Terms explained

Scroll, stack, or hide columns. Which pattern fits which table, the CSS for each, and why a table read as a grid should never be stacked.

Sortable, filterable HTML tables in about forty lines of plain JavaScript. Click-to-sort headers, a search box, and when a library is worth it.

colspan merges across, rowspan merges down. How to count the cells you must remove, why spans break tables, and the headers attribute for screen readers.

Force a print page break with break-before: page, keep blocks together with break-inside: avoid, and stop headings from stranding at the foot of a page.

Use the @page rule to set letter size and margins, size an on-screen sheet in inches, and understand why the print dialog can still override you.

target="_blank" opens a link in a new tab. Why rel="noopener noreferrer" belongs with it, when a new tab helps, and how to mark it for screen readers.

How to write an HTML link to an anchor on the same page with id and a hash href. Covers the old name attribute, scroll offsets, and why anchors break.

How to write an HTML link to a section of a page, from another page or a chat message. Covers ids, full URLs with a hash, and text fragment links.

How to write an HTML link to a PDF, control whether it opens in the browser or downloads, and fix the case where the link only works on your own machine.

How to write an HTML link to a local file, why browsers block file links from web pages, and what to do when the page has to reach a document on disk.

How to write an HTML link to a network drive, why mapped letters and UNC paths break for other people, and what to send instead so the link opens.

How to write an HTML mailto link with multiple recipients, add cc and bcc, prefill a subject and body, and encode the characters that break the link.

How to make an HTML link for a phone number with tel:, why the number needs a country code, and how to handle extensions, SMS links and desktop clicks.

How to write an HTML link to a map location that opens the right place, using an encoded address or coordinates, plus the geo scheme and embedded maps.

How to remove the underline from an HTML link with text-decoration none, where to apply it, and where taking the underline off costs you readers.

How to set an HTML link hover color with the :hover pseudo-class, the order link visited hover active must follow, and what to do about touch devices.

How to make an HTML button with a link. Why a styled anchor beats a button element, the markup to copy, and the four patterns that break in real pages.

How to embed a YouTube video in HTML with an iframe, make it responsive, set a start time, and fix the blank box that appears on locked down networks.

Embed a YouTube playlist in HTML with one iframe and a list parameter. The two URL forms, the playlist ID, and why a page embed can go blank.

Embed a Google map in HTML without an API key by copying the Share embed iframe. When you need the Embed API instead, and how to make it responsive.

Embed a Google Form in HTML with the iframe from Send. Why the frame cuts off or scrolls twice, how to set the height, and when to send the link instead.

Embed Google Calendar in HTML with the code under Integrate calendar. Why readers see an empty grid, which parameters change the view, and how to size it.

Three tags embed a PDF in HTML and they behave differently. Which to use, why phones show a download instead, and the fallback link every embed needs.

Make an embedded PDF fill the window: the height rule everyone misses, the body margin that leaves a white edge, and the fit parameter for page width.

An autoplaying looping video needs muted and playsinline, not only autoplay and loop. The four attributes, the YouTube version, and the accessibility rule.

One iframe embeds a website inside another page, and many sites refuse. How to tell which, what the refusal looks like, and what to use when it is blocked.

Embed an image in HTML as base64 so the file carries its own pictures. The data URI format, how to encode one, the size cost, and when not to do it.

Three ways to zoom an image on click: a plain link, a dialog element, and a CSS-only toggle. Which one to use, with working markup for each.

Stop images stretching. Why height auto fixes most cases, when to use object-fit cover, and how the width and height attributes prevent layout jump.

Two CSS lines cover most responsive images. When one file is not enough, srcset and sizes serve the right size per screen. With the picture element too.

What an HTML image map is, how the map and area tags work, why coordinates break on responsive pages, and what to use instead for a floor plan or diagram.

How to change SVG color in HTML with fill, currentColor and CSS variables, and why an SVG loaded through an img tag ignores every style you write.

How to make an SVG scale to fit its container in HTML. What viewBox actually does, when to remove width and height, and how preserveAspectRatio crops.

How to use an SVG as a favicon in HTML, the one link tag you need, the ICO fallback for Safari and older browsers, and making the icon flip in dark mode.

How to add SVG icons to HTML, when to inline them and when to use a symbol sprite, sizing with em, currentColor, and the accessibility attributes to set.

How to draw on an HTML canvas with getContext 2d, the attribute size versus CSS size trap, and why your lines look blurry on a high density screen.

How to add zoom and pan to an HTML canvas. Keeping scale and offset in one state object, zooming to the pointer, and why CSS transform goes blurry.

Why a canvas cannot be converted to SVG directly, the three real routes including recording draw calls, and when to redraw from the data instead.

How to turn an HTML or CSS animation into a GIF. Screen recording, frame capture in the browser, file size limits, and when to send the live page instead.

How to run an animation when an HTML page loads, with CSS keyframes, staggered delays, scroll triggered reveals, and respecting reduced motion settings.

How a CSS hover transition works, why the transition belongs on the resting state and not inside hover, and what to do about touch screens and focus.

Why height auto does not transition in CSS, and the three fixes: grid-template-rows 0fr to 1fr, max-height, and measuring scrollHeight in script.

How a CSS gradient background works, with linear, radial and conic syntax side by side. Angle rules, colour stops, and fixes when it will not paint.

border-color will not take a gradient. Four working methods compared: border-image, background-clip layers, a pseudo-element ring, and a padded wrapper.

drop-shadow follows the shape, box-shadow follows the rectangle. Syntax for both, why PNG and SVG need the filter version, and values that look real.

Grid has no flex-wrap property. auto-fit and auto-fill with minmax are what make columns wrap, and the two behave differently when items run out.

How row-gap works in CSS grid, how the gap shorthand orders its values, and why gaps never appear on the outside edge or collapse like margins.

A font-family list is a fallback chain read left to right. Ready-made stacks for system, serif, and monospace text, plus the rules on quoting and generics.

Set HTML font color with the CSS color property, not the removed font tag. Value formats compared, inheritance rules, and contrast levels that hold up.

Change the font in HTML with the CSS font-family property. Where to put the rule, the font shorthand, size units that scale, and what survives sharing.

A working list of HTML meta tags grouped by what they affect: rendering, search results, preview cards, and crawler behaviour. Plus the ones now ignored.

The last-modified meta tag is read by nothing. What actually carries a modification date: the HTTP header, structured data, sitemaps, and visible text.

The title attribute shows a browser tooltip on hover. Why it is invisible on touch and to keyboard users, and a CSS tooltip that works everywhere.

Validate a form with required, type, pattern, min and max before writing any script. Attribute reference, the :invalid trap, and custom message wording.

A form with no action submits to its own page URL. What the browser does with GET and POST, when leaving it out is correct, and how to stop the reload.

Post an HTML form to a Google Sheet using Apps Script. The doPost function, the deployment settings that matter, and the CORS error everyone hits.

A hidden input carries a value the reader does not see but the server receives. What it is for, what it must never hold, and why it is not secure.

autocomplete="off" works for ordinary fields and is ignored for passwords. The tokens browsers actually honour, and when turning it off is the wrong call.

A date input only accepts YYYY-MM-DD in its value attribute, whatever the box displays. How to prefill it, default it to today, and avoid the timezone bug.

Removing bullets takes list-style plus a padding reset, and it silently drops list semantics in Safari. The two-line fix and the accessibility repair.