Instead of using dcc dropdown, consider using combination of a button that shows e.g. "Multiple", "24 selected" and on click will open (set visible) a dcc Checkbox div. This will have the input (the button) be compact while still making it easy to access all the options. Currently, experimenting with fixing the height/min-height/max-height css properties does not make dcc dropdown much better.
But focus on adding other functionalities first (plot etc)
Instead of using dcc dropdown, consider using combination of a button that shows e.g. "Multiple", "24 selected" and on click will open (set visible) a dcc Checkbox div. This will have the input (the button) be compact while still making it easy to access all the options. Currently, experimenting with fixing the height/min-height/max-height css properties does not make dcc dropdown much better.
But focus on adding other functionalities first (plot etc)