Center Widget Title

Can’t figure out how to center widget titles. Research yields this code
.sidebar .widget-title {text-align: center;} Which I added to CSS style sheet (First time I have done this so not sure I did it correctly). My site is WhoDatWarriors.com Can’t figure out what I am doing wrong. Tried without the sidebar in code but widget titles did not change, so am trying sidebar as part of the code.