/*
 * pong-ml — the site's identity, and it is its own.
 *
 * THEME COLOUR  #6366f1   indigo, taken by nothing else in the family
 * BACKGROUND    #0a0724   a near-black of the same hue
 * DRAWING       three soft glows over a slow base (3 radial + 2 linear), and a
 *               separate layer painting the ball's own geometry: a diamond mesh
 *               with wide vertical rails, faded by a mask — the lattice a rally
 *               draws across the court when you watch one for a while.
 *               Measured signature: 4 radial + 5 linear + masked. No site in the
 *               register shares it. There is no gradient anywhere else in this
 *               file, and no `background-size` in pixels, because both would
 *               change that signature by accident.
 *
 * The pattern is its OWN layer rather than another entry in the base gradient
 * stack: a mask on the base would fade the page's own colour with the pattern.
 */

:root {
  --bg: #0a0724;
  --panel: rgba(20, 16, 56, 0.72);
  --panel-solid: #14103a;
  --accent: #6366f1;
  --accent-lit: #818cf8;
  --accent-deep: #4338ca;
  --pale: #c7d2fe;
  --text: #e9ecff;
  --muted: #a3abd4;
  --hairline: rgba(129, 140, 248, 0.24);
  --radius: 14px;
  --container: 1080px;
  --consent-height: 0px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100vh;
  padding-bottom: calc(var(--consent-height) + 8px);
  background-color: var(--bg);
  background-image:
    radial-gradient(58% 42% at 18% 4%, rgba(99, 102, 241, 0.3) 0%, rgba(99, 102, 241, 0) 68%),
    radial-gradient(52% 40% at 84% 12%, rgba(79, 70, 229, 0.26) 0%, rgba(79, 70, 229, 0) 70%),
    radial-gradient(70% 52% at 50% 104%, rgba(129, 140, 248, 0.18) 0%, rgba(129, 140, 248, 0) 66%),
    linear-gradient(168deg, rgba(30, 24, 78, 0.9) 0%, rgba(10, 7, 36, 0) 62%),
    linear-gradient(0deg, rgba(99, 102, 241, 0.05) 0%, rgba(99, 102, 241, 0) 55%);
  background-attachment: fixed;
  color: var(--text);
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* The drawing. Its own fixed layer, masked so it dissolves rather than stopping. */
.dvs-pattern {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    repeating-linear-gradient(60deg, rgba(129, 140, 248, 0.15) 0 1px, transparent 1px 74px),
    repeating-linear-gradient(-60deg, rgba(129, 140, 248, 0.15) 0 1px, transparent 1px 74px),
    repeating-linear-gradient(90deg, rgba(99, 102, 241, 0.16) 0 1px, transparent 1px 236px);
  mask-image: radial-gradient(96% 78% at 50% 26%, #000 0%, rgba(0, 0, 0, 0.5) 46%, transparent 82%);
  -webkit-mask-image: radial-gradient(96% 78% at 50% 26%, #000 0%, rgba(0, 0, 0, 0.5) 46%, transparent 82%);
}

a {
  color: var(--accent-lit);
}

/* ------------------------------------------------------------------ the bar */

.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  position: sticky;
  top: 0;
  z-index: 10;
  padding: 12px 20px;
  background: rgba(10, 7, 36, 0.82);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--hairline);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text);
}

.brand .mark {
  width: 26px;
  height: 26px;
  display: block;
  flex: none;
}

.brand b {
  display: block;
  font-size: 15px;
  line-height: 1.1;
  letter-spacing: 0.2px;
}

.brand small {
  display: block;
  font-size: 11.5px;
  line-height: 1.2;
  letter-spacing: 0.4px;
  text-transform: uppercase;
  color: var(--muted);
}

/* --------------------------------------------------------------- the column */

main {
  position: relative;
  z-index: 1;
  max-width: var(--container);
  margin: 0 auto;
  padding: 30px 20px 56px;
}

section + section {
  margin-top: 34px;
}

h1 {
  font-size: clamp(1.9rem, 5.2vw, 3rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin: 0 0 14px;
}

h2 {
  font-size: clamp(1.25rem, 2.8vw, 1.6rem);
  line-height: 1.2;
  margin: 0 0 12px;
}

h3 {
  font-size: 1rem;
  margin: 0 0 6px;
}

p {
  margin: 0 0 14px;
}

.lede {
  font-size: 1.09rem;
  color: var(--text);
  max-width: 62ch;
}

.sub {
  color: var(--muted);
  max-width: 68ch;
}

.belief {
  color: var(--pale);
}

.card {
  background: var(--panel);
  border: 1px solid var(--hairline);
  border-radius: var(--radius);
  padding: 22px;
}

.card + .card {
  margin-top: 16px;
}

/* ----------------------------------------------------------------- the court */

.court-card {
  padding: 16px;
}

.court-frame {
  position: relative;
  width: 100%;
  aspect-ratio: 12 / 7;
  border-radius: 10px;
  overflow: hidden;
  background: var(--bg);
  border: 1px solid var(--hairline);
}

#court {
  display: block;
  width: 100%;
  height: 100%;
}

.hud {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(112px, 1fr));
  gap: 12px 18px;
  margin: 18px 0 4px;
}

/* TWO SCOREBOARDS, ONE RALLY. The table is the two learners; the grid above it is the
   rally they are taking part in, which is one number rather than two. */
.sides {
  width: 100%;
  border-collapse: collapse;
  margin: 6px 0 10px;
  font-variant-numeric: tabular-nums;
}

.sides caption {
  caption-side: top;
  text-align: left;
  font-size: 0.8rem;
  color: var(--muted);
  padding-bottom: 6px;
}

.sides th,
.sides td {
  text-align: right;
  padding: 7px 10px;
  border-bottom: 1px solid var(--hairline);
}

.sides thead th {
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.sides tbody th {
  text-align: left;
  font-weight: 500;
  color: var(--muted);
  font-size: 0.85rem;
}

.sides td {
  font-size: 1.1rem;
}

.sides thead th:first-child {
  text-align: left;
}

.stat-k {
  display: block;
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.stat-v {
  display: block;
  font-size: 1.25rem;
  font-variant-numeric: tabular-nums;
  line-height: 1.25;
}

.verdict {
  display: inline-block;
  margin: 6px 0 14px;
  padding: 5px 12px;
  border-radius: 999px;
  border: 1px solid var(--hairline);
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
}

.verdict[data-state='zero'] {
  color: var(--pale);
  border-color: rgba(199, 210, 254, 0.5);
}

.status-line {
  color: var(--muted);
  margin: 0 0 16px;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  gap: 16px;
  padding-top: 4px;
  border-top: 1px solid var(--hairline);
  margin-top: 12px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}

.field-wide {
  flex: 1 1 320px;
  min-width: 240px;
}

.field output {
  color: var(--text);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0;
  text-transform: none;
  font-size: 0.95rem;
}

select,
input[type='range'] {
  font: inherit;
  color: var(--text);
  background: var(--panel-solid);
  border: 1px solid var(--hairline);
  border-radius: 9px;
  padding: 7px 10px;
}

input[type='range'] {
  width: 100%;
  accent-color: var(--accent-lit);
  padding: 0;
  border: 0;
  background: transparent;
}

.slider-track {
  position: relative;
  height: 22px;
}

.slider-track .cap-marker {
  position: absolute;
  top: 15px;
  width: 2px;
  height: 9px;
  background: var(--pale);
  opacity: 0.8;
  transform: translateX(-1px);
  pointer-events: none;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font: inherit;
  font-size: 0.9rem;
  color: var(--text);
  background: var(--accent-deep);
  border: 1px solid transparent;
  border-radius: 9px;
  padding: 9px 15px;
  cursor: pointer;
}

.btn:hover {
  background: var(--accent);
}

.btn-ghost {
  background: transparent;
  border-color: var(--hairline);
  color: var(--muted);
}

.btn-ghost:hover {
  background: rgba(99, 102, 241, 0.14);
  color: var(--text);
}

.hint {
  font-size: 0.86rem;
  color: var(--muted);
  margin: 14px 0 0;
}

.hint:empty {
  display: none;
}

/* ------------------------------------------------------------------ the rest */

.ledger {
  margin: 0;
  padding-left: 1.1rem;
}

.ledger li {
  margin-bottom: 8px;
}

.ledger b {
  color: var(--pale);
  font-weight: 600;
}

.derivation {
  color: var(--muted);
  font-size: 0.94rem;
}

.chart {
  display: block;
  width: 100%;
  height: 210px;
}

/* FOUR CHARTS, ONE GRID. Each one is a thing the learner does, so they belong side by side rather
   than stacked into a column nobody scrolls. Two up on a normal window, one on a phone. */
.charts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 22px 26px;
}

.charts figure {
  margin: 0;
}

.charts figcaption {
  color: var(--muted);
  font-size: 0.86rem;
  line-height: 1.5;
  margin-top: 8px;
}

.charts figcaption b {
  color: var(--pale);
  font-weight: 600;
}

.plain {
  color: var(--muted);
  font-size: 0.9rem;
}

.door {
  display: inline;
  margin: 0;
  padding: 0;
  border: 0;
  background: none;
  color: var(--accent-lit);
  font: inherit;
  cursor: pointer;
  text-decoration: underline;
}

/* ----------------------------------------------------------------- the gate */

.consent-bar {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 30;
  background: rgba(12, 9, 42, 0.96);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-top: 1px solid var(--hairline);
  padding: 14px 20px;
}

.consent-inner {
  max-width: var(--container);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 18px;
}

.consent-ask,
.consent-prefs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 18px;
  width: 100%;
}

.consent-copy {
  flex: 1 1 320px;
  margin: 0;
  font-size: 0.9rem;
  color: var(--muted);
}

.consent-actions {
  display: flex;
  gap: 12px;
}

.consent-close {
  margin-left: auto;
  background: none;
  border: 0;
  color: var(--muted);
  font-size: 1.3rem;
  line-height: 1;
  cursor: pointer;
  padding: 4px 6px;
}

.switch {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font: inherit;
  font-size: 0.9rem;
  color: var(--text);
  background: transparent;
  border: 0;
  cursor: pointer;
  padding: 0;
}

.switch-track {
  width: 42px;
  height: 24px;
  border-radius: 999px;
  border: 1px solid var(--hairline);
  background: rgba(10, 7, 36, 0.9);
  position: relative;
  flex: none;
}

.switch-track::after {
  content: '';
  position: absolute;
  top: 3px;
  left: 3px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--muted);
  transition: transform 120ms ease;
}

.switch[aria-checked='true'] .switch-track::after {
  transform: translateX(18px);
  background: var(--accent-lit);
}

.consent-word {
  min-width: 2ch;
  color: var(--muted);
}

/* ----------------------------------------------------------------- the foot */

.site-footer {
  position: relative;
  z-index: 1;
  max-width: var(--container);
  margin: 0 auto;
  padding: 26px 20px 40px;
  border-top: 1px solid var(--hairline);
  font-size: 0.88rem;
  color: var(--muted);
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
  color: var(--text);
}

.footer-brand .mark {
  width: 22px;
  height: 22px;
  display: block;
  flex: none;
}

.footer-links {
  margin: 0 0 10px;
}

.footer-copy {
  margin: 0;
}

.footer-links a,
.footer-links .door {
  color: var(--accent-lit);
}

/* ------------------------------------------------------------------- motion */

@media (prefers-reduced-motion: reduce) {
  * {
    transition-duration: 0.001ms !important;
  }
}

@media (max-width: 640px) {
  main {
    padding: 22px 16px 48px;
  }
  .card {
    padding: 18px;
  }
  .court-card {
    padding: 12px;
  }
  .hud {
    grid-template-columns: repeat(auto-fit, minmax(96px, 1fr));
  }
}