此时SVG线不在此坐标（x1="200" x2="0" y1="200" y2="200"）处绘制线条。此问题仅在Firefox中发生。我犯了什么错误？
<svg xmlns="http://www.w3.org/2000/svg" version="1.1">
<line x1="0" x2="200" y1="0" y2="0" style="stroke:rgb(255,0,0);stroke-width:2"></line>
<line x1="200" x2="200" y1="0" y2="200" style="stroke:rgb(255,0,0);stroke-width:2"></line>
<line x1="0" x2="0" y1="0" y2="200" style="stroke:rgb(255,0,0);stroke-width:2"></line>
<line x1="200" x2="0" y1="200" y2="200" style="stroke:rgb(255,0,0);stroke-width:2"></line>
</svg>