You can easily convert  float color list (i.e. used in Kivy [1]) to Web RGB in Python [2] with oneliner:

c = [0.5019607843137255, 0.796078431372549, 0.7686274509803922, 1.0]
rgb = '#%02X%02X%02X%02X' % tuple(int(255*i) for i in c)
'#80CBC4FF'

[1] https://kivy.org/
[2] https://www.python.org/