docs: update design + colors (#7593)

Update design and colors in docs to match those in Figma

www/packages/docs-ui/src/components/Modal/Header/index.tsx

@@ -20,7 +20,7 @@ export const ModalHeader = ({ title }: ModalHeaderProps) => {
     >
       <span className={clsx("text-medusa-fg-base text-h2")}>{title}</span>
       <Button
-        variant="clear"
+        variant="transparent"
         className="cursor-pointer"
         onClick={() => closeModal()}
       >

www/packages/docs-ui/src/components/Modal/index.tsx

@@ -101,7 +101,7 @@ export const Modal = ({
         className={clsx(
           "bg-medusa-bg-base rounded-docs_sm",
           "border-medusa-border-base border border-solid",
-          "shadow-modal dark:shadow-modal-dark",
+          "shadow-elevation-modal dark:shadow-elevation-modal-dark",
           "w-[90%] md:h-auto md:w-[75%] lg:w-[560px]",
           modalContainerClassName
         )}