Order of selectors in a selector chain

Hello, why is it that in line 62 h.2 is placed before .destination whereas in line 65 .description is placed before h5?

What determines the order of selectors in a selector chain?

Link to Lesson

h2.destination selects h2 elements that have the class destination

.description h5 selects h5 elements that are descendants of elements that have the class description
(meaning h5 elements inside elements that have class description)