:root {
  color-scheme: light dark;
  --bg: #f4f5f8;
  --bg-glow: rgba(49, 94, 251, 0.12);
  --panel: #ffffff;
  --panel-soft: #f8f9fb;
  --text: #16181d;
  --muted: #5b6472;
  --line: #dfe3ea;
  --line-strong: #c7ccd8;
  --accent: #315efb;
  --accent-strong: #1f46d6;
  --accent-soft: #edf1ff;
  --ok: #137a4b;
  --ok-bg: #e7f7ef;
  --error: #b42318;
  --error-bg: #fdeceb;
  --warn: #8a5a00;
  --warn-bg: #fff3d1;
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.05), 0 18px 48px rgba(16, 24, 40, 0.08);
  --radius: 18px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1017;
    --bg-glow: rgba(78, 118, 255, 0.18);
    --panel: #151a23;
    --panel-soft: #1b2230;
    --text: #f1f4f9;
    --muted: #a2acbc;
    --line: #2a3343;
    --line-strong: #3a465a;
    --accent: #7f9bff;
    --accent-strong: #a7baff;
    --accent-soft: #1d2740;
    --ok: #6ee7b7;
    --ok-bg: #123326;
    --error: #fca5a5;
    --error-bg: #3a1b1b;
    --warn: #fcd34d;
    --warn-bg: #3a2d0e;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.35), 0 22px 60px rgba(0, 0, 0, 0.45);
  }
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

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

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(1000px 600px at 12% -10%, var(--bg-glow), transparent 65%),
    var(--bg);
  color: var(--text);
  font-family:
    "Inter", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  line-height: 1.55;
}

.shell {
  width: min(1120px, calc(100% - 2rem));
  margin: 0 auto;
  padding: clamp(1.5rem, 4vw, 4rem) 0 2.5rem;
}

.hero {
  max-width: 760px;
  margin-bottom: clamp(1.5rem, 4vw, 2.75rem);
}

.eyebrow {
  margin: 0 0 0.75rem;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.hero h1 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 3.55rem);
  line-height: 1.05;
  letter-spacing: -0.035em;
}

.lede {
  margin: 1rem 0 0;
  max-width: 62ch;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.16rem);
}

.demo {
  display: grid;
  grid-template-columns: minmax(0, 1.12fr) minmax(0, 0.88fr);
  gap: 1.25rem;
  align-items: start;
}

.paper-panel,
.result-panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: clamp(1rem, 2.5vw, 1.4rem);
}

.result-panel {
  position: sticky;
  top: 1rem;
  min-height: 320px;
}

.panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.9rem;
}

.panel-head h2 {
  margin: 0;
  font-size: 1.02rem;
  letter-spacing: -0.01em;
}

.session {
  color: var(--muted);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.74rem;
  white-space: nowrap;
}

.canvas-wrap {
  position: relative;
  width: 100%;
  aspect-ratio: 4 / 3;
  border: 1px solid var(--line-strong);
  border-radius: 14px;
  overflow: hidden;
  background: #ffffff;
}

#pad {
  display: block;
  width: 100%;
  height: 100%;
  background: #ffffff;
  cursor: crosshair;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
}

#pad:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: -3px;
}

.canvas-empty {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  margin: 0;
  padding: 1rem;
  color: #9aa3b2;
  font-size: clamp(0.82rem, 2.5vw, 1rem);
  text-align: center;
  pointer-events: none;
}

.canvas-empty span {
  color: #6b7484;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.canvas-empty.is-hidden {
  display: none;
}

.typed-field {
  display: block;
  margin-top: 1rem;
}

.typed-field > span {
  display: block;
  margin-bottom: 0.4rem;
  color: var(--muted);
  font-size: 0.82rem;
}

.typed-field textarea {
  display: block;
  width: 100%;
  resize: vertical;
  min-height: 4.2rem;
  padding: 0.7rem 0.8rem;
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  background: var(--panel-soft);
  color: var(--text);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.95rem;
  line-height: 1.5;
}

.typed-field textarea:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--accent) 35%, transparent);
  outline-offset: 1px;
  border-color: var(--accent);
}

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  margin-top: 1rem;
}

.button {
  appearance: none;
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 0.65rem 1.05rem;
  font: inherit;
  font-size: 0.92rem;
  font-weight: 650;
  cursor: pointer;
  transition:
    background 140ms ease,
    border-color 140ms ease,
    color 140ms ease,
    transform 140ms ease;
}

.button:active:not(:disabled) {
  transform: translateY(1px);
}

.button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

.button.primary {
  margin-left: auto;
  background: var(--accent);
  color: #ffffff;
  box-shadow: 0 8px 20px color-mix(in srgb, var(--accent) 28%, transparent);
}

.button.primary:hover:not(:disabled) {
  background: var(--accent-strong);
}

.button.ghost {
  background: var(--panel-soft);
  border-color: var(--line-strong);
  color: var(--text);
}

.button.ghost:hover:not(:disabled) {
  background: var(--accent-soft);
  border-color: var(--accent);
}

.button:focus-visible,
.solution-toggle:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--accent) 40%, transparent);
  outline-offset: 2px;
}

.input-note,
.footnote {
  color: var(--muted);
  font-size: 0.8rem;
}

.input-note {
  margin: 0.85rem 0 0;
}

.status {
  margin: 0;
  min-height: 1.4em;
  color: var(--muted);
  font-size: 0.9rem;
}

.status.is-loading {
  color: var(--accent);
}

.status.is-error {
  color: var(--error);
}

.solution-block {
  margin-top: 1rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.26rem 0.62rem;
  border-radius: 999px;
  font-size: 0.74rem;
  font-weight: 750;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.badge-ok {
  background: var(--ok-bg);
  color: var(--ok);
}

.badge-error {
  background: var(--error-bg);
  color: var(--error);
}

.badge-uncertain {
  background: var(--warn-bg);
  color: var(--warn);
}

.hint-card {
  margin-top: 1rem;
  padding: 0.95rem 1rem;
  border: 1px solid color-mix(in srgb, var(--accent) 26%, var(--line));
  border-left: 4px solid var(--accent);
  border-radius: 12px;
  background: var(--accent-soft);
}

.hint-card h3,
.result-section h3 {
  margin: 0 0 0.45rem;
  color: var(--muted);
  font-size: 0.74rem;
  font-weight: 750;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hint {
  margin: 0;
  font-size: clamp(1.02rem, 2.2vw, 1.18rem);
  font-weight: 650;
  line-height: 1.42;
}

.result-section {
  margin-top: 1.1rem;
}

.recognition,
.steps {
  margin: 0;
  padding-left: 1.35rem;
}

.recognition {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.92rem;
}

.steps {
  font-size: 0.92rem;
}

.recognition li,
.steps li {
  margin: 0.3rem 0;
  overflow-wrap: anywhere;
}

.recognition .placeholder,
.steps .placeholder {
  color: var(--muted);
  font-family: inherit;
  list-style: none;
  margin-left: -1.35rem;
}

.solution-toggle {
  appearance: none;
  padding: 0;
  border: 0;
  background: none;
  color: var(--accent);
  font: inherit;
  font-size: 0.84rem;
  font-weight: 650;
  text-decoration: underline;
  text-underline-offset: 3px;
  cursor: pointer;
}

.solution {
  margin: 0.55rem 0 0;
  padding: 0.6rem 0.8rem;
  border: 1px dashed var(--line-strong);
  border-radius: 10px;
  background: var(--panel-soft);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 1rem;
  overflow-wrap: anywhere;
}

.muted {
  margin: 0.5rem 0 0;
  color: var(--muted);
  font-size: 0.82rem;
}

.meta {
  margin: 1.15rem 0 0;
  padding-top: 0.75rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.72rem;
}

.footnote {
  display: grid;
  gap: 0.35rem;
  max-width: 78ch;
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
}

.footnote p {
  margin: 0;
}

@media (max-width: 860px) {
  .demo {
    grid-template-columns: 1fr;
  }

  .result-panel {
    position: static;
    min-height: 0;
  }

  .button.primary {
    margin-left: 0;
    flex: 1 1 100%;
  }
}

@media (max-width: 540px) {
  .shell {
    width: min(100% - 1.1rem, 1120px);
    padding-top: 1.1rem;
  }

  .paper-panel,
  .result-panel {
    border-radius: 15px;
    padding: 0.85rem;
  }

  .canvas-wrap {
    aspect-ratio: 1 / 1;
  }

  .toolbar {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }

  .button.primary {
    grid-column: 1 / -1;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    scroll-behavior: auto !important;
    transition: none !important;
  }
}