@font-face {
  font-family: "Teletext Mono";
  src: local("Monaco"), local("Menlo"), local("Courier New");
}

:root {
  color-scheme: dark;
  --black: #000;
  --white: #fff;
  --cyan: #00ffff;
  --yellow: #ffff00;
  --green: #00ff00;
  --red: #ff0000;
  --blue: #0000ff;
  --magenta: #ff00ff;
  --cell-size: clamp(13px, min(1.72vw, 2.72vh), 22px);
}

* { box-sizing: border-box; }
html, body { min-height: 100%; }

body {
  margin: 0;
  overflow-x: hidden;
  background: #101010;
  font-family: "Teletext Mono", ui-monospace, monospace;
}

.shell {
  width: 100%;
  min-height: 100svh;
  display: grid;
  place-items: center;
  padding: .5rem;
}

.screen {
  position: relative;
  width: min(96vw, 760px);
  height: auto;
  min-height: 0;
  overflow: hidden;
  outline: none;
  border: 10px solid #1c1c1c;
  border-radius: 4px;
  padding: .35rem .7rem .4rem;
  background: var(--black);
  color: var(--white);
  box-shadow: 0 16px 45px rgb(0 0 0 / .72), inset 0 0 32px rgb(255 255 255 / .02);
}

.screen::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 5;
  pointer-events: none;
  background: radial-gradient(ellipse at center, transparent 70%, rgb(0 0 0 / .25) 100%);
}

.status-line,
.help-line {
  position: relative;
  z-index: 2;
  width: 40ch;
  margin-inline: auto;
}

.status-line {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  height: 1.35em;
  padding: 0;
  color: var(--white);
  font-size: var(--cell-size);
  font-weight: 700;
  line-height: 1;
  text-transform: uppercase;
}

.status-line span:first-child { color: var(--cyan); }
.status-line span:nth-child(2) {
  color: var(--yellow);
  background: var(--blue);
  padding: 0 .35ch;
}
.status-line span:last-child { text-align: right; color: var(--white); }

.page {
  position: relative;
  z-index: 2;
  width: 40ch;
  height: 24em;
  margin: 0 auto;
  overflow: hidden;
  white-space: pre;
  font-family: inherit;
  font-size: var(--cell-size);
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0;
  text-shadow: 1px 0 0 currentColor;
  user-select: none;
  font-variant-ligatures: none;
}

.help-line {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: .3rem;
  align-items: stretch;
  padding-top: .38rem;
  border-top: 1px solid #262626;
  color: #b7b7b7;
  font-size: clamp(8px, .74vw, 10px);
  font-weight: 400;
}

.help-item {
  min-width: 0;
  display: grid;
  grid-template-columns: repeat(2, max-content);
  grid-template-rows: auto auto;
  justify-content: center;
  align-content: center;
  column-gap: .15rem;
  line-height: 1;
  text-align: center;
}

.help-item kbd:first-child:last-of-type { grid-column: 1 / -1; }
.help-item small {
  grid-column: 1 / -1;
  margin-top: .2rem;
  color: #777;
  font: inherit;
  font-size: .9em;
  letter-spacing: .02em;
  text-transform: uppercase;
}

kbd {
  min-width: 1.55em;
  padding: .08rem .28rem;
  border: 1px solid #3b3b3b;
  border-bottom-color: #202020;
  background: #191919;
  color: #f1f1f1;
  font: inherit;
  font-size: 1.08em;
  font-weight: 700;
  line-height: 1.1;
  text-align: center;
  box-shadow: inset 0 1px 0 rgb(255 255 255 / .06);
}

.scanlines {
  position: absolute;
  inset: 0;
  z-index: 4;
  pointer-events: none;
  opacity: .18;
  background: repeating-linear-gradient(to bottom, transparent 0, transparent 2px, rgb(0 0 0 / .82) 3px, rgb(0 0 0 / .82) 4px);
}

.screen.crt .page { animation: flicker 9s infinite steps(1); }
.screen:not(.crt) .scanlines,
.screen:not(.crt)::before { display: none; }

@keyframes flicker {
  0%, 96%, 100% { opacity: 1; transform: translateX(0); }
  97% { opacity: .96; transform: translateX(.25px); }
  98% { opacity: .99; transform: translateX(-.25px); }
}

@media (max-width: 760px) {
  :root { --cell-size: min(2.48vw, 2.55vh); }
  .shell { padding: 0; min-height: 100svh; }
  .screen {
    width: 100vw;
    border: 0;
    border-radius: 0;
    padding: .3rem 0 .35rem;
  }
  .status-line, .page { width: 40ch; }
  .help-line {
    width: min(96%, 40ch);
    grid-template-columns: repeat(3, 1fr);
    row-gap: .45rem;
    font-size: 9px;
  }
}