body {
  font-family: sans-serif;
  display: flex;
  flex-direction: column;
  margin: 0;
  height: 100vh;
}

#puzzle-container {
  width: 100%;
  height: 50vh;
}

#pieces-container {
  width: 100%;
  display: flex;
  background-color: #f0f0f0;
  padding: 10px;
  box-sizing: border-box;
}

#tray {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: flex-start;
  width: 100%;
  height: 100%;
  overflow-y: auto;
}

h1 {
  margin-top: 10px;
  margin-bottom: 10px;
}

.controls {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 5px;
}

#new-picture-btn {
  margin-right: 20px;
}

.difficulty-container {
  display: flex;
  align-items: center;
}

.difficulty-container label {
  margin-right: 10px;
}