fallback css

2 files changed, 25 insertions, 1 deletions

diff --git a/taler-fallback.css b/taler-fallback.css
new file mode 100644
index 0000000..72f7652
--- /dev/null
+++ b/taler-fallback.css
@@ -0,0 +1,16 @@
+/* Fallback stylesheet.  Should be included in the document as follows:
+ *
+ * <link rel="stylesheet"
+ *       href="taler-fallback.css"
+ *       id="taler-presence-stylesheet />
+ *
+ * When either the taler-wallet-lib is included or the wallet is presence,
+ * it will take over this stylesheet for presence detection.
+ *
+ * This fallback stylesheet makes sure that classes for presence detection
+ * are displayed correctly, even if JavaScript is disabled and the wallet
+ * is not present.
+ */
+
+.taler-installed-show { display: none; }
+.taler-installed-hide { display: none; }
diff --git a/taler-wallet-lib.ts b/taler-wallet-lib.ts
index c703246..433f5c3 100644
--- a/taler-wallet-lib.ts
+++ b/taler-wallet-lib.ts
@@ -375,7 +375,15 @@ namespace taler {
         // We've taken over the stylesheet now,
         // make it clear by clearing all the rules in it
         // and making it obvious in the DOM.
-        style.innerText = content;
+        if (style.tagName.toLowerCase() === "style") {
+          style.innerText = content;
+        }
+        if (style.sheet) {
+          throw Error("taler-presence-stylesheet should be a style sheet (<link> or <style>)");
+        }
+        while (sheet.rules.length > 0) {
+          sheet.deleteRule(0);
+        }
       }
       sheet = style.sheet as CSSStyleSheet;
     }