Textures which are stitched, such as the icons.png have overlapping textures.
Also some textures remove black outlines as if they were supposed to be transparent.

[Note: These are not issues caused by Client mods, or due to bigger textures]
Example Provided shows:
Hearts Overlapping
Connection Bar showing up in the Reticule.
Experience Bar missing it's black outline in game.

A Solution would be to make each texture it's own separate picture and load them where they should be constrained rather than overlap the edges of textures and remove the black borders in certain areas.