diff --git a/hatenablog/css/pseudocode.css b/hatenablog/css/pseudocode.css
new file mode 100644
index 00000000..d666d65e
--- /dev/null
+++ b/hatenablog/css/pseudocode.css
@@ -0,0 +1,101 @@
+body {
+    font-family: Lato;
+}
+button {
+    font-family: Lato;
+    color: #5f6368;
+    background-color: white;
+    border-radius: 4px;
+    border: 1px solid #dadce0;
+}
+button:focus {
+    color: white;
+    background-color: #ffadba;
+    border-radius: 4px;
+    border: 1px solid #ffadba;
+    font-weight: bold;
+    outline: 2px solid rgba(255, 173, 186, 0.7);
+}
+.error {
+    font-family: monospace;
+    color: #a11
+}
+.frame-wrapper {
+    position: relative;
+}
+.frame-wrapper .text-label {
+    background-color: white;
+    box-shadow: 5px 0 0 white,-5px 0 0 white;
+    color: #5f6368;
+    display: inline;
+    font-size: 12px;
+    left: 12px;
+    margin-bottom: 0;
+    max-width: 300px;
+    padding: 0;
+    position: absolute;
+    top: 0px;
+    word-wrap: break-word;
+}
+.frame-wrapper .div-label {
+    background-color: white;
+    box-shadow: 5px 0 0 white,-5px 0 0 white;
+    color: #5f6368;
+    display: inline;
+    font-size: 12px;
+    left: 12px;
+    margin-bottom: 0;
+    max-width: 300px;
+    padding: 0;
+    position: absolute;
+    top: -8px;
+    word-wrap: break-word;
+}
+.frame-wrapper .text-label.focused, .frame-wrapper .div-label.focused {
+    color: #ffadba;
+}
+.frame-wrapper .textinput {
+    border: 1px solid #dadce0;
+    border-radius: 4px;
+    box-sizing: border-box;
+    color: #3c4043;
+    font-family: 'TheSansMonoCd',monospace;
+    font-weight: 450;
+    font-size: 14px;
+    margin: 8px 0;
+}
+.frame-wrapper input.textinput {
+    padding: 1px 8px;
+    height: 36px;
+}
+.frame-wrapper textarea.textinput {
+    padding: 8px;
+    min-height: 36px;
+    width: 100%;
+}
+.frame-wrapper div.textinput {
+    padding: 8px;
+    min-height: 30px;
+}
+.frame-wrapper .textinput:focus {
+    border: 1px solid #ffadba;
+    outline: 1px solid rgba(255, 173, 186, 0.7);
+}
+
+.pseudocode {
+    -moz-border-radius: 3px;
+    -moz-box-shadow: 0 2px 0 rgba(34,58,112,0.4),0 0 0 2px #fff inset;
+    -webkit-border-radius :3px;
+    -webkit-box-shadow: 0 2px 0 rgba(34,58,112,0.4),0 0 0 2px #fff inset;
+    background-color: #eee;
+    border: 1px solid #ccc;
+    border-radius: 5px;
+    box-shadow: 0 2px 0 rgba(34,58,112,0.4),0 0 0 2px #fff inset;
+    color: #333;
+    display: block;
+    font-family: Menlo, monospace;
+    line-height: 1.4;
+    margin: .4em .1em;
+    padding: .8em 1.8em;
+    text-shadow: 0 0px 0 #fff;
+}
diff --git a/hatenablog/js/pseudocode.js b/hatenablog/js/pseudocode.js
new file mode 100644
index 00000000..3827005d
--- /dev/null
+++ b/hatenablog/js/pseudocode.js
@@ -0,0 +1,86 @@
+function markup(code, elt) {
+  let out = "";
+  let indent = [0];
+  let lineno = 0;
+  let opening = false;
+  let opened = false;
+  let keep = false;
+
+  const RE = /(?:\$(?<TEX>(?:\\.|[^$\\])+)\$)|(?<KW>[\w-]+)/g;
+  const INDENT = /^ */;
+
+  for (const line of code.split("\n")) {
+    let cur = "";
+    let len = line.match(INDENT)[0].length;
+    if (len === line.length) {
+      continue;
+    }
+
+    if (indent[indent.length - 1] < len) {
+      indent.push(len);
+    } else if (indent[indent.length - 1] > len) {
+      indent.pop();
+    }
+
+    for (const match of line.matchAll(RE)) {
+      if (cur !== "") {
+        cur += "\\;";
+      }
+
+      if (match.groups.TEX) {
+        cur += `${match.groups.TEX}`;
+      } else if (match.groups.KW) {
+        if (["function"].includes(match.groups.KW)) {
+          opening = true;
+        }
+        if (/\b(?:const|let|global)/.test(match.groups.KW)) {
+          keep = true;
+        }
+        cur += `\\text{\\textbf{${match.groups.KW}}}`;
+      }
+    }
+
+    if (cur !== "") {
+      if (lineno > 0) {
+        out += "\\\\\n";
+      }
+
+      if (keep) {
+        out += " \\quad".repeat(indent.length - 1);
+      } else if (!opening) {
+        out += `\\qquad {\\scriptsize ${++lineno}}{\\scriptsize\\colon} &`;
+        out += " \\quad".repeat(indent.length - 1);
+      }
+      if (opening) {
+        if (opened) {
+          out += "\n\\end{aligned}\\\\\n";
+          lineno = 0;
+        }
+        out += `& ${cur} \\\\\n`;
+        out += "&\\begin{aligned}\n";
+        opened = true;
+      } else if (keep && !opened) {
+        out += `& ${cur} \\\\\n`;
+      } else {
+        out += ` ${cur}`;
+      }
+    }
+
+    keep = false;
+    opening = false;
+  }
+
+  if (opened) {
+    out += "\n\\end{aligned}";
+  }
+
+  elt.outerHTML = katex.renderToString(`<div><span class="pseudocode">\\begin{aligned}${out}\\end{aligned}</span></div>`, { macros });
+}
+
+document.addEventListener('DOMContentLoaded', (() => {
+  [...document.getElementsByTagName('pre')]
+    .filter((pre) => pre.getAttribute('data-lang') === 'pseudocode')
+    .forEach((pre) => {
+      markup(pre.innerText, pre);
+    });
+}));