Structure legacy-compatible frontend CSS

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

@@ -1,4 +1,7 @@
 @import 'tailwindcss';
+@import './styles/tokens.css';
+@import './styles/game-shell.css';
+@import './styles/ref-shell.css';
 
 @theme {
     --color-sammo-ink: #000;
@@ -15,7 +18,7 @@ body {
     margin: 0;
     background: #000;
     color: #fff;
-    font-family: Pretendard, 'Apple SD Gothic Neo', 'Noto Sans KR', 'Malgun Gothic', sans-serif;
+    font-family: var(--sammo-font-sans);
     font-size: 14px;
     line-height: 1.3;
 }
@@ -29,17 +32,17 @@ textarea {
 
 .legacy-bg0 {
     background-color: #302016;
-    background-image: url('/image/game/back_walnut.jpg');
+    background-image: var(--sammo-texture-walnut);
 }
 
 .legacy-bg1 {
     background-color: #14241b;
-    background-image: url('/image/game/back_green.jpg');
+    background-image: var(--sammo-texture-green);
 }
 
 .legacy-bg2 {
     background-color: #172a52;
-    background-image: url('/image/game/back_blue.jpg');
+    background-image: var(--sammo-texture-blue);
 }
 
 .legacy-button {

app/game-frontend/src/assets/styles/game-shell.css

@@ -0,0 +1,54 @@
+/*
+ * Shared shell for the main dashboard family.
+ *
+ * Keep geometry here limited to declarations that are identical on the main,
+ * chief-center, and public screens. Page-specific grids remain scoped in their
+ * owning SFC so a generic class cannot silently change a ref measurement.
+ */
+.game-shell {
+    min-height: 100vh;
+    padding: 24px;
+    display: flex;
+    flex-direction: column;
+    gap: 16px;
+}
+
+.game-shell__header {
+    display: flex;
+    flex-wrap: wrap;
+    justify-content: space-between;
+    gap: 12px;
+    border-bottom: 1px solid var(--sammo-color-border);
+    padding-bottom: 12px;
+}
+
+.game-shell__title {
+    font-size: 1.6rem;
+    font-weight: 600;
+}
+
+.game-shell__subtitle {
+    font-size: 0.85rem;
+    color: var(--sammo-color-text-muted);
+}
+
+.game-shell__actions {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 8px;
+}
+
+.game-shell__action {
+    border: 1px solid var(--sammo-color-border);
+    padding: 6px 12px;
+    background: var(--sammo-color-action-bg);
+    color: inherit;
+    text-decoration: none;
+    font-size: 0.8rem;
+    cursor: pointer;
+}
+
+.game-feedback--error {
+    color: var(--sammo-color-error);
+    font-size: 0.85rem;
+}

app/game-frontend/src/assets/styles/ref-shell.css

@@ -0,0 +1,77 @@
+/*
+ * Fixed ref geometry. This namespace is intentionally separate from
+ * .game-shell: its 1000/500px contract must win over generic responsive styles.
+ */
+.ref-shell {
+    width: 100%;
+    min-width: 500px;
+    max-width: 1000px;
+    min-height: 100vh;
+    margin: 0 auto;
+    padding: 0;
+    display: flex;
+    flex-direction: column;
+    gap: 0;
+    background-color: #302016;
+    background-image: var(--sammo-texture-walnut);
+    color: var(--sammo-color-text);
+    font-family: var(--sammo-font-sans);
+    font-size: 14px;
+    line-height: 1.5;
+}
+
+.ref-shell__topbar {
+    position: relative;
+    min-height: 32px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    gap: 10px;
+    flex-wrap: wrap;
+    padding: 0 8px;
+    border: 1px solid #666;
+    background-color: #302016;
+    background-image: var(--sammo-texture-walnut);
+}
+
+.ref-shell__title {
+    font-size: 17px;
+    font-weight: 500;
+}
+
+.ref-shell__subtitle {
+    display: none;
+}
+
+.ref-shell__actions {
+    position: absolute;
+    left: 0;
+    top: 0;
+    display: flex;
+    flex-wrap: wrap;
+    gap: 4px;
+}
+
+.ref-shell__control {
+    min-height: 32px;
+    border: 1px solid #777;
+    border-radius: 0;
+    background: #303030;
+    color: inherit;
+    padding: 4px 8px;
+    font: inherit;
+    cursor: pointer;
+}
+
+.ref-feedback--error {
+    padding: 5px 8px;
+    border: 1px solid #a33;
+    color: #ff7777;
+    text-align: center;
+}
+
+@media (max-width: 991px) {
+    .ref-shell {
+        width: 500px;
+    }
+}

app/game-frontend/src/assets/styles/tokens.css

@@ -0,0 +1,12 @@
+:root {
+    --sammo-font-sans: Pretendard, 'Apple SD Gothic Neo', 'Noto Sans KR', 'Malgun Gothic', sans-serif;
+    --sammo-color-text: #fff;
+    --sammo-color-text-muted: rgba(232, 221, 196, 0.7);
+    --sammo-color-accent: #f39c12;
+    --sammo-color-border: rgba(201, 164, 90, 0.4);
+    --sammo-color-action-bg: rgba(16, 16, 16, 0.6);
+    --sammo-color-error: #f5b7b1;
+    --sammo-texture-walnut: url('/image/game/back_walnut.jpg');
+    --sammo-texture-green: url('/image/game/back_green.jpg');
+    --sammo-texture-blue: url('/image/game/back_blue.jpg');
+}