Edit in JSFiddle

body {
  float: left;
  margin: 0;
  padding: 0;
  width: 100%;
}

.macwrapper {
  width: 100%;
  /* whatever width you want */
  display: inline-block;
  position: relative;
}

.macwrapper:after {
  padding-top: 75%;
  /* 16:9 ratio */
  display: block;
  content: '';
}

.macmain {
  position: absolute;
  top: 0;
  bottom: 0;
  right: 0;
  left: 0;
  /* fill parent */
  background-color: #7e9db1;
  /* let's see it! */
  color: white;
}

.macouter {
  width: 60%;
  height: auto;
  margin: 2% auto 0;
}

.macinner {
  width: 100%;
  display: inline-block;
  position: relative;
  background-color: #baac87;
  border-top-left-radius: 5%;
  border-top-right-radius: 5%;
}

.macinner:after {
  padding-top: 120%;
  display: block;
  content: '';
}

.macworkspace {
  position: absolute;
  top: 0;
  bottom: 12%;
  right: 0;
  left: 0;
  /* fill parent */
  background-color: #d4c7a4;
  /* let's see it! */
  color: white;
  border-radius: 5%;
}

.macindent {
  background-color: #b9ac8a;
  width: 85%;
  margin: 5% auto 0;
  position: relative;
  border-radius: 4%;
  padding-top: 70%
}

.macscreen {
  position: absolute;
  top: 3%;
  left: 3%;
  bottom: 3%;
  right: 3%;
  background-color: #323232;
  border-radius: 4%;
}

.macfloppydrive {
  background-color: #000555;
  width: 50%;
  position: relative;
  left: 42%;
  margin-top: 15%;
}

.macfloppydrivelight {
  float: right;
  width: 50%;
  background-color: #baab8a;
  padding: 2%;
  border-radius: 5px;
}

.macfloppydrivedark {
  position: relative;
  margin: 0 auto;
  background-color: #a3947d;
  width: 90%;
  padding-top: 30%;
  border-radius: 3px;
}

.macfloppytray {
  position: absolute;
  background-color: #333333;
  width: 95.5%;
  padding-top: 5%;
  margin-top: 7%;
}

.macpowerlight {
  position: absolute;
  margin: 22% 0 0 10%;
  border: 2px solid #333333;
  background-color: #336B33;
  width: 4%;
  padding-top: 3%;
  border-radius: 2px;
}

.macpowerswitch {
  position: absolute;
  top: 91%;
  left: 65.5%;
  z-index: 2;
  width: 25%;
  border: 1.5px solid #333333;
  border-radius: 2px;
}

.macbutton {
  float: right;
  width: 20%;
  padding: 10%;
  margin: 1px;
  background-color: #333333;
  border-radius: 2px;
}