[TASK] Improve accessbility

html/index.html

lib/filters/filtergui.js

lib/filters/hostname.js

lib/gui.js

lib/infobox/location.js

lib/infobox/main.js

lib/legend.js

lib/main.js

lib/map.js

lib/map/button.js

lib/sidebar.js

lib/utils/language.js

locale/en.json

scss/modules/_base.scss

scss/modules/_button.scss

scss/modules/_filter.scss

scss/modules/_legend.scss

scss/modules/_sidebar.scss