/* Braille Blitz - pure black, white, big and bold. Built for low vision first. */
:root {
  --bg: #000; --ink: #fff; --ink-2: #d8d8d8; --dim: #8a8a8a; --line: #3a3a3a;
  --accent: #ffd60a;        /* focus, progress, highlights */
  --good: #3ddc84; --bad: #ff5c5c; --info: #4fc3f7;
  --sat: env(safe-area-inset-top, 0px); --sab: env(safe-area-inset-bottom, 0px);
  --sal: env(safe-area-inset-left, 0px); --sar: env(safe-area-inset-right, 0px);
  color-scheme: dark;
}
* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html { font-size: 18px; }
@media (min-width: 700px) { html { font-size: 20px; } }
body {
  margin: 0; min-height: 100vh; background: var(--bg); color: var(--ink);
  font-family: "Helvetica Neue", Helvetica, Arial, "Liberation Sans", sans-serif; font-weight: 700; line-height: 1.3;
  padding: var(--sat) var(--sar) var(--sab) var(--sal);
  -webkit-text-size-adjust: 100%;
}
.sr-only { position: absolute !important; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--accent); color: #000; padding: 10px 14px; border-radius: 8px; z-index: 10; }
.skip:focus { left: 8px; }
:focus-visible { outline: 4px solid var(--accent); outline-offset: 3px; }
h1:focus, h2:focus { outline: none; }   /* headings take focus for screen readers when a screen changes; no ring needed */

.top { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 10px 14px 0; }
.brand { margin: 0; font-size: 1.1rem; letter-spacing: 0.14em; }
.brand span { color: var(--accent); }
.site-back, .icon-btn {
  width: 56px; height: 56px; border-radius: 50%; display: flex; align-items: center; justify-content: center; flex: 0 0 auto;
  background: #111; color: var(--ink); border: 3px solid var(--line); text-decoration: none; font: inherit; font-size: 1.6rem; cursor: pointer;
}
.site-back { font-size: 2rem; line-height: 1; padding-bottom: 4px; }
.icon-btn[aria-pressed="true"] { background: var(--accent); color: #000; border-color: var(--accent); }

main { max-width: 760px; margin: 0 auto; padding: 8px 16px 24px; }
.screen[hidden] { display: none !important; }
h1 { font-size: 2.4rem; margin: 10px 0 0; letter-spacing: 0.02em; }
h2 { font-size: 1.7rem; margin: 18px 0 8px; }
h3 { font-size: 1.2rem; margin: 22px 0 8px; color: var(--ink-2); }
p { margin: 8px 0; }
.tagline { color: var(--ink-2); font-size: 1.15rem; margin-bottom: 18px; }

/* Buttons: big, bold, white on black with a thick rim. Never under 64px tall. */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px; min-height: 64px; min-width: 64px; padding: 12px 20px;
  background: #000; color: var(--ink); border: 4px solid var(--ink); border-radius: 16px; font: inherit; font-size: 1.15rem; font-weight: 800;
  cursor: pointer; text-decoration: none; touch-action: manipulation; user-select: none;
}
.btn:hover { background: #1a1a1a; }
.btn:active { transform: scale(0.98); }
.btn.big { min-height: 80px; font-size: 1.4rem; background: var(--ink); color: #000; }
.btn.big:hover { background: #e6e6e6; }
.btn.small { min-height: 64px; font-size: 1rem; padding: 8px 14px; border-width: 3px; }
.btn.danger { border-color: var(--bad); color: var(--bad); }
.btn.danger.big { background: var(--bad); color: #000; }
.btn[disabled] { opacity: 0.45; cursor: default; }
.row { display: flex; flex-wrap: wrap; gap: 12px; margin: 18px 0 0; }
.row > .btn { flex: 1 1 160px; }

/* Home: mode cards */
.modes { display: grid; grid-template-columns: 1fr; gap: 12px; }
@media (min-width: 560px) { .modes { grid-template-columns: 1fr 1fr; } }
.mode-btn { display: flex; flex-direction: column; align-items: flex-start; text-align: left; min-height: 96px; padding: 14px 18px; border-radius: 18px; }
.mode-btn .mode-name { font-size: 1.5rem; }
.mode-btn .mode-blurb { font-size: 0.95rem; font-weight: 500; color: var(--ink-2); margin-top: 4px; }
.mode-btn .mode-count { font-size: 0.85rem; color: var(--accent); margin-top: 6px; }
.mode-btn.sub { min-height: 64px; border-style: dashed; }
.path { margin-top: 24px; }
.path-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 8px; }
.path-list li { display: flex; align-items: center; gap: 12px; padding: 10px 12px; border: 3px solid var(--line); border-radius: 14px; font-weight: 600; }
.path-list li .stage-no { flex: 0 0 auto; width: 44px; height: 44px; border-radius: 50%; display: flex; align-items: center; justify-content: center; background: #111; border: 3px solid var(--ink); font-weight: 900; }
.path-list li.done { border-color: var(--good); }
.path-list li.done .stage-no { background: var(--good); color: #000; border-color: var(--good); }
.path-list li.now { border-color: var(--accent); }
.path-list li.now .stage-no { border-color: var(--accent); color: var(--accent); }
.path-list li .stage-text { flex: 1 1 auto; }
.path-list li .stage-sub { display: block; font-size: 0.85rem; color: var(--ink-2); font-weight: 500; }
.path-note { color: var(--dim); font-size: 0.9rem; font-weight: 500; }

/* Play */
.hud { display: flex; align-items: baseline; justify-content: space-between; gap: 10px; flex-wrap: wrap; margin-top: 4px; }
.hud-mode { margin: 0; font-size: 1.2rem; color: var(--accent); letter-spacing: 0.06em; text-transform: uppercase; }
.hud-q { margin: 0; font-size: 1.1rem; }
.hud-score { margin: 0; font-size: 1.1rem; }
.hud-score .ok { color: var(--good); }
.hud-score .sep { color: var(--dim); }
.progress { height: 14px; background: #1a1a1a; border: 2px solid var(--line); border-radius: 999px; overflow: hidden; margin: 8px 0 6px; }
.progress-fill { height: 100%; width: 0; background: var(--accent); transition: width 0.25s ease; }
.stage { display: grid; grid-template-columns: 1fr; gap: 12px; }
.question { text-align: center; }
.prompt { font-size: 1.6rem; margin: 10px 0 0; }
.instruction { font-size: 1rem; color: var(--ink-2); font-weight: 500; min-height: 1.3em; margin: 4px 0 0; }
.cells { display: flex; justify-content: center; align-items: center; gap: clamp(10px, 3vw, 22px); margin: 10px 0 6px; }
.cell { display: block; width: clamp(96px, 36vmin, 200px); height: auto; }
.cells.many .cell { width: clamp(64px, 18vmin, 140px); }
.cells .sign { opacity: 0.92; }
.cell .raised { fill: #fff; stroke: #000; stroke-width: 2; }
.cell .empty { fill: none; stroke: #9a9a9a; stroke-width: 4; }
.cell .frame { fill: #0a0a0a; stroke: #3a3a3a; stroke-width: 3; }
.cell .no { fill: #6a6a6a; font: 700 13px Helvetica, Arial, sans-serif; }
.feedback { min-height: 2.2em; margin: 4px 0 0; font-size: 1.5rem; font-weight: 900; }
.feedback.good { color: var(--good); }
.feedback.bad { color: var(--bad); }
.answers { display: grid; grid-template-columns: 1fr; gap: 14px; }
@media (min-width: 560px) { .answers { grid-template-columns: repeat(3, 1fr); } }
.answers .btn { min-height: 96px; font-size: 3rem; border-width: 5px; border-radius: 22px; padding: 10px; }
.answers .btn .k { position: absolute; left: 12px; top: 8px; font-size: 0.8rem; color: var(--dim); font-weight: 700; }
.answers .btn { position: relative; }
.answers .btn.reverse { min-height: 160px; font-size: 1rem; }
.answers .btn.reverse .cell { width: clamp(64px, 16vmin, 110px); }
.answers .btn.reverse .cells { margin: 0; gap: 8px; }
.answers .btn.right { border-color: var(--good); background: #0d2a1a; }
.answers .btn.wrong { border-color: var(--bad); background: #2d0f0f; }
.answers .btn[disabled] { opacity: 1; }
.answers .btn[disabled]:not(.right):not(.wrong) { opacity: 0.55; }
.controls { display: flex; gap: 10px; margin-top: 16px; }
.controls .btn { flex: 1 1 0; }
/* Landscape phones: cell on the left, answers on the right. */
@media (orientation: landscape) and (max-height: 520px) {
  .top { padding: 4px 12px 0; }
  .top .brand { display: none; }
  .site-back, .icon-btn { width: 44px; height: 44px; font-size: 1.2rem; }
  .site-back { font-size: 1.6rem; }
  main { padding-top: 2px; }
  .hud { margin-top: 0; }
  .hud-mode, .hud-q, .hud-score { font-size: 0.95rem; }
  .progress { height: 10px; margin: 4px 0; }
  .stage { grid-template-columns: 1fr 1fr; align-items: center; gap: 10px; }
  .answers { grid-template-columns: 1fr; gap: 8px; }
  .answers .btn { min-height: 64px; font-size: 1.8rem; border-width: 4px; }
  .answers .btn.reverse { min-height: 64px; }
  .answers .btn.reverse .cell { width: clamp(40px, 12vh, 64px); }
  .cell { width: clamp(80px, 32vh, 150px); }
  .cells.many .cell { width: clamp(48px, 20vh, 90px); }
  .prompt { font-size: 1.15rem; margin-top: 2px; }
  .instruction { font-size: 0.85rem; }
  .cells { margin: 4px 0 2px; }
  .feedback { min-height: 1.4em; font-size: 1.15rem; }
  .controls { margin-top: 8px; }
  .controls .btn { min-height: 48px; font-size: 0.9rem; }
}
.overlay { position: fixed; inset: 0; background: rgba(0, 0, 0, 0.9); display: flex; align-items: center; justify-content: center; padding: 20px; z-index: 20; }
.overlay[hidden] { display: none; }
.overlay-card { background: #000; border: 4px solid var(--ink); border-radius: 22px; padding: 22px; max-width: 460px; width: 100%; display: grid; gap: 12px; text-align: center; }
.overlay-card h2 { margin: 0; }
.overlay-card p { font-weight: 500; color: var(--ink-2); }

/* Summary and stats */
.tiles { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 12px; margin-top: 8px; }
.tile { border: 3px solid var(--line); border-radius: 16px; padding: 12px; }
.tile .v { display: block; font-size: 2rem; line-height: 1.05; }
.tile .l { display: block; font-size: 0.85rem; color: var(--ink-2); font-weight: 600; margin-top: 4px; }
.tile.good .v { color: var(--good); }
.tile.accent .v { color: var(--accent); }
.sum-note { font-size: 1.1rem; color: var(--ink-2); font-weight: 600; }
.char-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(96px, 1fr)); gap: 8px; }
.char { border: 3px solid var(--line); border-radius: 12px; padding: 8px 6px 6px; text-align: center; }
.char .c { font-size: 1.6rem; line-height: 1; }
.char .u { font-size: 1.4rem; line-height: 1; color: var(--ink-2); }
.char .bar { height: 10px; border-radius: 999px; background: #1a1a1a; border: 2px solid var(--line); overflow: hidden; margin: 6px 0 4px; }
.char .bar i { display: block; height: 100%; background: var(--accent); }
.char .lv { font-size: 0.72rem; color: var(--dim); letter-spacing: 0.06em; text-transform: uppercase; }
.char.mastered { border-color: var(--good); }
.char.mastered .lv { color: var(--good); }
.char.mastered .bar i { background: var(--good); }
.char.weak { border-color: var(--bad); }
.char.weak .lv { color: var(--bad); }
.missed { padding-left: 28px; font-size: 1.1rem; }
.missed li { margin: 4px 0; }
.missed .u { color: var(--ink-2); margin-left: 6px; }
.recent-strip { display: flex; flex-wrap: wrap; gap: 6px; }
.recent-strip span { width: 28px; height: 28px; border-radius: 6px; display: flex; align-items: center; justify-content: center; font-size: 0.9rem; color: #000; }
.recent-strip .y { background: var(--good); }
.recent-strip .n { background: var(--bad); }
.legend { color: var(--dim); font-size: 0.9rem; font-weight: 500; }

/* Settings */
.settings { display: grid; gap: 12px; }
.setting { display: flex; align-items: center; justify-content: space-between; gap: 14px; border: 3px solid var(--line); border-radius: 16px; padding: 12px 14px; }
.setting .s-text { flex: 1 1 auto; }
.setting .s-name { font-size: 1.2rem; }
.setting .s-sub { display: block; font-size: 0.85rem; color: var(--ink-2); font-weight: 500; margin-top: 2px; }
.switch { flex: 0 0 auto; min-width: 96px; min-height: 64px; border-radius: 999px; border: 4px solid var(--ink); background: #000; color: var(--ink); font: inherit; font-weight: 900; font-size: 1.05rem; cursor: pointer; }
.switch[aria-pressed="true"] { background: var(--accent); color: #000; border-color: var(--accent); }
.switch[disabled] { opacity: 0.4; cursor: default; }
.seg { display: flex; gap: 6px; }
.seg .btn.small { min-width: 64px; }
.seg .btn[aria-pressed="true"] { background: var(--accent); color: #000; border-color: var(--accent); }

/* Help */
.help-cell { display: flex; justify-content: center; }
.help-cell .cell { width: 150px; }
.uni { font-size: 1.5em; line-height: 1; vertical-align: -0.1em; }
ul { padding-left: 24px; font-weight: 500; }
li { margin: 6px 0; }
.foot { text-align: center; color: var(--dim); font-size: 0.8rem; font-weight: 500; padding: 10px 16px 20px; }
.foot a { color: var(--ink-2); }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
}