Set Custom CSS inline property in OAF

• Import the below library 
• import oracle.cabo.style.CSSStyle;
• Create new CSS Style
• CSSStyle noteStyle = new CSSStyle();
• Add the Style property
• noteStyle.setProperty("font-size","15px");
• Assign the style to message Style Text Field
• noteMsgBean.setInlineStyle(noteStyle);

Complete Code:

OAMessageStyledTextBean noteMsgBean = (OAMessageStyledTextBean)webBean.findChildRecursive("NotesRN");

    CSSStyle noteStyle = new CSSStyle();

    noteStyle.setProperty("font-size","15px");

noteMsgBean.setValue(pageContext,validNoteMsg);

noteMsgBean.setInlineStyle(noteStyle);