button { width:22px; height:22px; background-color:white; border-width:1px; }

.a { background-color:yellow; }
.b { background-color:red;    }
.c { background-color:black;  }

.give   { color:black;                    border-color:black;                          }

.mult   { color:black; border-style:none;                     background-color:yellow; }
.null   { color:white; border-style:none;                     background-color:yellow; }

.play   { color:red;   border-color:red;                                               }

#number { color:black; border-color:black; width:72px; height:72px; border-width:2px;                         border-style:none; display:none; }
#count  { color:black; border-color:red;   width:72px; height:72px; border-width:2px; background-color:white; border-style:none;               }

.play:hover  { color:white; background-color:red; }
.play:active { color:white; background-color:red; }