Themes

There wont be a single rule, so you will probably need to go through each instance (or at least each type of instance - e.g. H1, H2, H3, text input boxes, buttons, etc) using something like firebug or chrome developer tools and reduce the padding/margins as appropriate.  (or at least as you want them)

Hi,

The More theme does not set the styles for the form page you refered to, this is set in Moodle via the BootstrapBase theme. Here is a link to the form.less file where you may find some answers to your question of how to reduce vertical space. 

Start off by looking for margin-top or margin-bottom.

https://github.com/lazydaisy/moodle/blob/master/theme/bootstrapbase/less/moodle/forms.less

Mary

I know that sometimes little things can be "big" things.

I use MORE and have made quite a few modifications via CSS code in the normal customization page.  I did tighten things up a bit, but not on the screen that you are showing.  Quite honestly, since this screen is typically seen by students once or twice, I wouldn't put my effort into improving it.  I would put my effort into screens that students see every day.  Take this as only a suggestion, not trying to be critical of what you are trying to achieve.

Let me know if you want to have my current CSS code.  You can get a glimpse of my moodle (front page) right here.  If needed, I might be able to add you to my MoodleCloud (experimental) course for you to navigate as a student would.  I have tried to make my moodlecloud course look like my production server (and it really does.)

Further to my last comment here is the CSS you might like to try.

body#page-login-signup #region-main .mform:not(.unresponsive) .fitem .fitemtitle { margin: 0;}
body#page-login-signup #region-main .mform:not(.unresponsive) .femptylabel .felement { margin: 0;}
body#page-login-signup #region-main h2 { margin: 0;}
body#page-login-signup legend.ftoggler { margin-bottom: 0;}
body#page-login-signup .collapsible-actions { float: right;}
body#page-login-signup .form-item .form-description, .felement.fstatic { margin: 0; padding-top: 0;}
body#page-login-signup #fitem_id_username,
body#page-login-signup #fitem_id_password,
body#page-login-signup #fitem_id_username .fitemtitle,
body#page-login-signup #fitem_id_passwprd .fitemtitle { margin: 0; padding: 0;}
body#page-login-signup input[type="text"],
body#page-login-signup input[type="password"]{margin: 0; padding: 6px; line-height: 1; height: 10px; vertical-align: middle;}
body#page-login-signup #region-main .mform:not(.unresponsive) .femptylabel .felement { margin: 0; padding: 0;}
body#page-login-signup form-item,
body#page-login-signup .mform .fitem { margin: 0;}

I did it just to see how hard it really was to find. Took me quite a while approx 45 minutes.

I hope it solves your problem?

You can add it to the More custom css settings page:

Site Administration > Appearance > Themes > More (settings)

Cheers

Mary