क्यों कुछ सीएसएस समारोह में काम नहीं मेरे WPF WebBrowser तत्व?

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<table cellSpacing="0"  cellPadding="0" width="100%" class="lb_table"><tr><td colspan="2" class="lb_table_subtitle">Technische Spezifikationen</td></tr><tr><td>Prozessor</td><td>Intel Xeon</td></tr><tr><td>Prozessortyp</td><td>Xeon MP</td></tr><tr><td>Anzahl der CPUs</td><td>2</td></tr><tr><td>Anzahl der CPU-Steckplätze</td><td>4</td></tr><tr><td>Prozessortakt (MHz)</td><td>1900</td></tr><tr><td>Prozessor Cache (kb)</td><td>1024</td></tr><tr><td>Front Side Bus - FSB (MHz)</td><td>400</td></tr><tr><td>Arbeitsspeicher (GB)</td><td>1</td></tr><tr><td>Festplattentyp</td><td>SCSI</td></tr><tr><td>Grafikkarte onboard</td><td>ja</td></tr><tr><td>Sound</td><td>nein</td></tr><tr><td>Anzahl der Netzteile</td><td>2</td></tr><tr><td>Bauart</td><td>Rack</td></tr><tr><td colspan="2" class="lb_table_subtitle">Festplatten - weitere HDDs oder einzelne Rahmen auf Anfrage</td></tr><tr><td>36 GB SCSI</td><td>1</td></tr><tr><td>Gesamtkapazität (GB)</td><td>36</td></tr><tr><td>max. Festplatten</td><td>3</td></tr><tr><td colspan="2" class="lb_table_subtitle">Weitere Laufwerke</td></tr><tr><td>CD-ROM</td><td>ja</td></tr><tr><td>Diskettenlaufwerk</td><td>ja</td></tr><tr><td colspan="2" class="lb_table_subtitle">PCI-Devices onboard</td></tr><tr><td>Device_1</td><td>Ethernet Pro 100</td></tr><tr><td>Device_2</td><td>SCSI-Controller U160</td></tr><tr><td colspan="2" class="lb_table_subtitle">Erweiterungssteckplätze</td></tr><tr><td>PCI 64-bit 33MHz</td><td>1</td></tr><tr><td>PCI 64-bit 66MHz</td><td>4</td></tr><tr><td>PCI-X 133MHz</td><td>1</td></tr><tr><td colspan="2" class="lb_table_subtitle">Anschlüsse</td></tr><tr><td>VGA</td><td>1</td></tr><tr><td>Ethernet RJ45</td><td>1</td></tr><tr><td>PS/2</td><td>2</td></tr><tr><td>Serial Port</td><td>1</td></tr><tr><td>USB</td><td>3</td></tr></table>