Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
iCloud.com Gets Updated With Similar Design To iOS 7
Apple has just updated the design of their beta iCloud website, beta.icloud.com. The new redesign now makes iCloud fit in with iOS 7 by sharing many design ascetics.
This is the first real web product we have seen from Apple which is designed like iOS 7. Apple has been inviting more and more people lately to the iCloud beta ahead of the iOS 7 launch which is expected around September 18th.