:root {
  --bg: #0a0908;
  --panel: #171310;
  --edge: #2c241e;
  --text: #d8cfc4;
  --dim: #8a7f72;
  --red: #c22e1e;
  --amber: #e0a422;
  --green: #4f9e3f;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html, body { height: 100%; }

body {
  background: radial-gradient(ellipse at 50% 30%, #14100d 0%, var(--bg) 70%);
  color: var(--text);
  font-family: "Courier New", ui-monospace, monospace;
  display: flex;
  overflow: hidden;
}

/* ------------------------------------------------ left sidebar */

aside {
  flex: 0 0 280px;
  padding: 16px 14px;
  border-right: 1px solid var(--edge);
  background: rgba(0, 0, 0, 0.25);
  display: flex;
  flex-direction: column;
  gap: 12px;
  overflow-y: auto;
  scrollbar-width: thin;               /* Firefox */
  scrollbar-color: var(--edge) transparent;
}

/* WebKit scrollbar, styled to match the panel */
aside::-webkit-scrollbar { width: 8px; }
aside::-webkit-scrollbar-track { background: transparent; }
aside::-webkit-scrollbar-thumb {
  background: var(--edge);
  border-radius: 4px;
}
aside::-webkit-scrollbar-thumb:hover { background: var(--dim); }

body.collapsed aside { display: none; }

.title-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

aside h1 {
  font-size: 1.4rem;
  letter-spacing: 0.35em;
  color: var(--red);
  text-shadow: 0 0 12px rgba(194, 46, 30, 0.5);
}

#collapse, #expand {
  background: transparent;
  border: 1px solid var(--edge);
  color: var(--dim);
  padding: 2px 8px;
  font-size: 0.9rem;
}
#collapse:hover, #expand:hover { color: var(--text); filter: none; }

#expand {
  display: none;
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 10;
}
body.collapsed #expand { display: block; }

aside footer {
  margin-top: auto;
  padding-top: 12px;
  border-top: 1px solid var(--edge);
  color: var(--dim);
  font-size: 0.62rem;
  line-height: 1.6;
}
aside footer a { color: var(--amber); text-decoration: none; }
aside footer a:hover { text-decoration: underline; }

button {
  background: var(--red);
  border: none;
  color: #fff;
  font-family: inherit;
  font-weight: bold;
  padding: 8px 14px;
  cursor: pointer;
  letter-spacing: 0.08em;
}
button:hover { filter: brightness(1.15); }

button.secondary {
  background: var(--panel);
  border: 1px solid var(--edge);
  color: var(--text);
}

a.download {
  display: block;
  text-align: center;
  background: var(--panel);
  border: 1px solid var(--amber);
  color: var(--amber);
  padding: 6px 12px;
  font-size: 0.78rem;
  font-weight: bold;
  letter-spacing: 0.06em;
  text-decoration: none;
}
a.download:hover { filter: brightness(1.2); }

.badges { display: flex; flex-wrap: wrap; gap: 6px; }

.badge {
  border: 1px solid var(--edge);
  color: var(--dim);
  padding: 3px 8px;
  font-size: 0.7rem;
}
.badge.on { color: var(--green); border-color: var(--green); }
.badge.off { color: var(--red); border-color: var(--red); }

#devmsg {
  color: var(--amber);
  font-size: 0.7rem;
  min-height: 1em;
  word-break: break-word;
}

.group {
  border: 1px solid var(--edge);
  background: var(--panel);
  padding: 10px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.group label,
.group summary {
  color: var(--dim);
  font-size: 0.7rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}
.group summary { cursor: pointer; }

select {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--edge);
  font-family: inherit;
  padding: 6px;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--red);
}

.hint { color: var(--dim); font-size: 0.65rem; line-height: 1.5; }
.hint code { color: var(--text); word-break: break-all; }

.group table {
  border-collapse: collapse;
  font-size: 0.68rem;
  color: var(--dim);
}
.group td { border-bottom: 1px solid var(--edge); padding: 3px 4px; vertical-align: top; }
.group td:first-child { color: var(--text); white-space: nowrap; padding-right: 8px; }

/* ------------------------------------------------ the CRT */

main {
  flex: 1 1 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 0;
  padding: 14px;
}

#crt {
  /* as large as fits, at 4:3, without overflowing */
  width: min(100%, calc((100vh - 28px) * 4 / 3));
  aspect-ratio: 4 / 3;
  max-height: 100%;
  background: linear-gradient(145deg, #262220, #131110);
  border-radius: 18px;
  padding: clamp(10px, 1.8vmin, 22px);
  box-shadow:
    0 24px 70px rgba(0, 0, 0, 0.8),
    inset 0 1px 0 rgba(255, 255, 255, 0.06),
    inset 0 -2px 6px rgba(0, 0, 0, 0.6);
}

#screen-glass {
  position: relative;
  width: 100%;
  height: 100%;
  overflow: hidden;
  border-radius: 4.5% / 5.5%;
  background: #050403;
  box-shadow:
    inset 0 0 clamp(18px, 4vmin, 48px) rgba(0, 0, 0, 0.9),
    inset 0 0 4px rgba(0, 0, 0, 0.9);
}

#screen {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  image-rendering: pixelated;
  filter: brightness(1.08) contrast(1.06) saturate(1.15) blur(0.35px);
  transform: scale(1.012, 1.02);
  animation: flicker 0.12s infinite;
}

#scanlines {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: repeating-linear-gradient(
    to bottom,
    rgba(0, 0, 0, 0) 0px,
    rgba(0, 0, 0, 0) 2px,
    rgba(0, 0, 0, 0.28) 3px,
    rgba(0, 0, 0, 0) 4px
  );
  mix-blend-mode: multiply;
}

#grille {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: repeating-linear-gradient(
    to right,
    rgba(255, 60, 60, 0.05) 0px,
    rgba(60, 255, 60, 0.04) 1px,
    rgba(60, 60, 255, 0.05) 2px,
    rgba(0, 0, 0, 0) 3px
  );
}

#vignette {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(
    ellipse at center,
    rgba(0, 0, 0, 0) 58%,
    rgba(0, 0, 0, 0.25) 82%,
    rgba(0, 0, 0, 0.65) 100%
  );
}

#glare {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(ellipse 55% 32% at 50% 6%, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0) 70%),
    radial-gradient(ellipse 90% 60% at 50% 115%, rgba(255, 255, 255, 0.03), rgba(255, 255, 255, 0) 60%);
}

@keyframes flicker {
  0%   { opacity: 0.985; }
  50%  { opacity: 1; }
  100% { opacity: 0.99; }
}

@media (prefers-reduced-motion: reduce) {
  #screen { animation: none; }
}

/* ------------------------------------------------ overlay */

#overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  text-align: center;
  color: var(--dim);
}
#overlay p:first-child {
  color: var(--amber);
  font-size: clamp(1.2rem, 4vmin, 2.2rem);
  letter-spacing: 0.3em;
  animation: blink 1.6s steps(2) infinite;
}
#overlay .small { font-size: clamp(0.65rem, 1.6vmin, 0.85rem); line-height: 1.6; }
#overlay.hidden { display: none; }

@keyframes blink { 50% { opacity: 0.25; } }

/* ------------------------------------------------ intro popup */

#intro {
  position: fixed;
  inset: 0;
  z-index: 20;
  background: rgba(5, 4, 3, 0.75);
  backdrop-filter: blur(2px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
#intro.hidden { display: none; }

.intro-box {
  max-width: 34rem;
  max-height: 90vh;
  overflow-y: auto;
  background: var(--panel);
  border: 1px solid var(--edge);
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.8);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  font-size: 0.8rem;
  line-height: 1.65;
}
.intro-box h2 {
  color: var(--red);
  letter-spacing: 0.35em;
  text-shadow: 0 0 12px rgba(194, 46, 30, 0.5);
}
.intro-box a { color: var(--amber); text-decoration: none; }
.intro-box a:hover { text-decoration: underline; }
.intro-box button { align-self: flex-end; }

/* fullscreen: pure tube */
#crt:fullscreen {
  border-radius: 0;
  width: auto;
  max-height: none;
  background: #000;
  display: flex;
  align-items: center;
  justify-content: center;
}
#crt:fullscreen #screen-glass {
  height: min(100%, calc(100vw * 0.75));
  aspect-ratio: 4 / 3;
  width: auto;
}