I am using the ComboBox component in IE11.  When the control has a value, the clear button covers the select arrow at the right of the control.  This occurs because IE11 does not allow nested calc() calls in the CSS width property, e.g. 

.k-dropdown-wrap .k-clear-value {
    right: calc(calc( 0.75rem + 17px) + 6.5px);
}

Removing the inner calc() works well enough:

.k-dropdown-wrap .k-clear-value {
    right: calc(( 0.75rem + 17px) + 6.5px);
}

Unfortunately, this rule seems to originate from a CSS function call to which I do not have access.  Is it possible to remove the inner calc()?