[web-client] simple theme: move sources to client/simple/src

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

client/simple/src/less/code.less

@@ -0,0 +1,51 @@
+@import "../../generated/pygments.less";
+
+.codelines {
+  margin: @results-margin 0 0 0;
+  padding: @result-padding 0 0 0;
+}
+
+.code-highlight-sxng() {
+  .code-highlight {
+    pre {
+      overflow: auto;
+      margin: 0;
+      padding: 0 0 0.75rem 0;
+    }
+
+    .linenos {
+      user-select: none;
+      cursor: default;
+
+      &::selection {
+        background: transparent; /* WebKit/Blink Browsers */
+      }
+
+      &::-moz-selection {
+        background: transparent; /* Gecko Browsers */
+      }
+      margin-right: 8px;
+      text-align: right;
+    }
+
+    span.linenos {
+      color: var(--color-line-number);
+    }
+  }
+}
+
+.code-highlight-sxng();
+
+/// Dark Theme (autoswitch based on device pref)
+@media (prefers-color-scheme: dark) {
+  :root.theme-auto {
+    .code-highlight-dark();
+    .code-highlight-sxng();
+  }
+}
+
+// Dark Theme by preferences
+:root.theme-dark {
+  .code-highlight-dark();
+  .code-highlight-sxng();
+}