diff --git a/backend/services/langchain_service.py b/backend/services/langchain_service.py
index 006a51b..1fd9bcd 100644
--- a/backend/services/langchain_service.py
+++ b/backend/services/langchain_service.py
@@ -107,6 +107,8 @@ class LangChainRAGService:
         8. 중요한 정보나 주의사항이 있다면 강조하세요
         9. 문서에 없는 내용은 추측하지 말고 "문서에 명시되지 않음"이라고 하세요
         10. 마크다운 형식을 사용하여 구조화된 답변을 제공하세요
+        11. 영어로 된 사고 과정이나 내부 대화를 절대 포함하지 마세요
+        12. "part. but the user", "wait, the initial", "let me check" 같은 영어 표현을 절대 사용하지 마세요
         
         **참조 문서:**
         {context}
@@ -217,24 +219,27 @@ class LangChainRAGService:
                 korean_found = False
                 
                 for line in lines:
-                    line = line.strip()
-                    if not line:
-                        filtered_lines.append(line)
+                    original_line = line  # 원본 줄 보존 (들여쓰기, 공백 등)
+                    line_stripped = line.strip()
+                    
+                    # 빈 줄은 그대로 유지 (마크다운 구조 보존)
+                    if not line_stripped:
+                        filtered_lines.append(original_line)
                         continue
                     
                     # 한국어가 포함된 줄이 나오면 korean_found = True
-                    if re.search(r'[가-힣]', line):
+                    if re.search(r'[가-힣]', line_stripped):
                         korean_found = True
                     
                     # 한국어가 발견되기 전까지는 모든 영어 줄 무조건 제거
                     if not korean_found:
-                        if re.match(r'^[A-Za-z]', line):
+                        if re.match(r'^[A-Za-z]', line_stripped):
                             continue
                     
-                    # 한국어가 발견된 후에도 영어 사고 과정 제거
-                    if re.match(r'^[A-Za-z]', line):
+                    # 한국어가 발견된 후에도 영어 사고 과정 제거 (극강화)
+                    if re.match(r'^[A-Za-z]', line_stripped):
                         # 모든 영어 패턴 제거 (더 많은 패턴 추가)
-                        if any(phrase in line.lower() for phrase in [
+                        if any(phrase in line_stripped.lower() for phrase in [
                             'let me', 'i need to', 'i should', 'i will', 'i can',
                             'the answer should', 'make sure', 'avoid any',
                             'structure the answer', 'break down', 'organize',
@@ -243,24 +248,90 @@ class LangChainRAGService:
                             'thinking process', 'internal thought',
                             'i need to focus', 'main content', 'tag', 'thinking',
                             'tag or any', 'so i need', 'focus on', 'main content of',
-                            'documents', 'thinking', 'process', 'internal'
+                            'documents', 'thinking', 'process', 'internal',
+                            'part. but the user', 'wait, the initial', 'let me check',
+                            'user also wants', 'answer in markdown', 'instructions say',
+                            'use markdown for', 'check again', 'but the user also',
+                            'wants the answer in', 'markdown. wait', 'the initial instructions',
+                            'say to use markdown', 'for the answer', 'let me check again',
+                            'part. but the user also wants the answer in markdown',
+                            'wait, the initial instructions say to use markdown',
+                            'let me check again', 'but the user also wants',
+                            'wants the answer in markdown', 'markdown. wait',
+                            'the initial instructions', 'say to use markdown for the answer'
                         ]):
                             continue
                         # 영어 문장이지만 중요한 내용이 아닌 경우 제거
-                        if len(line) > 10 and any(word in line.lower() for word in [
+                        if len(line_stripped) > 10 and any(word in line_stripped.lower() for word in [
                             'thinking', 'process', 'structure', 'format', 'markdown',
                             'tag', 'focus', 'content', 'documents', 'internal',
-                            'answer', 'should', 'make', 'sure', 'avoid'
+                            'answer', 'should', 'make', 'sure', 'avoid',
+                            'user', 'wants', 'instructions', 'check', 'again',
+                            'part', 'but', 'let', 'me', 'say', 'use', 'for',
+                            'wait', 'initial', 'also', 'the', 'in', 'to'
                         ]):
                             continue
                         # 짧은 영어 문장도 제거 (사고 과정일 가능성)
-                        if len(line) < 200 and not re.search(r'[가-힣]', line):
+                        if len(line_stripped) < 200 and not re.search(r'[가-힣]', line_stripped):
                             continue
                     
-                    filtered_lines.append(line)
+                    # 원본 줄 유지 (들여쓰기, 공백 등 마크다운 구조 보존)
+                    filtered_lines.append(original_line)
                 
                 answer = '\n'.join(filtered_lines).strip()
                 
+                # 마크다운 구조 보존을 위한 추가 처리
+                # 연속된 빈 줄을 하나로 정리하되, 마크다운 구조는 유지
+                answer = re.sub(r'\n\s*\n\s*\n+', '\n\n', answer)
+                
+                # 마크다운 문법이 있는지 확인하고, 없다면 강제로 마크다운 형식 적용
+                if not re.search(r'^#{1,6}\s|^\*\*|^[-*]\s|^\d+\.\s|^\|', answer, re.MULTILINE):
+                    # 마크다운 문법이 없으면 첫 번째 줄을 제목으로 만들기
+                    lines = answer.split('\n')
+                    if lines and lines[0].strip():
+                        # 첫 번째 줄이 제목이 될 수 있는 내용인지 확인
+                        first_line = lines[0].strip()
+                        if len(first_line) > 5 and not first_line.endswith('.'):
+                            lines[0] = f"# {first_line}"
+                            answer = '\n'.join(lines)
+                
+                # 추가 영어 사고 과정 제거 (전체 텍스트 레벨)
+                english_phrases_to_remove = [
+                    "part. but the user also wants the answer in markdown. wait, the initial instructions say to use markdown for the answer. let me check again.",
+                    "part. but the user also wants the answer in markdown",
+                    "wait, the initial instructions say to use markdown",
+                    "let me check again",
+                    "but the user also wants",
+                    "wants the answer in markdown",
+                    "markdown. wait",
+                    "the initial instructions",
+                    "say to use markdown for the answer",
+                    "part. but the user",
+                    "user also wants",
+                    "answer in markdown",
+                    "initial instructions",
+                    "use markdown",
+                    "check again"
+                ]
+                
+                for phrase in english_phrases_to_remove:
+                    answer = answer.replace(phrase, '').strip()
+                    answer = answer.replace(phrase.lower(), '').strip()
+                    answer = answer.replace(phrase.upper(), '').strip()
+                    answer = answer.replace(phrase.capitalize(), '').strip()
+                
+                # 정규식으로 영어 사고 과정 제거
+                import re
+                english_thinking_patterns = [
+                    r'^[A-Za-z].*user.*wants.*answer.*markdown.*$',
+                    r'^[A-Za-z].*part\.\s*but.*user.*also.*wants.*$',
+                    r'^[A-Za-z].*wait.*initial.*instructions.*$',
+                    r'^[A-Za-z].*let.*me.*check.*again.*$'
+                ]
+                
+                for pattern in english_thinking_patterns:
+                    answer = re.sub(pattern, '', answer, flags=re.MULTILINE | re.IGNORECASE).strip()
+                
                 response = {
                     "answer": answer,
                     "references": references,
diff --git a/frontend/src/components/ChatInterface.tsx b/frontend/src/components/ChatInterface.tsx
index 86d716c..1d1309c 100644
--- a/frontend/src/components/ChatInterface.tsx
+++ b/frontend/src/components/ChatInterface.tsx
@@ -96,7 +96,7 @@ const ChatInterface: React.FC = () => {
   };
 
   return (
-    <div className="flex-1 flex flex-col h-full">
+    <div className="flex-1 flex flex-col min-h-0">
       {/* 메시지 영역 */}
       <div className="flex-1 overflow-y-auto p-4 space-y-16 bg-white">
         {messages.length === 0 ? (
@@ -140,7 +140,19 @@ const ChatInterface: React.FC = () => {
       </div>
 
       {/* 입력 영역 */}
-      <div className="bg-white border-t border-gray-200 p-4">
+      <div 
+        className="bg-white p-4 input-area"
+        style={{
+          position: 'relative',
+          zIndex: 1000,
+          display: 'block',
+          visibility: 'visible',
+          opacity: 1,
+          minHeight: '80px',
+          backgroundColor: 'white',
+          borderTop: 'none'
+        }}
+      >
         <div className="w-full max-w-none mx-auto px-4" style={{ maxWidth: '80vw' }}>
           <div className="flex space-x-3">
             <div className="flex-1 relative">
@@ -153,6 +165,18 @@ const ChatInterface: React.FC = () => {
                 placeholder="질문을 입력하세요..."
                 className="w-full px-4 py-3 border border-gray-300 rounded-xl focus:ring-2 focus:ring-blue-500 focus:border-transparent outline-none transition-all"
                 disabled={isLoading}
+                style={{ 
+                  border: '1px solid #d1d5db',
+                  backgroundColor: 'white',
+                  color: '#374151',
+                  display: 'block',
+                  visibility: 'visible',
+                  opacity: 1,
+                  width: '100%',
+                  minHeight: '48px',
+                  paddingLeft: '20px',
+                  paddingRight: '16px'
+                }}
               />
             </div>
             <motion.button
@@ -161,6 +185,13 @@ const ChatInterface: React.FC = () => {
               onClick={handleSendMessage}
               disabled={!inputMessage.trim() || isLoading}
               className="px-6 py-3 bg-gradient-to-r from-blue-600 to-purple-600 text-white rounded-xl font-medium disabled:opacity-50 disabled:cursor-not-allowed transition-all btn-animate"
+              style={{
+                display: 'block',
+                visibility: 'visible',
+                opacity: 1,
+                backgroundColor: 'linear-gradient(to right, #2563eb, #9333ea)',
+                color: 'white'
+              }}
             >
               <Send className="w-5 h-5" />
             </motion.button>
diff --git a/frontend/src/components/MessageBubble.tsx b/frontend/src/components/MessageBubble.tsx
index 908e3ee..9de90a2 100644
--- a/frontend/src/components/MessageBubble.tsx
+++ b/frontend/src/components/MessageBubble.tsx
@@ -1,11 +1,9 @@
 import React, { useState } from 'react';
 import { motion } from 'framer-motion';
 import { User, FileText } from 'lucide-react';
-import ReactMarkdown from 'react-markdown';
-import remarkGfm from 'remark-gfm';
-import remarkBreaks from 'remark-breaks';
 import { Message } from '../contexts/ChatContext';
 import PDFViewer from './PDFViewer';
+import SimpleMarkdownRenderer from './SimpleMarkdownRenderer';
 
 interface MessageBubbleProps {
   message: Message;
@@ -115,45 +113,7 @@ const MessageBubble: React.FC<MessageBubbleProps> = ({ message }) => {
                 {message.content}
               </div>
             ) : (
-              <div className="markdown-content">
-                <ReactMarkdown
-                  remarkPlugins={[remarkGfm, remarkBreaks]}
-                  components={{
-                    // pre 태그를 완전히 제거하고 일반 div로 대체
-                    pre: ({ children }) => <div>{children}</div>,
-                    // code 태그 처리
-                    code: ({ children, className }) => {
-                      const isInline = !className;
-                      return isInline ? (
-                        <code className="bg-gray-200 px-2 py-1 rounded text-sm font-mono text-gray-800">{children}</code>
-                      ) : (
-                        <div className="bg-gray-100 text-gray-800 p-4 rounded-lg overflow-x-auto mb-4 font-mono text-sm">{children}</div>
-                      );
-                    },
-                    // 모든 마크다운 요소에 대한 커스텀 스타일링
-                    h1: ({ children }) => <h1 className="text-2xl font-bold mb-4 text-gray-800 border-b border-gray-200 pb-2">{children}</h1>,
-                    h2: ({ children }) => <h2 className="text-xl font-bold mb-3 text-gray-800 mt-6">{children}</h2>,
-                    h3: ({ children }) => <h3 className="text-lg font-bold mb-2 text-gray-800 mt-4">{children}</h3>,
-                    h4: ({ children }) => <h4 className="text-base font-bold mb-2 text-gray-800 mt-3">{children}</h4>,
-                    p: ({ children }) => <p className="mb-3 text-gray-700 leading-relaxed">{children}</p>,
-                    ul: ({ children }) => <ul className="list-disc list-inside mb-4 text-gray-700 space-y-1 ml-4">{children}</ul>,
-                    ol: ({ children }) => <ol className="list-decimal list-inside mb-4 text-gray-700 space-y-1 ml-4">{children}</ol>,
-                    li: ({ children }) => <li className="mb-1">{children}</li>,
-                    strong: ({ children }) => <strong className="font-bold text-gray-800">{children}</strong>,
-                    em: ({ children }) => <em className="italic text-gray-700">{children}</em>,
-                    blockquote: ({ children }) => <blockquote className="border-l-4 border-blue-300 pl-4 italic text-gray-600 bg-blue-50 py-2 rounded-r mb-4">{children}</blockquote>,
-                    table: ({ children }) => <div className="overflow-x-auto mb-4"><table className="min-w-full border-collapse border border-gray-300">{children}</table></div>,
-                    thead: ({ children }) => <thead className="bg-gray-50">{children}</thead>,
-                    tbody: ({ children }) => <tbody>{children}</tbody>,
-                    tr: ({ children }) => <tr className="border-b border-gray-200 hover:bg-gray-50">{children}</tr>,
-                    th: ({ children }) => <th className="border border-gray-300 px-4 py-2 text-left font-semibold text-gray-800 bg-gray-100">{children}</th>,
-                    td: ({ children }) => <td className="border border-gray-300 px-4 py-2 text-gray-700">{children}</td>,
-                    hr: () => <hr className="my-6 border-gray-300" />,
-                  }}
-                >
-                  {message.content}
-                </ReactMarkdown>
-              </div>
+              <SimpleMarkdownRenderer content={message.content || ''} />
             )}
             
             {/* 소스 정보 */}
@@ -214,4 +174,4 @@ const MessageBubble: React.FC<MessageBubbleProps> = ({ message }) => {
   );
 };
 
-export default MessageBubble;
+export default MessageBubble;
\ No newline at end of file
diff --git a/frontend/src/index.css b/frontend/src/index.css
index 3eb7cfc..dc3618a 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -16,7 +16,6 @@ body {
     sans-serif;
   -webkit-font-smoothing: antialiased;
   -moz-osx-font-smoothing: grayscale;
-  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
   min-height: 100vh;
 }
 
@@ -310,18 +309,8 @@ code {
   border: none !important;
 }
 
-/* 모든 div 요소의 상단 테두리 제거 */
-div {
-  border-top: none !important;
-}
-
-/* 특정 클래스의 테두리 제거 */
-.border-t {
-  border-top: none !important;
-}
-
-/* 모든 가능한 선과 배경 제거 */
-* {
+/* 특정 클래스의 테두리 제거 (입력 영역 제외) */
+.border-t:not(input):not(.input-area) {
   border-top: none !important;
 }
 
@@ -437,6 +426,42 @@ div {
   line-height: inherit !important;
 }
 
+/* 마크다운 pre 래퍼 스타일 */
+.markdown-pre-wrapper {
+  white-space: normal !important;
+  word-wrap: break-word !important;
+  background: transparent !important;
+  border: none !important;
+  padding: 0 !important;
+  margin: 0 !important;
+  font-family: inherit !important;
+  font-size: inherit !important;
+  line-height: inherit !important;
+  display: block !important;
+  overflow: visible !important;
+}
+
+/* react-markdown이 생성하는 모든 pre 태그에 대한 강력한 리셋 */
+.markdown-content pre,
+.markdown-content > pre,
+.markdown-content pre[class*="language-"],
+.markdown-content pre:not([class]),
+.markdown-content pre code,
+.markdown-content > pre code {
+  white-space: normal !important;
+  word-wrap: break-word !important;
+  background: transparent !important;
+  border: none !important;
+  padding: 0 !important;
+  margin: 0 !important;
+  font-family: inherit !important;
+  font-size: inherit !important;
+  line-height: inherit !important;
+  display: block !important;
+  overflow: visible !important;
+  color: inherit !important;
+}
+
 /* 실제 코드 블록에만 적용되는 pre 태그 스타일 */
 .markdown-content pre {
   background-color: #F3F4F6 !important;
@@ -491,9 +516,49 @@ div {
 }
 
 .markdown-content hr {
+  display: none !important;
+  visibility: hidden !important;
+  height: 0 !important;
+  margin: 0 !important;
+  padding: 0 !important;
   border: none !important;
-  border-top: 1px solid #E5E7EB !important;
-  margin: 2rem 0 !important;
+  border-top: none !important;
+  border-bottom: none !important;
+  border-left: none !important;
+  border-right: none !important;
+  outline: none !important;
+  box-shadow: none !important;
+}
+
+/* 모든 hr 요소 강제 숨김 */
+hr {
+  display: none !important;
+  visibility: hidden !important;
+  height: 0 !important;
+  margin: 0 !important;
+  padding: 0 !important;
+  border: none !important;
+  outline: none !important;
+  box-shadow: none !important;
+}
+
+/* 모든 가능한 가로줄 요소 강제 숨김 */
+hr,
+.hr,
+.horizontal-line,
+.border-t,
+.border-top,
+[class*="border-t"],
+[class*="border-top"] {
+  display: none !important;
+  visibility: hidden !important;
+  height: 0 !important;
+  margin: 0 !important;
+  padding: 0 !important;
+  border: none !important;
+  border-top: none !important;
+  outline: none !important;
+  box-shadow: none !important;
 }
 
 /* 참조 문서 섹션의 모든 선과 배경 제거 */
@@ -505,4 +570,65 @@ div {
   border-right: none !important;
   background: transparent !important;
   background-color: transparent !important;
+  outline: none !important;
+  box-shadow: none !important;
+}
+
+/* 모든 hr 태그 완전 제거 */
+hr {
+  display: none !important;
+  visibility: hidden !important;
+  height: 0 !important;
+  margin: 0 !important;
+  padding: 0 !important;
+  border: none !important;
+  background: none !important;
+}
+
+/* 참조 문서 위의 모든 선 제거 */
+.mt-3.pt-3::before,
+.mt-3.pt-3::after {
+  display: none !important;
+  content: none !important;
+}
+
+/* 입력 영역 스타일 보호 */
+.input-area {
+  border-top: none !important;
+  background: white !important;
+  position: relative !important;
+  z-index: 10 !important;
+  display: block !important;
+  visibility: visible !important;
+  opacity: 1 !important;
+  height: auto !important;
+  min-height: 80px !important;
+}
+
+.input-area input {
+  border: 1px solid #d1d5db !important;
+  background: white !important;
+  color: #374151 !important;
+  display: block !important;
+  visibility: visible !important;
+  opacity: 1 !important;
+  width: 100% !important;
+  height: auto !important;
+  min-height: 48px !important;
+  padding-left: 20px !important;
+  padding-right: 16px !important;
+}
+
+.input-area input:focus {
+  border: 1px solid #3b82f6 !important;
+  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1) !important;
+}
+
+/* 입력 영역 버튼 스타일 */
+.input-area button {
+  display: block !important;
+  visibility: visible !important;
+  opacity: 1 !important;
+  background: linear-gradient(to right, #2563eb, #9333ea) !important;
+  color: white !important;
 }