diff --git a/README.md b/README.md
index df1701f..6c024aa 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# __Nasal - Modern Interpreter__
+# <img src="./doc/svg/nasal_transparent.svg" height="50px"/> __Nasal - Modern Interpreter__
 
 <img src="./doc/pic/header.png" style="width:600px"></img>
 
diff --git a/doc/README_zh.md b/doc/README_zh.md
index c5b0831..6970633 100644
--- a/doc/README_zh.md
+++ b/doc/README_zh.md
@@ -1,4 +1,4 @@
-# __Nasal - Modern Interpreter__
+# <img src="./svg/nasal_transparent.svg" height="50px"/> __Nasal - Modern Interpreter__
 
 <img src="../doc/pic/header.png" style="width:600px"></img>
 
diff --git a/doc/svg/nasal.svg b/doc/svg/nasal.svg
new file mode 100644
index 0000000..389651a
--- /dev/null
+++ b/doc/svg/nasal.svg
@@ -0,0 +1,18 @@
+<svg width="100" height="100" viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg">
+  <rect width="100" height="100" fill="#9eb0d8"/>
+  <g transform="translate(6,0)">
+    <g fill="#1d2c4e">
+      <!-- left side -->
+      <path d="M 10 10 L 10 80 L 20 90 L 25 90 L 25 20 L 15 10 Z"/>
+      <path d="M 10 10 L 85 85 L 85 90 L 70 90 L 10 30 Z"/>
+      <!-- right-up corner -->
+      <path d="M 30 10 L 70 50 L 70 55 L 30 15 Z" />
+      <path d="M 30 10 L 40 10 L 70 40 L 70 55 Z" />
+      <path d="M 30 10 L 80 10 L 80 15 L 30 15 Z" />
+      <path d="M 72 10 L 72 55 L 65 55 L 65 10 Z" />
+      <path d="M 55 10 L 70 25 L 70 35 L 45 10 Z"/>
+      <path d="M 70 55 L 65 55 L 55 45 L 55 35 Z"/>
+      <path d="M 70 10 L 80 10 L 80 15 L 70 25 Z"/>
+      </g>
+  </g>
+</svg>
\ No newline at end of file
diff --git a/doc/svg/nasal_transparent.svg b/doc/svg/nasal_transparent.svg
new file mode 100644
index 0000000..e26e972
--- /dev/null
+++ b/doc/svg/nasal_transparent.svg
@@ -0,0 +1,18 @@
+<svg width="100" height="100" viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg">
+  <!-- <rect width="100" height="100" fill="#9eb0d8"/> -->
+  <g transform="translate(6,0)">
+    <g fill="#6e93e9">
+      <!-- left side -->
+      <path d="M 10 10 L 10 80 L 20 90 L 25 90 L 25 20 L 15 10 Z"/>
+      <path d="M 10 10 L 85 85 L 85 90 L 70 90 L 10 30 Z"/>
+      <!-- right-up corner -->
+      <path d="M 30 10 L 70 50 L 70 55 L 30 15 Z" />
+      <path d="M 30 10 L 40 10 L 70 40 L 70 55 Z" />
+      <path d="M 30 10 L 80 10 L 80 15 L 30 15 Z" />
+      <path d="M 72 10 L 72 55 L 65 55 L 65 10 Z" />
+      <path d="M 55 10 L 70 25 L 70 35 L 45 10 Z"/>
+      <path d="M 70 55 L 65 55 L 55 45 L 55 35 Z"/>
+      <path d="M 70 10 L 80 10 L 80 15 L 70 25 Z"/>
+      </g>
+  </g>
+</svg>
\ No newline at end of file
diff --git a/doc/tutorial.md b/doc/tutorial.md
index 1dbd2ab..18efbf5 100644
--- a/doc/tutorial.md
+++ b/doc/tutorial.md
@@ -1,4 +1,4 @@
-# __Tutorial__
+# <img src="./svg/nasal_transparent.svg" height="50px"/> __Tutorial__
 
 ![mandelbrotset](../doc/pic/mandelbrotset.png)
 
diff --git a/doc/tutorial_zh.md b/doc/tutorial_zh.md
index bc2220a..715782c 100644
--- a/doc/tutorial_zh.md
+++ b/doc/tutorial_zh.md
@@ -1,4 +1,4 @@
-# __教程__
+# <img src="./svg/nasal_transparent.svg" height="50px"/> __教程__
 
 ![mandelbrotset](../doc/pic/mandelbrotset.png)
 
diff --git a/src/main.cpp b/src/main.cpp
index 70e344f..aac6c26 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -44,7 +44,7 @@ std::ostream& logo(std::ostream& out) {
     << " - http://fgprc.org\n"
     << " - http://fgprc.org.cn\n"
     << "\n"
-    << "input <nasal -h> to get help .\n\n";
+    << "input <nasal -h> to get help.\n\n";
     return out;
 }