how to fix - Fatal error: Uncaught Error: Call to undefined function mb_convert_encoding()

In this case my anchor this week becomes driving almost 2hrs outside of Atlanta to one of my favorite hard core gyms in the world.. MetroFlex aka The Dungeon. The gym owners turn the heat way up so it becomes a fun sweat box and the gym members just watch from afar and leave me alone. I happily drive myself long distances to find MY ANCHOR. Our anchor allows us to have balance, focus and be as productive as possible. And if you're in the middle of a heavy set and your headphones start to fall off your head, like mine did here.. well.. f*ck the headphones. Let em break and fall. You can always get a new pair, but the iron ain't ever gonna lift itself.
Unknown

brightness()

The brightness() CSS function applies a linear multiplier to the input image, making it appear brighter or darker. Its result is a <filter-function>.
brightness() css reference