In an article on MSDN, How to: Create a Master Page Preview File in SharePoint 2013 the instructions, “Create a master page preview file” include
- Make a copy of a master page preview. SharePoint 2013 includes oslo.preview and seattle.preview
The preferred method of working with these pages is with SharePoint Designer 2013. As a preliminary step, be sure to activate the SharePoint Server Publishing features both at the Site Collection and Site levels. The SharePoint Server Publishing Feature is activated with a click on “Site Setting” (located in the drop down menu accessed with a click of the mouse on the gear symbol on the upper right of a site page), and, then, a click on “Manage site features” in the “Site Actions” menu.
Once the publishing feature is correctly activated, “Master Page” will also be added to the “Look and Feel” section of the “Site Settings” screen. Once you’ve created a preview file for the master page you wish to use, and have added it to SharePoint Online, you will then have an option to use the “Master Page” screen to configure the page defaults for your site as either “seattle” or “oslo” master pages.
From SharePoint Designer, 2013, we clicked on “Master Pages” from the left hand Navigation for the Site Collection we selected.
We located “oslo.preview” and “seattle.preview” on the lower section of the Master Pages list. We easily copied the preview file we chose to work with (oslo.preview) and pasted it into a new file we could safely edit.
Once we opened the editable version of the preview file, we found the color palette setting following the “pre” tag just below the “head” section of the file. We located the font setting immediately below the color palette setting, set off from the rest of the file by a pair of [SECTION] tags, one above the font setting, and one immediately below. By replacing the color and font settings with custom files for your specific organization, you can rapidly create a new .preview file that meets your needs.
© Rehmani Consulting, Inc. & Ira Michael Blonder, 2013 All Rights Reserved