fix(theme): style share modal and inputs for dark mode compatibility

frontend/src/index.css

@@ -178,8 +178,54 @@ body {
     border-color: var(--border-danger);
   }
 
-  /* Zentrales Texteingabefeld */
-  .input-field {
+  /* Sekundärer Button */
+  .btn-secondary {
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    gap: 0.375rem;
+    height: 1.75rem;
+    padding-left: 0.75rem;
+    padding-right: 0.75rem;
+    background-color: var(--bg-panel-elevated);
+    border: 1px solid var(--border-color);
+    border-radius: var(--radius-btn);
+    color: var(--text-main);
+    font-size: 0.75rem;
+    font-weight: 500;
+    transition: all 120ms ease;
+    cursor: pointer;
+  }
+  .btn-secondary:hover {
+    background-color: var(--bg-panel-hover);
+    border-color: var(--border-strong);
+  }
+
+  /* Gefahren-/Löschen-Button */
+  .btn-danger {
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    gap: 0.375rem;
+    height: 1.75rem;
+    padding-left: 0.75rem;
+    padding-right: 0.75rem;
+    background-color: var(--bg-danger);
+    border: 1px solid var(--border-danger);
+    border-radius: var(--radius-btn);
+    color: var(--color-danger);
+    font-size: 0.75rem;
+    font-weight: 500;
+    transition: all 120ms ease;
+    cursor: pointer;
+  }
+  .btn-danger:hover {
+    filter: brightness(1.15);
+  }
+
+  /* Zentrales Texteingabefeld & Aliasse */
+  .input-field,
+  .input-base {
     background-color: var(--bg-input);
     border: 1px solid var(--border-color);
     border-radius: var(--radius-input);
@@ -187,11 +233,13 @@ body {
     font-size: 0.75rem;
     transition: border-color 120ms ease;
   }
-  .input-field:focus {
+  .input-field:focus,
+  .input-base:focus {
     outline: none;
     border-color: var(--accent-primary);
   }
-  .input-field::placeholder {
+  .input-field::placeholder,
+  .input-base::placeholder {
     color: var(--text-faint);
   }