/* =========================================================
   Knight's Travails

   Light, editorial, cool greys. The board carries all the
   colour: an indigo ramp for how far the search had got, and
   one vermilion for the path it settled on.
   ========================================================= */

:root {
  --paper: #f4f4f2;
  --card: #ffffff;
  --ink: #16181c;
  --ink-2: #43474e;
  --muted: #666b74;
  --rule: #dedfdd;

  --light-sq: #e7e8ea;
  --dark-sq: #c6cad0;

  --accent: #c74424;
  --accent-soft: #fbe9e3;

  --display: "Instrument Serif", Georgia, "Times New Roman", serif;
  --ui: "Space Grotesk", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

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

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--ui);
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

button,
input {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

button {
  cursor: pointer;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

code {
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.9em;
  color: var(--ink-2);
}

.page {
  max-width: 1080px;
  margin-inline: auto;
  padding: clamp(1.5rem, 5vw, 3.5rem) clamp(1rem, 4vw, 2rem) 3rem;
}

/* --- masthead --- */

.kicker {
  margin: 0;
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}

.masthead h1 {
  margin: 0.5rem 0 0;
  font-family: var(--display);
  font-weight: 400;
  font-size: clamp(2.4rem, 7vw, 4.2rem);
  line-height: 1.02;
  letter-spacing: -0.015em;
  max-width: 16ch;
}

.masthead h1 em {
  font-style: italic;
  color: var(--accent);
}

.lede {
  max-width: 56ch;
  margin: 1rem 0 0;
  color: var(--ink-2);
}

/* --- layout --- */

.layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 20rem);
  gap: clamp(1.25rem, 4vw, 2.5rem);
  align-items: start;
  margin-top: clamp(1.75rem, 5vw, 2.75rem);
}

/* --- board --- */

.board-wrap {
  display: grid;
  grid-template-columns: 1.35rem minmax(0, 1fr);
  grid-template-rows: minmax(0, 1fr) 1.35rem;
  grid-template-areas:
    "ranks board"
    ".     files";
  gap: 0.35rem;
}

.ranks {
  grid-area: ranks;
  display: grid;
  grid-template-rows: repeat(8, 1fr);
}

.files {
  grid-area: files;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
}

.ranks span,
.files span {
  display: grid;
  place-items: center;
  font-size: 0.68rem;
  font-weight: 500;
  color: var(--muted);
}

.board {
  grid-area: board;
  position: relative;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  aspect-ratio: 1;
  border: 1px solid var(--ink);
  background: var(--light-sq);
}

.sq {
  position: relative;
  border: 0;
  padding: 0;
  background: var(--light-sq);
  display: grid;
  place-items: center;
  font-size: clamp(0.6rem, 1.6vw, 0.78rem);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  color: transparent;
  transition: background-color 160ms ease;
}

.sq.dark {
  background: var(--dark-sq);
}

.sq:hover:not(:disabled) {
  box-shadow: inset 0 0 0 2px var(--ink);
}

/*
 * A square the search reached. The tint comes from --ring, set per square from
 * its distance, so the board reads as bands radiating out from the knight.
 */
.sq.reached {
  background: hsl(232 48% var(--ring-l));
  color: var(--ink);
}

/*
 * The ramp passes through a band where neither dark nor white text clears
 * 4.5:1 against it — at ring 4 the two options measure 4.09 and 3.54. Near
 * black rather than a tinted dark ink lifts that to 5.02, and rings 5 and 6
 * are dark enough to take white at 4.80 and 6.58.
 */
.sq.reached[data-ring="5"],
.sq.reached[data-ring="6"] {
  color: #fff;
}

/* the knight is standing here; the 0 underneath it is just noise */
.sq.reached[data-ring="0"] {
  color: transparent;
}

.sq.on-path {
  background: var(--accent);
  color: #fff;
}

.sq.is-target {
  box-shadow: inset 0 0 0 3px var(--ink);
}

.sq.is-start {
  box-shadow: inset 0 0 0 3px var(--ink);
}

/* the knight itself, floating over the grid */

.knight {
  position: absolute;
  top: 0;
  left: 0;
  width: 12.5%;
  height: 12.5%;
  display: grid;
  place-items: center;
  font-size: clamp(1.3rem, 5.5vw, 2.6rem);
  line-height: 1;
  color: var(--ink);
  pointer-events: none;
  transition: transform 280ms cubic-bezier(0.4, 1.4, 0.5, 1);
  text-shadow: 0 1px 0 rgba(255, 255, 255, 0.65);
}

.knight[hidden] {
  display: none !important;
}

/* --- status --- */

.status {
  margin: 0.85rem 0 0;
  min-height: 2.8em;
  color: var(--ink-2);
  max-width: 54ch;
}

.status b {
  color: var(--ink);
  font-weight: 600;
}

/* --- panel --- */

.panel {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.readout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.stat {
  border-top: 1px solid var(--ink);
  padding-top: 0.5rem;
}

.stat-label {
  margin: 0;
  font-size: 0.66rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}

.stat-value {
  margin: 0.1rem 0 0;
  font-family: var(--display);
  font-size: 2.6rem;
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

.route {
  margin: 0;
  padding: 0.6rem 0.75rem;
  background: var(--card);
  border: 1px solid var(--rule);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.78rem;
  color: var(--ink-2);
  word-break: break-word;
  min-height: 3.4em;
}

.buttons {
  display: flex;
  gap: 0.45rem;
}

.primary,
.quiet {
  flex: 1;
  padding: 0.5rem 0.8rem;
  font-size: 0.82rem;
  font-weight: 500;
  border: 1px solid var(--ink);
  border-radius: 2px;
}

.primary {
  background: var(--ink);
  color: var(--paper);
}

.primary:hover {
  background: var(--accent);
  border-color: var(--accent);
}

.quiet {
  background: transparent;
  color: var(--ink);
}

.quiet:hover {
  background: var(--card);
}

button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.toggle {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  font-size: 0.82rem;
  color: var(--ink-2);
  cursor: pointer;
}

.toggle input {
  margin: 0.28rem 0 0;
  accent-color: var(--accent);
}

.toggle em {
  font-style: italic;
  color: var(--ink);
}

.legend[hidden] {
  display: none !important;
}

.legend-label {
  margin: 0 0 0.3rem;
  font-size: 0.66rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}

.ramp {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 2px;
}

.ramp li {
  flex: 1;
  display: grid;
  place-items: center;
  height: 1.6rem;
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--ink);
}

.ramp li[data-ring="5"],
.ramp li[data-ring="6"] {
  color: #fff;
}

.note {
  border-top: 1px solid var(--rule);
  padding-top: 0.75rem;
}

.note h2 {
  margin: 0.9rem 0 0.3rem;
  font-family: var(--display);
  font-weight: 400;
  font-size: 1.2rem;
}

.note h2:first-child {
  margin-top: 0;
}

.note p {
  margin: 0 0 0.6rem;
  font-size: 0.83rem;
  color: var(--ink-2);
}

.note em {
  font-style: italic;
  color: var(--ink);
}

.colophon {
  margin-top: 2.5rem;
  padding-top: 0.9rem;
  border-top: 1px solid var(--rule);
  font-size: 0.78rem;
  color: var(--muted);
}

.colophon p {
  margin: 0;
}

.colophon a {
  color: var(--ink-2);
  text-underline-offset: 3px;
}

/* --- narrow --- */

@media (max-width: 820px) {
  .layout {
    grid-template-columns: minmax(0, 1fr);
  }

  .masthead h1 {
    max-width: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .knight,
  .sq {
    transition: none;
  }
}