[UX-331] fix a bug where line numbers stopped displaying (apparently only in Chrome), caused by opacity; also tweaked counter CSS to align with what is more commonly cited on the web as proper solution
[UX-331] fix a bug where line numbers stopped displaying (apparently only in Chrome), caused by opacity; also tweaked counter CSS to align with what is more commonly cited on the web as proper solution

jenkinsci/blueocean-plugin,alvarolobato/blueocean-plugin,jenkinsci/blueocean-plugin,kzantow/blueocean-plugin,cliffmeyers/jenkins-design-language,cliffmeyers/jenkins-design-language,alvarolobato/blueocean-plugin,kzantow/blueocean-plugin,cliffmeyers/jenkins-design-language,jenkinsci/jenkins-design-language,alvarolobato/blueocean-plugin,jenkinsci/blueocean-plugin,jenkinsci/jenkins-design-language,jenkinsci/blueocean-plugin,kzantow/blueocean-plugin,jenkinsci/blueocean-plugin,alvarolobato/blueocean-plugin,kzantow/blueocean-plugin