/* =========================================================================
   V10c · TELETEXT  ·  BBC Ceefax page system
   Pure black ground, the canonical 7 teletext colours, VT323 monospace,
   ~40-column grid, big page number top-right, scrolling news ticker,
   numeric page-flip nav with FastText colour-key bar at the bottom.
   The medium constraint: 25 rows × 40 columns of coloured ASCII, broadcast
   over the vertical blanking interval of an analog TV signal in 1985.
   ========================================================================= */

:root {
  /* the canonical seven */
  --bk: #000000;
  --rd: #FF1818;
  --gr: #18E418;
  --ye: #FFFF18;
  --bl: #1818FF;
  --mg: #FF18FF;
  --cy: #18FFFF;
  --wh: #FFFFFF;

  --dim: #888888;

  --tt-font: 'VT323', 'IBM Plex Mono', 'Courier New', monospace;
}

*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: #050505; }

body.teletext {
  background: radial-gradient(circle at 50% 50%, #1A1A1A 0%, #050505 100%);
  color: var(--wh);
  font-family: var(--tt-font);
  font-size: 18px;
  line-height: 1.0;
  min-height: 100vh;
  padding: 24px 16px;
  -webkit-font-smoothing: none;
  font-smooth: never;
}

p, h1, h2, h3, h4, ol, ul, li, pre, dl, dd { margin: 0; padding: 0; }
ol, ul { list-style: none; }

::selection { background: var(--ye); color: var(--bk); }

/* =========================================================================
   THE 7 COLOURS — utility classes for inline coloured text
   ========================================================================= */

.c-bk { color: var(--bk); }
.c-rd { color: var(--rd); }
.c-gr { color: var(--gr); }
.c-ye { color: var(--ye); }
.c-bl { color: var(--bl); }
.c-mg { color: var(--mg); }
.c-cy { color: var(--cy); }
.c-wh { color: var(--wh); }

/* =========================================================================
   CRT FRAME — the screen
   ========================================================================= */

.crt {
  max-width: 880px;
  margin: 0 auto;
  background: var(--bk);
  border: 1px solid #222;
  box-shadow:
    0 0 0 6px #0F0F0F,
    0 0 0 8px #1A1A1A,
    0 0 0 12px #050505,
    0 18px 60px rgba(0, 0, 0, 0.85),
    inset 0 0 80px rgba(0, 0, 0, 0.5);
  position: relative;
  overflow: hidden;
  padding: 0;
  border-radius: 8px;
}

/* faint scanlines */
.crt::before {
  content: "";
  position: absolute; inset: 0;
  pointer-events: none;
  background-image: repeating-linear-gradient(
    to bottom,
    rgba(0,0,0,0)   0,
    rgba(0,0,0,0)   2px,
    rgba(0,0,0,0.35) 2px,
    rgba(0,0,0,0.35) 3px
  );
  z-index: 9;
  mix-blend-mode: multiply;
}

/* very subtle CRT bloom + vignette */
.crt::after {
  content: "";
  position: absolute; inset: 0;
  pointer-events: none;
  background:
    radial-gradient(120% 80% at 50% 50%, transparent 55%, rgba(0,0,0,0.55) 100%);
  z-index: 8;
}

/* =========================================================================
   HEADER ROW
   ========================================================================= */

.head {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 8px;
  padding: 8px 16px 4px;
  font-family: var(--tt-font);
  font-size: 22px;
  letter-spacing: 0.02em;
  line-height: 1;
  color: var(--wh);
  background: var(--bk);
  position: relative;
  z-index: 5;
}
.head__svc  { color: var(--wh); text-align: left;   }
.head__svc b { color: var(--cy); }
.head__net  { color: var(--wh); text-align: center; }
.head__net b { color: var(--ye); }
.head__sub  { color: var(--cy); margin-left: 8px; font-size: 19px; }
.head__clock { color: var(--ye); text-align: right; font-weight: 400; }

@media (max-width: 600px) {
  .head { grid-template-columns: 1fr; padding: 6px 12px; font-size: 18px; gap: 2px; }
  .head__net, .head__clock { text-align: left; }
}

/* =========================================================================
   TITLE BAR
   ========================================================================= */

.title {
  margin: 0;
  padding: 4px 16px 0;
  font-family: var(--tt-font);
  font-size: clamp(32px, 5vw, 44px);
  line-height: 1;
  font-weight: 400;
  text-align: center;
  background: var(--bk);
  letter-spacing: 0.02em;
  position: relative;
  z-index: 5;
}
.title .c-ye { background: var(--cy); color: var(--bk); padding: 0 6px; }

.subtitle {
  text-align: center;
  font-family: var(--tt-font);
  font-size: 20px;
  padding: 4px 16px 8px;
  background: var(--bk);
  letter-spacing: 0.02em;
  color: var(--wh);
  border-bottom: 2px solid var(--cy);
  position: relative;
  z-index: 5;
}

/* =========================================================================
   PAGE NAV — top numeric tabs
   ========================================================================= */

.pagenav {
  display: flex;
  gap: 0;
  padding: 0;
  background: var(--bk);
  border-bottom: 2px solid var(--wh);
  position: relative;
  z-index: 5;
  overflow-x: auto;
}
.tab {
  appearance: none;
  background: transparent;
  border: 0;
  border-right: 1px solid #333;
  padding: 10px 12px;
  font-family: var(--tt-font);
  font-size: 20px;
  letter-spacing: 0.02em;
  color: var(--wh);
  cursor: pointer;
  flex: 1;
  text-align: center;
  white-space: nowrap;
  line-height: 1;
}
.tab:last-child { border-right: 0; }
.tab:hover { background: #111; }
.tab.is-active { background: var(--bl); color: var(--wh); }
.tab.is-active span { color: var(--ye); }

@media (max-width: 600px) {
  .tab { font-size: 16px; padding: 8px 6px; }
}

/* =========================================================================
   SCREEN — page area, 40 columns of monospace
   ========================================================================= */

.screen {
  background: var(--bk);
  padding: 14px 16px 20px;
  min-height: 520px;
  position: relative;
  z-index: 5;
  font-family: var(--tt-font);
  font-size: 20px;
  line-height: 1.05;
  color: var(--wh);
}

.page { display: none; }
.page.is-active {
  display: block;
  animation: load 220ms steps(8, end);
}
@keyframes load {
  0%   { opacity: 0; }
  100% { opacity: 1; }
}

.page__hd {
  background: var(--bl);
  color: var(--wh);
  padding: 2px 6px;
  margin-bottom: 10px;
  font-size: 22px;
  letter-spacing: 0.02em;
}
.page__hd .c-ye, .page__hd .c-cy, .page__hd .c-gr, .page__hd .c-mg, .page__hd .c-rd {
  background: var(--bl);
  padding: 0 2px;
}

.block {
  margin: 10px 0 6px;
  font-size: 20px;
  letter-spacing: 0.02em;
  white-space: pre;
}

.ln {
  font-size: 20px;
  letter-spacing: 0.02em;
  line-height: 1.15;
  white-space: pre-wrap;
}

.ascii {
  font-size: 18px;
  line-height: 1.15;
  white-space: pre;
  margin: 8px 0 14px;
  color: var(--wh);
}

.ticker-line {
  background: var(--ye);
  color: var(--bk);
  padding: 2px 6px;
  margin: 10px 0;
  font-size: 18px;
}
.ticker-line .c-cy { color: var(--bk); font-weight: 400; }
.ticker-line .c-cy { background: var(--cy); padding: 0 4px; }
.ticker-line .c-wh { color: var(--bk); background: var(--ye); }

/* links inline */
a {
  color: var(--ye);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}
a:hover { background: var(--ye); color: var(--bk); }

/* =========================================================================
   FASTEXT (the coloured bar at the bottom of every Ceefax page)
   ========================================================================= */

.fasttext {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  background: var(--bk);
  border-top: 2px solid var(--wh);
  position: relative;
  z-index: 5;
}
.fk {
  display: block;
  padding: 8px 6px;
  text-align: center;
  font-family: var(--tt-font);
  font-size: 19px;
  letter-spacing: 0.04em;
  color: var(--bk);
  text-decoration: none;
  border-right: 2px solid var(--bk);
  line-height: 1;
}
.fk:last-child { border-right: 0; }
.fk--rd { background: var(--rd); }
.fk--gr { background: var(--gr); }
.fk--ye { background: var(--ye); }
.fk--cy { background: var(--cy); }
.fk:hover { color: var(--bk); filter: brightness(1.2); }

/* =========================================================================
   TICKER (bottom news rail)
   ========================================================================= */

.ticker {
  display: flex;
  align-items: center;
  background: var(--bk);
  border-top: 1px solid #222;
  overflow: hidden;
  position: relative;
  z-index: 5;
  height: 28px;
}
.ticker__lab {
  background: var(--rd);
  color: var(--wh);
  padding: 0 10px;
  font-family: var(--tt-font);
  font-size: 18px;
  height: 100%;
  display: inline-flex;
  align-items: center;
  letter-spacing: 0.04em;
  flex: 0 0 auto;
}
.ticker__rail {
  flex: 1;
  overflow: hidden;
  height: 100%;
  position: relative;
}
.ticker__strip {
  display: inline-block;
  white-space: nowrap;
  font-family: var(--tt-font);
  font-size: 19px;
  letter-spacing: 0.02em;
  color: var(--wh);
  padding-left: 100%;
  animation: scroll 38s linear infinite;
  line-height: 28px;
}
@keyframes scroll {
  0%   { transform: translateX(0); }
  100% { transform: translateX(-50%); }
}

/* =========================================================================
   RESPONSIVE
   ========================================================================= */

@media (max-width: 600px) {
  body.teletext { padding: 10px 6px; }
  .screen { font-size: 17px; min-height: 420px; padding: 10px 10px 14px; }
  .ln, .block { font-size: 17px; }
  .ascii { font-size: 14px; }
  .ticker, .ticker__strip { font-size: 16px; }
  .fk { font-size: 16px; padding: 6px 4px; }
}