Learn Swedish: Varför stirrar du på spegelbilden som om du vore galen? - Why do you stare at the reflection as if you were crazy?

Vore is a special hypothetical form of the verb att vara (to be). We use it after som om (as if) because the situation is an unreal comparison: you aren't actually crazy, you are just acting like it. You will also often hear Swedes use the regular past tense var here, which is completely correct, but vore is very common for these imaginary scenarios.

Since som om starts a subordinate clause, where would we put inte if we wanted to say 'as if you were not crazy'?

You would put it before the verb: som om du inte vore galen. In subordinate clauses (dependent clauses), Swedish follows a strict rule where sentence adverbs like inte must come before the conjugated verb. This is often called the BIFF-rule by Swedish teachers.

Why does the sentence use the preposition på after stirrar?

While in English you stare 'at' something, in Swedish you stare 'on' it. The fixed expression is always att stirra på (to stare at).

What are the root words that make up spegelbilden?

It is a compound word made from en spegel (a mirror) and bilden (the picture or the image). To say 'the reflection', Swedish literally says 'the mirror-picture'.