Mission/MAKIMA backdrop: solid dark plate (no horizon bleed)

The panel backdrop was rgba(11,17,36,0.62→0.85) — semi-transparent —
so the page's dusk-pink horizon at the bottom of the gradient bled
through behind the panel content, drawing the eye to the page edge
and making the background gradient stand out instead of disappearing.

Switched to a near-opaque #0a1024 → #0b1530 vertical gradient (slight
slope kept for depth) and bumped backdrop-filter to blur(20px)
saturate(80%) so any residual ambient is fully diffused. The panel
now reads as its own surface rather than a tinted overlay.

Verified: bottom-center pixel is rgb(10,20,47) — uniform deep night
across the whole panel, no pink bleed at the page bottom.

1 files changed, 10 insertions, 4 deletions

diff --git a/frontend/src/styles/heisei.css b/frontend/src/styles/heisei.css
index 3ccec4d..d0bb3f9 100644
--- a/frontend/src/styles/heisei.css
+++ b/frontend/src/styles/heisei.css
@@ -120,11 +120,17 @@ body { background: var(--hz-night); color: var(--hz-ink); }
   );
 }
 
-/* Mission-mode backdrop — softer, less black-curtain */
+/* Mission-mode backdrop — solid plate so the dusk-pink horizon and
+   bokeh from the page background don't bleed through behind the
+   panel content. The panel reads as its own surface, not a tinted
+   overlay over the homepage. */
 .modern-landing-page.manga-style .taisho-cover.mission-mode .cover-backdrop {
-  background: linear-gradient(180deg, rgba(11, 17, 36, 0.62) 0%, rgba(11, 17, 36, 0.85) 100%);
-  backdrop-filter: blur(8px);
-  -webkit-backdrop-filter: blur(8px);
+  /* Near-opaque dark plate, uniform top-to-bottom (slight gradient kept
+     for depth so it doesn't read as flat-painted). */
+  background: linear-gradient(180deg, #0a1024 0%, #0b1530 100%);
+  /* Strong blur so even residual ambient bleed is fully diffused */
+  backdrop-filter: blur(20px) saturate(80%);
+  -webkit-backdrop-filter: blur(20px) saturate(80%);
 }
 
 /* ----------------------------------------------------------------