42DevOps

Interactive Hand-Drawn Annotations with neat-annotations

2026-07-23T02:00:00+00:00

This blog is now powered by neat-annotations — a zero-JS CSS library for hand-drawn arrows, handwritten labels, and inline highlights.

Here is a quick reference guide on how to annotate text in your Markdown articles!

Inline Highlights (Recommended for body text)

When annotating inline body text, use highlight-only markers without floating notes or arrows. They render cleanly without disrupting line height or overlapping adjacent text:

You can mark important words, highlight key metrics, or emphasize critical commands seamlessly inside any paragraph.

Code & Specification Showcase (“In the Wild”)

When you want to point arrows at code tokens, parameters, or specifications, give lines generous line-height (3.4em) so hand-drawn labels sit cleanly around the target text:

●●● docs/specs/cli.md

- [ ] CLI-042 Add export command #cli !high @blocked_by:CLI-041

Write task output as JSON for scripts and agents

Markdown Markup Syntax

To add annotations to your Markdown posts, simply wrap your target text in a <span> tag:

<!-- Highlight only (no arrow) -->
<span class="ann ann-amber">important note</span>

<!-- Arrow pointing South with handwritten label -->
<span class="ann ann-s ann-blue" data-note="stable ID">CLI-042</span>

<!-- Arrow pointing North with handwritten label -->
<span class="ann ann-n ann-amber" data-note="description">JSON</span>

Math Tests

2020-04-15T00:00:00+00:00

This article showcases mathematical rendering support in Jekyll using KaTeX, demonstrating both inline and block equations.

\[R_{\mu \nu} - {1 \over 2}g_{\mu \nu}\,R + g_{\mu \nu} \Lambda = {8 \pi G \over c^4} T_{\mu \nu}\]

The equation $(x_i \cdot x_j)^2$ is called kernel function and is often written as $k(x_i, x_j)$.

\[\arg\max_\alpha \sum_j \alpha_j - \frac{1}{2} \sum_{j,k} \alpha_j, \alpha_k y_j y_k (x_j \cdot x_k)\] \[f(X) = \frac{1}{(2\pi)^{\frac{n}{2} |\Sigma|^{\frac{1}{2}}}} e^{ - \frac{1}{2} (X - \mu)^T \Sigma^{-1} (X - \mu)}\] \[\mu_i = \sum_{j=1}^N \frac{p_{ij} x}{n_i} \\ \Sigma_i = \sum_{j=1}^N \frac{p_{ij} (x_j - \mu_i) (x_j - \mu_i)^T}{n_i}\\ w_i = \frac{n_i}{N}\] \[S_i^{(t)} = \big \{ x_p : \big \| x_p - \mu^{(t)}_i \big \|^2 \le \big \| x_p - \mu^{(t)}_j \big \|^2 \ \forall j, 1 \le j \le k \big\}\]

Language Tests

2019-06-23T00:00:00+00:00

1. 日本語テスト

This is a Japanese test post to show you how japanese is displayed.

私は昨日ついにその助力家というのの上よりするたなけれ。最も今をお話団はちょうどこの前後なかろでくらいに困りがいるたをは帰着考えたなかって、そうにもするでうたらない。がたを知っないはずも同時に九月をいよいよたありた。

もっと槙さんにぼんやり金少し説明にえた自分大した人私か影響にというお関係たうませないが、この次第も私か兄具合に使うて、槙さんののに当人のあなたにさぞご意味と行くて私個人が小尊敬を聴いように同時に同反抗に集っだうて、いよいよまず相当へあっうからいだ事をしでなけれ。

それでそれでもご時日をしはずはたったいやと突き抜けるますて、その元がは行ったてという獄を尽すていけですた。

この中道具の日その学校はあなたごろがすまなりかとネルソンさんの考えるですん、辺の事実ないというご盲従ありたですと、爺さんのためが薬缶が結果までの箸の当時してならて、多少の十月にためからそういう上からとにかくしましないと触れべきものたで、ないうですと多少お人達したのでたた。

From すぐ使えるダミーテキスト - 日本語 Lorem ipsum.

2. 繁体中文测试

This is a chinese test post to show you how chinese is displayed.

善我王上魚、產生資西員合兒臉趣論。畫衣生這著爸毛親可時，安程幾？合學作。觀經而作建。都非子作這！法如言子你關！手師也。

以也座論頭室業放。要車時地變此親不老高小是統習直麼調未，行年香一？

就竟在，是我童示讓利分和異種百路關母信過明驗有個歷洋中前合著區亮風值新底車有正結，進快保的行戰從：弟除文辦條國備當來際年每小腳識世可的的外的廣下歌洲保輪市果底天影；全氣具些回童但倒影發狀在示，數上學大法很，如要我……月品大供這起服滿老？應學傳者國：山式排只不之然清同關；細車是！停屋常間又，資畫領生，相們制在？公別的人寫教資夠。資再我我！只臉夫藝量不路政吃息緊回力之；兒足灣電空時局我怎初安。意今一子區首者微陸現際安除發連由子由而走學體區園我車當會，經時取頭，嚴了新科同？很夫營動通打，出和導一樂，查旅他。坐是收外子發物北看蘭戰坐車身做可來。道就學務。

國新故。

工步他始能詩的，裝進分星海演意學值例道……於財型目古香亮自和這乎？化經溫詩。只賽嚴大一主價世哥受的沒有中年即病行金拉麼河。主小路了種就小為廣不？

From 亂數假文產生器 - Chinese Lorem Ipsum.

3. 简体中文测试

效育声去本义然空，各值太法心想，场强实地。题铁习点儿表管少间千，只何政亲织文意部，千影画派证男须。手反取长风治增非等直难群，连取及天他己事头级，影数弦适把气快目人。专议以省通引而千个，格则口段度样水热马，地教少务改磨。包思外心半院应她算斯，市外会快记路又火学，劳如肃它准众丧边。

团算部住县单总边素格军所，合音府教看和广光采率位转，位用品根确针百。证其标元角工方海接交他，论象切万世认一响义，治然身本风弦带题。向我次路持加北，她不反心。说总元军例市决，现始即算证养，规走还壳。

因林可相儿应满军，热影省条律因资再，整肃赤心将届。局广写两量备验还，南教事争工民的，备进研上布。素身电活非直，速这区交示从，百层达。资量那毛什京身，白这快。半打容三手开常价或，手严量般象式效，名可重芽门适。来设什一我么，光界美么或，住身式准。造酸改表委验众办地百养，商物战众本列听度名院，制压录丽快与千机内。住需当四议决得命南然照按民置，当住命形金决否矿单外。气象理离开新集增际，三划方工义很年关，拉许准孝口。构片出干计由备美打养，持育总指承入无己。

From 假文生成器， lorem ipsum Chinese

宇宙超级压缩算法的传说

2019-06-18T03:45:19+00:00

话说有一天，外星人开着飞船降落在地球。地球人急忙问：大佬你来干什么？外星人说：我来考察，想带走你们星球上所有的书籍、电影和代码资料回去研究。

地球人赶紧准备，拉来了几千卡车的硬盘保存的数据资料，看着外星人的小飞船：看你怎么带走。

外星人把所有数据扫描完毕后，掏出一把刻度笔，在飞船外壳上一画，留下了一个极其精准的小点，随后开着飞船扬长而去。

问：外星人究竟是如何用一个小点带走全地球数据的？宇宙超级压缩算法如何实现的？

核心算法：四步实现宇宙级压缩

这个谜题的解答，藏在类似于圆周率 $\pi$ 的展开序列与实数精度的特性里。

全人类的所有数据都可以编码进 1 米长飞船上的一个几何位置中：

数据进制转换：将全人类所有的海量数据转成二进制，再转成一串超长的十进制数字 $xxxx\dots$。
构建单位小数：在数字前加上零和小数点，变成一个介于 0 到 1 之间的小数 0.xxxx…。
飞船刻度映射：将飞船全长设为 1 个单位，在距离头部正好为 0.xxxx… 的位置画一个点。
解码还原数据：回到主星后，精准测量该点距离飞船头部的相对位置 $0.xxxx\dots$，读取小数点后的所有数字，即可完整还原全人类数据。

几何线段上的无限容量

在几何学中，长度为 1 的线段包含着无限多个无大小的实数点。

无论小数点后面跟着多少亿位数字，它在长度为 1 的线段上都对应着一个唯一确定的刻度位置。外星人利用整艘飞船作为单位标尺，将全人类的数据编码进唯一的距离刻度中。

Hello World!

2019-06-18T03:45:19+00:00

You’ll find this post in your _posts directory. Go ahead and edit it and re-build the site to see your changes. You can rebuild the site in many different ways, but the most common way is to run jekyll serve, which launches a web server and auto-regenerates your site when a file is updated.

To add new posts, simply add a file in the _posts directory that follows the convention YYYY-MM-DD-name-of-post.ext and includes the necessary front matter. Take a look at the source for this post to get an idea about how it works.

Jekyll also offers powerful support for code snippets:

def print_hi(name)
puts "Hi, #{name}"
end
print_hi('Tom')
#=> prints 'Hi, Tom' to STDOUT.

Check out the Jekyll docs for more info on how to get the most out of Jekyll. File all bugs/feature requests at Jekyll’s GitHub repo. If you have questions, you can ask them on Jekyll Talk.

Code Highlight Tests

2016-05-01T00:00:00+00:00

Test for C

#define UNICODE
#include <windows.h>
 
int main(int argc, char **argv) {
  int speed = 0, speed1 = 0, speed2 = 0; // 1-20
  printf("Set Mouse Speed by Maverick\n");
 
  SystemParametersInfo(SPI_GETMOUSESPEED, 0, &speed, 0);
  printf("Current speed: %2d\n", speed);
 
  if (argc == 1) return 0;
  if (argc >= 2) sscanf(argv[1], "%d", &speed1);
  if (argc >= 3) sscanf(argv[2], "%d", &speed2);
 
  if (argc == 2) // set speed to first value
    speed = speed1;
  else if (speed == speed1 || speed == speed2) // alternate
    speed = speed1 + speed2 - speed;
  else
    speed = speed1;  // start with first value
 
  SystemParametersInfo(SPI_SETMOUSESPEED, 0,  speed, 0);
  SystemParametersInfo(SPI_GETMOUSESPEED, 0, &speed, 0);
  printf("New speed:     %2d\n", speed);
  return 0;
}

Test for Java

import java.util.Map;
import java.util.TreeSet;
 
public class GetEnv {
  /**
   * let's test generics
   * @param args the command line arguments
   */
  public static void main(String[] args) {
    // get a map of environment variables
    Map<String, String> env = System.getenv();
    // build a sorted set out of the keys and iterate
    for(String k: new TreeSet<String>(env.keySet())) {
      System.out.printf("%s = %s\n", k, env.get(k));
    }
  }    
}

Test for Perl

#!perl -w
 
# Time-stamp: <2002/04/06, 13:12:13 (EST), maverick, csvformat.pl>
# Two pass CSV file to table formatter
 
$delim = $#ARGV >= 1 ? $ARGV[1] : ',';
print STDERR "Split pattern: $delim\n";
 
# first pass
open F, "<$ARGV[0]" or die;
while(<F>)
{
  chomp;
  $i = 0;
  map { $max[$_->[1]] = $_->[0] if $_->[0] > ($max[$_->[1]] || 0) }
    (map {[length $_, $i++]} split($delim));
}
close F;
 
print STDERR 'Field width:   ', join(', ', @max), "\n";
print STDERR join(' ', map {'-' x $_} @max);
 
# second pass
open F, "<$ARGV[0]" or die;
while(<F>)
  {
  chomp;
  $i = 0;
  map { printf("%-$max[$_->[1]]s ", $_->[0]) }
    (map {[$_, $i++]} split($delim));
  print "\n";
}
close F;

Test for Python

# test python (sample from offlineimap)
 
class ExitNotifyThread(Thread):
    """This class is designed to alert a "monitor" to the fact that a thread has
    exited and to provide for the ability for it to find out why."""
    def run(self):
        global exitthreads, profiledir
        self.threadid = thread.get_ident()
        try:
            if not profiledir:          # normal case
                Thread.run(self)
            else:
                try:
                    import cProfile as profile
                except ImportError:
                    import profile
                prof = profile.Profile()
                try:
                    prof = prof.runctx("Thread.run(self)", globals(), locals())
                except SystemExit:
                    pass
                prof.dump_stats( \
                            profiledir + "/" + str(self.threadid) + "_" + \
                            self.getName() + ".prof")
        except:
            self.setExitCause('EXCEPTION')
            if sys:
                self.setExitException(sys.exc_info()[1])
                tb = traceback.format_exc()
                self.setExitStackTrace(tb)
        else:
            self.setExitCause('NORMAL')
        if not hasattr(self, 'exitmessage'):
            self.setExitMessage(None)
 
        if exitthreads:
            exitthreads.put(self, True)
 
    def setExitCause(self, cause):
        self.exitcause = cause
    def getExitCause(self):
        """Returns the cause of the exit, one of:
        'EXCEPTION' -- the thread aborted because of an exception
        'NORMAL' -- normal termination."""
        return self.exitcause
    def setExitException(self, exc):
        self.exitexception = exc
    def getExitException(self):
        """If getExitCause() is 'EXCEPTION', holds the value from
        sys.exc_info()[1] for this exception."""
        return self.exitexception
    def setExitStackTrace(self, st):
        self.exitstacktrace = st
    def getExitStackTrace(self):
        """If getExitCause() is 'EXCEPTION', returns a string representing
        the stack trace for this exception."""
        return self.exitstacktrace
    def setExitMessage(self, msg):
        """Sets the exit message to be fetched by a subsequent call to
        getExitMessage.  This message may be any object or type except
        None."""
        self.exitmessage = msg
    def getExitMessage(self):
        """For any exit cause, returns the message previously set by
        a call to setExitMessage(), or None if there was no such message
        set."""
        return self.exitmessage

Test for Bash

#!/bin/bash
cd $ROOT_DIR
DOT_FILES="lastpass weechat ssh Xauthority"
for dotfile in $DOT_FILES; do conform_link "$DATA_DIR/$dotfile" ".$dotfile"; done
 
# TODO: refactor with suffix variables (or common cron values)
 
case "$PLATFORM" in
    linux)
        #conform_link "$CONF_DIR/shell/zshenv" ".zshenv"
        crontab -l > $ROOT_DIR/tmp/crontab-conflict-arch
        cd $ROOT_DIR/$CONF_DIR/cron
        if [[ "$(diff ~/tmp/crontab-conflict-arch crontab-current-arch)" == ""
            ]];
            then # no difference with current backup
                logger "$LOG_PREFIX: crontab live settings match stored "\
                    "settings; no restore required"
                rm ~/tmp/crontab-conflict-arch
            else # current crontab settings in file do not match live settings
                crontab $ROOT_DIR/$CONF_DIR/cron/crontab-current-arch
                logger "$LOG_PREFIX: crontab stored settings conflict with "\
                    "live settings; stored settings restored. "\
                    "Previous settings recorded in ~/tmp/crontab-conflict-arch."
        fi
    ;;

Test for Haskell

{-# LANGUAGE OverloadedStrings #-}
module Main where
 
--import Prelude hiding (id)
--import Control.Category (id)
import Control.Arrow ((>>>), (***), arr)
import Control.Monad (forM_)
-- import Data.Monoid (mempty, mconcat)
 
-- import System.FilePath
 
import Hakyll
 
 
main :: IO ()
main = hakyll $ do
 
    route   "css/*" $ setExtension "css"
    compile "css/*" $ byExtension (error "Not a (S)CSS file")
        [ (".css",  compressCssCompiler)
        , (".scss", sass)
        ]
 
    route   "js/**" idRoute
    compile "js/**" copyFileCompiler
 
    route   "img/*" idRoute
    compile "img/*" copyFileCompiler
 
    compile "templates/*" templateCompiler
 
    forM_ ["test.md", "index.md"] $ \page -> do
        route   page $ setExtension "html"
        compile page $ pageCompiler
            >>> applyTemplateCompiler "templates/default.html"
            >>> relativizeUrlsCompiler
 
sass :: Compiler Resource String
sass = getResourceString >>> unixFilter "sass" ["-s", "--scss"]
                         >>> arr compressCss

Test for PHP

<?php
require_once($GLOBALS['g_campsiteDir']. "/$ADMIN_DIR/country/common.php");
require_once($GLOBALS['g_campsiteDir']. "/classes/SimplePager.php");
camp_load_translation_strings("api");
 
$f_country_language_selected = camp_session_get('f_language_selected', '');
$f_country_offset = camp_session_get('f_country_offset', 0);
if (empty($f_country_language_selected)) {
    $f_country_language_selected = null;
}
$ItemsPerPage = 20;
$languages = Language::GetLanguages(null, null, null, array(), array(), true);
$numCountries = Country::GetNumCountries($f_country_language_selected);
 
$pager = new SimplePager($numCountries, $ItemsPerPage, "index.php?");
 
$crumbs = array();
$crumbs[] = array(getGS("Configure"), "");
$crumbs[] = array(getGS("Countries"), "");
echo camp_html_breadcrumbs($crumbs);
 
?>
 
<?php  if ($g_user->hasPermission("ManageCountries")) { ?>
<table BORDER="0" CELLSPACING="0" CELLPADDING="1">
    <tr>
        <td><a href="add.php"><?php putGS("Add new"); ?></a></td>
    </tr>
</table>

Test for Javascript

import isTypedArray from 'lodash/isTypedArray';
import reverse from 'lodash/reverse';
import sortBy from 'lodash/sortBy';
import take from 'lodash/take';
import { food101Classes } from './food101';

export function food101topK(classProbabilities, k = 5) {
  const probs = isTypedArray(classProbabilities)
    ? Array.prototype.slice.call(classProbabilities)
    : classProbabilities;

  const sorted = reverse(
    sortBy(
      probs.map((prob, index) => [ prob, index ]),
      probIndex => probIndex[0]
    )
  );

  const topK = take(sorted, k).map(probIndex => {
    const iClass = food101Classes[probIndex[1]];
    return {
      id: probIndex[1],
      name: iClass.replace(/_/, ' '),
      probability: probIndex[0]
    };
  });
  return topK;
};

Test for HTML

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head>
<title>A Tiny Page</title>
<style type="text/css">
<!--
      p { font-size:15pt; color:#000 }
    -->
</style></head><!-- real comment -->
<body bgcolor="#FFFFFF" text="#000000" link="#0000CC">
<script language="javascript" type="text/javascript">
      function changeHeight(h) {
        var tds = document.getElementsByTagName("td");
        for(var i = 0; i < tds.length; i++) {
          tds[i].setAttribute("height", h + "px");
      }}
</script>
<h1>abc</h1>
<h2>def</h2>
<p>Testing page</p>
</body></html>

Test for CSS

/*
Monokai style - ported by Luigi Maselli - http://grigio.org
*/

.hljs {
  display: block;
  overflow-x: auto;
  padding: 0.5em;
  background: #272822; color: #ddd;
}

.hljs-tag,
.hljs-keyword,
.hljs-selector-tag,
.hljs-literal,
.hljs-strong,
.hljs-name {
  color: #f92672;
}

.hljs-code {
  color: #66d9ef;
}

.hljs-class .hljs-title {
  color: white;
}

Long Article

2016-04-23T00:00:00+00:00

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce bibendum neque eget nunc mattis eu sollicitudin enim tincidunt. Vestibulum lacus tortor, ultricies id dignissim ac, bibendum in velit. Proin convallis mi ac felis pharetra aliquam. Curabitur dignissim accumsan rutrum. In arcu magna, aliquet vel pretium et, molestie et arcu. Mauris lobortis nulla et felis ullamcorper bibendum. Phasellus et hendrerit mauris. Proin eget nibh a massa vestibulum pretium. Suspendisse eu nisl a ante aliquet bibendum quis a nunc. Praesent varius interdum vehicula. Aenean risus libero, placerat at vestibulum eget, ultricies eu enim. Praesent nulla tortor, malesuada adipiscing adipiscing sollicitudin, adipiscing eget est.

Short Article

2016-03-19T00:00:00+00:00

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Post Content Styles

2016-02-06T00:00:00+00:00

Great heading (h1)

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce bibendum neque eget nunc mattis eu sollicitudin enim tincidunt. Vestibulum lacus tortor, ultricies id dignissim ac, bibendum in velit.

Some great heading (h2)

Proin convallis mi ac felis pharetra aliquam. Curabitur dignissim accumsan rutrum. In arcu magna, aliquet vel pretium et, molestie et arcu.

Mauris lobortis nulla et felis ullamcorper bibendum. Phasellus et hendrerit mauris. Proin eget nibh a massa vestibulum pretium. Suspendisse eu nisl a ante aliquet bibendum quis a nunc. Praesent varius interdum vehicula. Aenean risus libero, placerat at vestibulum eget, ultricies eu enim. Praesent nulla tortor, malesuada adipiscing adipiscing sollicitudin, adipiscing eget est.

Another great heading (h2)

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce bibendum neque eget nunc mattis eu sollicitudin enim tincidunt. Vestibulum lacus tortor, ultricies id dignissim ac, bibendum in velit.

Some great subheading (h3)

Proin convallis mi ac felis pharetra aliquam. Curabitur dignissim accumsan rutrum. In arcu magna, aliquet vel pretium et, molestie et arcu. Mauris lobortis nulla et felis ullamcorper bibendum.

Phasellus et hendrerit mauris. Proin eget nibh a massa vestibulum pretium. Suspendisse eu nisl a ante aliquet bibendum quis a nunc.

Some great subheading (h3)

Praesent varius interdum vehicula. Aenean risus libero, placerat at vestibulum eget, ultricies eu enim. Praesent nulla tortor, malesuada adipiscing adipiscing sollicitudin, adipiscing eget est.

This quote will change your life. It will reveal the secrets of the universe, and all the wonders of humanity. Don’t misuse it.

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Some great subheading (h3)

Vestibulum lacus tortor, ultricies id dignissim ac, bibendum in velit. Proin convallis mi ac felis pharetra aliquam. Curabitur dignissim accumsan rutrum.

<html>
  <head>
  </head>
  <body>
    <p>Hello, World!</p>
  </body>
</html>