Hi there!

Here are some places letter-spacing should not apply.

at the end of a line:

SPHINX
BLACK

QUARTZ

to spaces not fully contained by the element:

SPHINX

Here is a screenshot of how this page renders in Chrome 73 on Mac:

And here a rough mockup of how I would expect it to render, given both the definition of letter-spacing in the css3 spec and general typographic traditions:

Read more about letter-spacing: https://drafts.csswg.org/css-text-3/#propdef-letter-spacing