:root {
  --ink: #162033;
  --muted: #667085;
  --line: #d8dee8;
  --soft-line: #edf0f5;
  --panel: #ffffff;
  --panel-soft: #f7f9fc;
  --accent: #246bfe;
  --accent-soft: #e8f0ff;
  --accent-strong: #174fd0;
  --green: #15803d;
  --green-soft: #eaf7ef;
  --amber: #a16207;
  --amber-soft: #fff7df;
  --red: #b42318;
  --shadow: 0 18px 45px rgba(25, 38, 70, 0.08);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-width: 320px;
  background: #ffffff;
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  letter-spacing: 0;
}

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

.app-shell {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
  padding: 28px 0 40px;
}

.topbar {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  padding: 0 2px 20px;
}

.eyebrow {
  margin: 0 0 6px;
  color: var(--accent);
  font-size: 0.79rem;
  font-weight: 700;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 0;
  font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1;
  letter-spacing: 0;
}

h2 {
  margin-bottom: 5px;
  font-size: 1.05rem;
}

h3 {
  margin-bottom: 0;
  font-size: 0.95rem;
}

.top-controls,
.perm-form,
.transposition-mode-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.select-label,
.perm-form label {
  color: var(--muted);
  font-size: 0.86rem;
  font-weight: 700;
}

select,
input {
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--ink);
  padding: 0 12px;
  outline: none;
}

input {
  width: 150px;
}

select:focus,
input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.workspace {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(320px, 0.9fr);
  gap: 22px;
  align-items: start;
}

.main-panel,
.fact-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: var(--shadow);
}

.main-panel {
  padding: 22px;
}

.panel-head {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 16px;
}

.panel-head p,
.control-heading span {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.history-actions {
  display: flex;
  gap: 8px;
}

.icon-btn {
  width: 40px;
  height: 40px;
  display: inline-grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--ink);
  font-size: 1.2rem;
}

.icon-btn:disabled,
button:disabled {
  cursor: not-allowed;
  opacity: 0.42;
}

.tiles {
  display: grid;
  grid-template-columns: repeat(var(--tile-count), minmax(52px, 1fr));
  gap: 10px;
  margin: 28px 0 18px;
}

.tile {
  position: relative;
  min-height: 76px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: linear-gradient(180deg, #ffffff 0%, #f8fbff 100%);
  box-shadow: inset 0 -1px 0 rgba(22, 32, 51, 0.04);
  color: var(--ink);
  font-size: clamp(1.5rem, 5vw, 2.25rem);
  font-weight: 800;
  transition: border-color 160ms ease, background 160ms ease, transform 160ms ease;
}

.tile::before {
  content: attr(data-position);
  position: absolute;
  top: 8px;
  left: 9px;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 700;
}

.tile.changed {
  border-color: var(--accent);
  background: var(--accent-soft);
  transform: translateY(-2px);
}

.tile.value-changed {
  border-color: var(--green);
  background: var(--green-soft);
  transform: translateY(-2px);
}

.perm-form {
  padding-bottom: 8px;
}

button {
  min-height: 42px;
  border: 1px solid var(--accent);
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  padding: 0 15px;
  font-weight: 750;
}

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

button.secondary,
.segmented button {
  border-color: var(--line);
  background: #fff;
  color: var(--ink);
}

button.secondary:hover:not(:disabled),
.segmented button:hover:not(:disabled) {
  border-color: var(--accent);
  background: var(--accent-soft);
  color: var(--accent-strong);
}

.input-message {
  min-height: 22px;
  margin: 0;
  color: var(--red);
  font-size: 0.86rem;
}

.input-message.ok {
  color: var(--green);
}

.control-card {
  margin-top: 16px;
  padding: 16px;
  border: 1px solid var(--soft-line);
  border-radius: 8px;
  background: var(--panel-soft);
}

.control-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
}

.button-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(76px, 1fr));
  gap: 8px;
}

.reduced-word-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 12px;
  align-items: end;
  margin-bottom: 12px;
}

.mini-label {
  margin-bottom: 6px;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 800;
  text-transform: uppercase;
}

.simple-btn {
  border-color: var(--line);
  background: #fff;
  color: var(--ink);
}

.simple-btn.raise {
  border-color: rgba(21, 128, 61, 0.32);
  background: var(--green-soft);
}

.simple-btn.lower {
  border-color: rgba(180, 35, 24, 0.32);
  background: #fff0ef;
}

.segmented {
  display: inline-flex;
  padding: 3px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.segmented button {
  min-height: 34px;
  border: 0;
  padding: 0 12px;
}

.segmented button.active {
  background: var(--ink);
  color: #fff;
}

.transposition-mode-row {
  justify-content: flex-start;
  margin-bottom: 12px;
}

.transposition-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(86px, 1fr));
  gap: 8px;
}

.transposition-btn {
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  border-color: var(--line);
  background: #fff;
  color: var(--ink);
}

.transposition-btn small {
  min-width: 30px;
  border-radius: 999px;
  padding: 3px 7px;
  font-weight: 900;
}

.transposition-btn.raise {
  border-color: rgba(21, 128, 61, 0.32);
  background: var(--green-soft);
}

.transposition-btn.raise small {
  background: #fff;
  color: var(--green);
}

.transposition-btn.lower {
  border-color: rgba(180, 35, 24, 0.32);
  background: #fff0ef;
}

.transposition-btn.lower small {
  background: #fff;
  color: var(--red);
}

.transposition-btn.same {
  opacity: 0.74;
}

.side-panel {
  display: grid;
  gap: 18px;
}

.fact-card {
  padding: 18px;
}

.facts {
  display: grid;
  gap: 12px;
  margin: 15px 0 0;
}

.facts div {
  display: grid;
  gap: 3px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--soft-line);
}

.facts div:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

dt {
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 800;
  text-transform: uppercase;
}

dd {
  margin: 0;
  overflow-wrap: anywhere;
  font-size: 0.98rem;
}

.compact {
  gap: 9px;
}

.word-display,
.witness-word {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  min-height: 40px;
  align-items: center;
  padding: 12px;
  border: 1px solid var(--soft-line);
  border-radius: 8px;
  background: var(--panel-soft);
}

.word-display {
  margin-top: 0;
}

.word-letter {
  display: inline-flex;
  min-width: 42px;
  min-height: 34px;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  font-weight: 800;
  cursor: default;
  user-select: none;
  -webkit-user-select: none;
}

.word-letter[data-link-key] {
  cursor: pointer;
}

.word-letter.mark-delete {
  border-color: var(--red);
  background: #fff0ef;
  color: var(--red);
}

.word-letter.linked-hover,
.transposition-btn.linked-hover {
  border-color: var(--ink) !important;
  box-shadow: 0 0 0 2px rgba(22, 32, 51, 0.12);
}

.word-letter.linked-selected,
.transposition-btn.linked-selected {
  border-color: var(--ink) !important;
  background-image: linear-gradient(180deg, rgba(22, 32, 51, 0.08), rgba(22, 32, 51, 0.03));
  box-shadow: 0 0 0 3px rgba(22, 32, 51, 0.22), inset 0 0 0 1px rgba(22, 32, 51, 0.28);
}

.word-letter.linked-selected.linked-hover,
.transposition-btn.linked-selected.linked-hover {
  box-shadow: 0 0 0 3px rgba(22, 32, 51, 0.28), inset 0 0 0 2px rgba(22, 32, 51, 0.38);
}

.simple-sub {
  position: relative;
  top: 0.24em;
  margin-left: 1px;
  font-size: 0.66em;
  line-height: 0;
}

.empty-word {
  color: var(--muted);
  font-size: 0.9rem;
}

.status-pill {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  border-radius: 999px;
  padding: 0 10px;
  font-size: 0.84rem;
  font-weight: 800;
}

.status-pill.good {
  background: var(--green-soft);
  color: var(--green);
}

.status-pill.warn {
  background: var(--amber-soft);
  color: var(--amber);
}

.exchange-panel {
  display: grid;
  gap: 12px;
  margin-top: 14px;
}

.exchange-note {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: #fff;
}

.exchange-note h3 {
  margin-bottom: 8px;
}

.exchange-note p {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.reason-step {
  display: grid;
  gap: 7px;
}

.operation-line {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px;
  border: 1px solid var(--soft-line);
  border-radius: 8px;
  background: var(--panel-soft);
  color: var(--muted);
  font-weight: 850;
}

.operation-line .witness-word {
  flex: 1;
  min-height: 38px;
  padding: 8px;
  background: #fff;
}

.down-arrow {
  color: var(--muted);
  font-size: 1.45rem;
  font-weight: 900;
  line-height: 1;
  text-align: center;
}

.step-spacer {
  height: 4px;
}

.hidden {
  display: none !important;
}

@media (max-width: 900px) {
  .workspace {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 620px) {
  .app-shell {
    width: min(100% - 20px, 1180px);
    padding-top: 18px;
  }

  .topbar,
  .panel-head,
  .control-heading,
  .reduced-word-row {
    align-items: stretch;
    flex-direction: column;
  }

  .reduced-word-row {
    display: flex;
  }

  .main-panel,
  .fact-card {
    padding: 14px;
  }

  .tiles {
    gap: 7px;
  }

  .tile {
    min-height: 60px;
  }
}