The reason there’s still a gap at the top one the pages where the announcement bar is hidden is because the CSS rules that push the header down to accommodate for the announcement bar are still in place.
I’ve also simplified your logic to make the code easier to maintain.
{% if page.handle == 'germs-on-toothbrushes' or page.handle == 'toothbrush-sanitizer-effectiveness' %}
{% endif %}
It worked perfectly, thank you so much for the help! On another note, how could I reduce the space under my header? This is mainly just a problem for those two pages.