Custom text underline(using + and - symbols)

I need implement custom text decoration, see image below:

It is simple to simulate - row with next styles:

color: red;
border-bottom: 3px dashed; // 3px - just for example, 2.5 also looks fine.

But I can't find out how to implement underline using + symbols. Actually, I know that it is possible to have background-image, but it wouldn't work if text would be long.

I would appreciate any help. Thank you in advance.

UPD: Simple code snippet to play with:

<main>
    <h1>Here goes some heading <span class="deleted">and this is deleted</span></h1>
    <p>And here goes more text. <span class="added">This was inserted.</span> More text <span class="deleted">This was deleted</span></p>
</main>

Solution

You can do this with gradient like below:

.deleted {
  background:
    repeating-linear-gradient(to right,red 0 4px,transparent 4px 6px) 
    bottom/100% 2px no-repeat;
}
.added {
  background:
    repeating-linear-gradient(to right,green 0px 1px,transparent 1px 5px) 
    bottom 0 left 2px/100% 5px no-repeat,
    linear-gradient(green,green) bottom 2px left 0/100% 1px no-repeat;
  padding-bottom:4px;
}

<main>
    <h1>Here goes some heading <span class="deleted">and this is deleted</span></h1>
    <p>And here goes more text. <span class="added">This was inserted.</span> More text <span class="deleted">This was deleted</span></p>
</main>

If you want some spaces between the +

.deleted {
  background:
    repeating-linear-gradient(to right,red 0 4px,transparent 4px 6px) 
    bottom/100% 2px no-repeat;
}
.added {
  background:
    repeating-linear-gradient(to right,green 0 1px,transparent 1px 7px) 
    bottom 0 left 2px/100% 5px no-repeat,
    repeating-linear-gradient(to right,green 0 5px,transparent 5px 7px) 
    bottom 2px left 0/100% 1px no-repeat;
  padding-bottom:4px;
}

<main>
    <h1>Here goes some heading <span class="deleted">and this is deleted</span></h1>
    <p>And here goes more text. <span class="added">This was inserted.</span> More text <span class="deleted">This was deleted</span></p>
</main>

It will also work with multiline text:

.deleted {
  background:
    repeating-linear-gradient(to right,red 0 4px,transparent 4px 6px) 
    bottom/100% 2px no-repeat;
}
.added {
  background:
    repeating-linear-gradient(to right,green 0 1px,transparent 1px 7px) 
    bottom 0 left 2px/100% 5px no-repeat,
    repeating-linear-gradient(to right,green 0 5px,transparent 5px 7px) 
    bottom 2px left 0/100% 1px no-repeat;
  padding-bottom:4px;
}

<main>
    <h1>Here goes some heading <span class="deleted">and this is deleted</span></h1>
    <p>And here goes more text. <span class="added">This is long long long long long long long long long long text was inserted.</span> More text <span class="deleted">This was deleted</span></p>
</main>