背景图片不变形的css写法

<pre style="background-color:#262e37;color:#ffffff;font-family:&#39;Consolas&#39;,monospace;font-size:11.3pt;"><span style="color:#66d9ef;font-style:italic;">background</span>: <span style="color:#a6e22e;">#ffffff</span>; <br/><span style="color:#66d9ef;font-style:italic;">background-size</span>: <span style="color:#68e868;font-weight:bold;">cover</span>; <br/><span style="color:#66d9ef;font-style:italic;">background-attachment</span>: <span style="color:#68e868;font-weight:bold;">fixed</span>;<br/><span style="color:#66d9ef;font-style:italic;">background-image</span>: <span style="color:#66d9ef;">url</span>(<span style="color:#e6db74;">&quot;../img/loginbg.jpg&quot;</span>);<br/><span style="color:#66d9ef;font-style:italic;">background-repeat</span>: <span style="color:#68e868;font-weight:bold;">no-repeat</span>; <br/><span style="color:#66d9ef;font-style:italic;">background-position</span>: <span style="color:#68e868;font-weight:bold;">center center</span>;</pre><p><br/></p>