Is it possible to render border-image-outset value of 0.5 in Safari?

I want to render a 1px border in between sibling nodes. I have constructed a solution using an SVG as a border-image that works in almost all modern browsers with this:

.svg-border {
  border-style: solid;
  border-width: 1px;
  border-image-source: url("data:image/svg+xml...");
  border-image-slice: 1 1;
  border-image-outset: .5;  
}

However, I’m stuck on Safari: it doesn’t appear to accept .5 as a value for border-image-offset, so the borders appear as 2px width between adjacent siblings.

Does anyone know a workaround or other method to getting this to work?

See CodePen demo here

Is it possible to render border-image-outset value of 0.5 in Safari?