OnePress Social Locker is a tool that you can use to hide content in WordPress posts until the user shares it, I use it for articles I believe that offer a lot of value for free so that they should be shared with others. There is an issues with it currently that the fonts do not display correctly no matter what theme you use. I emailed there support ( who where excellent and replied within minutes ) and they sent the following fix. In you themes CSS file, simply enter the code below and the fonts will display correctly.
.ui-social-locker, .ui-social-locker .ui-social-locker -text, .ui-social-locker .ui-social-locker-timer { color: #111; }