Wide notebook outputs should have a max-width and scroll

[choldgraf]

Currently, the notebook outputs from MyST NB don't have a maximum width, and so if they are particularly wide, then they'll make the whole page horizontally scrollable. For example, from this page:

Proposal

We should cap the width of the output container in notebook outputs, and make it horizontally scrollable along with adding scrollbar-style to it. For example, by adding this rule we can make it scrollable:

div.cell_output .output {
    max-width: 100%;
    overflow-x: auto;
}

results in:

[12rambau]

should we add the custom scrollbar as well ?

[choldgraf]

Makes sense to me!