init mod menu + bem class + button presets

src/ui/util/bem.h

@@ -0,0 +1,33 @@
+#ifndef RECOMPUI_ELEMENTS_BEM
+#define RECOMPUI_ELEMENTS_BEM
+
+#include <string>
+
+namespace recompui {
+    // BEM base class
+    class BEM {
+    public:
+        std::string block;
+
+        BEM(const std::string &block) : block(block) {}
+        virtual ~BEM() = default;
+
+        const std::string get_block() const {
+            return block;
+        }
+
+        const std::string el(const std::string &element) const {
+            return block + "__" + element;
+        }
+
+        const BEM bem_el(const std::string &element) const {
+            return BEM(el(element));
+        }
+
+        const std::string mod(const std::string &modifier) const {
+            return block + "--" + modifier;
+        }
+    };
+} // namespace recompui
+
+#endif