diff --git a/src/main/java/app/handler/RegisterWithPost.java b/src/main/java/app/handler/RegisterWithPost.java
index f1844c3a1..066683b9b 100644
--- a/src/main/java/app/handler/RegisterWithPost.java
+++ b/src/main/java/app/handler/RegisterWithPost.java
@@ -11,7 +11,7 @@
 import web.filter.authentication.UserRole;
 import web.handler.SingleArgHandler;
 import web.response.HandlerResponse;
-import web.response.StaticViewResponse;
+import web.response.RedirectResponse;
 
 public class RegisterWithPost extends SingleArgHandler<QueryParameters> {
     private static final Logger log = LoggerFactory.getLogger(RegisterWithPost.class);
@@ -27,6 +27,6 @@ public HandlerResponse handle(QueryParameters params) {
         String password = params.getQueryValue("password").orElseThrow(()-> new ServiceException(ErrorCode.MISSING_REGISTER_TOKEN, "password required"));
         Database.addUser(new User(password, nickname, email, UserRole.MEMBER.toString()));
         log.info("Registered - password:{}, nickname:{}, email:{}", password, nickname, email);
-        return StaticViewResponse.of("/login");
+        return RedirectResponse.to("/login");
     }
 }
diff --git a/src/main/java/config/AppConfig.java b/src/main/java/config/AppConfig.java
index d98b5eb29..64c8413d1 100644
--- a/src/main/java/config/AppConfig.java
+++ b/src/main/java/config/AppConfig.java
@@ -18,6 +18,7 @@
 import web.dispatch.argument.resolver.HttpRequestResolver;
 import web.dispatch.argument.resolver.QueryParamsResolver;
 import web.filter.*;
+import web.handler.DefaultViewHandler;
 import web.handler.StaticContentHandler;
 import web.handler.WebHandler;
 import web.renderer.DynamicViewRenderer;
@@ -88,7 +89,8 @@ public List<WebHandler> webHandlerList() {
                         registerWithPost(),
                         loginWithPost(),
                         logoutWithPost(),
-                        homeHandler())
+                        homeHandler(),
+                        defaultViewHandler())
         );
     }
 
@@ -99,6 +101,10 @@ public StaticContentHandler staticContentHandler() {
         );
     }
 
+    public DefaultViewHandler defaultViewHandler(){
+        return getOrCreate("defaultViewHandler", DefaultViewHandler::new);
+    }
+
     public RegisterWithGet registerWithGet() {
         return getOrCreate(
                 "registerWithGet",
diff --git a/src/main/java/web/handler/DefaultViewHandler.java b/src/main/java/web/handler/DefaultViewHandler.java
new file mode 100644
index 000000000..88cd4af40
--- /dev/null
+++ b/src/main/java/web/handler/DefaultViewHandler.java
@@ -0,0 +1,43 @@
+package web.handler;
+
+import config.VariableConfig;
+import exception.ErrorException;
+import http.HttpMethod;
+import http.HttpStatus;
+import http.request.HttpRequest;
+import web.response.DynamicViewResponse;
+import web.response.HandlerResponse;
+
+import java.io.File;
+import java.util.List;
+
+public class DefaultViewHandler implements DefaultHandler{
+    private final List<String> roots = VariableConfig.DYNAMIC_RESOURCE_ROOTS;
+    private final HttpMethod method = HttpMethod.GET;
+
+    @Override
+    public String getPath() {
+        throw new ErrorException("DynamicViewHandler::getPath should not be called");
+    }
+
+    @Override
+    public HttpMethod getMethod() {
+        return this.method;
+    }
+    @Override
+    public boolean checkEndpoint(HttpMethod method, String path) {
+        if(!method.equals(this.method)) return false;
+        return roots.stream().anyMatch(root ->{
+            File requestedFile = new File(root + path);
+            String indexFilePath = path + (path.endsWith("/") ? "index.html" : "/index.html");
+            File indexFile = new File(root + indexFilePath);
+            return (requestedFile.exists() && requestedFile.isFile()) || (indexFile.exists() && indexFile.isFile());
+        });
+    }
+
+    @Override
+    public HandlerResponse handle(HttpRequest request) {
+        String path = request.getPath() + (request.getPath().endsWith("/") ? "index.html" : "/index.html");
+        return DynamicViewResponse.of(HttpStatus.OK, path);
+    }
+}
diff --git a/src/main/resources/static/article/index.html b/src/main/resources/templates/article/index.html
similarity index 60%
rename from src/main/resources/static/article/index.html
rename to src/main/resources/templates/article/index.html
index 6d2c8eeef..41de15965 100644
--- a/src/main/resources/static/article/index.html
+++ b/src/main/resources/templates/article/index.html
@@ -3,24 +3,12 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <link href="../reset.css" rel="stylesheet" />
-    <link href="../global.css" rel="stylesheet" />
+    <link href="../../static/reset.css" rel="stylesheet" />
+    <link href="../../static/global.css" rel="stylesheet" />
   </head>
   <body>
     <div class="container">
-      <header class="header">
-        <a href="/main"><img src="../img/signiture.svg" /></a>
-        <ul class="header__menu">
-          <li class="header__menu__item">
-            <a class="btn btn_contained btn_size_s" href="/article">글쓰기</a>
-          </li>
-          <li class="header__menu__item">
-            <button id="logout-btn" class="btn btn_ghost btn_size_s">
-              로그아웃
-            </button>
-          </li>
-        </ul>
-      </header>
+      {{> /layout/header.html}}
       <div class="page">
         <h2 class="page-title">게시글 작성</h2>
         <form class="form">
diff --git a/src/main/resources/static/comment/index.html b/src/main/resources/templates/comment/index.html
similarity index 60%
rename from src/main/resources/static/comment/index.html
rename to src/main/resources/templates/comment/index.html
index 35df2b252..eca5bb38f 100644
--- a/src/main/resources/static/comment/index.html
+++ b/src/main/resources/templates/comment/index.html
@@ -3,24 +3,12 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <link href="../reset.css" rel="stylesheet" />
-    <link href="../global.css" rel="stylesheet" />
+    <link href="../../static/reset.css" rel="stylesheet" />
+    <link href="../../static/global.css" rel="stylesheet" />
   </head>
   <body>
     <div class="container">
-      <header class="header">
-        <a href="/main"><img src="../img/signiture.svg" /></a>
-        <ul class="header__menu">
-          <li class="header__menu__item">
-            <a class="btn btn_contained btn_size_s" href="/article">글쓰기</a>
-          </li>
-          <li class="header__menu__item">
-            <button id="logout-btn" class="btn btn_ghost btn_size_s">
-              로그아웃
-            </button>
-          </li>
-        </ul>
-      </header>
+      {{> /layout/header.html}}
       <div class="page">
         <h2 class="page-title">댓글 작성</h2>
         <form class="form">
diff --git a/src/main/resources/templates/layout/error-popup.html b/src/main/resources/templates/layout/error-popup.html
new file mode 100644
index 000000000..7b9516f8a
--- /dev/null
+++ b/src/main/resources/templates/layout/error-popup.html
@@ -0,0 +1,121 @@
+<style>
+    .error-popup-wrapper {
+      position: fixed;
+      top: 16px;
+      right: 50px;
+      z-index: 1000;
+    }
+    .error-popup {
+      display: none;
+      background: #ffffff;
+      border-radius: 8px;
+      padding: 14px 18px;
+      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+      min-width: 260px;
+    }
+    .error-popup__title {
+      font-size: 14px;
+      font-weight: 600;
+      margin-bottom: 6px;
+      color: #d32f2f;
+    }
+    .error-popup__message {
+      font-size: 13px;
+      margin-bottom: 10px;
+    }
+    .error-popup__actions {
+      display: flex;
+      justify-content: flex-end;
+    }
+    .error-popup__ok-btn {
+      cursor: pointer;
+      padding: 4px 12px;
+      font-size: 13px;
+      border-radius: 4px;
+      border: none;
+    }
+</style>
+
+<div class="error-popup-wrapper">
+    <div id="error-popup" class="error-popup">
+        <div class="error-popup__title">알림</div>
+        <div id="error-popup-message" class="error-popup__message"></div>
+        <div class="error-popup__actions">
+            <button id="error-popup-ok" class="error-popup__ok-btn" type="button">
+                OK
+            </button>
+        </div>
+    </div>
+</div>
+
+<script>
+    (function () {
+      const popup = document.getElementById("error-popup");
+      const msgEl = document.getElementById("error-popup-message");
+      const okBtn = document.getElementById("error-popup-ok");
+
+      window.showErrorPopup = function (message, title) {
+        const titleEl = popup.querySelector(".error-popup__title");
+        msgEl.textContent = message || "오류가 발생했습니다.";
+        if (title) titleEl.textContent = title;
+        popup.style.display = "block";
+      };
+
+      window.hideErrorPopup = function () {
+        popup.style.display = "none";
+      };
+
+      okBtn.addEventListener("click", () => window.hideErrorPopup());
+
+      // ---- 공통 submit 가로채기 (B안: data-ajax 있는 폼만) ----
+      document.addEventListener("submit", async (e) => {
+        const form = e.target;
+        if (!(form instanceof HTMLFormElement)) return;
+
+        // 안전하게: data-ajax="true"인 폼만 가로챔
+        if (form.dataset.ajax !== "true") return;
+
+        e.preventDefault();
+
+        // multipart/form-data는 여기서 처리 안 함(파일 업로드 등)
+        const enctype = (form.enctype || "").toLowerCase();
+        if (enctype.includes("multipart/form-data")) {
+          window.showErrorPopup("파일 업로드 폼은 지원하지 않습니다.", "오류");
+          return;
+        }
+
+        const body = new URLSearchParams(new FormData(form));
+
+        try {
+          const res = await fetch(form.action, {
+            method: (form.method || "POST").toUpperCase(),
+            headers: {
+              "Accept": "application/json",
+              "Content-Type": "application/x-www-form-urlencoded",
+            },
+            body,
+            credentials: "same-origin",
+          });
+
+          if (res.redirected) {
+            window.location.href = res.url;
+            return;
+          } else if (res.ok) {
+            window.location.href = "/";
+            return;
+          }
+
+          let err = null;
+          try { err = await res.json(); } catch {}
+
+          const message =
+            (err && (err.message || err.errorMessage)) ||
+            "요청 처리에 실패했습니다.";
+
+          window.showErrorPopup(message, "요청 실패");
+        } catch (networkError) {
+          window.showErrorPopup("서버와 통신 중 문제가 발생했습니다.", "오류");
+        }
+      }, true); // capture로 잡으면 더 안정적으로 submit을 가로챌 수 있음
+    })();
+</script>
diff --git a/src/main/resources/templates/layout/header.html b/src/main/resources/templates/layout/header.html
index 0b5bfd3be..678006c49 100644
--- a/src/main/resources/templates/layout/header.html
+++ b/src/main/resources/templates/layout/header.html
@@ -4,7 +4,10 @@
     <ul class="header__menu">
         {{#if1 isLoginUser}}
         <li class="header__menu__item">
-            <span class="header__menu__nickname">닉네임: {{userNickname}}</span>
+            <a class="header__menu__nickname" href="/mypage">닉네임: {{userNickname}}</a>
+        </li>
+        <li class="header__menu__item">
+            <a class="btn btn_contained btn_size_s" href="/article">글쓰기</a>
         </li>
         <form action="/user/logout" method="POST">
             <button type="submit">로그아웃</button>
diff --git a/src/main/resources/static/login/index.html b/src/main/resources/templates/login/index.html
similarity index 65%
rename from src/main/resources/static/login/index.html
rename to src/main/resources/templates/login/index.html
index 7c87ea590..481c62717 100644
--- a/src/main/resources/static/login/index.html
+++ b/src/main/resources/templates/login/index.html
@@ -3,27 +3,15 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <link href="../reset.css" rel="stylesheet" />
-    <link href="../global.css" rel="stylesheet" />
+    <link href="../../static/reset.css" rel="stylesheet" />
+    <link href="../../static/global.css" rel="stylesheet" />
   </head>
   <body>
     <div class="container">
-      <header class="header">
-        <a href="/"><img src="../img/signiture.svg" /></a>
-        <ul class="header__menu">
-          <li class="header__menu__item">
-            <a class="btn btn_contained btn_size_s" href="/login">로그인</a>
-          </li>
-          <li class="header__menu__item">
-            <a class="btn btn_ghost btn_size_s" href="/registration">
-              회원 가입
-            </a>
-          </li>
-        </ul>
-      </header>
+      {{> /layout/header.html}}
       <div class="page">
         <h2 class="page-title">로그인</h2>
-        <form class="form" action="/user/login" method="post">
+        <form class="form" action="/user/login" method="post" data-ajax="true">
           <div class="textfield textfield_size_s">
             <p class="title_textfield">이메일</p>
             <input
@@ -54,5 +42,6 @@ <h2 class="page-title">로그인</h2>
         </form>
       </div>
     </div>
+    {{> /layout/error-popup.html}}
   </body>
 </html>
diff --git a/src/main/resources/static/mypage/index.html b/src/main/resources/templates/mypage/index.html
similarity index 78%
rename from src/main/resources/static/mypage/index.html
rename to src/main/resources/templates/mypage/index.html
index 7ab744957..6f7db6ee4 100644
--- a/src/main/resources/static/mypage/index.html
+++ b/src/main/resources/templates/mypage/index.html
@@ -3,24 +3,13 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <link href="../reset.css" rel="stylesheet" />
-    <link href="../global.css" rel="stylesheet" />
+      <link href="../../static/reset.css" rel="stylesheet" />
+      <link href="../../static/global.css" rel="stylesheet" />
   </head>
   <body>
     <div class="container">
-      <header class="header">
-        <a href="/"><img src="../img/signiture.svg" /></a>
-        <ul class="header__menu">
-        <li class="header__menu__item">
-            <a class="btn btn_contained btn_size_s" href="/article">글쓰기</a>
-          </li>
-          <li class="header__menu__item">
-            <button id="logout-btn" class="btn btn_ghost btn_size_s">
-              로그아웃
-            </button>
-          </li>
-        </ul>
-      </header>
+      {{> /layout/header.html}}
+
       <div class="page">
         <h2 class="page-title">마이페이지</h2>
 
@@ -74,8 +63,10 @@ <h2 class="page-title">마이페이지</h2>
               변경사항 저장
             </button>
 
-        </form>
-      </div>
+            </form>
+          </div>
+        </div>
     </div>
+        {{> /layout/error-popup.html}}
   </body>
 </html>
diff --git a/src/main/resources/static/registration/index.html b/src/main/resources/templates/registration/index.html
similarity index 71%
rename from src/main/resources/static/registration/index.html
rename to src/main/resources/templates/registration/index.html
index 4222dd38a..83ee68c5a 100644
--- a/src/main/resources/static/registration/index.html
+++ b/src/main/resources/templates/registration/index.html
@@ -3,27 +3,15 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <link href="../reset.css" rel="stylesheet" />
-    <link href="../global.css" rel="stylesheet" />
+    <link href="../../static/reset.css" rel="stylesheet" />
+    <link href="../../static/global.css" rel="stylesheet" />
   </head>
   <body>
     <div class="container">
-      <header class="header">
-        <a href="/"><img src="../img/signiture.svg" /></a>
-        <ul class="header__menu">
-          <li class="header__menu__item">
-            <a class="btn btn_contained btn_size_s" href="/login">로그인</a>
-          </li>
-          <li class="header__menu__item">
-            <a class="btn btn_ghost btn_size_s" href="/registration">
-              회원 가입
-            </a>
-          </li>
-        </ul>
-      </header>
+      {{> /layout/header.html}}
       <div class="page">
         <h2 class="page-title">회원가입</h2>
-        <form class="form" action="/user/create" method="post">
+        <form class="form" action="/user/create" method="post" data-ajax="true">
           <div class="textfield textfield_size_s">
             <p class="title_textfield">이메일</p>
             <input
@@ -63,5 +51,6 @@ <h2 class="page-title">회원가입</h2>
         </form>
       </div>
     </div>
+    {{> /layout/error-popup.html}}
   </body>
 </html>