message: set backgournd color in PDFRenderer
diff: @@ -35,7 +35,8 @@ export class GraphicsPreview {
  filePath = this.joinFilePath(document, relPath)
  }
  if (/\.pdf$/i.exec(relPath)) {
  - const svg = await this.pdfRenderer.renderToSVG(filePath, { height: 250, width: 500 })
  + const svg0 = await this.pdfRenderer.renderToSVG(filePath, { height: 250, width: 500 })
  + const svg = this.setBackgroundColor(svg0)
  const dataUrl = svgToDataUrl(svg)
  const md = new vscode.MarkdownString(`![pdf](${dataUrl})`)
  return new vscode.Hover(md, range)
  @@ -49,6 +50,10 @@ export class GraphicsPreview {
  return undefined
  }
  + setBackgroundColor(svg: string): string {
  + return svg.replace(/(<\/svg:style>)/, 'svg { background-color: white };$1')
  + }
  +
  joinFilePath(document: vscode.TextDocument, relPath: string) {
  const docPath = document.uri.fsPath
  const dirPath = path.dirname(docPath)
  