diff --git a/js/highlighter.js b/js/highlighter.js
index 79dd640..d0e382c 100644
--- a/js/highlighter.js
+++ b/js/highlighter.js
@@ -62,10 +62,13 @@ export class Highlighter {
     const parent = ta.parentElement;
     const cs = getComputedStyle(ta);
     this._origColor = cs.color;
+    const origBg = cs.backgroundColor;
 
     const bd = document.createElement("div");
     bd.className = "pte-hl-backdrop";
     const s = bd.style;
+    // 背景はバックドロップ側に持たせる(textareaを透明化すると黒背景が消えるため)
+    s.background = origBg && origBg !== "rgba(0, 0, 0, 0)" ? origBg : "var(--comfy-input-bg, #222)";
     s.position = "absolute";
     s.margin = "0";
     s.borderWidth = cs.borderWidth;
diff --git a/js/tag_editor.js b/js/tag_editor.js
index a5f7fd8..128fd2f 100644
--- a/js/tag_editor.js
+++ b/js/tag_editor.js
@@ -24,18 +24,22 @@ export class TagEditor {
     this.tokens = [];
     this.editing = false;       // inline編集中(逆同期抑制用)
     this._dragIndex = -1;
+    this._trailingSep = "";      // 末尾のカンマ(+空白)を保持
     this.container.classList.add("pte-chips");
   }
 
   // 外部の文字列からチップを再構築(逆同期時)
   setFromString(str) {
     if (this.editing) return; // 編集中は再構築しない
+    // 末尾のカンマ(全角/半角+空白)を記憶し、チップ操作後も維持する
+    const m = (str || "").match(/[,，][ \t]*$/);
+    this._trailingSep = m ? m[0] : "";
     this.tokens = tokenize(str);
     this.render();
   }
 
   _emit() {
-    this.onChange(serialize(this.tokens));
+    this.onChange(serialize(this.tokens) + this._trailingSep);
   }
 
   _emitAndRender() {