very small butterfly

Last days I saw them flying, more than one.
but when I came closer, to have a better look
this very small butterfly flies away before I can see.

I tried to chase him today... without being very successful
Only later this day he perched on one the flowers of lady's mantle (vrouwenmantel)(Alchemilla).
where he posed a while for a close by shot.
Only he did not want to show his inside wings.
another one rested on the hairy stem of a papaver.
I have no idea what kind of butterfly this is.