feat(frontend): restore legacy gateway and hall styling

app/game-frontend/src/assets/main.css

@@ -1,12 +1,73 @@
 @import 'tailwindcss';
 
 @theme {
-    --color-sammo-ink: #101010;
-    --color-sammo-parchment: #e8ddc4;
-    --color-sammo-gold: #c9a45a;
+    --color-sammo-ink: #000;
+    --color-sammo-parchment: #fff;
+    --color-sammo-gold: #f39c12;
+}
+
+html {
+    color-scheme: dark;
 }
 
 body {
-    @apply bg-sammo-ink text-sammo-parchment;
-    font-family: 'Galmuri11', 'Noto Serif KR', 'Malgun Gothic', serif;
+    min-width: 320px;
+    margin: 0;
+    background: #000;
+    color: #fff;
+    font-family: Pretendard, 'Apple SD Gothic Neo', 'Noto Sans KR', 'Malgun Gothic', sans-serif;
+    font-size: 14px;
+    line-height: 1.3;
+}
+
+button,
+input,
+select,
+textarea {
+    font: inherit;
+}
+
+.legacy-bg0 {
+    background-color: #302016;
+    background-image: url('/image/game/back_walnut.jpg');
+}
+
+.legacy-bg1 {
+    background-color: #14241b;
+    background-image: url('/image/game/back_green.jpg');
+}
+
+.legacy-bg2 {
+    background-color: #172a52;
+    background-image: url('/image/game/back_blue.jpg');
+}
+
+.legacy-button {
+    display: inline-block;
+    border: 1px solid #12195b;
+    border-radius: 3px;
+    background: #141c65;
+    color: #fff;
+    padding: 5px 10px;
+    font-weight: 700;
+    line-height: 1.5;
+    cursor: pointer;
+}
+
+.legacy-button:hover,
+.legacy-button:focus,
+.legacy-button:active {
+    border-color: #0f154c;
+    background: #101651;
+    color: #fff;
+}
+
+.legacy-button:focus-visible {
+    outline: 2px solid #f39c12;
+    outline-offset: 1px;
+}
+
+.legacy-button:disabled {
+    cursor: default;
+    opacity: 0.65;
 }