Mysterio made specifically for use with an optifine cape. It's no secret that capes don't look good glued to the back of your skin, so I make my skins optifine cape friendly. For the specific banner design I used with this cape, paste this in the URL section: nafcfBfKfp
Now just fill in the other boxes with this HTML code: 8647B2 and you'll have a seamless looking cape made for this skin.

Finished cape design w/ skin:
imgur.com/MoxmBGJ