0;
        padding: 20px;
    }
    
    .content {
        width: 100%;
        margin-bottom: 10px;
    }
    
    #displayArea {
        height: 80px;
        font-size: 2.5em;
    }
    
    #buttonArea {
        padding: 0;
        grid-template-columns: repeat(4, 1fr);
    }
    
    button {
        height: 70px;
        font-size: 1.2em;
    }
}