feat: 재학생 인증메일 문구 수정 및 CSS 스타일링 (#197)

feat: 이메일 문구 수정 및 CSS 스타일링

src/main/java/com/gdschongik/gdsc/domain/email/application/UnivEmailVerificationLinkSendService.java

@@ -34,11 +34,17 @@ public class UnivEmailVerificationLinkSendService {
     private final MemberUtil memberUtil;
     public static final Duration VERIFICATION_CODE_TIME_TO_LIVE = Duration.ofMinutes(10);
 
-    private static final String NOTIFICATION_MESSAGE = "<div style='margin:20px;'>"
-            + "<h1> 안녕하세요 GDSC Hongik 재학생 인증 메일입니다. </h1> <br>"
-            + "<h3> 아래의 링크를 %d분 안에 클릭해주세요. </h3> <br>"
-            + "<h3> 감사합니다. </h3> <br>"
-            + "CODE : <strong>";
+    private static final String NOTIFICATION_MESSAGE =
+            """
+<div style='font-family: "Roboto", sans-serif; margin: 40px; background-color: #ffffff; padding: 20px; border-radius: 8px; box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);'>
+    <h3 style='color: #202124;'>GDSC Hongik 재학생 인증 메일</h3>
+    <p style='color: #5f6368;'>안녕하세요!</p>
+    <p style='color: #5f6368;'>GDSC Hongik 커뮤니티에 지원해주셔서 대단히 감사드립니다.</p>
+    <p style='color: #5f6368;'>아래의 버튼을 클릭하여 재학생 인증을 완료해주세요. 링크는 %d분 동안 유효합니다.</p>
+    <a href='%s' style='display: inline-block; background-color: #4285F4; color: white; padding: 12px 24px; margin: 20px 0; border-radius: 4px; text-decoration: none; font-weight: 500;'>재학생 인증하기</a>
+    <p style='color: #5f6368;'>감사합니다.<br>GDSC Hongik Team</p>
+</div>
+""";
 
     public void send(String univEmail) {
         hongikUnivEmailValidator.validate(univEmail);
@@ -60,7 +66,7 @@ private void validateUnivEmailNotVerified(String univEmail) {
     }
 
     private String writeMailContentWithVerificationLink(String verificationLink) {
-        return String.format(NOTIFICATION_MESSAGE, VERIFICATION_CODE_TIME_TO_LIVE.toMinutes()) + verificationLink;
+        return NOTIFICATION_MESSAGE.formatted(VERIFICATION_CODE_TIME_TO_LIVE.toMinutes(), verificationLink);
     }
 
     private void saveUnivEmailVerification(String univEmail, String verificationCode) {

src/main/java/com/gdschongik/gdsc/global/common/constant/EmailConstant.java

@@ -5,7 +5,7 @@ public class EmailConstant {
     public static final String VERIFY_EMAIL_API_ENDPOINT = "/onboarding/verify-email?%s=";
     public static final String VERIFY_EMAIL_REQUEST_PARAMETER_KEY = "token";
     public static final String HONGIK_UNIV_MAIL_DOMAIN = "@g.hongik.ac.kr";
-    public static final String SENDER_PERSONAL = "GDSC Hongik 운영팀";
+    public static final String SENDER_PERSONAL = "GDSC Hongik";
     public static final String SENDER_ADDRESS = "[email protected]";
     public static final String VERIFICATION_EMAIL_SUBJECT = "GDSC Hongik 이메일 인증 코드입니다.";