Here's another reminder why expressive, namespaced ids are important.
This time is about a label's
<input id="phone"> <label for="phone"></label
This would work just as expected unless, for example, we have a svg sprite at the beginning of the document that includes an svg with a "phone"
<symbol id="phone" viewBox="0 0 61.4 48">...</symbol> ... <input id="phone"> <label for="phone"></label
In this case, the label's
for will match the first in a top-down order that has the target id.
And you will never know why clicking the label won't trigger the input.