[SPARK-32177][WEBUI] Remove the weird line from near the Spark logo on mouseover in the WebUI

[sarutak]

What changes were proposed in this pull request?

This PR changes webui.css to fix a style issue on moving mouse cursor on the Spark logo.

Why are the changes needed?

In the webui, the Spark logo is on the top right side.
When we move mouse cursor on the logo, a weird underline appears near the logo.

Does this PR introduce any user-facing change?

Yes. After this change applied, no more weird line shown even if mouse cursor moves on the logo.

How was this patch tested?

By moving mouse cursor on the Spark logo and confirmed no more weird line there.

[SparkQA]

Test build #124966 has finished for PR 29003 at commit c7cf8d7.

• This patch fails build dependency tests.
• This patch merges cleanly.
• This patch adds no public classes.

[sarutak]

retest this please.

[SparkQA]

Test build #124968 has started for PR 29003 at commit c7cf8d7.

[dongjoon-hyun]

Hi, @sarutak . If you want to backport this to branch-3.0, could you set the JIRA type as Bug instead of Improvement?

[dongjoon-hyun]

BTW, when I tried at Apache Spark 3.0.0 with Safari Private Window mode, I cannot reproduce the weird line.

• Is this Chrome only bug?
• Does this occur only at the long version name with -SNAPSHOT?

[dongjoon-hyun]

I verified this bug in 3.1.0-SNAPSHOT, but cannot reproduce at 3.0.1-SNAPSHOT with both Safari and Chrome.
Shall we drop 3.0.0 from the Affected Version in SPARK-32177?

[sarutak]

I reproduced it in 3.0.0-SNAPSHOT as follows.

It's for the SNAPSHOT so I'll confirm again for the released one.

[sarutak]

It's strange but I've confirmed there are no weird line in 3.0.0 and 3.0.1-SNAPSHOT (maybe, I've seen the line in the 3.0.0's history with 3.1.0's HistoryServer).
So I'll drop 3.0.0 from the Affect Version.

[dongjoon-hyun]

Thank you, @sarutak !

[dongjoon-hyun]

+1, LGTM. Thank you, @sarutak .
I verified this manually and this CSS-change PR is irrelevant to Jenkins UT.
Merged to master.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/124968/
Test FAILed.