What is the meaning for a Dark Blue Pokestop?

Whenever I visit a Pokestop, it is one of two colors: Light Blue and Light Pink. The two colors signify it is ready to use and during it's cool down period.

Today, I saw a Pokestop was dark blueish/purple. What is the meaning behind it?

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Solution 1:

Right after you use a pokestop, it will turn purple. Then it will fade from purple back to blue meaning you can use it again. The dark blue means that it isn't freshly used, but can't be used again yet.