feat: highlight reply if visible, render it as floating preview if not visible

src/components/post/post-desktop/post-desktop.tsx

@@ -287,7 +287,7 @@ const PostDesktop = ({ openReplyModal, post, roles, showAllReplies, showReplies
               <div key={index} className={styles.replyContainer} ref={(el) => (replyRefs.current[index] = el)}>
                 <div className={styles.replyDesktop}>
                   <div className={styles.sideArrows}>{'>>'}</div>
-                  <div className={`${styles.reply} ${isRouteLinkToReply && styles.highlight}`}>
+                  <div className={`${styles.reply} ${isRouteLinkToReply && styles.highlight}`} id={reply?.cid}>
                     <PostInfo openReplyModal={openReplyModal} post={reply} roles={roles} />
                     {reply.link && isValidURL(reply.link) && <PostMedia post={reply} />}
                     {reply.content && <PostMessage post={reply} />}

src/components/post/post-mobile/post-mobile.tsx

@@ -232,7 +232,7 @@ const PostMobile = ({ openReplyModal, post, roles, showAllReplies, showReplies =
               <div key={index} className={styles.replyContainer} ref={(el) => (replyRefs.current[index] = el)}>
                 <div className={styles.replyMobile}>
                   <div className={styles.reply}>
-                    <div className={`${styles.replyContainer} ${isRouteLinkToReply && styles.highlight}`}>
+                    <div className={`${styles.replyContainer} ${isRouteLinkToReply && styles.highlight}`} id={reply?.cid}>
                       <PostInfoAndMedia openReplyModal={openReplyModal} post={reply} roles={roles} />
                       {reply.content && <PostMessageMobile post={reply} />}
                       <ReplyBacklinks post={reply} />

src/components/post/reply-quote-preview/reply-quote-preview.tsx

@@ -15,8 +15,32 @@ interface ReplyQuotePreviewProps {
   quotelinkReply?: Comment;
 }
 
+const handleQuoteHover = (cid: string, onElementOutOfView: () => void) => {
+  const targetElement = document.getElementById(cid);
+
+  if (!targetElement) return;
+
+  const isInViewport = (element: HTMLElement) => {
+    const bounding = element.getBoundingClientRect();
+    return (
+      bounding.top >= 0 &&
+      bounding.left >= 0 &&
+      bounding.bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
+      bounding.right <= (window.innerWidth || document.documentElement.clientWidth)
+    );
+  };
+
+  if (isInViewport(targetElement)) {
+    targetElement.classList.add('highlight');
+  } else {
+    targetElement.classList.remove('highlight');
+    onElementOutOfView();
+  }
+};
+
 const DesktopQuotePreview = ({ backlinkReply, quotelinkReply, isBacklinkReply, isQuotelinkReply }: ReplyQuotePreviewProps) => {
   const [hoveredCid, setHoveredCid] = useState<string | null>(null);
+  const [outOfViewCid, setOutOfViewCid] = useState<string | null>(null);
   const placementRef = useRef<Placement>('right');
   const availableWidthRef = useRef<number>(0);
 
@@ -56,18 +80,37 @@ const DesktopQuotePreview = ({ backlinkReply, quotelinkReply, isBacklinkReply, i
     };
   }, [update]);
 
+  const handleMouseOver = (cid: string | undefined) => {
+    if (!cid) return;
+
+    handleQuoteHover(cid, () => setOutOfViewCid(cid));
+    setHoveredCid(cid);
+  };
+
+  const handleMouseLeave = (cid: string | null) => {
+    if (cid) {
+      const targetElement = document.getElementById(cid);
+      if (targetElement) {
+        targetElement.classList.remove('highlight');
+      }
+    }
+    setHoveredCid(null);
+    setOutOfViewCid(null);
+  };
+
   const replyBacklink = (
     <>
       <Link
         className={styles.backlink}
         to={`/p/${backlinkReply?.subplebbitAddress}/c/${backlinkReply?.cid}`}
         ref={refs.setReference}
-        onMouseOver={() => setHoveredCid(backlinkReply?.cid)}
+        onMouseOver={() => handleMouseOver(backlinkReply?.cid)}
-        onMouseLeave={() => setHoveredCid(null)}
+        onMouseLeave={() => handleMouseLeave(backlinkReply?.cid)}
       >
         c/{backlinkReply?.shortCid}
       </Link>
       {hoveredCid === backlinkReply?.cid &&
+        outOfViewCid === backlinkReply?.cid &&
         createPortal(
           <div className={styles.replyQuotePreview} ref={refs.setFloating} style={floatingStyles}>
             <Post post={backlinkReply} showReplies={false} />
@@ -83,13 +126,14 @@ const DesktopQuotePreview = ({ backlinkReply, quotelinkReply, isBacklinkReply, i
         to={`/p/${quotelinkReply?.subplebbitAddress}/c/${quotelinkReply?.cid}`}
         ref={refs.setReference}
         className={styles.quoteLink}
-        onMouseOver={() => setHoveredCid(quotelinkReply?.cid)}
+        onMouseOver={() => handleMouseOver(quotelinkReply?.cid)}
-        onMouseLeave={() => setHoveredCid(null)}
+        onMouseLeave={() => handleMouseLeave(quotelinkReply?.cid)}
       >
         {`c/${quotelinkReply?.cid && Plebbit.getShortCid(quotelinkReply.cid)}`}
       </Link>
       <br />
       {hoveredCid === quotelinkReply?.cid &&
+        outOfViewCid === quotelinkReply?.cid &&
         createPortal(
           <div className={styles.replyQuotePreview} ref={refs.setFloating} style={floatingStyles}>
             <Post post={quotelinkReply} showReplies={false} />
@@ -104,6 +148,7 @@ const DesktopQuotePreview = ({ backlinkReply, quotelinkReply, isBacklinkReply, i
 
 const MobileQuotePreview = ({ backlinkReply, quotelinkReply, isBacklinkReply, isQuotelinkReply }: ReplyQuotePreviewProps) => {
   const [hoveredCid, setHoveredCid] = useState<string | null>(null);
+  const [outOfViewCid, setOutOfViewCid] = useState<string | null>(null);
 
   const { refs, floatingStyles, update } = useFloating({
     placement: 'bottom',
@@ -118,15 +163,39 @@ const MobileQuotePreview = ({ backlinkReply, quotelinkReply, isBacklinkReply, is
     };
   }, [update]);
 
+  const handleMouseOver = (cid: string | undefined) => {
+    if (!cid) return;
+
+    handleQuoteHover(cid, () => setOutOfViewCid(cid));
+    setHoveredCid(cid);
+  };
+
+  const handleMouseLeave = (cid: string | null) => {
+    if (cid) {
+      const targetElement = document.getElementById(cid);
+      if (targetElement) {
+        targetElement.classList.remove('highlight');
+      }
+    }
+    setHoveredCid(null);
+    setOutOfViewCid(null);
+  };
+
   const replyBacklink = (
     <>
-      <span className={styles.backlink} ref={refs.setReference} onMouseOver={() => setHoveredCid(backlinkReply?.cid)} onMouseLeave={() => setHoveredCid(null)}>
+      <span
+        className={styles.backlink}
+        ref={refs.setReference}
+        onMouseOver={() => handleMouseOver(backlinkReply?.cid)}
+        onMouseLeave={() => handleMouseLeave(backlinkReply?.cid)}
+      >
         c/{backlinkReply?.shortCid}{' '}
       </span>
       <Link to={`/p/${backlinkReply?.subplebbitAddress}/c/${backlinkReply?.cid}`} className={styles.backlinkHash}>
         #
       </Link>
       {hoveredCid === backlinkReply?.cid &&
+        outOfViewCid === backlinkReply?.cid &&
         createPortal(
           <div className={styles.replyQuotePreview} ref={refs.setFloating} style={floatingStyles}>
             <Post post={backlinkReply} showReplies={false} />
@@ -138,7 +207,12 @@ const MobileQuotePreview = ({ backlinkReply, quotelinkReply, isBacklinkReply, is
 
   const replyQuotelink = (
     <>
-      <span ref={refs.setReference} className={styles.quoteLink} onMouseOver={() => setHoveredCid(quotelinkReply?.cid)} onMouseLeave={() => setHoveredCid(null)}>
+      <span
+        ref={refs.setReference}
+        className={styles.quoteLink}
+        onMouseOver={() => handleMouseOver(quotelinkReply?.cid)}
+        onMouseLeave={() => handleMouseLeave(quotelinkReply?.cid)}
+      >
         c/{quotelinkReply?.shortCid}{' '}
       </span>
       <Link className={styles.quoteLink} to={`/p/${quotelinkReply?.subplebbitAddress}/c/${quotelinkReply?.cid}`}>
@@ -146,6 +220,7 @@ const MobileQuotePreview = ({ backlinkReply, quotelinkReply, isBacklinkReply, is
       </Link>
       <br />
       {hoveredCid === quotelinkReply?.cid &&
+        outOfViewCid === quotelinkReply?.cid &&
         createPortal(
           <div className={styles.replyQuotePreview} ref={refs.setFloating} style={floatingStyles}>
             <Post post={quotelinkReply} showReplies={false} />

src/index.css

@@ -26,6 +26,10 @@ hr {
   color: var(--post-greentext-color);
 }
 
+.highlight {
+  background: var(--reply-highlight-background-color) !important;
+}
+
 @media (max-width: 640px) {
   .button {
     font-size: var(--button-font-size-mobile);