Fixed CSS selectors in documentation examples.
Fixed CSS selectors in documentation examples.

haolee1990/trackpad-scroll-emulator,dmxfee/trackpad-scroll-emulator,sixthedge/trackpad-scroll-emulator,jnicol/trackpad-scroll-emulator,sixthedge/trackpad-scroll-emulator,chrismoulton/trackpad-scroll-emulator,chrismoulton/trackpad-scroll-emulator,haolee1990/trackpad-scroll-emulator,dmxfee/trackpad-scroll-emulator