primefaces panelgrid column width not consistent if there is checkbox or radiobox

I have below code that show the problem. If I have two panelGrid. One is text. another is checkbox and text. Then the column width not in consistent if I have set the same column width. Do you know why? how to solve if I want to be consistent in width.

<p:panelGrid columns="1" style="border: 1px solid #8c4eea;">
        <p:panelGrid styleClass="ui-edb-noneborder-grid">
            <p:row>
                <p:column style="width:300px;"><p:outputLabel id="lblStatus1s4" value="#{upd_quali.status}" style="#{upd_quali.getFontStyle()}"/></p:column>
                <p:column style="background-color:silver; width:300px;"><p:outputLabel  id="lblStatusO1s4" value="Original data"/></p:column>
                <p:column colspan="2"><p:outputLabel id="lblStatusU1s4" value="Updated data"/></p:column>
            </p:row>
            <p:row>
                <p:column style="width:300px"><p:outputLabel id="lblQualification1s4" value="Qualification Held:"/></p:column>
                <p:column style="background-color:silver; width:300px;"><p:outputLabel id="lblQualificationO1s4" value="#{org_quali.qualiHeld}"/></p:column>
                <p:column style="width:30px"><p:selectBooleanCheckbox id="chk1"></p:selectBooleanCheckbox></p:column>
                <p:column style="width:300px"><p:outputLabel id="lblQualificationU1s4"  value="#{upd_quali.qualiHeld}" style="#{getCellFont(flag_quali.qualiHeld)}"/></p:column>
            </p:row>

        </p:panelGrid>
        </p:panelGrid>
<br/>
<p:panelGrid columns="1" style="border: 1px solid #8c4eea;">
        <p:panelGrid id="panelGrid1s4a7" styleClass="ui-edb-noneborder-grid">
            <p:row><p:column rowspan="3" style="vertical-align:top;width:300px;"><p:outputLabel id="lblStatus1s4a3" value="Updated" /></p:column>
            <p:column style="background-color:silver;width:300px;"><p:outputLabel id="lblStatusO1s4a3" value="Original data" /></p:column>
            <p:column style="width:300px;"><p:outputLabel id="lblStatusU1s4a3" value="Updated data" /></p:column>
            </p:row>
            <p:row>
            <p:column style="background-color:silver; white-space:pre-line; width:300px;"><p:selectBooleanCheckbox id="chkChineseOriginalQualify" value="#{org_quali_Chinese}"></p:selectBooleanCheckbox><p:outputLabel value="Acquired relevant degree qualification for Chinese language teachers" /></p:column>
            <p:column style="white-space:pre-line; width:300px;"><p:selectBooleanCheckbox id="chkChineseUpdateQualify" value="#{upd_quali_Chinese}"></p:selectBooleanCheckbox><p:outputLabel value="Acquired relevant degree qualification for Chinese language teachers" style="#{getCellFont(flag_quali_Chinese)}"/></p:column>
            </p:row>

        </p:panelGrid>
        </p:panelGrid>