message: using png image for logo
diff: @@ -109,7 +109,7 @@ const IotexLogo = () => (
  <Link to="/">
  <img
  alt="iotex-logo"
  - src={assetURL("/logo_explorer.svg")}
  + src={assetURL("/logo_explorer.png")}
  style={{
  height: 38,
  width: "auto"
  