diff --git a/README.md b/README.md
index 1bccbca56..6d2731d02 100644
--- a/README.md
+++ b/README.md
@@ -59,16 +59,16 @@ to build.
    web server.
 
 Note that `npm run dist` is not supported on Windows, so Windows users can run `npm
-run build`, which will build all the necessary files into the `vector`
-directory. The version of Vector will not appear in Settings without
-using the dist script. You can then mount the vector directory on your
+run build`, which will build all the necessary files into the `webapp`
+directory. The version of Riot will not appear in Settings without
+using the dist script. You can then mount the `webapp` directory on your
 webserver to actually serve up the app, which is entirely static content.
 
 config.json
 ===========
 
-You can configure the app by copying `vector/config.sample.json` to
-`vector/config.json` and customising it:
+You can configure the app by copying `config.sample.json` to
+`config.json` and customising it:
 
 1. `default_hs_url` is the default home server url.
 1. `default_is_url` is the default identity server url (this is the server used
@@ -110,6 +110,11 @@ You can configure the app by copying `vector/config.sample.json` to
 1. `update_base_url` (electron app only): HTTPS URL to a web server to download
    updates from. This should be the path to the directory containing `install`
    and `update`.
+1. `cross_origin_renderer_url`: URL to a static HTML page hosting code to help display
+   encrypted file attachments. This MUST be hosted on a completely separate domain to
+   anything else since it is used to isolate the privileges of file attachments to this
+   domain. Default: `usercontent.riot.im`. This needs to contain v1.html from
+   https://github.com/matrix-org/usercontent/blob/master/v1.html
 
 Running as a Desktop app
 ========================
diff --git a/src/skins/vector/css/matrix-react-sdk/views/messages/MImageBody.css b/src/skins/vector/css/matrix-react-sdk/views/messages/MImageBody.css
index 1134f2f6f..003ef1030 100644
--- a/src/skins/vector/css/matrix-react-sdk/views/messages/MImageBody.css
+++ b/src/skins/vector/css/matrix-react-sdk/views/messages/MImageBody.css
@@ -44,3 +44,17 @@ limitations under the License.
     vertical-align: middle;
     pointer-events: none;
 }
+
+/* Remove the border and padding for iframes for download links. */
+.mx_MImageBody_download iframe {
+    margin: 0px;
+    padding: 0px;
+    border: none;
+    width: 100%;
+    /* Set the height of the iframe to be 1 line of text.
+     * Iframes don't automatically size themselves to fit their content.
+     * So either we have to fix the height of the iframe using CSS or
+     * use javascript's cross-origin postMessage API to communicate how
+     * big the content of the iframe is. */
+    height: 1.5em;
+}