Rouge seems to be more actively developed, and most importantly its CSS class names are compatible with Pygments, which means there are more up-to-date themes available for it.
I found a good source (a gist) for Solarized themes that included the Pygments variables, and I built them as SCSS using variables. In order to support dark theme when enabled by the user's (browser) preferences, the dark theme has to override the light theme's directives.
Rouge seems to be more actively developed, and most importantly its CSS class names are compatible with Pygments, which means there are more up-to-date themes available for it.
I found a good source (a gist) for Solarized themes that included the Pygments variables, and I built them as SCSS using variables. In order to support dark theme when enabled by the user's (browser) preferences, the dark theme has to override the light theme's directives.