The MathML 1.01 style attributes: fontfamily, fontweight, fontstyle, fontsize, color and background are deprecated in MathML 2 and 3. As a general rule, whenever there is a conflict between these deprecated attributes and the corresponding attributes, the former attributes should be ignored. MathML Fundamentals
<math> <mspace linebreak="newline" indentalign="center"></mspace> <mtext style="border:1px;" mathsize="big">Deprecated style attributes on token elements</mtext> <mspace linebreak="newline" indentalign="center"></mspace> <mrow style="border:1px;" > <mtext fontfamily="monospace">ABCDEFGHIJKLMNOPQRSTUVXYZWabcdefghijklmnopqrstuvxyzw0123456789</mtext> </mrow> <mspace linebreak="newline" indentalign="center"></mspace> <mrow style="border:1px;" > <mtext fontweight="bold">ABCDEFGHIJKLMNOPQRSTUVXYZWabcdefghijklmnopqrstuvxyzw0123456789</mtext> </mrow> <mspace linebreak="newline" indentalign="center"></mspace> <mrow style="border:1px;" > <mtext fontstyle="italic">ABCDEFGHIJKLMNOPQRSTUVXYZWabcdefghijklmnopqrstuvxyzw0123456789</mtext> </mrow> <mspace linebreak="newline" indentalign="center"></mspace> <mrow style="border:1px;" > <mtext fontsize="25">ABCDEFGHIJKLMNOPQRSTUVXYZWabcdefghijklmnopqrstuvxyzw0123456789</mtext> </mrow> <mspace linebreak="newline" indentalign="center"></mspace> <mrow style="border:1px;" > <mtext color="blue">ABCDEFGHIJKLMNOPQRSTUVXYZWabcdefghijklmnopqrstuvxyzw0123456789</mtext> </mrow> <mspace linebreak="newline" indentalign="center"></mspace> <mrow style="border:1px;" > <mtext background="red">ABCDEFGHIJKLMNOPQRSTUVXYZWabcdefghijklmnopqrstuvxyzw0123456789</mtext> </mrow> </math>