syntax error on line1

Hi, can anyone kindly advise what I am doing wrong. I have followed the instruction carefully but nothing happens. I am trying to set a transparent block behind text, using my text block ref and code as shown below. many thanks! 

#block-yui_3_17_2_1_1630301539576_7763 {background: rgba{0,0,0,0.6} }

Your syntax error is the double closing brackets at the end. Change } } to }.

Let us know how it goes.