main.css

#canvas {
  display: block;
  margin: 0 auto;
  border: 1px solid #000;
}
#controller {
  width: 800px;
  margin: 0 auto;
}
.op_btn {
  float:right;
  margin: 10px 0 0 10px;
  border: 2px solid #aaa;
  width: 80px;
  height: 40px;
  line-height: 40px;
  font-size: 20px;
  text-align: center;
  border-radius: 5px 5px;
  cursor: pointer;
  background-color: white;
  font-weight: bold;
  font-family: Microsoft Yahei, Arial;
}
.op_btn:hover {
  background-color: #def;
}
.clearfix {
  clear: both;
}
.color_btn {
  float:left;
  margin: 10px 10px 0 0;
  border: 5px solid white;
  width:  40px;
  height:  40px;
  border-radius: 5px 5px;
  cursor: pointer;
}
.color_btn:hover {
  border: 5px solid violet;
}
.color_btn_selected {
  border: 5px solid blueviolet;
}
#black_btn {
  background-color: black
}
#blue_btn {
  background-color: blue
}
#green_btn {
  background-color: green
}
#red_btn {
  background-color: red
}
#orange_btn {
  background-color: orange 
}
#yellow_btn {
  background-color: yellow
}