Some parts were took from f00f, otherx are quite comm9n here (read: CRT scanlines) and the font part I made it myself. I then edited it (the CSS not the font part) so that the things that the font didn't apply to actually got the same font (what I made is pretty clear because of how I do the indentartions)

I doubt you want a DOS program tho (a la EDIT.COM)

@font-face {
	font-family: "msdos";
	src: url(/api/v0/util/ext/image?img=https://files.catbox.moe/q2s1gv.ttf);
}

body, button, input {
	font-family: "msdos";
	image-rendering: pixelated;
	--radius: 0;
}

body::before {
  content: " ";
  display: block;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  background: linear-gradient(rgb(120 255 120 / 30%) 50%, rgb(120 255 120 / 0%) 50%);
    background-size: auto;
  z-index: 2;
  background-size: 100% 2px, 3px 100%;
  pointer-events: none;
}

.notification {
  background: inherit;
  color: inherit;
  font-size: inherit;
  font-family: inherit;
}

nav button::before, nav a::before, .card:not(:has(form)) button, .card:not(:has(form)) a.button {
  border-radius: 0;
}

.pillmenu {
  border: none;
  border-radius: 0;
  --radius: 0;
}

.card, .card-nest, .card-nest .card:last-child {
  border: none;
}

This is everything I currently have, but I'm not sure if you want your page to look like a terminal.

html, html.legacy, html.legacy *, html:not(.legacy), html:not(.legacy) *, button, input {
  --radius: 0;
}


* {
  font-family: "Noto Mono", monospace;
}
* {
  font-size: 11pt;
}

.notification {
  background: inherit;
  color: inherit;
  font-size: inherit;
}

button.primary, a.button.primary {
  background: var(--color-lowered);
  color: var(--color-primary);
}

button.primary:hover, a.button.primary:hover, button:not(nav *):hover, a.button:not(nav *):hover {
  background: var(--color-super-lowered)
}

nav, nav:not(.legacy *), nav button, nav a.button, .pillmenu a, .sidenav a {
  padding: 0 0.75rem;
  border: none;
  height: unset;
}

nav button::before, nav a::before, .card:not(:has(form)) button, .card:not(:has(form)) a.button, .card:not(:has(form)) button:not(dialog *), .card:not(:has(form)) a.button:not(dialog *), .avatar {
  border-radius: 0;
}

.pillmenu {
  border: none;
  --radius: 0;
}

.card, .card-nest, .card-nest .card:last-child {
  border: none;
}

::selection {
  background-color: #fff;
  color: hsl(0, 0%, 21%);
}

.response:has(.card:first-of-type[style="display: none"]) .card:last-of-type {
    flex-direction: column-reverse;
}

dialog::backdrop {
  backdrop-filter: brightness(0.4);
  -webkit-backdrop-filter: brightness(0.4);
}

nav:not(.legacy *) a.active::after, nav:not(.legacy *) a:hover::after, .pillmenu:not(.legacy *) a.active::after {
  display: none;
}

nav:not(.legacy *) a.active, nav:not(.legacy *) a:hover {
  color: var(--color-primary-raised)
}