diff --git a/include/config.h b/include/config.h
index 2d238ad..25f5886 100644
--- a/include/config.h
+++ b/include/config.h
@@ -45,7 +45,7 @@ namespace cfg {
  * The default implementation is using @p static_cast.
  *
  * @tparam From The original type.
- * @tparam To   A new type.
+ * @tparam To A new type.
  *
  * @note
  * If a custom type needs to be saved to a configuration file,
@@ -282,9 +282,7 @@ class VarConverter<std::unordered_map<std::string, T>, std::string> {
     }
 };
 
-/**
- * Basic information about a configuration variable.
- */
+//! Basic information about a configuration variable.
 class VarBase {
 public:
     using Ptr = std::shared_ptr<VarBase>;
@@ -314,9 +312,9 @@ class VarBase {
 /**
  * @brief The configuration variable.
  *
- * @tparam T        The variable type.
- * @tparam FromStr  A converter that can convert a string into a type-matching value.
- * @tparam ToStr    A converter that can convert a type-matching value into a string.
+ * @tparam T The variable type.
+ * @tparam FromStr A converter that can convert a string into a type-matching value.
+ * @tparam ToStr A converter that can convert a type-matching value into a string.
  */
 template <typename T, typename FromStr = VarConverter<std::string, T>,
           typename ToStr = VarConverter<T, std::string>>
@@ -329,8 +327,8 @@ class Var : public VarBase {
     /**
      * @brief The listener for value change events.
      *
-     * @param old_val   The old value before changing.
-     * @param new_val   The new value after changing.
+     * @param old_val The old value before changing.
+     * @param new_val The new value after changing.
      */
     using OnChange = std::function<void(const T& old_val, const T& new_val)>;
 
@@ -387,7 +385,7 @@ class Var : public VarBase {
     /**
      * @brief Remove a listener.
      *
-     * @param key   A unique key corresponding to the listener.
+     * @param key A unique key corresponding to the listener.
      */
     void RemoveListener(const std::uint64_t key) noexcept {
         const std::unique_lock locker {mtx_};
@@ -397,7 +395,7 @@ class Var : public VarBase {
     /**
      * @brief Add a listener for value change events.
      *
-     * @param listener  A listener.
+     * @param listener A listener.
      * @return A unique key corresponding to the listener.
      */
     std::uint64_t AddListener(OnChange listener) noexcept {
@@ -420,9 +418,7 @@ class Var : public VarBase {
     std::unordered_map<std::uint64_t, OnChange> listeners_;
 };
 
-/**
- * The configuration.
- */
+//! The configuration.
 class Config {
 public:
     using Ptr = std::shared_ptr<Config>;
@@ -458,8 +454,8 @@ class Config {
     /**
      * @brief Lookup a variable by its name.
      *
-     * @tparam T    A variable type.
-     * @param name  A variable name.
+     * @tparam T A variable type.
+     * @param name A variable name.
      * @return The found variable or @p nullptr.
      *
      * @exception std::invalid_argument The type of the found variable does not match @p T.
diff --git a/include/containers/block_deque.h b/include/containers/block_deque.h
index 6e0f947..505045b 100644
--- a/include/containers/block_deque.h
+++ b/include/containers/block_deque.h
@@ -24,9 +24,7 @@
 
 namespace ws {
 
-/**
- * The block double-ended queue.
- */
+//! The block double-ended queue.
 template <typename T>
 class BlockDeque {
 public:
diff --git a/include/containers/buffer.h b/include/containers/buffer.h
index cf5adf4..6c89457 100644
--- a/include/containers/buffer.h
+++ b/include/containers/buffer.h
@@ -42,6 +42,7 @@ enum class NewLine {
  * @brief An auto-expandable buffer, supporting storing bytes and strings.
  *
  * @details
+ * @code
  *                 Writing Offset ──────┐
  * Reading Offset ─────┐                │
  *                     │                │
@@ -49,6 +50,8 @@ enum class NewLine {
  * ┌───────────────────▼────────────────▼────────────────┐
  * │ Prependable Bytes │ Readable Bytes │ Writable Bytes │
  * └───────────────────┴────────────────┴────────────────┘
+ * @endcode
+ *
  * Prependable space can be reused.
  */
 class Buffer {
@@ -163,9 +166,7 @@ class Buffer {
     std::atomic<std::size_t> write_pos_ {0};
 };
 
-/**
- * An enhanced buffer supporting I/O reading and writing.
- */
+//! An enhanced buffer supporting I/O reading and writing.
 class IOBuffer : public Buffer {
 public:
     using Buffer::Buffer;
diff --git a/include/containers/epoller.h b/include/containers/epoller.h
index c3b8567..86e2130 100644
--- a/include/containers/epoller.h
+++ b/include/containers/epoller.h
@@ -24,7 +24,10 @@
 namespace ws {
 
 /**
+ * @brief
  * The I/O event notification facility.
+ *
+ * @details
  * It monitors multiple file descriptors to see if I/O is possible on any of them.
  */
 class Epoller {
@@ -34,7 +37,7 @@ class Epoller {
     /**
      * @brief Create an epoller.
      *
-     * @param capacity  The maximum number of file descriptors to be monitored.
+     * @param capacity The maximum number of file descriptors to be monitored.
      *
      * @exception std::system_error Creation failed.
      */
@@ -65,7 +68,7 @@ class Epoller {
     /**
      * @brief Wait for events.
      *
-     * @param time_out  The maximum time to wait.
+     * @param time_out The maximum time to wait.
      * @return
      * The number of file descriptors ready for the requested I/O,
      * or zero if getting a time-out.
@@ -94,8 +97,8 @@ class Epoller {
     /**
      * @brief Perform control operations on a file descriptor.
      *
-     * @param ctl   Addition, deletion or modification.
-     * @param fd    A file descriptor.
+     * @param ctl Addition, deletion or modification.
+     * @param fd A file descriptor.
      * @param events
      * The event associated with the file descriptor.
      * It can be @p std::nullopt if the operation is deletion.
diff --git a/include/containers/heap_timer.h b/include/containers/heap_timer.h
index 7b7152a..aea80ad 100644
--- a/include/containers/heap_timer.h
+++ b/include/containers/heap_timer.h
@@ -32,10 +32,12 @@ namespace ws {
 /**
  * @brief
  * The timer system based on a min-heap.
+ *
+ * @details
  * Timers are maintained in a min-heap ordered by expiration time.
  * When a timer expires, its callback will be invoked.
  *
- * @tparam Key  The type of node keys.
+ * @tparam Key The type of node keys.
  */
 template <typename Key>
 class HeapTimer {
@@ -63,8 +65,8 @@ class HeapTimer {
     /**
      * @brief Adjust a node's expiration time.
      *
-     * @param key           A key.
-     * @param expiration    A new duration from now to its expiration time.
+     * @param key A key.
+     * @param expiration A new duration from now to its expiration time.
      *
      * @exception std::out_of_range The timer system does not contain any node with the specific key.
      */
@@ -73,8 +75,8 @@ class HeapTimer {
     /**
      * @brief Adjust a node's expiration time.
      *
-     * @param key           A key.
-     * @param expiration    A new expiration time.
+     * @param key A key.
+     * @param expiration A new expiration time.
      *
      * @exception std::out_of_range The timer system does not contain any node with the specific key.
      */
@@ -83,9 +85,9 @@ class HeapTimer {
     /**
      * @brief Push a node into the timer system.
      *
-     * @param key           A key.
-     * @param expiration    A duration from now to its expiration time.
-     * @param callback      A time-out callback that will be invoked when the node expires.
+     * @param key A key.
+     * @param expiration A duration from now to its expiration time.
+     * @param callback A time-out callback that will be invoked when the node expires.
      */
     void Push(const Key& key, Clock::duration expiration,
               TimeOutCallback callback) noexcept;
@@ -93,9 +95,9 @@ class HeapTimer {
     /**
      * @brief Push a node into the timer system.
      *
-     * @param key           A key.
-     * @param expiration    An expiration time.
-     * @param callback      A time-out callback that will be invoked when the node expires.
+     * @param key A key.
+     * @param expiration An expiration time.
+     * @param callback A time-out callback that will be invoked when the node expires.
      */
     void Push(const Key& key, Clock::time_point expiration,
               TimeOutCallback callback) noexcept;
@@ -212,6 +214,7 @@ class HeapTimer {
     std::optional<std::size_t> Parent(std::size_t idx) const noexcept;
 
     /**
+     * @brief
      * Get the index of a node's child that has a shorter expiration time,
      * or @p std::nullopt if it does not exist.
      */
diff --git a/include/containers/thread_pool.h b/include/containers/thread_pool.h
index a1bdd7b..335ae03 100644
--- a/include/containers/thread_pool.h
+++ b/include/containers/thread_pool.h
@@ -26,9 +26,7 @@
 
 namespace ws {
 
-/**
- * The thread pool.
- */
+//! The thread pool.
 class ThreadPool {
 public:
     using Task = std::function<void()>;
@@ -62,15 +60,16 @@ class ThreadPool {
     void Push(Task task) noexcept;
 
     /**
-     * Close the thread pool.
+     * @brief Close the thread pool.
+     *
+     * @details
      * The remaining tasks will not be executed.
      */
     void Close() noexcept;
 
 private:
     /**
-     * @brief
-     * Continually pop and execute tasks.
+     * @brief Continually pop and execute tasks.
      *
      * @warning
      * Any exceptions raised in callbacks will not be rethrown.
diff --git a/include/http.h b/include/http.h
index 05265b1..1a7005f 100644
--- a/include/http.h
+++ b/include/http.h
@@ -69,6 +69,7 @@ std::ostream& operator<<(std::ostream& os, Method method) noexcept;
 inline constexpr std::string_view new_line {"\r\n"};
 
 /**
+ * @brief
  * Get a file's content type.
  * @p application/octet-stream is used to indicate that a file contains arbitrary binary data.
  */
@@ -93,6 +94,7 @@ char DecodeURLEncodedCharacter(const std::string& str);
 std::string DecodeURLEncodedString(const std::string& str);
 
 /**
+ * @brief
  * Get the HTML placeholder for an HTTP parameter.
  * It can be used to insert actual data into an HTML page.
  */
@@ -188,9 +190,7 @@ class ConnectionImpl {
     MappedReadOnlyFile file_;
 };
 
-/**
- * The HTTP connection.
- */
+//! The HTTP connection.
 template <ValidIPAddr IPAddr>
 class Connection : public ConnectionImpl {
 public:
diff --git a/include/io.h b/include/io.h
index bf5eef6..420e69c 100644
--- a/include/io.h
+++ b/include/io.h
@@ -25,10 +25,7 @@ class Buffer;
 
 namespace io {
 
-/**
- * @interface IReader
- * @brief An I/O reading interface interacting with buffers.
- */
+//! An I/O reading interface interacting with buffers.
 class IReader {
 public:
     virtual ~IReader() noexcept = default;
@@ -37,10 +34,7 @@ class IReader {
     virtual std::size_t ReadFrom(Buffer& buf) = 0;
 };
 
-/**
- * @interface IWriter
- * @brief An I/O writing interface interacting with buffers.
- */
+//! An I/O writing interface interacting with buffers.
 class IWriter {
 public:
     virtual ~IWriter() noexcept = default;
@@ -49,14 +43,13 @@ class IWriter {
     virtual std::size_t WriteTo(Buffer& buf) = 0;
 };
 
-/**
- * @interface IReadWriter
- * @brief An I/O interface interacting with buffers.
- */
+//! An I/O interface interacting with buffers.
 class IReadWriter : public virtual IReader, public virtual IWriter {};
 
 /**
- * Null I/O.
+ * @brief Null I/O.
+ *
+ * @details
  * It simply consumes a buffer's all readable or writable space,
  * without reading or writing anything.
  */
@@ -67,9 +60,7 @@ class Null : public virtual IReadWriter {
     std::size_t ReadFrom(Buffer& buf) noexcept override;
 };
 
-/**
- * I/O for string streams.
- */
+//! I/O for string streams.
 class StringStream : public virtual IReadWriter {
 public:
     /**
@@ -105,9 +96,7 @@ class StringStream : public virtual IReadWriter {
     std::ostream& write_;
 };
 
-/**
- * I/O for file descriptors.
- */
+//! I/O for file descriptors.
 class FileDescriptor : public virtual IReadWriter {
 public:
     /**
@@ -135,14 +124,8 @@ class FileDescriptor : public virtual IReadWriter {
 
     FileDescriptor& operator=(FileDescriptor&&) = delete;
 
-    /**
-     * @exception std::system_error Failed to read data from the descriptor.
-     */
     std::size_t WriteTo(Buffer& buf) override;
 
-    /**
-     * @exception std::system_error Failed to write data to the descriptor.
-     */
     std::size_t ReadFrom(Buffer& buf) override;
 
 private:
diff --git a/include/ip.h b/include/ip.h
index 3784e45..9044f21 100644
--- a/include/ip.h
+++ b/include/ip.h
@@ -20,10 +20,7 @@
 
 namespace ws {
 
-/**
- * @interface IPAddr
- * @brief The interface of IP address.
- */
+//! The interface of IP address.
 class IPAddr {
 public:
     virtual ~IPAddr() noexcept = default;
@@ -42,9 +39,7 @@ class IPAddr {
     virtual std::string IPAddress() const noexcept = 0;
 };
 
-/**
- * The IPv4 address.
- */
+//! The IPv4 address.
 class IPv4Addr : public IPAddr {
 public:
     static constexpr int version {AF_INET};
@@ -76,9 +71,7 @@ class IPv4Addr : public IPAddr {
     sockaddr_in raw_ {};
 };
 
-/**
- * The IPv6 address.
- */
+//! The IPv6 address.
 class IPv6Addr : public IPAddr {
 public:
     static constexpr int version {AF_INET6};
@@ -110,12 +103,6 @@ class IPv6Addr : public IPAddr {
     sockaddr_in6 raw_ {};
 };
 
-/**
- * @concept ValidIPAddr
- * @brief A valid IP address.
- *
- * @tparam T    @p IPv4Addr or @p IPv6Addr.
- */
 template <typename T>
 concept ValidIPAddr = std::same_as<T, IPv4Addr> || std::same_as<T, IPv6Addr>;
 
diff --git a/include/log.h b/include/log.h
index c07254e..3f40f1d 100644
--- a/include/log.h
+++ b/include/log.h
@@ -1,6 +1,7 @@
 /**
  * @file log.h
  * @brief The logging system.
+ *
  * @details
  * The supported tags and corresponding fields.
  * - @p m: Dispaly the event message.
@@ -79,9 +80,7 @@ std::ostream& operator<<(std::ostream& os, AppenderType type) noexcept;
  */
 AppenderType StringToAppenderType(std::string str);
 
-/**
- * The log event.
- */
+//! The log event.
 class Event {
 public:
     using Ptr = std::shared_ptr<Event>;
@@ -91,10 +90,10 @@ class Event {
     /**
      * @brief Create an event.
      *
-     * @param level     The event level.
-     * @param location  The event location.
+     * @param level The event level.
+     * @param location The event location.
      * @param thread_id The ID of the thread where the event occurred.
-     * @param time      The event time.
+     * @param time The event time.
      *
      * @todo Replace @p std::experimental::source_location with @p std::source_location.
      */
@@ -145,9 +144,7 @@ class Event {
 
 Event::Ptr operator<<(Event::Ptr event, std::string_view msg) noexcept;
 
-/**
- * The event formatter.
- */
+//! The event formatter.
 class Formatter {
 public:
     using Ptr = std::shared_ptr<Formatter>;
@@ -155,7 +152,6 @@ class Formatter {
     static Formatter::Ptr Default() noexcept;
 
     /**
-     * @interface Field
      * @brief
      * The field formatter for different information.
      * A formatter usually needs multiple field formatters, such as for thread ID and time.
@@ -169,7 +165,7 @@ class Formatter {
         /**
          * @brief Create a field formatter.
          *
-         * @param format    An optional format required for some fields.
+         * @param format An optional format required for some fields.
          */
         explicit Field(std::string_view format = "") noexcept;
 
@@ -180,6 +176,7 @@ class Formatter {
                             const Event& event) noexcept = 0;
 
         /**
+         * @brief
          * Get the tag representing a field.
          * The tag does not contain the preceding symbol @p %.
          */
@@ -189,7 +186,7 @@ class Formatter {
     /**
      * @brief Create a formatter.
      *
-     * @param pattern   A format pattern, consisting of multiple fields and their format.
+     * @param pattern A format pattern, consisting of multiple fields and their format.
      *
      * @exception std::invalid_argument The pattern is invalid.
      */
@@ -205,9 +202,7 @@ class Formatter {
     std::list<Field::Ptr> fields_;
 };
 
-/**
- * The appender that writes events to a specific place.
- */
+//! The appender that writes events to a specific place.
 class Appender {
 public:
     using Ptr = std::shared_ptr<Appender>;
@@ -253,9 +248,7 @@ class Appender {
     Formatter::Ptr formatter_;
 };
 
-/**
- * The appender that writes events to the standard output stream.
- */
+//! The appender that writes events to the standard output stream.
 class StdOutAppender : public Appender {
 public:
     using Ptr = std::shared_ptr<StdOutAppender>;
@@ -267,9 +260,7 @@ class StdOutAppender : public Appender {
     std::string ToYamlString() const noexcept override;
 };
 
-/**
- * The appender that writes events to a file.
- */
+//! The appender that writes events to a file.
 class FileAppender : public Appender {
 public:
     using Ptr = std::shared_ptr<FileAppender>;
@@ -295,6 +286,7 @@ class FileAppender : public Appender {
 };
 
 /**
+ * @brief
  * The logger, containing a list of appenders.
  * It can work synchronously or asynchronously.
  */
@@ -305,7 +297,7 @@ class Logger {
     /**
      * @brief Create a logger.
      *
-     * @param name  A name.
+     * @param name A name.
      * @param level
      * The lowest event level.
      * Any event with a level lower than it will not be processed.
@@ -343,7 +335,10 @@ class Logger {
     Formatter::Ptr GetDefaultFormatter() const noexcept;
 
     /**
+     * @brief
      * Set a default formatter.
+     *
+     * @details
      * If a newly added appender does not provide a formatter,
      * the default formatter will be used.
      */
@@ -392,6 +387,7 @@ Logger::Ptr operator<<(Logger::Ptr logger, Event::Ptr event) noexcept;
  *
  * @details
  * It can be used as follows:
+ *
  * @code {.cpp}
  * EventWriter {logger, event}.MessageStream() << "A message";
  * @endcode
@@ -417,9 +413,7 @@ class EventWriter {
     Event::Ptr event_;
 };
 
-/**
- * The logger manager, maintaining a collection of loggers.
- */
+//! The logger manager, maintaining a collection of loggers.
 class Manager {
 public:
     /**
diff --git a/include/test_util.h b/include/test_util.h
index 5bd3583..5d9fd41 100644
--- a/include/test_util.h
+++ b/include/test_util.h
@@ -25,6 +25,7 @@ namespace ws::test {
  *
  * @details
  * The format is @p SuiteName.CaseName.
+ *
  * @code {.cpp}
  * TEST(SuiteName, CaseName) {
  *     // ...
diff --git a/include/util.h b/include/util.h
index 3ecf55c..87d619c 100644
--- a/include/util.h
+++ b/include/util.h
@@ -59,8 +59,8 @@ std::vector<std::string> SplitStringToLines(const std::string& str) noexcept;
 /**
  * @brief Load a @p YAML node from a string.
  *
- * @param str               A @p YAML string.
- * @param required_fields   Required fields.
+ * @param str A @p YAML string.
+ * @param required_fields Required fields.
  *
  * @exception std::invalid_argument The node does not contain all required fields.
  */
@@ -97,9 +97,9 @@ std::uint32_t CurrentThreadId() noexcept;
 /**
  * @brief Get a backtrace for the calling program.
  *
- * @param[out] stack    An address array.
- * @param size          The maximum number of addresses.
- * @param skip          The number of addresses to ignore.
+ * @param[out] stack An address array.
+ * @param size The maximum number of addresses.
+ * @param skip The number of addresses to ignore.
  */
 void Backtrace(std::vector<std::string>& stack, std::size_t size,
                std::size_t skip = 0) noexcept;
@@ -107,8 +107,8 @@ void Backtrace(std::vector<std::string>& stack, std::size_t size,
 /**
  * @brief Get a backtrace for the calling program.
  *
- * @param size  The maximum number of addresses.
- * @param skip  The number of addresses to ignore.
+ * @param size The maximum number of addresses.
+ * @param skip The number of addresses to ignore.
  * @return A string containing the backtrace.
  */
 std::string Backtrace(std::size_t size, std::size_t skip = 0,
@@ -117,7 +117,7 @@ std::string Backtrace(std::size_t size, std::size_t skip = 0,
 /**
  * @brief The singleton pattern interface for references.
  *
- * @tparam T    A type using the singleton pattern.
+ * @tparam T A type using the singleton pattern.
  * @tparam Args The arguments of the singleton instance, referring to one of its constructors.
  */
 template <typename T, typename... Args>
@@ -138,7 +138,7 @@ class Singleton {
 /**
  * @brief The singleton pattern interface for smart points.
  *
- * @tparam T    A type using the singleton pattern.
+ * @tparam T A type using the singleton pattern.
  * @tparam Args The argument types of the singleton instance, referring to one of its constructors.
  */
 template <typename T, typename... Args>
@@ -164,8 +164,8 @@ class RAII {
     /**
      * @brief Create a RAII for an object.
      *
-     * @param obj       An object needing to be cleaned.
-     * @param cleaner   A cleaner.
+     * @param obj An object needing to be cleaned.
+     * @param cleaner A cleaner.
      */
     explicit RAII(T obj, Cleaner cleaner) noexcept :
         obj_ {std::move(obj)}, cleaner_ {std::move(cleaner)} {}
@@ -192,7 +192,10 @@ class RAII {
 };
 
 /**
+ * @brief
  * RAII for a read-only file that has been mapped into memory.
+ *
+ * @details
  * It encapsulates @p stat, @p mmap and @p munmap of Linux system.
  */
 class MappedReadOnlyFile {
@@ -213,8 +216,8 @@ class MappedReadOnlyFile {
      * @brief Map a file into memory.
      *
      * @exception std::invalid_argument The path refers to a directory.
-     * @exception std::runtime_error    No permission to access the file.
-     * @exception std::system_error     Failed to map the file.
+     * @exception std::runtime_error No permission to access the file.
+     * @exception std::system_error Failed to map the file.
      */
     std::byte* Map(std::string path);
 
@@ -235,8 +238,8 @@ class MappedReadOnlyFile {
      * @brief Check the file.
      *
      * @exception std::invalid_argument The path refers to a directory.
-     * @exception std::runtime_error    No permission to access the file.
-     * @exception std::system_error     Other system errors.
+     * @exception std::runtime_error No permission to access the file.
+     * @exception std::system_error Other system errors.
      */
     void Check();
 
diff --git a/include/web_server.h b/include/web_server.h
index a6b0df1..cfdff88 100644
--- a/include/web_server.h
+++ b/include/web_server.h
@@ -53,7 +53,7 @@ class WebServer {
     /**
      * @brief Create a web server.
      *
-     * @param port          A listening port.
+     * @param port A listening port.
      * @param alive_time
      * A maximum alive time for client timers.
      * A client's timer will be refreshed if it sends or receives data.
@@ -385,9 +385,7 @@ class WebServer {
     log::Logger::Ptr logger_;
 };
 
-/**
- * The builder for web servers.
- */
+//! The builder for web servers.
 template <ValidIPAddr IPAddr>
 class WebServerBuilder {
 public:
diff --git a/src/config/config.cpp b/src/config/config.cpp
index 59814d6..2251855 100644
--- a/src/config/config.cpp
+++ b/src/config/config.cpp
@@ -13,19 +13,21 @@ namespace {
  * @details
  * The return value recursively contains members on every level, not just leaves.
  * For example, for the following @p YAML file:
+ *
  * @code {.yaml}
  * system:
  *   port: 80
  *   ip: "127.0.0.1"
  * @endcode
+ *
  * This method will return a list of fours items:
  * - A node with an empty name representing the entire node.
  * - A node with named @p system representing the port and ip address.
  * - A node with named @p system.port representing the port.
  * - A node with named @p system.ip representing the ip address.
  *
- * @param node      A @p YAML node.
- * @param prefix    A prefix representing the node level.
+ * @param node A @p YAML node.
+ * @param prefix A prefix representing the node level.
  * @return A list of members and names representing their levels.
  */
 std::list<std::pair<std::string, YAML::Node>> ExtractMembers(
diff --git a/src/http/request.cpp b/src/http/request.cpp
index 5df6843..b0683d8 100644
--- a/src/http/request.cpp
+++ b/src/http/request.cpp
@@ -8,10 +8,7 @@
 
 namespace ws::http {
 
-/**
- * @interface State
- * @brief The interface of parsing state.
- */
+//! The interface of parsing state.
 class Request::State {
 public:
     explicit State(Request& parser) noexcept : parser_ {parser} {}
diff --git a/src/http/request.h b/src/http/request.h
index 658bf78..68fb3e7 100644
--- a/src/http/request.h
+++ b/src/http/request.h
@@ -21,9 +21,7 @@
 
 namespace ws::http {
 
-/**
- * The HTTP request parser.
- */
+//! The HTTP request parser.
 class Request {
 public:
     class State;
diff --git a/src/http/response.h b/src/http/response.h
index 28d0b4d..710673e 100644
--- a/src/http/response.h
+++ b/src/http/response.h
@@ -22,9 +22,7 @@
 
 namespace ws::http {
 
-/**
- * The HTTP response builder.
- */
+//! The HTTP response builder.
 class Response {
 public:
     /**
@@ -53,8 +51,8 @@ class Response {
     /**
      * @brief Build an HTTP response from a file request.
      *
-     * @param[out] buf  An output buffer where the response content will be written to.
-     * @param file      A file path. If it is a relative path, it will be relative to the root directory.
+     * @param[out] buf An output buffer where the response content will be written to.
+     * @param file A file path. If it is a relative path, it will be relative to the root directory.
      * @param[out] code The HTTP status code representing the file request.
      * @return
      * A read-only mapped file.  @p std::nullopt if the file request failed.
@@ -68,7 +66,7 @@ class Response {
     /**
      * @brief Build an HTTP response from a file request.
      *
-     * @param[out] buf  An output buffer where the response content will be written to.
+     * @param[out] buf An output buffer where the response content will be written to.
      * @param html
      * The path of an HTML page.
      * If it is a relative path, it will be relative to the root directory.
@@ -87,9 +85,9 @@ class Response {
     /**
      * @brief Build a response from HTTP status.
      *
-     * @param[out] buf  An output buffer where the response content will be written to.
-     * @param code      An HTTP status code.
-     * @param msg       An optional message.
+     * @param[out] buf An output buffer where the response content will be written to.
+     * @param code An HTTP status code.
+     * @param msg An optional message.
      */
     void Build(Buffer& buf, StatusCode code, std::string msg = "") noexcept;
 
diff --git a/src/log/config_init.h b/src/log/config_init.h
index 9bd8256..f3b1a2a 100644
--- a/src/log/config_init.h
+++ b/src/log/config_init.h
@@ -5,6 +5,7 @@
  * @details
  * @p YAML configuration.
  * An example is shown below:
+ *
  * @code {.yaml}
  * loggers:
  *   - name: root
@@ -37,9 +38,7 @@
 
 namespace ws::log {
 
-/**
- * The appender configuration.
- */
+//! The appender configuration.
 struct AppenderConfig {
     AppenderType type;
 
@@ -54,9 +53,7 @@ bool operator==(const AppenderConfig&, const AppenderConfig&) noexcept;
 
 bool operator!=(const AppenderConfig&, const AppenderConfig&) noexcept;
 
-/**
- * The logger configuration.
- */
+//! The logger configuration.
 struct LoggerConfig {
     std::string name;
 
@@ -77,9 +74,7 @@ bool operator!=(const LoggerConfig&, const LoggerConfig&) noexcept;
 
 }  // namespace ws::log
 
-/**
- * The hash for unordered sets.
- */
+//! The hash for unordered sets.
 template <>
 struct std::hash<ws::log::LoggerConfig> {
     std::size_t operator()(const ws::log::LoggerConfig& logger) const noexcept {
@@ -192,8 +187,8 @@ namespace log {
 /**
  * @brief Set the listener callback for a logger configuration.
  *
- * @param loggers   A logger configuration.
- * @param manager   A logger manager. It will adjust its loggers when the configuration changes.
+ * @param loggers A logger configuration.
+ * @param manager A logger manager. It will adjust its loggers when the configuration changes.
  */
 cfg::Var<std::unordered_set<LoggerConfig>>::Ptr SetListener(
     cfg::Var<std::unordered_set<LoggerConfig>>::Ptr loggers,
diff --git a/src/log/field.h b/src/log/field.h
index a4062d0..65286a1 100644
--- a/src/log/field.h
+++ b/src/log/field.h
@@ -149,7 +149,9 @@ class LoggerName : public Formatter::Field {
 };
 
 /**
- * The raw field.
+ * @brief The raw field.
+ *
+ * @details
  * It is an internal structure for conversion between field tags and sub-formatters.
  */
 struct RawField {
@@ -157,13 +159,18 @@ struct RawField {
     bool raw_str;
 
     /**
+     * @brief A raw string.
+     *
+     * @details
      * If the raw field is a raw string, this field will save its content.
      * Otherwise this field is a tag. For example, @p t means a thread ID.
      */
     std::string content;
 
     /**
-     * An optional format.
+     * @brief An optional format.
+     *
+     * @details
      * For example, @p %Y-%m-%d can be used for date display.
      * If the raw field is a raw string, this field will be empty.
      */
diff --git a/src/log/log.cpp b/src/log/log.cpp
index f77c3f8..b68b866 100644
--- a/src/log/log.cpp
+++ b/src/log/log.cpp
@@ -205,9 +205,6 @@ void Logger::AddAppender(const Appender::Ptr appender) noexcept {
     appenders_.push_back(appender);
 }
 
-/**
- * @todo Replace @p std::remove_if with @p std::ranges::remove_if.
- */
 void Logger::RemoveAppender(const Appender::Ptr appender) noexcept {
     const std::lock_guard locker {mtx_};
     std::remove_if(
diff --git a/src/main.cpp b/src/main.cpp
index ffa54bf..30c0a69 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -33,8 +33,8 @@ cfg::Config::Ptr InitDefaultConfig() noexcept {
 /**
  * @brief Load a local configuration.
  *
- * @param config    An existing configuration.
- * @param file      A configuration file.
+ * @param config An existing configuration.
+ * @param file A configuration file.
  */
 cfg::Config::Ptr LoadConfig(const cfg::Config::Ptr config,
                             const std::string& file) {
diff --git a/tests/log_test.cpp b/tests/log_test.cpp
index cda8ce3..c9f7e2c 100644
--- a/tests/log_test.cpp
+++ b/tests/log_test.cpp
@@ -7,9 +7,7 @@
 
 using namespace ws::log;
 
-/**
- * The fake appender that writes events to a string stream.
- */
+//! The fake appender that writes events to a string stream.
 class FakeAppender : public Appender {
 public:
     using Ptr = std::shared_ptr<FakeAppender>;