Preserve QPowerPoint hidden slides in PPTX

src/styles.css

@@ -927,6 +927,22 @@ button {
   border-color: var(--accent);
 }
 
+.slide-thumb.is-hidden {
+  box-shadow: inset 0 0 0 999px rgb(0 0 0 / 14%);
+}
+
+.slide-hidden-badge {
+  display: inline-flex;
+  align-items: center;
+  gap: 5px;
+  width: fit-content;
+  padding: 3px 7px;
+  border-radius: 999px;
+  background: rgb(255 255 255 / 18%);
+  font-size: 12px;
+  font-weight: 700;
+}
+
 .slide-stage {
   display: grid;
   grid-template-rows: auto minmax(0, 1fr);
@@ -1053,6 +1069,27 @@ button {
   gap: 4px;
 }
 
+.slide-hidden-toggle {
+  grid-template-columns: auto minmax(0, 1fr);
+  align-items: center;
+  gap: 8px 10px;
+}
+
+.slide-hidden-toggle > span:first-child {
+  grid-column: 1 / -1;
+}
+
+.slide-hidden-toggle input[type="checkbox"] {
+  width: 18px;
+  height: 18px;
+  margin: 0;
+}
+
+.slide-hidden-toggle-text {
+  color: var(--text);
+  font-size: 13px;
+}
+
 .danger-command {
   margin-top: 10px;
   border-color: #f3b4b4;