/* =========================================================
   SERP Climber v2 : mini-jeu 404 (charge uniquement sur /404)
   Tokens : design system (main.css). Mobile-first, radius 0.

   Principes de mise en page :
   - le plateau a une hauteur FIXE (--serp-row-h x --serp-visible) et les
     ecrans (regles / pause / fin) sont des overlays : zero CLS ;
   - les lignes de la SERP sont en position absolue et ne bougent qu'en
     transform : la remontee est animee sans reflow ;
   - au-dessus de 40rem on affiche les 10 positions, en dessous une "camera"
     suit le joueur pour garder la jauge de timing visible sans scroller.
   ========================================================= */

.serp-404 {
  position: relative;
  padding-block: clamp(var(--sp-7), 7vw, var(--sp-9)) var(--sp-8);
  overflow: clip;
}

.serp-404::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(ellipse 70% 45% at 15% 0%, color-mix(in srgb, var(--brand-secondary) 18%, transparent), transparent 60%),
    radial-gradient(ellipse 55% 40% at 90% 10%, color-mix(in srgb, var(--brand-tertiary) 14%, transparent), transparent 55%);
  z-index: 0;
}

.serp-404 > .wrap-tight {
  position: relative;
  z-index: 1;
}

.serp-404__intro {
  text-align: center;
  max-width: 38rem;
  margin-inline: auto;
  margin-block-end: var(--sp-6);
}

.serp-404__intro h1 {
  font-size: clamp(1.75rem, 4.5vw, 2.75rem);
  letter-spacing: -0.03em;
  margin-block-end: var(--sp-3);
}

.serp-404__intro .lead {
  color: var(--text-dim);
  max-width: 32rem;
  margin-inline: auto;
}

.serp-404__code {
  font-family: var(--font-serif);
  font-style: italic;
  font-weight: 400;
  font-size: clamp(3.5rem, 12vw, 6rem);
  line-height: 0.9;
  letter-spacing: -0.04em;
  color: var(--text);
  margin: var(--sp-3) 0 var(--sp-2);
  text-shadow:
    1px 0 color-mix(in srgb, var(--brand-secondary) 70%, transparent),
    -1px 0 color-mix(in srgb, var(--brand-tertiary) 70%, transparent);
}

.serp-404__seo {
  margin-block-start: var(--sp-6);
}

.serp-404__seo-title {
  font-size: var(--fs-xs);
  text-transform: uppercase;
  letter-spacing: var(--tr-label);
  color: var(--muted);
  text-align: center;
  margin-block-end: var(--sp-3);
}

.serp-404__seo-list {
  justify-content: center;
}

.serp-404__seo-list a.tag {
  text-decoration: none;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease), background 0.2s var(--ease);
}

.serp-404__seo-list a.tag:hover,
.serp-404__seo-list a.tag:focus-visible {
  color: var(--text);
  border-color: color-mix(in srgb, var(--brand-secondary) 45%, var(--stroke));
  background: color-mix(in srgb, var(--brand-secondary) 12%, var(--surface));
}

.serp-404__cta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-3);
  justify-content: center;
  margin-block-start: var(--sp-7);
}

/* =============================================== Coquille du jeu ========= */

.serp-climber {
  --serp-row-h: 2.75rem;
  --serp-visible: 6;
  --serp-gutter-w: 2rem;
  --serp-good: var(--brand-secondary);
  --serp-perfect: var(--brand-tertiary);
  --serp-bad: color-mix(in srgb, #d08a72 72%, var(--text));
  position: relative;
  background: var(--surface);
  border: 1px solid var(--stroke);
  padding: var(--sp-4) var(--sp-3);
  box-shadow: var(--shadow-sm);
}

@media (min-width: 40rem) {
  .serp-climber {
    --serp-row-h: 3rem;
    --serp-visible: 10;
    --serp-gutter-w: 2.5rem;
    padding: var(--sp-5);
  }
}

/* --- Barre "navigateur" + reglage --- */

.serp-climber__chrome {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  margin-block-end: var(--sp-3);
}

.serp-climber__query {
  flex: 1 1 auto;
  min-width: 0;
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  min-height: 2.25rem;
  padding: 0.4rem 0.7rem;
  background: var(--bg);
  border: 1px solid var(--stroke-2);
  color: var(--text);
  font-size: var(--fs-sm);
}

.serp-climber__query svg {
  width: 1rem;
  height: 1rem;
  color: var(--muted-2);
  flex: none;
}

.serp-climber__query span {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.serp-climber__query em {
  margin-inline-start: auto;
  font-style: normal;
  font-size: var(--fs-xs);
  color: var(--muted-2);
  flex: none;
}

.serp-climber__calm {
  flex: none;
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  min-height: 2.25rem;
  padding: 0.35rem 0.6rem;
  background: var(--bg);
  border: 1px solid var(--stroke-2);
  color: var(--muted);
  font: inherit;
  font-size: var(--fs-xs);
  cursor: pointer;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.serp-climber__calm::before {
  content: "";
  width: 0.6rem;
  height: 0.6rem;
  border: 1px solid currentColor;
  background: transparent;
  transition: background 0.2s var(--ease);
}

.serp-climber__calm[aria-pressed="true"] {
  color: var(--text);
  border-color: color-mix(in srgb, var(--serp-good) 55%, var(--stroke-2));
}

.serp-climber__calm[aria-pressed="true"]::before {
  background: var(--serp-good);
}

.serp-climber__calm:hover {
  color: var(--text);
}

@media (max-width: 29.99rem) {
  .serp-climber__calm span {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip-path: inset(50%);
    white-space: nowrap;
  }
}

/* --- HUD --- */

.serp-climber__hud {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 1px;
  margin: 0 0 1px;
  background: var(--stroke);
  border: 1px solid var(--stroke);
}

.serp-climber__stat {
  display: grid;
  gap: 0.05rem;
  padding: 0.35rem 0.45rem;
  background: var(--bg);
  text-align: center;
}

.serp-climber__stat dt {
  font-size: 0.625rem;
  line-height: 1.2;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted-2);
}

.serp-climber__stat dd {
  margin: 0;
}

.serp-climber__stat b {
  font-family: var(--font-serif);
  font-style: italic;
  font-weight: 400;
  font-size: 1.05rem;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--text);
  font-variant-numeric: tabular-nums;
}

@media (min-width: 40rem) {
  .serp-climber__stat {
    padding: 0.45rem 0.6rem;
  }
  .serp-climber__stat b {
    font-size: 1.2rem;
  }
}

.serp-climber__stat[data-serp-combo-stat][data-level="2"] b {
  color: color-mix(in srgb, var(--serp-good) 70%, var(--text));
}

.serp-climber__stat[data-serp-combo-stat][data-level="3"] b {
  color: color-mix(in srgb, var(--serp-perfect) 70%, var(--text));
}

.serp-climber__timebar {
  position: relative;
  height: 3px;
  background: var(--stroke);
  overflow: hidden;
  margin-block-end: var(--sp-3);
}

.serp-climber__timebar > span {
  position: absolute;
  inset: 0;
  transform-origin: left center;
  background: linear-gradient(90deg, var(--serp-good), var(--serp-perfect));
}

.serp-climber__timebar[data-low="true"] > span {
  background: var(--serp-bad);
}

/* --- Plateau SERP --- */

.serp-climber__board {
  position: relative;
  border: 1px solid var(--stroke);
  background: var(--bg);
  overflow: hidden;
  touch-action: manipulation;
  -webkit-user-select: none;
  user-select: none;
}

.serp-climber__viewport {
  position: relative;
  height: calc(var(--serp-row-h) * var(--serp-visible));
  overflow: hidden;
}

.serp-climber__camera {
  position: absolute;
  inset-inline: 0;
  top: 0;
  height: calc(var(--serp-row-h) * 10);
  display: grid;
  grid-template-columns: var(--serp-gutter-w) 1fr;
  transform: translate3d(0, calc(var(--serp-row-h) * var(--serp-cam, 0)), 0);
  transition: transform 380ms var(--ease-out);
}

.serp-climber__gutter {
  display: grid;
  grid-template-rows: repeat(10, var(--serp-row-h));
  border-inline-end: 1px solid var(--stroke);
  background: color-mix(in srgb, var(--surface-2) 60%, var(--bg));
}

.serp-climber__gutter-cell {
  display: grid;
  place-items: center;
  font-size: var(--fs-xs);
  font-variant-numeric: tabular-nums;
  color: var(--muted-2);
  transition: color 0.25s var(--ease), background 0.25s var(--ease);
}

.serp-climber__gutter-cell:first-child {
  color: color-mix(in srgb, var(--serp-perfect) 60%, var(--muted));
}

.serp-climber__gutter-cell[data-current] {
  color: var(--bg);
  background: var(--serp-good);
  font-weight: 600;
}

.serp-climber__stack {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0;
  height: 100%;
}

.serp-climber__row {
  position: absolute;
  inset-inline: 0;
  top: 0;
  height: var(--serp-row-h);
  display: grid;
  grid-template-columns: 1.35rem minmax(0, 1fr) auto;
  align-items: center;
  gap: var(--sp-2);
  padding-inline: var(--sp-2);
  border-block-end: 1px solid color-mix(in srgb, var(--stroke) 70%, transparent);
  background: var(--bg);
  transition: transform 380ms var(--ease-out);
  will-change: transform;
}

@media (min-width: 40rem) {
  .serp-climber__row {
    grid-template-columns: 1.5rem minmax(0, 1fr) auto;
    padding-inline: var(--sp-3);
    gap: var(--sp-3);
  }
}

.serp-climber__favicon {
  display: grid;
  place-items: center;
  width: 1.35rem;
  height: 1.35rem;
  background: var(--surface-2);
  border: 1px solid var(--stroke);
  color: var(--muted-2);
  font-size: 0.6875rem;
  font-weight: 600;
  line-height: 1;
}

.serp-climber__result {
  min-width: 0;
  display: grid;
  gap: 0.05rem;
}

.serp-climber__title,
.serp-climber__url {
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  line-height: 1.25;
}

.serp-climber__title {
  font-size: var(--fs-sm);
  color: var(--text-dim);
}

.serp-climber__url {
  font-size: 0.6875rem;
  color: var(--muted-2);
}

/* Ligne du joueur */

.serp-climber__row.is-player {
  background: color-mix(in srgb, var(--serp-good) 9%, var(--bg));
  box-shadow: inset 2px 0 0 var(--serp-good);
  z-index: 2;
}

.serp-climber__row.is-player .serp-climber__title {
  color: var(--text);
  font-weight: 600;
}

.serp-climber__row.is-player .serp-climber__favicon {
  background: var(--serp-good);
  border-color: var(--serp-good);
  color: var(--bg);
}

.serp-climber__fill {
  position: absolute;
  inset: 0;
  transform-origin: left center;
  transform: scaleX(0);
  background: linear-gradient(
    90deg,
    color-mix(in srgb, var(--serp-good) 26%, transparent),
    color-mix(in srgb, var(--serp-perfect) 26%, transparent)
  );
  transition: transform 260ms var(--ease-out);
  pointer-events: none;
}

.serp-climber__gauge {
  position: relative;
  font-size: 0.6875rem;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.04em;
  color: color-mix(in srgb, var(--serp-good) 60%, var(--text));
  padding-inline: 0.35rem;
  border: 1px solid color-mix(in srgb, var(--serp-good) 40%, var(--stroke));
  line-height: 1.5;
}

.serp-climber__row.is-climbing {
  animation: serpClimbFlash 520ms var(--ease-out);
}

/* Toast de position */

.serp-climber__toast {
  position: absolute;
  z-index: 4;
  top: var(--sp-2);
  right: var(--sp-2);
  margin: 0;
  padding: 0.25rem 0.55rem;
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--bg);
  background: var(--serp-good);
  pointer-events: none;
}

.serp-climber__toast[data-tone="bad"] {
  background: var(--serp-bad);
}

.serp-climber__toast.is-live {
  animation: serpToast 1.2s var(--ease-out) forwards;
}

/* --- Overlays (regles, pause, fin) --- */

.serp-climber__overlay {
  position: absolute;
  inset: 0;
  z-index: 5;
  display: grid;
  place-items: center;
  padding: var(--sp-3);
  background: color-mix(in srgb, var(--surface) 86%, transparent);
  backdrop-filter: blur(3px);
  transition: opacity 220ms var(--ease);
}

.serp-climber[data-phase="playing"] .serp-climber__overlay {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.serp-climber__screen {
  display: none;
  flex-direction: column;
  align-items: center;
  gap: var(--sp-3);
  width: 100%;
  max-width: 30rem;
  text-align: center;
}

.serp-climber[data-phase="idle"] [data-serp-idle],
.serp-climber[data-phase="paused"] [data-serp-paused],
.serp-climber[data-phase="won"] [data-serp-end],
.serp-climber[data-phase="lost"] [data-serp-end] {
  display: flex;
}

.serp-climber__screen h2 {
  font-size: clamp(1.15rem, 3.4vw, 1.6rem);
  margin: 0;
  letter-spacing: -0.02em;
}

.serp-climber__screen p {
  margin: 0;
  font-size: var(--fs-sm);
  color: var(--text-dim);
}

.serp-climber__rules {
  display: grid;
  gap: 0.35rem;
  margin: 0;
  padding: 0;
  list-style: none;
  text-align: start;
  width: 100%;
}

.serp-climber__rules li {
  display: grid;
  grid-template-columns: 1.1rem 1fr;
  gap: var(--sp-2);
  align-items: start;
  font-size: var(--fs-xs);
  color: var(--text-dim);
  line-height: 1.4;
}

.serp-climber__rules b {
  display: grid;
  place-items: center;
  width: 1.1rem;
  height: 1.1rem;
  background: var(--serp-good);
  color: var(--bg);
  font-size: 0.625rem;
  font-weight: 700;
}

.serp-climber__screen-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2);
  justify-content: center;
}

.serp-climber__kbd {
  font-size: var(--fs-xs);
  color: var(--muted-2);
}

.serp-climber__kbd kbd,
.serp-climber__hint kbd {
  font-family: inherit;
  font-size: 0.6875rem;
  padding: 0.1rem 0.35rem;
  border: 1px solid var(--stroke-2);
  background: var(--bg);
  color: var(--text-dim);
}

/* Ecran de fin */

.serp-climber__end-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  width: 100%;
  margin: 0;
  background: var(--stroke);
  border: 1px solid var(--stroke);
}

.serp-climber__end-stats div {
  background: var(--bg);
  padding: 0.4rem 0.25rem;
}

.serp-climber__end-stats dt {
  font-size: 0.625rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted-2);
}

.serp-climber__end-stats dd {
  margin: 0;
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 1.05rem;
  color: var(--text);
  font-variant-numeric: tabular-nums;
}

.serp-climber__record {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.15rem 0.5rem;
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--bg);
  background: var(--serp-perfect);
}

.serp-climber__record[hidden] {
  display: none;
}

.serp-climber[data-phase="won"] .serp-climber__screen h2 {
  color: color-mix(in srgb, var(--serp-good) 45%, var(--text));
}

/* --- Deck : evenement + jauge + actions --- */

.serp-climber__deck {
  margin-block-start: var(--sp-3);
  display: grid;
  gap: var(--sp-3);
}

.serp-climber__banner {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: center;
  gap: var(--sp-2);
  min-height: 2.4rem;
  margin: 0;
  padding: 0.35rem 0.6rem;
  border: 1px dashed var(--stroke);
  background: var(--bg);
  font-size: var(--fs-xs);
  color: var(--muted-2);
  transition: border-color 0.25s var(--ease), background 0.25s var(--ease);
}

.serp-climber__banner::before {
  content: "";
  width: 0.5rem;
  height: 0.5rem;
  background: var(--stroke-2);
  transition: background 0.25s var(--ease);
}

.serp-climber__banner[data-active="false"] .serp-climber__banner-text::after {
  content: "Aucun signal algo pour l’instant.";
  color: var(--muted-2);
}

.serp-climber__banner[data-active="true"] {
  border-style: solid;
  border-color: color-mix(in srgb, var(--serp-good) 45%, var(--stroke));
  background: color-mix(in srgb, var(--serp-good) 7%, var(--bg));
}

.serp-climber__banner[data-active="true"]::before {
  background: var(--serp-good);
}

.serp-climber__banner[data-tone="bad"] {
  border-color: color-mix(in srgb, var(--serp-bad) 55%, var(--stroke));
  background: color-mix(in srgb, var(--serp-bad) 8%, var(--bg));
}

.serp-climber__banner[data-tone="bad"]::before {
  background: var(--serp-bad);
}

.serp-climber__banner[data-tone="threat"] {
  border-color: color-mix(in srgb, var(--serp-perfect) 55%, var(--stroke));
  background: color-mix(in srgb, var(--serp-perfect) 8%, var(--bg));
}

.serp-climber__banner[data-tone="threat"]::before {
  background: var(--serp-perfect);
}

.serp-climber__banner[data-pending="true"]::before {
  animation: serpPulse 0.55s var(--ease-in-out) infinite;
}

.serp-climber__banner-text {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.serp-climber__banner-label {
  color: var(--text);
  font-weight: 600;
}

.serp-climber__banner-detail {
  color: var(--text-dim);
}

.serp-climber__banner-detail::before {
  content: " · ";
  color: var(--muted-2);
}

.serp-climber__banner-detail:empty::before {
  content: none;
}

/* Jauge de timing */

.serp-climber__meter {
  display: grid;
  gap: 0.4rem;
  padding: var(--sp-2);
  border: 1px solid var(--stroke);
  background: var(--bg);
  touch-action: manipulation;
  -webkit-user-select: none;
  user-select: none;
}

.serp-climber__meter-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: var(--sp-3);
  font-size: 0.625rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted-2);
}

.serp-climber__feedback {
  margin: 0;
  font-size: var(--fs-xs);
  text-transform: none;
  letter-spacing: 0;
  color: var(--text-dim);
  text-align: end;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.serp-climber__feedback[data-tone="perfect"] {
  color: color-mix(in srgb, var(--serp-perfect) 65%, var(--text));
  font-weight: 600;
}

.serp-climber__feedback[data-tone="good"] {
  color: color-mix(in srgb, var(--serp-good) 65%, var(--text));
}

.serp-climber__feedback[data-tone="bad"] {
  color: var(--serp-bad);
}

.serp-climber__feedback.is-live {
  animation: serpFeedback 320ms var(--ease-out);
}

.serp-climber__track {
  position: relative;
  height: 2.25rem;
  background: color-mix(in srgb, var(--surface-2) 70%, var(--bg));
  border: 1px solid var(--stroke-2);
  overflow: hidden;
  cursor: pointer;
}

@media (min-width: 40rem) {
  .serp-climber__track {
    height: 2.5rem;
  }
}

.serp-climber__zone {
  position: absolute;
  top: 0;
  bottom: 0;
  background: color-mix(in srgb, var(--serp-good) 26%, transparent);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--serp-good) 55%, transparent);
  pointer-events: none;
}

.serp-climber__zone::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  width: 32%;
  transform: translateX(-50%);
  background: color-mix(in srgb, var(--serp-perfect) 42%, transparent);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--serp-perfect) 60%, transparent);
}

.serp-climber__needle {
  position: absolute;
  top: -1px;
  bottom: -1px;
  left: 0;
  width: 3px;
  margin-left: -1.5px;
  background: var(--text);
  pointer-events: none;
  will-change: transform;
}

.serp-climber__marks {
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.serp-climber__mark {
  position: absolute;
  bottom: 0;
  width: 1px;
  height: 0.4rem;
  margin-left: -0.5px;
  background: var(--muted-2);
  opacity: 0.55;
}

.serp-climber__mark[data-tone="perfect"] {
  background: var(--serp-perfect);
  opacity: 0.9;
}

.serp-climber__mark[data-tone="good"] {
  background: var(--serp-good);
  opacity: 0.8;
}

.serp-climber__mark[data-tone="bad"] {
  background: var(--serp-bad);
}

/* Flash de resultat sur la piste */

.serp-climber[data-hit="perfect"] .serp-climber__track,
.serp-climber[data-hit="good"] .serp-climber__track,
.serp-climber[data-hit="miss"] .serp-climber__track {
  animation: serpTrackFlash 240ms var(--ease-out);
}

.serp-climber[data-hit="perfect"] .serp-climber__track {
  border-color: color-mix(in srgb, var(--serp-perfect) 70%, var(--stroke-2));
}

.serp-climber[data-hit="good"] .serp-climber__track {
  border-color: color-mix(in srgb, var(--serp-good) 70%, var(--stroke-2));
}

.serp-climber[data-hit="miss"] .serp-climber__track {
  border-color: var(--serp-bad);
}

/* Actions */

.serp-climber__actions {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--sp-2);
  align-items: center;
}

.serp-climber__actions .btn {
  width: 100%;
  justify-content: center;
}

.serp-climber__actions .btn[disabled] {
  opacity: 0.45;
  pointer-events: none;
}

.serp-climber__hint {
  grid-column: 1 / -1;
  margin: 0;
  font-size: var(--fs-xs);
  color: var(--muted-2);
  text-align: center;
}

/* --- Etats globaux --- */

.serp-climber.is-shaking .serp-climber__board {
  animation: serpShake 0.4s var(--ease-in-out);
}

.serp-climber[data-calm="true"] .serp-climber__camera,
.serp-climber[data-calm="true"] .serp-climber__row,
.serp-climber[data-calm="true"] .serp-climber__fill {
  transition-duration: 120ms;
}

.serp-climber[data-calm="true"] .serp-climber__row.is-climbing,
.serp-climber[data-calm="true"] .serp-climber__toast.is-live,
.serp-climber[data-calm="true"] .serp-climber__feedback.is-live,
.serp-climber[data-calm="true"] .serp-climber__banner[data-pending="true"]::before,
.serp-climber[data-calm="true"].is-shaking .serp-climber__board,
.serp-climber[data-calm="true"] .serp-climber__track {
  animation: none;
}

@keyframes serpClimbFlash {
  0% { background: color-mix(in srgb, var(--serp-good) 42%, var(--bg)); }
  100% { background: color-mix(in srgb, var(--serp-good) 9%, var(--bg)); }
}

@keyframes serpToast {
  0% { opacity: 0; transform: translateY(0.4rem); }
  18% { opacity: 1; transform: translateY(0); }
  75% { opacity: 1; transform: translateY(0); }
  100% { opacity: 0; transform: translateY(-0.3rem); }
}

@keyframes serpFeedback {
  0% { opacity: 0.2; transform: translateY(0.25rem); }
  100% { opacity: 1; transform: translateY(0); }
}

@keyframes serpTrackFlash {
  0% { background: color-mix(in srgb, var(--text) 14%, var(--bg)); }
  100% { background: color-mix(in srgb, var(--surface-2) 70%, var(--bg)); }
}

@keyframes serpPulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.25; }
}

@keyframes serpShake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-3px); }
  75% { transform: translateX(3px); }
}

@media (prefers-reduced-motion: reduce) {
  .serp-climber__camera,
  .serp-climber__row,
  .serp-climber__fill,
  .serp-climber__gutter-cell {
    transition: none;
  }
  .serp-climber__row.is-climbing,
  .serp-climber__toast.is-live,
  .serp-climber__feedback.is-live,
  .serp-climber.is-shaking .serp-climber__board,
  .serp-climber .serp-climber__track,
  .serp-climber__banner[data-pending="true"]::before {
    animation: none;
  }
}

html.perf-lite .serp-404::before {
  content: none;
  background: none;
}

html.perf-lite .serp-climber__overlay {
  backdrop-filter: none;
  background: var(--surface);
}

/* Mode accessible : fonds teintes trop faibles remplaces par du contraste */
html[data-a11y="on"] .serp-climber__row.is-player {
  background: var(--bg);
  box-shadow: inset 3px 0 0 var(--serp-good);
}

html[data-a11y="on"] .serp-climber__overlay {
  background: var(--surface);
  backdrop-filter: none;
}

html[data-a11y="on"] .serp-climber__zone {
  background: color-mix(in srgb, var(--serp-good) 34%, transparent);
}