fix: refine create page layout spacing

apps/ui/src/styles.css

@@ -324,7 +324,8 @@ button {
 }
 
 .page-header {
-  margin-bottom: 24px;
+  max-width: 1240px;
+  margin: 0 auto 24px;
 }
 
 .page-header h1 {
@@ -405,7 +406,14 @@ button {
 
 .builder-stack {
   width: 100%;
-  max-width: 1320px;
+}
+
+.builder-content {
+  width: 100%;
+  max-width: 1240px;
+  margin: 0 auto;
+  display: grid;
+  gap: 16px;
 }
 
 .page-section,
@@ -470,6 +478,11 @@ button {
   padding: 0 24px 24px;
 }
 
+.builder-content .form-grid {
+  grid-template-columns: repeat(2, minmax(280px, 420px));
+  justify-content: space-between;
+}
+
 .proto-grid {
   display: grid;
   grid-template-columns: repeat(3, minmax(0, 1fr));
@@ -859,8 +872,9 @@ button {
   align-items: center;
   justify-content: space-between;
   gap: 16px;
-  padding: 12px 20px;
-  border-radius: var(--radius-xl);
+  width: 100%;
+  padding: 12px 28px;
+  border-radius: 0;
   background: rgba(255, 255, 255, 0.9);
   backdrop-filter: blur(16px);
   border: 1px solid var(--border);
@@ -1114,7 +1128,7 @@ pre {
     padding: 20px;
   }
 
-  .builder-stack {
+  .builder-content {
     max-width: none;
   }
 }
@@ -1144,4 +1158,9 @@ pre {
     padding-left: 16px;
     padding-right: 16px;
   }
+
+  .sticky-action-bar {
+    padding-left: 16px;
+    padding-right: 16px;
+  }
 }