<svg viewBox="0 0 300 300" width="300" height="300">
  <line x1="0" y1="0" x2="300" y2="300" stroke="red" stroke-width="3" stroke-dasharray="10,4"/>
  <rect x="50" y="50" width="150" height="50" stroke-width="5" stroke="green" fill="yellow" rx="10" ry="10"/>
</svg>

body {
  background: #ccc;
}

svg {
  background: #fff;
}