Category Display on Multiple Lines

It is probably a style conflict with your theme. Can you provide a link so I can see?

Adding the following CSS rule should fix it:

table.spiffy.cat-key {
    table-layout: auto;
}

You have 3 options. Enter the new rule in any one of these places:

Customize > Additional CSS

Spiffy Calendar > Options > Custom CSS styles

Customize > Spiffy Calendar > Custom CSS styles