Color discrepancy between drawing color in HTML vs Three.JS using Vertex Colors

There seems to be some differences between the color drawn to screen by HTML (background-color) used to draw a legend vs the same color drawn in THREE using Basic or MeshStandard (can’t recall) Material using vertexColors. This screenshot is not from our application but illustrates the issue quite well

Any idea what could go wrong and/or how to fix it? I know that Three may be doing some color correction stuff automatically, but I obviously don’t know WHAT it is doing so I can’t replicate the same in my HTML legend. And no, setting the color dynamically from JS is not an option as we are doing this through Blazor + JS interop (possible but not practical). I would rather just understand what is going on and then react to have these display the same color. The vertex colors for each geometry are identical (repeated for each vertex) and consist of three floating point values 0-1 (normalized RGB I think it may be called?)