To edit the layout and the visual part of item in Dash you need to dive into the CSS part of stuff. As a reference take a look at this question from another user:
Take note of the ‘style’ option he sets at the end of his Div containers. Here you can manage the place placement and appearance of whatever you put in it. You can also make a separate CSS stylesheet which you can apply for your whole app, but I do not have the necessary CSS/Dash mojo to tell you how. 