fix: iframe fills frame area to remove top black gap

Co-authored-by: Cursor <cursoragent@cursor.com>

static/style.css

@@ -118,15 +118,16 @@ a:hover {
 }
 
 .frame-wrap {
+  position: relative;
   flex: 1;
-  display: flex;
-  flex-direction: column;
   min-width: 0;
+  min-height: 0;
   background: #0a0e12;
 }
 
 .frame-placeholder {
-  flex: 1;
+  position: absolute;
+  inset: 0;
   display: flex;
   align-items: center;
   justify-content: center;
@@ -135,10 +136,12 @@ a:hover {
 }
 
 .frame-wrap iframe {
-  flex: 1;
+  position: absolute;
+  inset: 0;
   width: 100%;
+  height: 100%;
   border: none;
-  background: #fff;
+  background: #0a0e12;
 }
 
 /* 登录页 */