commit 69f1ad523f30a20976901019e89b10e582664617 · dunkirk.sh/zera

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content/blog/2025-03-18_adding-a-copy-button.md

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       title = "Adding a copy code button"

     

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       date = 2025-03-14

     

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       slug = "adding-a-copy-button"

     

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       description = "continuing the chain :)"

     

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       [taxonomies]

     

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       tags = ["accessibility"]

     

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       +++

     

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       It took me a little over a month but I finally continued the chain of adding copy code buttons to your code blocks. It started with Salma Alam-Naylor’s [post](https://whitep4nth3r.com/blog/how-to-build-a-copy-code-snippet-button/) which I saw on Hacker News but then [David Bushell](https://dbushell.com/2025/02/14/copy-code-button/) also posted on it and [Ragman](https://www.ragman.net/musings/copy_code/) made a bluesky post (sky? bloop? atproto bloop? honestly not sure what a more interesting name would be) and it's been saved in my mind since then that I should add it.

     

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       <!-- more -->

     

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       What finally pushed me over the edge was seeing the [Duckquill](https://duckquill.daudix.one) theme and its fancy code blocks. I cloned the theme (`git clone https://codeberg.org/daudix/duckquill.git`) and figured out that the actual copy code was some reasonably simple js in `static/copy-button.js`. I copied that file and messed with it a bit as well as the css (`sass/_pre-container.scss` and some icon stuff in `sass/_icon.scss`) to make it work with my theme and style. 

     

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       A quick hash for cache busting and import later it all worked!

     

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       > templates/head.html

     

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       ```html

     

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       {% set jsHash = get_hash(path="js/copy-button.js", sha_type=256,

     

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       base64=true) %}

     

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       <script

     

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         src="{{ get_url(path='js/copy-button.js?' ~ jsHash, trailing_slash=false) | safe }}"

     

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         defer

     

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       ></script>

     

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       ```

     

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       The one thing I expanded on was the ability to specify a file name / comment for the code block. When js is disabled a markdown `>` blockquote on the line before the code block will create a header tab for the code block. I snipped the header tab idea from [chevyray.dev](https://chevyray.dev) and I grew to quite like it so I didn't want to abandon it over a copy button.

     

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       Here is my code should you want to use it:

     

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       > static/js/copy-button.js

     

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       ```js

     

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       // Based on https://www.roboleary.net/2022/01/13/copy-code-to-clipboard-blog.html

     

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       document.addEventListener("DOMContentLoaded", () => {

     

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         const blocks = document.querySelectorAll("pre[class^='language-']");

     

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         for (const block of blocks) {

     

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           if (navigator.clipboard) {

     

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             // Code block header title

     

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             const title = document.createElement("span");

     

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             const lang = block.getAttribute("data-lang");

     

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             const comment =

     

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               block.previousElementSibling &&

     

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               (block.previousElementSibling.tagName === "blockquote" ||

     

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                 block.previousElementSibling.nodeName === "BLOCKQUOTE")

     

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                 ? block.previousElementSibling

     

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                 : null;

     

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             if (comment) block.previousElementSibling.remove();

     

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             title.innerHTML =

     

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               lang + (comment ? ` (${comment.textContent.trim()})` : "");

     

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             // Copy button icon

     

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             const icon = document.createElement("i");

     

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             icon.classList.add("icon");

     

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             // Copy button

     

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             const button = document.createElement("button");

     

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             const copyCodeText = "Copy code"; // Use hardcoded text instead of getElementById

     

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             button.setAttribute("title", copyCodeText);

     

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             button.appendChild(icon);

     

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             // Code block header

     

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             const header = document.createElement("div");

     

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             header.classList.add("header");

     

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             header.appendChild(title);

     

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             header.appendChild(button);

     

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             // Container that holds header and the code block itself

     

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             const container = document.createElement("div");

     

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             container.classList.add("pre-container");

     

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             container.appendChild(header);

     

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             // Move code block into the container

     

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             block.parentNode.insertBefore(container, block);

     

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             container.appendChild(block);

     

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             button.addEventListener("click", async () => {

     

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               await copyCode(block, header, button); // Pass the button here

     

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             });

     

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           }

     

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         }

     

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         async function copyCode(block, header, button) {

     

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           const code = block.querySelector("code");

     

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           const text = code.innerText;

     

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           await navigator.clipboard.writeText(text);

     

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           header.classList.add("active");

     

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           button.setAttribute("disabled", true);

     

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           header.addEventListener(

     

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             "animationend",

     

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             () => {

     

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               header.classList.remove("active");

     

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               button.removeAttribute("disabled");

     

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             },

     

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             { once: true },

     

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           );

     

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         }

     

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       });

     

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       ```

     

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       and the css:

     

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       > sass/css/_copy-button.scss

     

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       ```scss

     

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       i.icon {

     

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           display: inline-block;

     

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           mask-size: cover;

     

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           background-color: currentColor;

     

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           width: 1rem;

     

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           height: 1rem;

     

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           font-style: normal;

     

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           font-variant: normal;

     

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           line-height: 0;

     

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           text-rendering: auto;

     

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       }

     

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       .pre-container {

     

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           --icon-copy: url("data:image/svg+xml,%3Csvg viewBox='0 0 16 16' height='16' width='16' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M0 3c0-1.645 1.355-3 3-3h5c1.645 0 3 1.355 3 3 0 .55-.45 1-1 1s-1-.45-1-1c0-.57-.43-1-1-1H3c-.57 0-1 .43-1 1v5c0 .57.43 1 1 1 .55 0 1 .45 1 1s-.45 1-1 1c-1.645 0-3-1.355-3-3zm5 5c0-1.645 1.355-3 3-3h5c1.645 0 3 1.355 3 3v5c0 1.645-1.355 3-3 3H8c-1.645 0-3-1.355-3-3zm2 0v5c0 .57.43 1 1 1h5c.57 0 1-.43 1-1V8c0-.57-.43-1-1-1H8c-.57 0-1 .43-1 1m0 0'/%3E%3C/svg%3E");

     

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           --icon-done: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16'%3E%3Cpath d='M7.883 0q-.486.008-.965.074a7.98 7.98 0 0 0-4.602 2.293 8.01 8.01 0 0 0-1.23 9.664 8.015 8.015 0 0 0 9.02 3.684 8 8 0 0 0 5.89-7.75 1 1 0 1 0-2 .008 5.986 5.986 0 0 1-4.418 5.816 5.996 5.996 0 0 1-6.762-2.766 5.99 5.99 0 0 1 .922-7.25 5.99 5.99 0 0 1 7.239-.984 1 1 0 0 0 1.363-.371c.273-.48.11-1.09-.371-1.367A8 8 0 0 0 9.492.14 8 8 0 0 0 7.882 0m7.15 1.998-.1.002a1 1 0 0 0-.687.34L7.95 9.535 5.707 7.29A1 1 0 0 0 4 8a1 1 0 0 0 .293.707l3 3c.195.195.465.3.742.293.277-.012.535-.133.719-.344l7-8A1 1 0 0 0 16 2.934a1 1 0 0 0-.34-.688 1 1 0 0 0-.627-.248'/%3E%3C/svg%3E");

     

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           margin: 1rem 0 1rem;

     

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           border-radius: 0.75rem;

     

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           .header {

     

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               display: flex;

     

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               justify-content: space-between;

     

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               align-items: center;

     

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               border-radius: 0.2em 0.2em 0 0;

     

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               background-color: var(--accent);

     

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               background-size: 200%;

     

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               padding: 0.25rem;

     

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               height: 2.5rem;

     

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               span {

     

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                   margin-inline-start: 0.75rem;

     

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                   color: var(--purple-gray);

     

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                   font-weight: bold;

     

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                   line-height: 1;

     

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               }

     

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               button {

     

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                   appearance: none;

     

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                   transition: 200ms;

     

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                   cursor: pointer;

     

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                   border: none;

     

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                   border-radius: 0.4rem;

     

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                   background-color: transparent;

     

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                   padding: 0.5rem;

     

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                   color: var(--purple-gray);

     

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                   line-height: 0;

     

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                   &:hover {

     

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                       background-color: color-mix(

     

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                           in oklab,

     

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                           var(--accent) 80%,

     

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                           var(--purple-gray)

     

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                       );

     

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                   }

     

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                   &:focus {

     

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                       background-color: color-mix(

     

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                           in oklab,

     

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                           var(--accent) 80%,

     

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                           var(--purple-gray)

     

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                       );

     

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                   }

     

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                   &:active {

     

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                       transform: scale(0.9);

     

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                   }

     

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                   &:disabled {

     

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                       cursor: not-allowed;

     

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                       &:active {

     

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                           transform: none;

     

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                       }

     

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                   }

     

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                   .icon {

     

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                       -webkit-mask-image: var(--icon-copy);

     

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                       mask-image: var(--icon-copy);

     

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                       transition: 200ms;

     

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                       :root[dir*="rtl"] & {

     

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                           transform: scaleX(-1);

     

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                       }

     

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                   }

     

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               }

     

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               &.active {

     

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                   button {

     

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                       animation: active-copy 0.3s;

     

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                       color: var(--purple-gray);

     

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                       .icon {

     

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                           -webkit-mask-image: var(--icon-done);

     

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                           mask-image: var(--icon-done);

     

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                       }

     

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                   }

     

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                   @keyframes active-copy {

     

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                       50% {

     

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                           transform: scale(0.9);

     

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                       }

     

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                       100% {

     

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                           transform: none;

     

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                       }

     

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                   }

     

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               }

     

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           }

     

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           pre {

     

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               margin: 0;

     

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               box-shadow: none;

     

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               border-radius: 0 0 0.2em 0.2em;

     

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           }

     

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       }

     

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       ```

templates/head.html

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         src="{{ get_url(path='js/copy-button.js?' ~ jsHash, trailing_slash=false) | safe }}"

     

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         defer

     

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       ></script>

     

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       <script>

     

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           function cb(res) {

     

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               const fmt = new Intl.NumberFormat('en', { notation: 'compact' });