# CRT screen

> Scanlines, flicker, curved glass and a rolling band, like an old monitor warming up.

- Category: [Backgrounds](https://library.aimran.es/components/patterns)
- Built with: HTML + CSS
- Live editor: https://library.aimran.es/blocks/pt-crt
- Library: AIMRAN Library (https://library.aimran.es), free, no sign-up, by Aimran Oukham

## Where to use it

A CRT effect is instant retro computing. Use it for the hero of a pixel-art game, a hacker-themed CTF event or a 404 page that pretends the system has crashed. It comes with a glowing “SYSTEM READY” line in the middle that you can swap for your own text. A retro CRT screen background, made in CSS.

Keep the flicker subtle if the page stays open for a while, and skip it on pages meant for reading. A monospaced font in the same green or amber as the glow finishes the look.

## Code

### HTML

```html
<div class="pt-crt"><b></b><em>SYSTEM READY</em><i></i><u></u><s></s></div>
```

### CSS

```css
.pt-crt {
  --c1: #34d399;
  --c2: #0071e3;
  --c3: #a7f3d0;
  --k: 1;
  /* velocidad */
  --d: 1;
  /* densidad / escala */
  --o: 1;
  /* opacidad */
  --bg: #05060a;
  --fg: #ffffff;
  --blend: screen;
  min-height: 100vh;
}

.pt-crt {
  position: relative;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg);
  container-type: size;
  isolation: isolate;
}

.pt-crt>* {
  opacity: var(--o);
}

.pt-crt {
  background: #050806!important;
}

.pt-crt b {
  position: absolute;
  inset: 0;
  background: radial-gradient(60% 50% at 30% 40%,color-mix(in srgb,var(--c1) 35%,transparent),transparent),radial-gradient(50% 60% at 75% 65%,color-mix(in srgb,var(--c2) 35%,transparent),transparent);
  animation: pt-crt-f calc(0.15s / var(--k)) steps(2) infinite;
}

.pt-crt em {
  position: absolute;
  left: 50%;
  top: 50%;
  translate: -50% -50%;
  font: 600 calc(28px * var(--d)) ui-monospace,monospace;
  font-style: normal;
  letter-spacing: .2em;
  color: var(--c3);
  text-shadow: 0 0 8px var(--c1),0 0 24px var(--c1);
  white-space: nowrap;
}

.pt-crt em::after {
  content: "_";
  animation: pt-crt-c calc(1s / var(--k)) steps(1) infinite;
}

.pt-crt i {
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(0deg,rgba(0,0,0,.45) 0 1px,transparent 1px 3px),repeating-linear-gradient(90deg,rgba(255,0,0,.05) 0 1px,rgba(0,255,0,.05) 1px 2px,rgba(0,0,255,.05) 2px 3px);
  background-size: 100% calc(3px * var(--d)),calc(3px * var(--d)) 100%;
}

.pt-crt u {
  position: absolute;
  left: 0;
  right: 0;
  height: 30%;
  background: linear-gradient(transparent,color-mix(in srgb,var(--c3) 12%,transparent),transparent);
  animation: pt-crt-r calc(6s / var(--k)) linear infinite;
}

.pt-crt s {
  position: absolute;
  inset: 0;
  border-radius: 6% / 10%;
  background: radial-gradient(ellipse at center,transparent 55%,rgba(0,0,0,.8) 100%);
  box-shadow: inset 0 0 80px rgba(0,0,0,.9);
}

@keyframes pt-crt-f {
  0% {
    opacity: var(--o);
  }
  50% {
    opacity: calc(var(--o) * .92);
  }
}

@keyframes pt-crt-c {
  50% {
    opacity: 0;
  }
}

@keyframes pt-crt-r {
  from {
    transform: translateY(-100%);
  }
  to {
    transform: translateY(400%);
  }
}
```

### React

```tsx
// @ts-nocheck
import { useEffect, useRef } from "react";

const css = `
.pt-crt {
  position: relative;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg);
  container-type: size;
  isolation: isolate;
}

.pt-crt>* {
  opacity: var(--o);
}

.pt-crt {
  background: #050806!important;
}

.pt-crt b {
  position: absolute;
  inset: 0;
  background: radial-gradient(60% 50% at 30% 40%,color-mix(in srgb,var(--c1) 35%,transparent),transparent),radial-gradient(50% 60% at 75% 65%,color-mix(in srgb,var(--c2) 35%,transparent),transparent);
  animation: pt-crt-f calc(0.15s / var(--k)) steps(2) infinite;
}

.pt-crt em {
  position: absolute;
  left: 50%;
  top: 50%;
  translate: -50% -50%;
  font: 600 calc(28px * var(--d)) ui-monospace,monospace;
  font-style: normal;
  letter-spacing: .2em;
  color: var(--c3);
  text-shadow: 0 0 8px var(--c1),0 0 24px var(--c1);
  white-space: nowrap;
}

.pt-crt em::after {
  content: "_";
  animation: pt-crt-c calc(1s / var(--k)) steps(1) infinite;
}

.pt-crt i {
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(0deg,rgba(0,0,0,.45) 0 1px,transparent 1px 3px),repeating-linear-gradient(90deg,rgba(255,0,0,.05) 0 1px,rgba(0,255,0,.05) 1px 2px,rgba(0,0,255,.05) 2px 3px);
  background-size: 100% calc(3px * var(--d)),calc(3px * var(--d)) 100%;
}

.pt-crt u {
  position: absolute;
  left: 0;
  right: 0;
  height: 30%;
  background: linear-gradient(transparent,color-mix(in srgb,var(--c3) 12%,transparent),transparent);
  animation: pt-crt-r calc(6s / var(--k)) linear infinite;
}

.pt-crt s {
  position: absolute;
  inset: 0;
  border-radius: 6% / 10%;
  background: radial-gradient(ellipse at center,transparent 55%,rgba(0,0,0,.8) 100%);
  box-shadow: inset 0 0 80px rgba(0,0,0,.9);
}

@keyframes pt-crt-f {
  0% {
    opacity: var(--o);
  }
  50% {
    opacity: calc(var(--o) * .92);
  }
}

@keyframes pt-crt-c {
  50% {
    opacity: 0;
  }
}

@keyframes pt-crt-r {
  from {
    transform: translateY(-100%);
  }
  to {
    transform: translateY(400%);
  }
}

`;

export default function PatternCrt() {
  const ref = useRef(null);
  return (
    <>
      <style>{css}</style>
      <div
        ref={ref}
        className="pt-crt"
        style={{
          "--c1": "#34d399",
          "--c2": "#0071e3",
          "--c3": "#a7f3d0",
          "--k": 1,
          "--d": 1,
          "--o": 1,
          "--bg": "#05060a",
          "--fg": "#ffffff",
          "--blend": "screen",
          minHeight: "100vh",
        }}
      >
        <b></b><em>SYSTEM READY</em><i></i><u></u><s></s>
      </div>
    </>
  );
}
```

## Prompt for AI assistants

Paste this into ChatGPT, Claude, Cursor, v0 or Lovable to adapt the block to your stack (Tailwind, Vue, Svelte…):

````text
I want to add the “CRT screen” block (Backgrounds) from AIMRAN Library to my project.

## What it is
Scanlines, flicker, curved glass and a rolling band, like an old monitor warming up.

## Chosen settings
- Color 1: #34d399
- Color 2: #0071e3
- Color 3: #a7f3d0
- Speed: 1x (from 0.2 to 3x)
- Density / scale: 1x (from 0.5 to 2x)
- Opacity: 1 (from 0.2 to 1)

## What I need
1. Add it to my project with the same look and animation as the reference code: same sizes, colours, radii, shadows, timings and easing.
2. It is built with plain HTML and CSS (the reference wraps it in a React component with its CSS). If my project uses something else (Vue, Svelte, Astro, plain HTML…), translate it without losing any behaviour. If I use Tailwind, turn the styles into classes; if not, keep the CSS in its own file.
3. Expose the settings above as props (or CSS variables) with those values as defaults.
4. Make it work well on phones: nothing that depends only on hover, touch targets of at least 44 px and no overflow on 320 px screens.
5. Make it look right in light and dark mode.
6. Keep it accessible: semantic HTML, roles and aria-* where needed, visible focus and keyboard support.
7. Respect prefers-reduced-motion: with reduced motion, no big animations but the same end result.

## Reference code
```tsx
// @ts-nocheck
import { useEffect, useRef } from "react";

const css = `
.pt-crt {
  position: relative;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg);
  container-type: size;
  isolation: isolate;
}

.pt-crt>* {
  opacity: var(--o);
}

.pt-crt {
  background: #050806!important;
}

.pt-crt b {
  position: absolute;
  inset: 0;
  background: radial-gradient(60% 50% at 30% 40%,color-mix(in srgb,var(--c1) 35%,transparent),transparent),radial-gradient(50% 60% at 75% 65%,color-mix(in srgb,var(--c2) 35%,transparent),transparent);
  animation: pt-crt-f calc(0.15s / var(--k)) steps(2) infinite;
}

.pt-crt em {
  position: absolute;
  left: 50%;
  top: 50%;
  translate: -50% -50%;
  font: 600 calc(28px * var(--d)) ui-monospace,monospace;
  font-style: normal;
  letter-spacing: .2em;
  color: var(--c3);
  text-shadow: 0 0 8px var(--c1),0 0 24px var(--c1);
  white-space: nowrap;
}

.pt-crt em::after {
  content: "_";
  animation: pt-crt-c calc(1s / var(--k)) steps(1) infinite;
}

.pt-crt i {
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(0deg,rgba(0,0,0,.45) 0 1px,transparent 1px 3px),repeating-linear-gradient(90deg,rgba(255,0,0,.05) 0 1px,rgba(0,255,0,.05) 1px 2px,rgba(0,0,255,.05) 2px 3px);
  background-size: 100% calc(3px * var(--d)),calc(3px * var(--d)) 100%;
}

.pt-crt u {
  position: absolute;
  left: 0;
  right: 0;
  height: 30%;
  background: linear-gradient(transparent,color-mix(in srgb,var(--c3) 12%,transparent),transparent);
  animation: pt-crt-r calc(6s / var(--k)) linear infinite;
}

.pt-crt s {
  position: absolute;
  inset: 0;
  border-radius: 6% / 10%;
  background: radial-gradient(ellipse at center,transparent 55%,rgba(0,0,0,.8) 100%);
  box-shadow: inset 0 0 80px rgba(0,0,0,.9);
}

@keyframes pt-crt-f {
  0% {
    opacity: var(--o);
  }
  50% {
    opacity: calc(var(--o) * .92);
  }
}

@keyframes pt-crt-c {
  50% {
    opacity: 0;
  }
}

@keyframes pt-crt-r {
  from {
    transform: translateY(-100%);
  }
  to {
    transform: translateY(400%);
  }
}

`;

export default function PatternCrt() {
  const ref = useRef(null);
  return (
    <>
      <style>{css}</style>
      <div
        ref={ref}
        className="pt-crt"
        style={{
          "--c1": "#34d399",
          "--c2": "#0071e3",
          "--c3": "#a7f3d0",
          "--k": 1,
          "--d": 1,
          "--o": 1,
          "--bg": "#05060a",
          "--fg": "#ffffff",
          "--blend": "screen",
          minHeight: "100vh",
        }}
      >
        <b></b><em>SYSTEM READY</em><i></i><u></u><s></s>
      </div>
    </>
  );
}
```

Give me the complete final code, ready to paste, and tell me in one line where to put it in my project.
````