Font Weight Changes Randomly

Hi there, I have built a theme that uses Museo Sans with H1 headlines set in a bold 700 weight. This shows up fine in editing and preview mode, but after opening the published file link in incognito mode the font drops down to a lighter weight. How can I ensure my headlines will look the same across all screens? I am working on a Chrome browser across the board. Please let me know if you need any more info.