Why do some of my thumbnails not fit into their...

Continuum automatically resizes and crops your images into several different sizes so that there will be an appropriately sized image to fit all of the various thumbnail areas. After installing Continuum, any image you upload will be appropriately sized into all the various sizes. However, if you are installing Continuum onto an existing WordPress installation with images previously uploaded, the correct sizes for your images will not exist to suit Continuum. Not to worry, there is a plugin that you can install that will fix all of your previously uploaded images. Install the AJAX Thumbnail Rebuild plugin, located here: http://wordpress.org/extend/plugins/ajax-thumbnail-rebuild/. Once you install it, run the plugin and it will automatically resize all of your images. If you have a large amount of images, just let it run until it’s finished as it may take some time to complete.