:root {
  --bg: #14181d;
  --panel: #1e242b;
  --panel-2: #262d36;
  --ink: #e8ebef;
  --muted: #9aa5b1;
  --accent: #e0a91b;
  --good: #3f9b46;
  --bad: #cc3333;
  --line: #333c46;
  --rock: #6b6157;
  --rock-2: #574e45;
  --crack-dark: #0b0d10;
  /* Shared fractal-noise grain (inline SVG); alpha channel varies, so it works
     both as a soft-light texture layer and as a gritty alpha mask. */
  --grain: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

* { box-sizing: border-box; }

/* The [hidden] attribute must always win, even over rules that set display
   (e.g. .verdict uses display:flex) — otherwise hidden elements stay visible. */
[hidden] { display: none !important; }

html, body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

/* ---------- top bar ---------- */
.topbar {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.6rem 1rem;
  background: var(--panel);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar h1 {
  font-size: 1.15rem;
  margin: 0;
  letter-spacing: 0.5px;
}
/* Full title on wide screens, "C&R" in the mobile menu bar. */
.title-short { display: none; }
@media (max-width: 560px) {
  .title-full { display: none; }
  .title-short { display: inline; }
}
.tabs { display: flex; gap: 0.25rem; margin-left: auto; }
.tab {
  background: transparent;
  border: 1px solid transparent;
  color: var(--muted);
  padding: 0.4rem 0.8rem;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.95rem;
}
.tab:hover { color: var(--ink); }
.tab.active { background: var(--panel-2); color: var(--ink); border-color: var(--line); }

.diff-select {
  background: var(--panel-2); color: var(--ink);
  border: 1px solid var(--line); border-radius: 8px;
  padding: 0.35rem 0.5rem; font-size: 0.9rem; cursor: pointer;
}
/* full-width red banner shown at the top whenever the screen is uncalibrated */
.cal-banner {
  background: var(--bad); color: #fff;
  text-align: center; padding: 0.6rem 1rem;
  font-size: 0.9rem; font-weight: 600;
}
.cal-banner a { color: #fff; text-decoration: underline; }

/* ---------- collapsible header ---------- */
.collapse-btn {
  background: var(--panel-2);
  border: 1px solid var(--line);
  color: var(--muted);
  width: 30px; height: 30px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.7rem;
  line-height: 1;
}
.collapse-btn:hover { color: var(--ink); }
.expand-btn {
  display: none;
  position: fixed;
  top: 8px; left: 10px;
  z-index: 20;
  background: var(--panel-2);
  border: 1px solid var(--line);
  color: var(--muted);
  padding: 0.35rem 0.6rem;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.8rem;
  box-shadow: 0 3px 10px rgba(0,0,0,0.4);
}
.expand-btn:hover { color: var(--ink); }
.header-collapsed .topbar { display: none; }
.header-collapsed .expand-btn { display: block; }
/* Keep content clear of the fixed expand button when the header is hidden. */
.header-collapsed main { padding-top: 3.2rem; }

/* ---------- layout ---------- */
main { max-width: 900px; margin: 0 auto; padding: 1.25rem 1rem 4rem; }
.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 1.25rem 1.4rem;
}
h2 { margin-top: 0; }
.lede { color: var(--muted); line-height: 1.5; max-width: 60ch; }
.hint { color: var(--muted); font-size: 0.9rem; line-height: 1.45; max-width: 60ch; }
.muted { color: var(--muted); }

/* ---------- calibration ---------- */
.seg {
  display: inline-flex;
  border: 1px solid var(--line);
  border-radius: 10px;
  overflow: hidden;
  margin: 0.5rem 0 1rem;
}
.seg-btn {
  background: var(--panel-2);
  border: none;
  color: var(--muted);
  padding: 0.5rem 1rem;
  cursor: pointer;
}
.seg-btn.active { background: var(--accent); color: #1a1a1a; font-weight: 600; }

.card-stage, .ruler-stage {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem 0;
  min-height: 160px;
}
.card-stage { min-height: 0; } /* portrait card can be tall; let it size itself */
.credit-card {
  background: linear-gradient(135deg, #3a4653, #2a333d);
  border: 1px solid #55606c;
  border-radius: 10px;
  position: relative;
  box-shadow: 0 6px 18px rgba(0,0,0,0.4);
  /* width/height set inline by JS to card aspect */
}
.card-note {
  position: absolute; bottom: 6px; right: 10px;
  font-size: 0.7rem; color: #aeb8c2;
}
.ruler-line {
  height: 3px;
  background: var(--accent);
  position: relative;
}
.ruler-line::before, .ruler-line::after {
  content: ""; position: absolute; top: -6px; width: 2px; height: 15px; background: var(--accent);
}
.ruler-line::before { left: 0; }
.ruler-line::after { right: 0; }

.slider-row { display: flex; align-items: center; gap: 0.6rem; margin: 0.4rem 0; }
.slider-row input[type="range"] { flex: 1; }
.slider-row input[type="number"] { width: 5rem; padding: 0.3rem; background: var(--panel-2); border: 1px solid var(--line); color: var(--ink); border-radius: 6px; }

.cal-readout { font-size: 1.4rem; margin: 0.8rem 0; }
.cal-readout .muted { font-size: 0.85rem; }

.btn-row { display: flex; gap: 0.6rem; margin-top: 0.8rem; }
button.primary {
  background: var(--accent); color: #1a1a1a; border: none;
  padding: 0.55rem 1.1rem; border-radius: 9px; font-weight: 600; cursor: pointer;
}
button.ghost {
  background: transparent; color: var(--muted); border: 1px solid var(--line);
  padding: 0.55rem 1.1rem; border-radius: 9px; cursor: pointer;
}

/* ---------- play ---------- */
.wall {
  position: relative;
  height: 360px;
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid var(--line);
  /* Layered granite: fine fractal-noise grain (inline SVG), broad light/dark
     mottling, then a warm base gradient. Grain is soft-light-blended so it reads
     as speckle rather than a flat overlay. */
  background-color: var(--rock);
  background-image:
    var(--grain),
    radial-gradient(120% 90% at 28% 22%, rgba(255,240,220,0.10), transparent 55%),
    radial-gradient(110% 100% at 78% 85%, rgba(0,0,0,0.38), transparent 55%),
    linear-gradient(180deg, #7c7165 0%, #574e45 60%, #443c34 100%);
  background-size: 160px 160px, cover, cover, cover;
  background-blend-mode: soft-light, normal, normal, normal;
  box-shadow: inset 0 0 70px 14px rgba(0,0,0,0.5); /* vignette for depth */
}
.crack {
  position: absolute;
  left: 50%;
  top: 50%;
  height: 220%; /* long enough to run off both edges at any angle */
  transform-origin: center center;
  transform: translate(-50%, -50%) rotate(0deg); /* width + rotate set inline by JS */
  /* The back of the crack is the same granite grain, but heavily darkened, with a
     multiply shading that deepens toward the centre (the deepest part of the gap). */
  background-color: #0d0906;
  background-image:
    var(--grain),
    linear-gradient(90deg,
      rgba(70,56,44,0.55) 0%, rgba(0,0,0,0.85) 42%, #000 50%,
      rgba(0,0,0,0.85) 58%, rgba(70,56,44,0.55) 100%),
    linear-gradient(180deg, #241b14, #0e0a07);
  background-size: 150px 150px, 100% 100%, 100% 100%;
  background-blend-mode: soft-light, multiply, normal;
  box-shadow: inset 0 0 26px 6px #000, 0 0 16px 5px rgba(0,0,0,0.6);
  /* width set inline by JS from true mm × pxPerMm (perpendicular gap, angle-invariant) */
}
/* Gritty lit lips: thin warm strips at each edge, broken up by the noise alpha
   mask so the highlight reads as rough stone rather than a clean line. */
.crack::before,
.crack::after {
  content: "";
  position: absolute; top: 0; bottom: 0;
  width: 2px;
  background: rgba(255,238,214,0.6);
  -webkit-mask-image: var(--grain); mask-image: var(--grain);
  -webkit-mask-size: 22px 22px; mask-size: 22px 22px;
  -webkit-mask-repeat: repeat; mask-repeat: repeat;
}
.crack::before { left: 0; }
.crack::after { right: 0; }

/* score / streak overlaid in the top corners of the crack window */
.hud {
  position: absolute; top: 8px; z-index: 3;
  font-size: 0.8rem; color: rgba(255,255,255,0.85);
  background: rgba(0,0,0,0.45); padding: 0.25rem 0.55rem; border-radius: 999px;
  pointer-events: none; text-shadow: 0 1px 2px #000;
}
.hud strong { color: #fff; font-size: 1rem; }
.hud-score { left: 8px; }
.hud-streak {
  right: 8px;
  transition: background 0.45s ease, box-shadow 0.45s ease, color 0.45s ease;
}
/* streak number follows the badge's (heat-dependent) text colour */
.hud-streak strong { color: inherit; }
.hud-streak.streak-max { animation: flamepulse 0.9s ease-in-out infinite alternate; }
@keyframes flamepulse {
  from { box-shadow: 0 0 14px 1px rgba(255,140,0,0.6); }
  to   { box-shadow: 0 0 26px 5px rgba(255,90,0,0.85); }
}

/* pass/fail marker centred over the crack after answering */
.verdict {
  position: absolute; inset: 0; z-index: 4;
  display: flex; align-items: center; justify-content: center;
  font-size: 8rem; line-height: 1; font-weight: 700;
  text-shadow: 0 2px 12px rgba(0,0,0,0.8);
  pointer-events: none;
}
.verdict.full { color: var(--good); }
.verdict.partial { color: var(--accent); }
.verdict.wrong { color: var(--bad); }

/* in-wall next chevron so phone users advance without scrolling */
.wall-next {
  position: absolute; top: 50%; right: 14px; transform: translateY(-50%);
  z-index: 5;
  background: none; border: none; padding: 0 0.3rem; cursor: pointer;
  color: var(--accent);
  font-size: 4rem; line-height: 1; font-weight: 700;
  text-shadow: 0 2px 8px rgba(0,0,0,0.7);
}
.wall-next:active { transform: translateY(-50%) scale(0.92); }

.prompt { text-align: center; font-size: 1.05rem; margin: 1rem 0 0.6rem; }

.gear-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.6rem;
}
@media (max-width: 560px) { .gear-grid { grid-template-columns: repeat(3, 1fr); gap: 0.4rem; } }
.gear-btn {
  display: flex; align-items: center; justify-content: center; gap: 0.5rem;
  background: var(--panel-2);
  border: 1px solid var(--line);
  color: var(--ink);
  padding: 0.6rem 0.5rem;
  border-radius: 10px;
  cursor: pointer;
  font-size: 0.95rem;
  transition: transform 0.05s ease, border-color 0.1s ease;
}
.gear-btn:hover:not(:disabled) { border-color: var(--accent); }
.gear-btn:active:not(:disabled) { transform: translateY(1px); }
.gear-btn:disabled { cursor: default; opacity: 0.85; }
.gear-btn .swatch { width: 18px; height: 18px; border-radius: 50%; border: 1px solid rgba(0,0,0,0.4); flex: none; }
.gear-btn .gsize { font-weight: 700; }
.gear-btn.correct { border-color: var(--good); background: #1f3524; }
.gear-btn.fits { border-color: #6ea36f; }
.gear-btn.chosen-bad { border-color: var(--bad); background: #3a1f1f; }
/* too large to display on this screen (interactive so it can explain why) */
.gear-btn.unavailable { opacity: 0.3; cursor: help; filter: grayscale(0.7); }
.gear-btn.unavailable:hover { border-color: var(--line); }   /* stay looking inert */
.gear-btn.unavailable:active { transform: none; }
.gear-note {
  margin: 0.5rem 0 0;
  font-size: 0.85rem;
  color: var(--accent);
  background: rgba(224,169,27,0.10);
  border: 1px solid rgba(224,169,27,0.35);
  border-radius: 8px;
  padding: 0.5rem 0.7rem;
}

/* ---------- feedback + range chart ---------- */
.feedback { margin-top: 1rem; background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 1rem; }
.feedback-text { margin: 0 0 0.8rem; line-height: 1.5; }
.feedback-text .tag { font-weight: 700; }
.feedback-text .tag.full { color: var(--good); }
.feedback-text .tag.partial { color: var(--accent); }
.feedback-text .tag.wrong { color: var(--bad); }

.range-chart, .study-chart { display: flex; flex-direction: column; gap: 6px; margin: 0.6rem 0 1rem; }
.rc-row { display: grid; grid-template-columns: 3.2rem 1fr; align-items: center; gap: 0.6rem; font-size: 0.8rem; }
.rc-track { position: relative; height: 16px; background: var(--panel-2); border-radius: 4px; }
.rc-bar { position: absolute; top: 0; bottom: 0; border-radius: 4px; opacity: 0.85; }
.rc-marker { position: absolute; top: -3px; bottom: -3px; width: 2px; background: #fff; box-shadow: 0 0 4px #000; }
.rc-row.is-best .rc-track { outline: 2px solid var(--good); outline-offset: 1px; }
.rc-label { display: flex; align-items: center; gap: 0.35rem; }
.rc-label .swatch { width: 12px; height: 12px; border-radius: 50%; }

/* ---------- study ---------- */
.cam-table { width: 100%; border-collapse: collapse; margin-top: 1rem; font-size: 0.9rem; }
.cam-table th, .cam-table td { text-align: left; padding: 0.4rem 0.6rem; border-bottom: 1px solid var(--line); }
.cam-table th { color: var(--muted); font-weight: 600; }
.cam-table .swatch { display: inline-block; width: 12px; height: 12px; border-radius: 50%; margin-right: 0.4rem; vertical-align: middle; }

/* ---------- rack selection ---------- */
.rack-name { color: var(--muted); font-size: 0.85rem; margin: 0.8rem 0 0; text-align: center; }
.rack-name strong { color: var(--ink); }
.rack-change { color: var(--accent); margin-left: 0.5rem; font-size: 0.8rem; }
.rack-list { display: flex; flex-direction: column; gap: 0.5rem; margin-top: 1rem; }
.rack-item {
  display: flex; flex-direction: column; gap: 0.15rem; text-align: left;
  background: var(--panel-2); border: 1px solid var(--line);
  color: var(--ink); border-radius: 10px; padding: 0.7rem 0.9rem; cursor: pointer;
}
.rack-item:hover { border-color: var(--accent); }
.rack-item.active { border-color: var(--accent); background: #2c2a1c; }
.rack-item-name { font-weight: 700; }
.rack-item-meta { color: var(--muted); font-size: 0.8rem; }

.view { animation: fade 0.15s ease; }
@keyframes fade { from { opacity: 0; } to { opacity: 1; } }

/* keep the (now busier) menu bar from overflowing on small screens */
@media (max-width: 560px) {
  .topbar { flex-wrap: wrap; row-gap: 0.4rem; column-gap: 0.5rem; }
  .tab { padding: 0.35rem 0.55rem; font-size: 0.9rem; }
}