Missing focus styles and button labels for podcast controls

[bryophyta]

Two related issues raised by DAC:

• Issue ID: DAC_Missing_Focus_Indicator11: https://drive.google.com/file/d/1CqPAicuAJagXiFWSpwwAcwBjEx7Oepl8/view

• Issue ID: DAC_Unlabelled_Form_Element1: https://drive.google.com/file/d/1qo4MWsCD0KQ1e8n3ZTuGFaOCYPaLDcR5/view

To summarise: There are no focus styles or text labels on the controls for the podcast player (e.g. on this page https://www.theguardian.com/politics/audio/2018/mar/14/are-the-eus-draft-trade-guidelines-reasonable-brexit-means-podcast#maincontent) which means it is very difficult to use the player with a keyboard or screenreader.