diff --git a/Public/css/highlight.css b/Public/css/highlight.css
index 0040fac..6ac380a 100644
--- a/Public/css/highlight.css
+++ b/Public/css/highlight.css
@@ -84,13 +84,23 @@
 .exp-special {
   color: #c0c;
 }
-span.match {
+
+span.match-char {
   background: rgba(112, 176, 224, 0.5);
   color: #101112;
   border-right: solid 1px #ffffff;
   border-left: solid 1px #ffffff;
   margin-right: -2px;
 }
+span.match-left {
+  border-left: solid 2px rgba(255, 0, 0, 0.2);
+  margin-left: -2px;
+}
+span.match-right {
+  border-right: solid 2px rgba(255, 0, 0, 0.2);
+  margin-right: -2px;
+}
+
 span.error {
   color: #d22;
   font-weight: 700;
diff --git a/Public/js/views/test_highlighter.js b/Public/js/views/test_highlighter.js
index 4617d4f..c332b04 100644
--- a/Public/js/views/test_highlighter.js
+++ b/Public/js/views/test_highlighter.js
@@ -7,8 +7,12 @@ import Utils from "../misc/utils";
 export default class TestHighlighter extends EventDispatcher {
   constructor(editor) {
     super();
+
     this.editor = editor;
     this.activeMarks = [];
+    this.widgets = [];
+
+    this.textHeight = editor.defaultTextHeight();
   }
 
   draw(tokens) {
@@ -20,13 +24,6 @@ export default class TestHighlighter extends EventDispatcher {
       const marks = this.activeMarks;
 
       for (const token of tokens) {
-        const className = "match";
-        const location = Editor.calcRangePos(
-          this.editor,
-          token.location.start,
-          token.location.end - token.location.start
-        );
-
         const match = Utils.htmlSafe(token.value);
         let tooltip = `<div class="text-start font-monospace">
         <div><span class="fw-bolder">match:</span> ${match}</div>
@@ -38,22 +35,101 @@ export default class TestHighlighter extends EventDispatcher {
           for (const [i, capture] of token.captures.entries()) {
             const value = Utils.htmlSafe(capture.value || "");
             tooltip += `<div class="text-start font-monospace">
-            <div><span class="fw-bolder">group #${i + 1}:</span> ${value}</div>
+            <div><span class="fw-bolder">group #${i + 1}:</span> ${
+              value === "" ? "empty string" : value
+            }</div>
             </div>`;
           }
         }
-        marks.push(
-          doc.markText(location.startPos, location.endPos, {
-            className: className,
-            attributes: {
-              "data-tippy-content": tooltip,
-            },
-          })
-        );
+
+        if (token.location.start < token.location.end) {
+          const location = Editor.calcRangePos(
+            editor,
+            token.location.start,
+            token.location.end - token.location.start
+          );
+          marks.push(
+            doc.markText(location.startPos, location.endPos, {
+              className: "match-char",
+              attributes: {
+                "data-tippy-content": tooltip,
+              },
+            })
+          );
+        } else {
+          const location = Editor.calcRangePos(editor, token.location.start, 1);
+
+          if (
+            location.startPos.line === location.endPos.line &&
+            location.startPos.ch === location.endPos.ch
+          ) {
+            this.addLeftAnchor(location, { "data-tippy-content": tooltip });
+          }
+          if (location.startPos.line === location.endPos.line) {
+            if (location.startPos.ch < location.endPos.ch) {
+              marks.push(
+                doc.markText(location.startPos, location.endPos, {
+                  className: "match-left",
+                  attributes: {
+                    "data-tippy-content": tooltip,
+                  },
+                })
+              );
+            } else {
+              // this.addRightAnchor(location, { "data-tippy-content": tooltip });
+            }
+          } else {
+            if (location.startPos.ch === 0 && location.endPos.ch === 0) {
+              this.addLeftAnchor(location, { "data-tippy-content": tooltip });
+            } else {
+              this.addRightAnchor(location, { "data-tippy-content": tooltip });
+            }
+          }
+        }
       }
     });
   }
 
+  addLeftAnchor(location, attributes = {}) {
+    const widget = document.createElement("span");
+    widget.className = "match-left";
+    widget.style.height = `${this.textHeight * 1.5}px`;
+    widget.style.width = "1px";
+    widget.style.zIndex = "10";
+
+    for (const [key, value] of Object.entries(attributes)) {
+      widget.setAttribute(key, value);
+    }
+
+    this.editor.addWidget(location.startPos, widget);
+
+    const coords = this.editor.charCoords(location.startPos, "local");
+    widget.style.left = `${coords.left}px`;
+    widget.style.top = `${coords.top + 2}px`;
+
+    this.widgets.push(widget);
+  }
+
+  addRightAnchor(location, attributes = {}) {
+    const widget = document.createElement("span");
+    widget.className = "match-right";
+    widget.style.height = `${this.textHeight * 1.5}px`;
+    widget.style.width = "1px";
+    widget.style.zIndex = "10";
+
+    for (const [key, value] of Object.entries(attributes)) {
+      widget.setAttribute(key, value);
+    }
+
+    this.editor.addWidget(location.endPos, widget);
+
+    const coords = this.editor.charCoords(location.startPos, "local");
+    widget.style.left = `${coords.left}px`;
+    widget.style.top = `${coords.top + 2}px`;
+
+    this.widgets.push(widget);
+  }
+
   clear() {
     this.editor.operation(() => {
       let marks = this.activeMarks;
@@ -61,6 +137,11 @@ export default class TestHighlighter extends EventDispatcher {
         marks[i].clear();
       }
       marks.length = 0;
+
+      for (const widget of this.widgets) {
+        widget.parentNode.removeChild(widget);
+      }
+      this.widgets.length = 0;
     });
   }
 }