-is-highlighted";
          }
        } else {
          // When the label is not floating, it should overlap the input element.
          if (label) {
            this.$.labelAndInputContainer.style.position = 'relative';
          }
        }
      } else {
        if (_inputHasContent) {
          cls += ' label-is-hidden';
        }
      }
      return cls;
    },

    _computeUnderlineClass: function(focused, invalid) {
      var cls = 'underline';
      if (invalid) {
        cls += ' is-invalid';
  