[fix] resolved every main layout errors

Author: minij02

src/index.css

@@ -1,7 +1,5 @@
-html, body, #root {
+html {
   height: 100%;
-  margin: 0;
-  padding: 0;
 }
 
 :root {
@@ -29,7 +27,8 @@ a:hover {
 }
 
 body {
-  height: 100%;
+  min-height: 100vh; /* 화면 이상일 때도 배경 유지됨 */
+  height: auto;
   margin: 0;
   padding: 0;
   background: linear-gradient(276deg, #5BA5FF 12.83%, #ABF1FF 53.52%, #BBFFE4 94.21%);

src/styles/global.css

@@ -1,11 +1,5 @@
 @import "./theme.css";
 
-html, body, #root {
-  height: 100%;
-  margin: 0;
-  padding: 0;
-}
-
 /* 전역 유틸리티 클래스 */
 .bg-gradient-main {
   width: var(--layout-width);

src/styles/theme.css

@@ -1,11 +1,5 @@
 @import "tailwindcss";
 
-html, body, #root {
-  height: 100%;
-  margin: 0;
-  padding: 0;
-}
-
 :root {
 
   /* Colors */