How to I change the colour of underline site-wide?

Site URL: https://beagle-tangerine-ex9m.squarespace.com/

Hi All,

I wondered whether anyone could tell me how I can change the colour of the underline style site wide.

I currently have H2 set to a custom underline but i'd like to make this style specific to when I use underline in markdown blocks <u>text</u> because when I use H2 it adjusts all the text on one line to being underlined and I would like to apply this underline style to specific words in text.

This is the current CSS:

h2 { 
  text-decoration-line: underline;
  text-decoration-style: solid;
  text-decoration-color: #3effb1;
  text-decoration-thickness: 20px;
}

I've tried this code but nothing happened: 

.underline {
text-decoration-line: underline;
  text-decoration-style: solid;
  text-decoration-color: #3effb1;
  text-decoration-thickness: 20px;
}

I'm new to coding so I have very little idea of what I'm doing haha. Any suggestions would be greatly appreciated!

Below attached image shows what underlining currently does (has same colour as font) and above is an example of H2 with the desired colour I hope to achieve.

Thanks,

Sarah

HI Sarah,

Your site is private, please provide a password so we can check

1 hour ago, bangank36 said:

HI Sarah,

Your site is private, please provide a password so we can check

I'm afraid it's not Live yet, is this an issue?

Just now, sarahgilchrist said:

I'm afraid it's not Live yet, is this an issue?

You can set a temporary site wide pasword in Permission section

the password is: digitalnative

4 hours ago, sarahgilchrist said:

the password is: digitalnative

You already change the underline color, what wrong?