Basically just have ublock origin installed in your browser, click the icon, go into the settings, click My Filters on the top, and paste the following.
After you apply and reload the page you should have a Nordic style theme that's a bit easier on the eyes.
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! Darker page background + main text color
news.ycombinator.com##body, .c00:style(background-color: #1e222a !important; color: #c8d0d9 !important;)
! Top orange bar (nav/header)
news.ycombinator.com##td[bgcolor="#ff6600"]:style(background-color: #2a2f3a !important;)
! Body content background
news.ycombinator.com##[bgcolor="#f6f6ef"]:style(background-color: #1e222a !important;)
! Full black elements background
news.ycombinator.com##[bgcolor="#000000"]:style(background-color: #2a2f3a !important;)
! Hide spacing row
news.ycombinator.com##tr#pagespace:style(display: none !important;)
! Hacker News title link
news.ycombinator.com##b.hnname > a:style(color: #8fcadb !important;)
! All links
news.ycombinator.com##a:style(color: #7fbacb !important;)
! Subtext (e.g., posted by, time)
news.ycombinator.com##.subline:style(color: #8a9c8b !important;)
! Subtext links
news.ycombinator.com##.subline a:style(color: #7aa5a8 !important;)
! Score + top navbar links
news.ycombinator.com##.score, #hnmain > tbody > tr td:last-child > span.pagetop:style(color: #d0aa55 !important;)
! Site domain (.sitestr)
news.ycombinator.com##.sitestr:style(color: #b56c70 !important;)
!Shrinks the text input box on the submit page. (Flashbang reduction)
news.ycombinator.com##textarea[name="text"]:style(width: 400px !important; height: 30px !important;)
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I got the idea from another poster and modified it a bit. I don't know why the textbox on the submit page is a locked size. But other than that little quirk I find it a lot easier on the eyes.
If anyone knows how to change the submission boxes to be a different color that would be nice as well.
I thought there was a way to post code on HN but I cannot seem to figure out the formatting. Sorry about that.