:root {
  font-family: Arial, Helvetica, sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  height: 100%;
  background: #f6f8fa;
}

.app {
  display: grid;
  grid-template-rows: auto 1fr;
  gap: 0.5rem;
  height: 100%;
  padding: 0.75rem;
}

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tool {
  border: 1px solid #d0d7de;
  background: #ffffff;
  color: #24292f;
  border-radius: 0.5rem;
  padding: 0.5rem 0.75rem;
  cursor: pointer;
}

.tool.active {
  border-color: #0969da;
  box-shadow: 0 0 0 2px #dbeafe;
}

.tool.clear {
  margin-left: auto;
}

#whiteboard {
  width: 100%;
  height: 100%;
  background: #ffffff;
  border: 1px solid #d0d7de;
  border-radius: 0.5rem;
  touch-action: none;
  cursor: crosshair;
}