Fix overflow blocking tooltip

Issue [#153](https://github.com/hummingbird-me/hummingbird/issues/153)

>The `overflow: hidden` property on `.series-content` causes the alternate title tooltip to clip when the canonical title is nearly as wide as the series content box.

>Examples:
>1 http://hummingbird.me/anime/otome-wa-boku-ni-koishiteru-futari-no-elder
>2 http://hummingbird.me/anime/ginga-eiyuu-densetsu-gaiden-rasen-meikyuu

>Reference: http://forums.hummingbird.me/t/alternate-title-overlapped/11827