diff --git a/include/modules/battery.hpp b/include/modules/battery.hpp
index 017b0e48..bbdd0eed 100644
--- a/include/modules/battery.hpp
+++ b/include/modules/battery.hpp
@@ -16,6 +16,7 @@
 #include <vector>
 
 #include "ALabel.hpp"
+#include "bar.hpp"
 #include "util/sleeper_thread.hpp"
 
 namespace waybar::modules {
@@ -28,7 +29,7 @@ namespace fs = std::filesystem;
 
 class Battery : public ALabel {
  public:
-  Battery(const std::string&, const Json::Value&);
+  Battery(const std::string&, const waybar::Bar&, const Json::Value&);
   virtual ~Battery();
   auto update() -> void override;
 
@@ -40,6 +41,7 @@ class Battery : public ALabel {
   const std::string getAdapterStatus(uint8_t capacity) const;
   const std::tuple<uint8_t, float, std::string, float> getInfos();
   const std::string formatTimeRemaining(float hoursRemaining);
+  void setBarClass(std::string&);
 
   int global_watch;
   std::map<fs::path, int> batteries_;
@@ -49,6 +51,7 @@ class Battery : public ALabel {
   std::mutex battery_list_mutex_;
   std::string old_status_;
   bool warnFirstTime_{true};
+  const Bar& bar_;
 
   util::SleeperThread thread_;
   util::SleeperThread thread_battery_update_;
diff --git a/man/waybar-battery.5.scd b/man/waybar-battery.5.scd
index 7827f4a8..52a6a2d1 100644
--- a/man/waybar-battery.5.scd
+++ b/man/waybar-battery.5.scd
@@ -167,3 +167,10 @@ The *battery* module allows one to define custom formats based on up to two fact
 	- *<state>* can be defined in the *config*. For more information see *states*.
 - *#battery.<status>.<state>*
 	- Combination of both *<status>* and *<state>*.
+
+The following classes are applied to the entire Waybar rather than just the
+battery widget:
+
+- *window#waybar.battery-<state>*
+	- *<state>* can be defined in the *config*, as previously mentioned.
+
diff --git a/src/factory.cpp b/src/factory.cpp
index 00fc42ed..2ad5b6fa 100644
--- a/src/factory.cpp
+++ b/src/factory.cpp
@@ -18,7 +18,7 @@ waybar::AModule* waybar::Factory::makeModule(const std::string& name,
     auto id = hash_pos != std::string::npos ? name.substr(hash_pos + 1) : "";
 #if defined(__FreeBSD__) || (defined(__linux__) && !defined(NO_FILESYSTEM))
     if (ref == "battery") {
-      return new waybar::modules::Battery(id, config_[name]);
+      return new waybar::modules::Battery(id, bar_, config_[name]);
     }
 #endif
 #ifdef HAVE_GAMEMODE
diff --git a/src/modules/battery.cpp b/src/modules/battery.cpp
index 70268c8a..2495b33a 100644
--- a/src/modules/battery.cpp
+++ b/src/modules/battery.cpp
@@ -1,12 +1,13 @@
 #include "modules/battery.hpp"
+#include <algorithm>
 #if defined(__FreeBSD__)
 #include <sys/sysctl.h>
 #endif
 #include <spdlog/spdlog.h>
 
 #include <iostream>
-waybar::modules::Battery::Battery(const std::string& id, const Json::Value& config)
-    : ALabel(config, "battery", id, "{capacity}%", 60) {
+waybar::modules::Battery::Battery(const std::string& id, const Bar& bar, const Json::Value& config)
+    : ALabel(config, "battery", id, "{capacity}%", 60), bar_(bar) {
 #if defined(__linux__)
   battery_watch_fd_ = inotify_init1(IN_CLOEXEC);
   if (battery_watch_fd_ == -1) {
@@ -641,6 +642,7 @@ auto waybar::modules::Battery::update() -> void {
                  [](char ch) { return ch == ' ' ? '-' : std::tolower(ch); });
   auto format = format_;
   auto state = getState(capacity, true);
+  setBarClass(state);
   auto time_remaining_formatted = formatTimeRemaining(time_remaining);
   if (tooltipEnabled()) {
     std::string tooltip_text_default;
@@ -689,3 +691,39 @@ auto waybar::modules::Battery::update() -> void {
   // Call parent update
   ALabel::update();
 }
+
+void waybar::modules::Battery::setBarClass(std::string& state) {
+  auto classes = bar_.window.get_style_context()->list_classes();
+  const std::string prefix = "battery-";
+
+  auto old_class_it = std::find_if(classes.begin(), classes.end(),
+    [&prefix](auto classname) {
+        return classname.rfind(prefix, 0) == 0;
+    });
+
+  auto new_class = prefix + state;
+
+  // If the bar doesn't have any `battery-` class
+  if(old_class_it == classes.end()) {
+    if(!state.empty()) {
+        bar_.window.get_style_context()->add_class(new_class);
+    }
+    return;
+  }
+
+  auto old_class = *old_class_it;
+
+  // If the bar has a `battery-` class,
+  // but `state` is empty
+  if(state.empty()) {
+    bar_.window.get_style_context()->remove_class(old_class);
+    return;
+  }
+
+  // If the bar has a `battery-` class,
+  // and `state` is NOT empty
+  if(old_class != new_class) {
+    bar_.window.get_style_context()->remove_class(old_class);
+    bar_.window.get_style_context()->add_class(new_class);
+  }
+}