I tried to test this PR.

Steps:
Log in to the admin panel.
Go to Users section.
Delete the email value.
Press Save.

Following are the results I got.

I have highlighted the text in order to view blank spaces. I cannot see much of a difference. Please tell me if I have followed wrong steps @andrepereiradasilva .

The difference in just the bottom margin. In the second print the top margin is the same as the bottom margin.
In the first print the bottom margin is double the top margin.

I have tested this item successfully on 2f97aa9

the CLI generatecss.php has not been applied to this PR.
It lacks the change in isis rtl

diff --git a/administrator/templates/isis/css/template-rtl.css b/administrator/templates/isis/css/template-rtl.css
index 29092b9..8454415 100644
--- a/administrator/templates/isis/css/template-rtl.css
+++ b/administrator/templates/isis/css/template-rtl.css
@@ -2791,4 +2791,7 @@
 }
 .alert h4 {
+   margin: 0 0 .5em;
+}
+.alert p {
    margin: 0;
 }

true, didn't use the CLI generatecss.php has not been applied to this PR.
That was to be done in linux right?

i do it on mac. unix system. you just have to use the .diff above if no time.

This PR has received new commits.

CC: @brianteeman

ok, did it manually.

I have tested this item successfully on ad0ecfd

@andrepereiradasilva sorry for not noticing it initially. :)

I have tested this item successfully on ad0ecfd

You can run the CLI generator on any system. For windows though - you just need to make sure you have PHP in your environment variables (e.g. http://stackoverflow.com/a/2736574/1195517)

@rehrumesh Please mark your test results here: https://issues.joomla.org/tracker/joomla-cms/9181 -> Login with GitHub account -> Button "Test this". Your current comment isn't counted as test result.

I have tested this item successfully on ad0ecfd

@grhcj Thanks for the info.

RTC