code: function normalizeGradientExpressionForQuickview(expression) {
              if (expression.indexOf("px") > 0) {
                  var paramStart = expression.indexOf("(") + 1,
                      paramEnd = expression.lastIndexOf(")"),
                      parameters = expression.substring(paramStart, paramEnd),
                      params = splitStyleProperty(parameters),
                      lowerBound = 0,
                      upperBound = $previewContainer.width(),
                      args,
                      thisSize,
                      i;
  
                  // find lower bound
                  for (i = 0; i < params.length; i++) {
                      args = params[i].split(" ");
  
                      if (hasLengthInPixels(args)) {
                          thisSize = parseFloat(args[1]);
  
                          upperBound = Math.max(upperBound, thisSize);
                          // we really only care about converting negative
                          //  pixel values -- so take the smallest negative pixel
                          //  value and use that as baseline for display purposes
                          if (thisSize < 0) {
                              lowerBound = Math.min(lowerBound, thisSize);
                          }
                      }
                  }
  
                  // convert negative lower bound to positive and adjust all pixel values
                  //  so that -20px is now 0px and 100px is now 120px
                  lowerBound = Math.abs(lowerBound);
  
                  // Offset the upperbound by the lowerBound to give us a corrected context
                  upperBound += lowerBound;
  
                  // convert to %
                  for (i = 0; i < params.length; i++) {
                      args = params[i].split(" ");
                      if (isGradientColorStop(args) && hasLengthInPixels(args)) {
                          if (upperBound === 0) {
                              thisSize = 0;
                          } else {
                              thisSize = ((parseFloat(args[1]) + lowerBound) / upperBound) * 100;
                          }
                          args[1] = thisSize + "%";
                      }
                      params[i] = args.join(" ");
                  }
  
                  // put it back together.
                  expression = expression.substring(0, paramStart) + params.join(", ") + expression.substring(paramEnd);
              }
              return expression;
          }
docs: Normalizes px color stops to %