Found the following HTML validation problems:
math_to_rd.html:81:2153: Warning: <svg> attribute "width" has invalid value "400em"
math_to_rd.html:81:2153: Warning: <svg> attribute "height" has invalid value "1.08em"
math_to_rd.html:81:795: Warning: trimming empty <span>
math_to_rd.html:81:1030: Warning: trimming empty <span>
math_to_rd.html:81:1116: Warning: trimming empty <span>
math_to_rd.html:81:1201: Warning: trimming empty <span>
math_to_rd.html:81:1314: Warning: trimming empty <span>
math_to_rd.html:81:1502: Warning: trimming empty <span>
math_to_rd.html:81:1803: Warning: trimming empty <span>
math_to_rd.html:81:2040: Warning: trimming empty <span>
math_to_rd.html:92:161: Warning: trimming empty <span>
math_to_rd.html:92:116: Warning: trimming empty <span>
math_to_rd.html:92:94: Warning: trimming empty <span>
math_to_rd.html:92:243: Warning: trimming empty <span>
math_to_rd.html:92:291: Warning: trimming empty <span>
math_to_rd.html:92:216: Warning: trimming empty <span>
math_to_rd.html:92:393: Warning: trimming empty <span>
math_to_rd.html:92:610: Warning: trimming empty <span>
math_to_rd.html:92:567: Warning: trimming empty <span>
math_to_rd.html:92:545: Warning: trimming empty <span>
math_to_rd.html:92:651: Warning: trimming empty <span>
math_to_rd.html:92:923: Warning: trimming empty <span>
math_to_rd.html:92:1129: Warning: trimming empty <span>
math_to_rd.html:92:1341: Warning: trimming empty <span>
math_to_rd.html:92:1545: Warning: trimming empty <span>
math_to_rd.html:92:1593: Warning: trimming empty <span>
math_to_rd.html:92:1516: Warning: trimming empty <span>
math_to_rd.html:92:1703: Warning: trimming empty <span>
math_to_rd.html:92:1988: Warning: trimming empty <span>
math_to_rd.html:92:1944: Warning: trimming empty <span>
math_to_rd.html:92:1922: Warning: trimming empty <span>
math_to_rd.html:92:2029: Warning: trimming empty <span>
math_to_rd.html:92:2171: Warning: trimming empty <span>
math_to_rd.html:92:2382: Warning: trimming empty <span>
math_to_rd.html:92:2629: Warning: trimming empty <span>
math_to_rd.html:92:2677: Warning: trimming empty <span>
math_to_rd.html:92:2600: Warning: trimming empty <span>
math_to_rd.html:92:2788: Warning: trimming empty <span>
math_to_rd.html:92:3163: Warning: trimming empty <span>
math_to_rd.html:92:3119: Warning: trimming empty <span>
math_to_rd.html:92:3097: Warning: trimming empty <span>
math_to_rd.html:92:3204: Warning: trimming empty <span>
math_to_rd.html:92:3503: Warning: trimming empty <span>
math_to_rd.html:102:377: Warning: trimming empty <span>
math_to_rd.html:102:499: Warning: trimming empty <span>
math_to_rd.html:102:585: Warning: trimming empty <span>
math_to_rd.html:102:670: Warning: trimming empty <span>
math_to_rd.html:102:1040: Warning: trimming empty <span>