asp.net core使用中间件美化开发环境异常页面

/// <summary>
/// 开发环境异常页面css美化 中间件
/// </summary>
public class DeveloperExceptionPrettifyMiddleware
{
    private readonly RequestDelegate _next;
    public DeveloperExceptionPrettifyMiddleware(
        RequestDelegate next)
    {
        _next = next;
    }
    public async Task Invoke(HttpContext context)
    {
        await _next.Invoke(context);

        using (TextWriter output = (TextWriter)new StreamWriter(context.Response.Body,
            new UTF8Encoding(false, true), 4096, true))
        {
            // 美化版 css/js
            var chars = @"
            <style>
                body{ color: inherit}
                h1{color:red}
                h3{color:inherit}
                .titleerror{color:maroon}
                body .location{ }
                #header li{color:blue}
                #header .selected{background:#44525e}
                #stackpage .source ol li{background-color:#ffffcc}
                #stackpage .source ol.collapsible li span{color:#000}
                .rawExceptionStackTrace{background-color:#ffffcc; padding:.5rem}
                :focus{outline:none}
                .showRawException{color:blue}
            </style>
            <script>
                document.querySelector('.expandCollapseButton').click()
            </script>
            ".ToCharArray();

            // 输出到响应流中
            await output.WriteAsync(chars, 0, chars.Length);
            await output.FlushAsync();
        }
    }
}