Hi Steve,
You are downloading some stylesheets that are applying conflicting CSS. I don't know anything about the library specifically, but some of these ui frameworks/tools/packages include css that restyles common browser elements to give everything on your site a consistent look, instead of using scoped css that only affects the elements it provides. You could try including the library *before* including blockly on the page, as if there's a "tie" in css specificity, the later value will win, so some of Blockly's styles may win that way. But otherwise you're going to have to find the conflicting styles from the ui framework you're using and disable or undo them.
Best,
Maribeth