Add core theme variables and service adapters

adapters/shlink.css

@@ -0,0 +1,62 @@
+/**
+ * RSP Works - Shlink Theme Adapter
+ * Applies blog theme to Shlink URL shortener
+ *
+ * Note: Shlink is a React app - theming is limited.
+ * This works best injected via Nginx or a browser extension.
+ *
+ * Deploy to: FR1 Nginx config as a location block,
+ * or inject via browser extension on short.rspworks.tech
+ */
+
+@import url('../css/core.css');
+
+/* Base */
+body {
+    background-color: var(--background) !important;
+    color: var(--text-primary) !important;
+    font-family: var(--font-family) !important;
+}
+
+/* Links */
+a {
+    color: var(--link-color) !important;
+}
+a:hover, a:focus {
+    color: var(--link-hover) !important;
+}
+
+/* Shlink uses Bootstrap-style classes */
+.btn-primary {
+    background-color: var(--text-secondary) !important;
+    border-color: var(--text-secondary) !important;
+    color: white !important;
+}
+.btn-primary:hover {
+    background-color: var(--link-hover) !important;
+}
+
+/* Cards */
+.card {
+    background-color: white !important;
+    border-color: #ddd !important;
+}
+
+/* Navbar */
+.navbar {
+    background-color: var(--text-secondary) !important;
+}
+.navbar a, .navbar .nav-link {
+    color: white !important;
+}
+
+/* Headings */
+h1, h2, h3, h4, h5, h6 {
+    color: var(--text-primary) !important;
+}
+
+/* Selection */
+::selection {
+    background: var(--selection-bg);
+    color: var(--selection-text);
+}