* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang HK", sans-serif;
  background: #fff3e0;
  color: #222;
  padding: 10px;
  max-width: 420px;
  margin: 0 auto;
  text-align: center;
}
header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 15px; }
h1 { font-size: 1.6rem; }
.big-btn {
  background: #ff9800;
  color: white;
  border: none;
  border-radius: 12px;
  padding: 14px 22px;
  font-size: 1.2rem;
  min-height: 50px;
  cursor: pointer;
}
#workspace {
  min-height: 200px;
  background: white;
  border-radius: 16px;
  margin: 15px 0;
  border: 3px solid #ffcc80;
  position: relative;
}
.shape {
  display: inline-block;
  margin: 8px;
  cursor: pointer;
  font-size: 3rem;
  padding: 10px;
  background: #ffe0b2;
  border-radius: 8px;
  border: 3px solid #ff9800;
}
#shapes { margin: 15px 0; }