How can I change the height of widgets?

If you don’t like the spacings before and after the widgets, you can change it by adding a custom CSS rule.

.wrap > .row { padding: 90px 0 120px !important; }
#header .container, #header .container > .row { padding: 0 15px !important;}

The first line will change the padding (empty space) of the widget

90px = size of the empty space before the widget in pixels
20px = size of the empty space after the widget in pixels

You can change thes values with smaller ones. Here are the default ones.

The second line will restore the normal spacings in the header.

If you want to target a specific widget, then you can add the widget ID before the first line rule.

#the_widget_id .wrap > .row { padding: 90px 0 120px !important; }

If you only target certain widgets, then the 2nd line is not mandatory.