polish: align back cover CSS design with front cover

- Add .back-overlay gradient vignette (mirrors front-overlay)
- Add .back-ornament-top (❧) and .back-ornament-bottom (· · ·)
- Add .back-rule decorative gold divider (mirrors front-rule)
- Add text-shadow to headline, synopsis and tagline for legibility
- Wrap bottom strip in container so ornament sits above tagline/barcode row

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/cover.html

@@ -148,6 +148,14 @@
       justify-content: space-between;
     }
 
+    .back-ornament-top {
+      font-family: var(--font-display);
+      font-size: 0.16in;
+      color: var(--color-gold);
+      letter-spacing: 0.3em;
+      margin-bottom: 0.12in;
+    }
+
     .back-headline {
       font-family: var(--font-display);
       font-style: italic;
@@ -155,6 +163,15 @@
       font-size: 0.22in;
       color: var(--color-gold);
       letter-spacing: 0.03em;
+      margin-bottom: 0.12in;
+      text-shadow: 0 1px 6px rgba(0,0,0,1), 0 2px 16px rgba(0,0,0,0.8);
+    }
+
+    /* Decorative rule — mirrors .front-rule */
+    .back-rule {
+      width: 1.2in;
+      height: 1px;
+      background: linear-gradient(to right, transparent, var(--color-gold), transparent);
       margin-bottom: 0.14in;
     }
 
@@ -164,10 +181,19 @@
       line-height: 1.8;
       color: var(--color-text);
       flex: 1;
+      text-shadow: 0 1px 4px rgba(0,0,0,0.9);
     }
 
     .back-synopsis p { margin-bottom: 0.1in; }
 
+    .back-ornament-bottom {
+      font-family: var(--font-display);
+      font-size: 0.12in;
+      color: var(--color-muted);
+      letter-spacing: 0.25em;
+      margin-bottom: 0.1in;
+    }
+
     .back-bottom {
       display: flex;
       justify-content: space-between;
@@ -182,6 +208,7 @@
       color: var(--color-muted);
       max-width: 60%;
       line-height: 1.6;
+      text-shadow: 0 1px 4px rgba(0,0,0,0.8);
     }
 
     /* Barcode placeholder — KDP places the barcode here if left blank */
@@ -202,6 +229,23 @@
       opacity: 0.35;
     }
 
+    /* Gradient vignette — mirrors front-overlay for depth and legibility */
+    .back-overlay {
+      position: absolute;
+      top: 0; left: 0;
+      width: 100%;
+      height: 100%;
+      background:
+        radial-gradient(ellipse 90% 90% at 50% 50%,
+          transparent 30%,
+          rgba(6, 6, 24, 0.55) 100%),
+        linear-gradient(to bottom,
+          rgba(6, 6, 24, 0.40) 0%,
+          rgba(6, 6, 24, 0.15) 35%,
+          rgba(6, 6, 24, 0.15) 65%,
+          rgba(6, 6, 24, 0.50) 100%);
+    }
+
     /* ── Spine content ──────────────────────────────────────── */
     .spine-content {
       position: absolute;
@@ -422,10 +466,13 @@
     {% if backImage %}
       <img class="back-artwork" src="{{ backImage }}" alt="Back cover artwork">
     {% endif %}
+    <div class="back-overlay"></div>
 
     <div class="back-content">
       <div>
+        <p class="back-ornament-top">❧</p>
         <p class="back-headline">Zwölf magische Reisen in die Welt der Träume</p>
+        <div class="back-rule"></div>
         <div class="back-synopsis">
           <p>
             Jede Nacht beginnt eine neue Reise – und dieses Buch hat gleich zwölf davon.
@@ -440,12 +487,15 @@
         </div>
       </div>
 
-      <div class="back-bottom">
-        <p class="back-tagline">
-          „Die schönsten Welten sind nur<br>mit geschlossenen Augen zu erreichen."
-        </p>
-        {# Empty white box — KDP places the ISBN barcode here automatically #}
-        <div class="barcode-placeholder"></div>
+      <div>
+        <p class="back-ornament-bottom">· · ·</p>
+        <div class="back-bottom">
+          <p class="back-tagline">
+            „Die schönsten Welten sind nur<br>mit geschlossenen Augen zu erreichen."
+          </p>
+          {# Empty white box — KDP places the ISBN barcode here automatically #}
+          <div class="barcode-placeholder"></div>
+        </div>
       </div>
     </div>