complement, compliment

Complement or complement ( com pleh ment ) means to go with or set off nicely--
That scarf  complements your coat nicely.
A large potted plant makes a complement to almost any room.

Compliment or compliment ( com plih ment ) means to flatter or praise, or the flattery or praise itself--
He always paid her cooking the compliment of asking for seconds.
When she disparaged her own cooking, we knew she was only fishing for a compliment.
Compliment is an old-fashioned word for gift--
They give every guest  a complimentary bowl of fruit.

Now that you know that, you can say--
"She considered it a compliment that he noticed how the pattern of the drapes made a nice complement to the sofa."

Note--"complimentary" means having the quality of flattery or praise--
She always said something complimentary about her mother-in-law's cooking.
"Complimentary" may also mean free, or a gift--
The firm offers each customer a complimentary calendar.
Not to be confused with "complementary", which means going together in a pleasing way--
The red plaid and the plain blue are complementary, don't you think?