style: remove unnecessary dividers and editor borders for a cleaner look

Author: AmirMohammad Cheraghali

src/components/dashboard/LabNotebook.tsx

@@ -336,7 +336,7 @@ export const LabNotebook: React.FC<{ isDrawer?: boolean }> = ({ isDrawer = false
                     {activeNotebook ? (
                         <div className={`flex-1 flex flex-col h-full w-full ${isDrawer ? '' : 'max-w-[1440px] mx-auto'}`}>
                             {/* Editor Toolbar */}
-                            <div className={`flex items-center justify-between py-4 border-b border-[var(--border-main)]/50 shrink-0 ${isDrawer ? 'px-4' : 'px-8'}`}>
+                            <div className={`flex items-center justify-between py-4 shrink-0 ${isDrawer ? 'px-4' : 'px-8'}`}>
                                 <div className="flex items-center gap-2">
                                     {isDrawer && (
                                         <button

src/components/dashboard/RichTextEditor.tsx

@@ -314,7 +314,7 @@ export const RichTextEditor: React.FC<RichTextEditorProps> = ({
   };
 
   return (
-    <div className="flex flex-col w-full h-full bg-[var(--bg-main)] border border-[var(--border-main)] rounded-xl focus-within:border-neutral-700 transition-colors">
+    <div className="flex flex-col w-full h-full bg-[var(--bg-main)] rounded-xl focus-within:border-neutral-700 transition-colors">
       {/* TOOLBAR */}
       <div className="flex items-center flex-wrap gap-0.5 p-1 bg-[var(--bg-header)] border-b border-[var(--border-main)] sticky top-0 z-20 rounded-t-xl">
         {/* History */}