Switching background colour breaks ASCII/ANSI-Art by adding horizontal padding

[z-e-y-a]

A minimal example to showcase the problem:

`F000`Bfff||||||||||``
`F000`Bfff|`Baaa|`Bfff|`Baaa|`Bfff|`Baaa|`Bfff|`Baaa|`Bfff|`Baaa|``

results in:

[...]
<span style="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); padding: 0px 2px; display: inline-block;"><span class="Mu-mws"><span class="Mu-mnt">|</span></span></span>
<span style="color: rgb(0, 0, 0); background-color: rgb(170, 170, 170); padding: 0px 2px; display: inline-block;"><span class="Mu-mws"><span class="Mu-mnt">|</span></span>
[...]