:root {
  --bg: #05060a;
  --bg-2: #0b0d14;
  --card: rgba(14, 16, 26, 0.82);
  --card-border: rgba(255, 255, 255, 0.08);
  --text: #eef0f6;
  --muted: #9aa3b5;
  --faint: #5c6578;
  --accent: #7ec8ff;
  --glow: 0 0 40px rgba(126, 200, 255, 0.15);
  --hud-h: 64px;
  --ruler-w: 56px;
  --card-w: min(420px, 42vw);
  --font: "Inter", system-ui, -apple-system, sans-serif;
  --serif: "Instrument Serif", Georgia, serif;
  --mono: "JetBrains Mono", ui-monospace, Menlo, monospace;
  --band-radio: #cfd6e4;
  --band-microwave: #ff6bcb;
  --band-infrared: #ff7a59;
  --band-visible: #ffd166;
  --band-ultraviolet: #b388ff;
  --band-xray: #7ec8ff;
  --band-gamma: #ffe08a;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body {
  min-height: 100vh;
  overflow-x: clip;
  background:
    radial-gradient(1200px 600px at 50% -10%, rgba(80, 100, 180, 0.12), transparent 60%),
    radial-gradient(800px 500px at 80% 40%, rgba(180, 60, 140, 0.06), transparent 50%),
    var(--bg);
}

.skip {
  position: absolute;
  left: -9999px;
  top: 0;
  background: #fff;
  color: #000;
  padding: 0.5rem 1rem;
  z-index: 100;
}
.skip:focus { left: 0.5rem; top: 0.5rem; }

/* ---------- canvas wave (fixed, centre) ---------- */
#wave {
  transition: opacity 0.25s linear;
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
}

/* ---------- HUD ---------- */
.hud {
  position: fixed;
  top: 0;
  left: 0;
  right: var(--ruler-w);
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.65rem 1.25rem;
  min-height: var(--hud-h);
  background: linear-gradient(180deg, rgba(5, 6, 10, 0.92), rgba(5, 6, 10, 0.55) 70%, transparent);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  pointer-events: none;
}
.hud-brand {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  flex-shrink: 0;
}
.hud-mark {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: conic-gradient(
    from 180deg,
    var(--band-gamma),
    var(--band-xray),
    var(--band-ultraviolet),
    #ff4d6d,
    #ffd166,
    #06d6a0,
    #4cc9f0,
    var(--band-microwave),
    var(--band-radio)
  );
  box-shadow: 0 0 12px rgba(126, 200, 255, 0.45);
}
.hud-title {
  font-weight: 600;
  font-size: 0.92rem;
  letter-spacing: 0.01em;
}
.hud-readout {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 1.35rem;
  justify-content: flex-end;
  pointer-events: none;
}
.hud-item {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  min-width: 0;
}
.hud-label {
  font-size: 0.62rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--faint);
  font-weight: 500;
}
.hud-value {
  font-family: var(--mono);
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--text);
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}
.hud-band .hud-value {
  color: var(--accent);
  font-family: var(--font);
  font-weight: 600;
}

/* ---------- ruler / minimap ---------- */
.ruler {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: var(--ruler-w);
  z-index: 25;
  padding: calc(var(--hud-h) + 0.5rem) 0.35rem 1.5rem;
  cursor: pointer;
  touch-action: none;
  user-select: none;
  background: linear-gradient(90deg, transparent, rgba(5, 6, 10, 0.55));
}
.ruler-track {
  position: relative;
  height: 100%;
  border-radius: 999px;
  overflow: hidden;
  background: #12141e;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.06);
}
.ruler-fill {
  position: absolute;
  inset: 0;
  background: linear-gradient(
    180deg,
    var(--band-radio) 0%,
    var(--band-microwave) 22%,
    var(--band-infrared) 38%,
    #ff4d6d 46%,
    #ffd166 49%,
    #06d6a0 52%,
    #4cc9f0 55%,
    var(--band-ultraviolet) 62%,
    var(--band-xray) 78%,
    var(--band-gamma) 100%
  );
  opacity: 0.85;
}
.ruler-thumb {
  position: absolute;
  left: 2px;
  right: 2px;
  height: 10px;
  border-radius: 6px;
  background: #fff;
  box-shadow: 0 0 10px rgba(255, 255, 255, 0.7);
  transform: translateY(-50%);
  top: 0%;
  transition: top 0.05s linear;
  pointer-events: none;
}
.ruler-labels {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 2;
}
.ruler-labels button {
  position: absolute;
  left: 50%;
  transform: translate(-50%, -50%);
  pointer-events: auto;
  cursor: pointer;
  font: 600 0.55rem/1.1 var(--font);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: #fff;
  background: rgba(5, 6, 10, 0.72);
  border: 0;
  border-radius: 6px;
  padding: 0.22rem 0.15rem;
  writing-mode: vertical-rl;
  text-orientation: mixed;
  white-space: nowrap;
  text-shadow: 0 1px 2px #000;
}
.ruler-labels button:hover, .ruler-labels button:focus-visible {
  background: rgba(5, 6, 10, 0.95);
  outline: 1px solid rgba(255, 255, 255, 0.55);
}
.ruler-ticks { position: absolute; inset: 0; pointer-events: none; }
.ruler-ticks i {
  position: absolute;
  left: 0;
  width: 5px;
  height: 1px;
  background: rgba(0, 0, 0, 0.55);
}
.ruler-ticks i.maj { width: 9px; background: rgba(0, 0, 0, 0.75); }

/* ---------- scroll column ---------- */
#scroll {
  position: relative;
  z-index: 10;
  width: 100%;
  padding-right: var(--ruler-w);
}

.hero, .outro {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: calc(var(--hud-h) + 2rem) 1.5rem 4rem;
  text-align: center;
}
.hero-inner, .outro-inner {
  max-width: 680px;
  margin: 0 auto;
}
.eyebrow {
  font-size: 0.75rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 1rem;
  font-weight: 600;
}
.hero h1, .outro h2 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: clamp(2.6rem, 7vw, 4.4rem);
  line-height: 1.05;
  margin: 0 0 1.25rem;
  letter-spacing: -0.02em;
}
.lede {
  font-size: clamp(1.05rem, 2.2vw, 1.25rem);
  color: var(--muted);
  margin: 0 auto 2rem;
  max-width: 36em;
}
.scroll-cue {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 0.55rem;
  color: var(--faint);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin: 2.5rem 0 0;
}
.scroll-cue-arrow {
  width: 18px;
  height: 28px;
  border: 1.5px solid var(--faint);
  border-radius: 10px;
  position: relative;
}
.scroll-cue-arrow::after {
  content: "";
  position: absolute;
  top: 5px;
  left: 50%;
  width: 3px;
  height: 6px;
  margin-left: -1.5px;
  border-radius: 2px;
  background: var(--accent);
  animation: cue 1.6s ease-in-out infinite;
}
@keyframes cue {
  0%, 100% { transform: translateY(0); opacity: 1; }
  50% { transform: translateY(8px); opacity: 0.3; }
}

/* ---------- cards ---------- */
#cards {
  position: relative;
  padding: 10vh 0 20vh;
}
.card-slot {
  position: relative;
  min-height: 70vh;
  display: flex;
  align-items: center;
  padding: 4vh 1.25rem;
  margin: 0;
}
.card-slot:nth-child(odd) { justify-content: flex-start; padding-left: max(1.25rem, 4vw); padding-right: calc(50% + 2rem); }
.card-slot:nth-child(even) { justify-content: flex-end; padding-right: max(1.25rem, calc(var(--ruler-w) + 2vw)); padding-left: calc(50% + 2rem); }

.card {
  width: 100%;
  max-width: 420px;
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: 16px;
  padding: 1.35rem 1.4rem 1.45rem;
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  box-shadow: var(--glow), 0 20px 50px rgba(0, 0, 0, 0.35);
  opacity: 0;
  transform: translateY(28px) scale(0.98);
  transition: opacity 0.55s ease, transform 0.55s ease, border-color 0.3s ease;
  border-top: 3px solid var(--band-color, var(--accent));
}
.card.is-visible {
  opacity: 1;
  transform: translateY(0) scale(1);
}
.card.aside {
  border-top-color: rgba(255, 255, 255, 0.25);
  background: rgba(16, 18, 30, 0.88);
}
.card-kicker {
  font-size: 0.68rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--band-color, var(--accent));
  font-weight: 600;
  margin: 0 0 0.35rem;
}
.card.aside .card-kicker { color: var(--muted); }
.card h2, .card h3 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: 1.7rem;
  line-height: 1.15;
  margin: 0 0 0.65rem;
  letter-spacing: -0.01em;
}
.card-range {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0.85rem;
  margin: 0 0 0.9rem;
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--muted);
}
.card-range .rn { font-family: var(--font); background: none; border: 0; color: var(--faint); padding-left: 0; }
.card-range span {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 6px;
  padding: 0.2rem 0.45rem;
}
.card-lede {
  margin: 0 0 1rem;
  color: var(--text);
  font-size: 0.98rem;
}
.card p { margin: 0 0 0.75rem; color: var(--muted); font-size: 0.92rem; }
.card p:last-child { margin-bottom: 0; }
.card .note {
  font-size: 0.82rem;
  color: var(--faint);
  border-left: 2px solid rgba(255, 255, 255, 0.12);
  padding-left: 0.7rem;
  margin-top: 0.85rem;
}
.card-section {
  margin-top: 0.85rem;
}
.card-section h4 .ic { display: inline-flex; width: 12px; height: 12px; margin-right: 0.4rem; vertical-align: -1px; color: var(--band-color, var(--accent)); }
.card-section h4 .ic svg { width: 12px; height: 12px; }
.card-section h4 {
  margin: 0 0 0.35rem;
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--faint);
  font-weight: 600;
}
.card-section ul {
  margin: 0;
  padding: 0 0 0 1.05rem;
  color: var(--muted);
  font-size: 0.88rem;
}
.card-section li { margin: 0.15rem 0; }
.card-section.who p, .card-section.fact p {
  margin: 0;
  font-size: 0.88rem;
}
.card-section.fact {
  background: rgba(126, 200, 255, 0.06);
  border-radius: 10px;
  padding: 0.7rem 0.85rem;
  margin-top: 1rem;
}
.card-section.fact h4 { color: var(--accent); }

.eq {
  font-family: var(--mono);
  color: var(--accent);
  font-size: 0.95em;
  white-space: nowrap;
}
.eqs {
  display: grid;
  gap: 0.65rem;
  margin: 0.9rem 0;
}
.eqs > div {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 10px;
  padding: 0.65rem 0.8rem;
}
.eqs .eq { display: block; font-size: 1.05rem; margin-bottom: 0.25rem; }
.eqs small { color: var(--faint); font-size: 0.78rem; line-height: 1.4; display: block; }

.card svg.inline {
  display: block;
  width: 100%;
  height: auto;
  margin: 0.85rem 0 0.4rem;
  border-radius: 10px;
  background: rgba(0, 0, 0, 0.25);
}

/* tables */
table.cmp, table.itu {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.78rem;
  margin: 0.7rem 0;
}
table.cmp th, table.cmp td,
table.itu th, table.itu td {
  text-align: left;
  padding: 0.35rem 0.4rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  vertical-align: top;
}
table.cmp th, table.itu th {
  color: var(--faint);
  font-weight: 600;
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
table.itu td:first-child {
  font-family: var(--mono);
  color: var(--accent);
  white-space: nowrap;
}
ul.bw {
  list-style: none;
  padding: 0;
  margin: 0.6rem 0 1rem;
}
ul.bw li {
  display: flex;
  gap: 0.6rem;
  align-items: baseline;
  padding: 0.3rem 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  font-size: 0.88rem;
  color: var(--muted);
}
ul.bw b {
  font-family: var(--mono);
  color: var(--text);
  min-width: 4.2em;
  font-weight: 500;
}
ul.bw span { color: var(--faint); margin-left: auto; font-size: 0.8rem; }

/* band colour accents */
.band-radio { --band-color: var(--band-radio); }
.band-microwave { --band-color: var(--band-microwave); }
.band-infrared { --band-color: var(--band-infrared); }
.band-visible { --band-color: var(--band-visible); }
.band-ultraviolet { --band-color: var(--band-ultraviolet); }
.band-xray { --band-color: var(--band-xray); }
.band-gamma { --band-color: var(--band-gamma); }

/* ---------- outro ---------- */
.outro {
  min-height: auto;
  padding-top: 12vh;
  padding-bottom: 8vh;
}
.overview {
  margin: 1.5rem auto 2.5rem;
  max-width: 760px;
}
.ov-strip {
  display: grid;
  grid-template-columns: 1.6fr 1.2fr 1.3fr 0.35fr 1fr 1.2fr 1.3fr;
  height: 34px;
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 1rem;
}
.overview .ov {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.6rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: #0a0a0a;
  font-weight: 700;
  overflow: hidden;
  white-space: nowrap;
}
.ov-visible { font-size: 0 !important; }
table.ov-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.8rem;
  text-align: left;
}
table.ov-table th, table.ov-table td {
  padding: 0.5rem 0.5rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.07);
  vertical-align: top;
}
table.ov-table th {
  font-size: 0.64rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--faint);
  font-weight: 600;
}
table.ov-table td { color: var(--muted); font-family: var(--mono); font-size: 0.74rem; }
table.ov-table td:first-child { font-family: var(--font); color: var(--text); font-weight: 600; font-size: 0.85rem; white-space: nowrap; }
table.ov-table td:last-child { font-family: var(--font); }
table.ov-table .dot {
  display: inline-block;
  width: 9px; height: 9px;
  border-radius: 50%;
  margin-right: 0.5rem;
  background: var(--band-color);
  box-shadow: 0 0 8px var(--band-color);
}
.ov-note { font-size: 0.78rem; color: var(--faint); margin-top: 0.8rem; }
.ov-radio { background: var(--band-radio); }
.ov-microwave { background: var(--band-microwave); color: #1a0614; }
.ov-infrared { background: var(--band-infrared); color: #1a0804; }
.ov-visible {
  background: linear-gradient(90deg, #ff2a2a, #ff7a12, #ffd21a, #33f05a, #2a9bff, #8a2cff);
}
.ov-ultraviolet { background: var(--band-ultraviolet); color: #140a22; }
.ov-xray { background: var(--band-xray); color: #061018; }
.ov-gamma { background: var(--band-gamma); color: #1a1504; }

.timeline {
  text-align: left;
  max-width: 520px;
  margin: 0 auto 2.5rem;
}
.timeline h3 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: 1.6rem;
  margin: 0 0 1rem;
  text-align: center;
}
.timeline ol {
  list-style: none;
  margin: 0;
  padding: 0;
  border-left: 2px solid rgba(255, 255, 255, 0.1);
}
.timeline li {
  position: relative;
  padding: 0.45rem 0 0.45rem 1.2rem;
  font-size: 0.9rem;
  color: var(--muted);
}
.timeline li::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 0.85rem;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 8px rgba(126, 200, 255, 0.5);
}
.timeline time {
  font-family: var(--mono);
  color: var(--accent);
  font-size: 0.78rem;
  margin-right: 0.5rem;
}
.timeline b { color: var(--text); font-weight: 600; }

.credits {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding-top: 1.75rem;
  color: var(--muted);
  font-size: 0.88rem;
}
.credits a { color: var(--accent); text-decoration: none; }
.credits a:hover { text-decoration: underline; }
.credits .sources {
  font-size: 0.75rem;
  color: var(--faint);
  max-width: 48em;
  margin: 0.85rem auto 0;
  line-height: 1.5;
}

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  :root { --ruler-w: 30px; --hud-h: 88px; }
  .hud {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.4rem;
    padding: 0.55rem 0.85rem;
  }
  .hud-readout {
    width: 100%;
    justify-content: space-between;
    gap: 0.25rem 0.6rem;
  }
  .hud-item { align-items: flex-start; }
  .hud-value { font-size: 0.78rem; }
  .hud-label { font-size: 0.55rem; }
  .hud-title { font-size: 0.82rem; }

  .card-slot,
  .card-slot:nth-child(odd),
  .card-slot:nth-child(even) {
    justify-content: center;
    /* generous gaps so the wave has the screen to itself between cards */
    padding: 32vh 0.85rem 32vh;
    padding-right: calc(var(--ruler-w) + 0.5rem);
    min-height: 100vh;
  }
  #cards { padding: 0 0 10vh; }
  .card {
    max-width: 100%;
    background: rgba(12, 14, 22, 0.8);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
  }
  .ruler { padding-left: 0.3rem; padding-right: 0.3rem; }
  .ruler-labels { display: none; }
  .ruler-ticks i { width: 4px; }
  .ruler-ticks i.maj { width: 7px; }
  .overview .ov { font-size: 0.48rem; }
  table.ov-table th:nth-child(5), table.ov-table td:nth-child(5) { display: none; }
  table.ov-table td { font-size: 0.66rem; }
  table.ov-table th, table.ov-table td { padding: 0.45rem 0.25rem; }
}

@media (max-width: 480px) {
  :root { --hud-h: 100px; }
  .hud-readout { display: grid; grid-template-columns: 1fr 1fr; }
  .card { padding: 1.1rem 1.05rem 1.2rem; border-radius: 14px; }
  .card h2, .card h3 { font-size: 1.4rem; }
  table.itu { font-size: 0.68rem; }
  table.itu td:nth-child(4) { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  .card { transition: opacity 0.2s ease; transform: none; }
  .scroll-cue-arrow::after { animation: none; }
}