body {
  margin:0;
  font-family:system-ui;
  background:#f4f4f4;
}

.app {
  display:flex;
  height:100vh;
}

aside {
  width:30%;
  background:#fff;
  border-right:1px solid #ddd;
  overflow-y:auto;
}

aside div {
  padding:15px;
  cursor:pointer;
}

aside div.active {
  background:#000;
  color:#fff;
}

main {
  flex:1;
  padding:15px;
  overflow-y:auto;
}

.item {
  background:#fff;
  padding:15px;
  margin-bottom:10px;
  border-radius:8px;
  display:flex;
  justify-content:space-between;
}

.order-btn {
  position:fixed;
  bottom:10px;
  left:10px;
  right:10px;
  padding:15px;
  font-size:18px;
  background:#000;
  color:#fff;
  border:none;
  border-radius:12px;
}