Clearly your Css is not loading.
Step 1 confirm that your Css is not loading by giving us the errors in your browser (you should see an error appearing in your page source).
Step 2 Goto Adminpanel->Advance perimeters->Performance check the smarty cache memory enable and clear the cache.
Step 3 is to verify that you disabled all caches for now. Clear your browsers/server cache too when testing. see if this works
Step 4 Check your server permissions.
Step 5 If this doesn't work give us the messages in your log files (are you using apache or Nginx?).
Let's Start by this.