Hello Sophie,
Have you done any custom development for skins?
Please can you check the following:
1. Repository for Skins has relevant .css file. See if there were any modifications done in the thtmlb styles directory. Also check the IE compatible .css files are present for skin 'nova'
2. SICF services for the skin directory paths are active -
/default_host/sap/bc/kw/mime
/SAP/BC/BSP/SAP/thtmlb_styles/sap_skins/nova/
2. SAP note - 2119656 - Readonly textArea uses wrong background color in NOVA skin
2027455 Corbu & Nova: F4 Spinning Wheel should display no borde
I hope above helps.
Thanks.