Full size container on Tablets

Hello,

I've removed the sidebars on tablets using the CSS -

@media (max-width: 800px) {
#right-sidebar {
display: none;
}
#left-sidebar {
display: none;
}
}

However, the content container (inside-article) is still having a limited width. What if I want to increase its width?

If I increase the width by using CSS width: 600px; it increases the width but overflows out of the screen on the right. Can you help me with this?