:root {
  --ink: #181716;
  --muted: #68645c;
  --paper: #f7f7f0;
  --panel: #fffffb;
  --line: #d8d1c3;
  --line-strong: #a79b88;
  --burgundy: #78263d;
  --teal: #0b6a64;
  --gold: #b97b16;
  --danger: #b4232b;
  --shadow: 0 18px 44px rgba(28, 24, 19, 0.11);
  --mono: "Cascadia Mono", "IBM Plex Mono", Consolas, monospace;
  --serif: "STIX Two Text", "Iowan Old Style", Cambria, Georgia, serif;
  --sans: "Aptos", "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  font-family: var(--sans);
  background:
    linear-gradient(rgba(24, 23, 22, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(24, 23, 22, 0.025) 1px, transparent 1px),
    var(--paper);
  background-size: 28px 28px;
}

button,
input,
select,
textarea {
  font: inherit;
}

.app-shell {
  width: min(1480px, calc(100vw - 28px));
  margin: 0 auto;
  padding: 18px 0 24px;
}

.topbar,
.panel,
.status-strip,
.summary-chip {
  border: 1px solid var(--line);
  background: rgba(255, 255, 251, 0.96);
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 14px 16px;
  box-shadow: var(--shadow);
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2 {
  margin: 0;
  font-family: var(--serif);
  font-weight: 700;
}

h1 {
  font-size: clamp(1.45rem, 2.1vw, 2.25rem);
}

h2 {
  font-size: 1.35rem;
}

.status-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  justify-content: flex-end;
  padding: 6px;
}

.status-strip span,
.summary-chip {
  min-height: 30px;
  padding: 6px 9px;
  color: var(--ink);
  font-family: var(--mono);
  font-size: 0.78rem;
  background: #f0efe5;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(360px, 0.9fr) minmax(520px, 1.35fr);
  gap: 14px;
  margin-top: 14px;
}

.panel {
  min-width: 0;
  padding: 14px;
  box-shadow: var(--shadow);
}

.panel-head {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
}

.control-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(72px, 0.35fr)) minmax(180px, 1fr);
  gap: 9px;
  align-items: end;
}

.mode-switch {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 6px;
  margin-bottom: 12px;
  padding: 4px;
  border: 1px solid var(--line);
  background: #f4f2e8;
}

.mode-btn {
  border-color: transparent;
  background: transparent;
}

.mode-btn.active {
  border-color: var(--teal);
  color: #fffdfa;
  background: var(--teal);
}

.number-field,
.select-field,
.paste-box {
  display: grid;
  gap: 5px;
}

.number-field span,
.select-field span,
.paste-box label {
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 700;
}

input,
select,
textarea {
  width: 100%;
  border: 1px solid var(--line-strong);
  border-radius: 0;
  color: var(--ink);
  background: var(--panel);
}

input,
select {
  min-height: 34px;
  padding: 6px 8px;
}

textarea {
  min-height: 92px;
  padding: 9px;
  resize: vertical;
  font-family: var(--mono);
  font-size: 0.86rem;
}

input:focus,
select:focus,
textarea:focus,
button:focus-visible {
  outline: 2px solid rgba(11, 106, 100, 0.35);
  outline-offset: 1px;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.button-row.end {
  justify-content: flex-end;
}

.select-field {
  grid-column: 1 / -1;
  max-width: 280px;
}

button {
  min-height: 34px;
  border: 1px solid var(--line-strong);
  border-radius: 0;
  padding: 6px 10px;
  cursor: pointer;
  color: var(--ink);
  background: #f0efe5;
}

button:hover {
  border-color: var(--ink);
  background: #e7e3d5;
}

.primary-btn {
  border-color: var(--burgundy);
  color: #fffdfa;
  background: var(--burgundy);
}

.primary-btn:hover {
  background: #5d1d30;
}

.ghost-btn.danger {
  color: var(--danger);
}

.message-stack {
  display: grid;
  gap: 6px;
  min-height: 0;
  margin: 10px 0;
}

.solve-hint {
  margin: 0 0 10px;
  border-left: 3px solid var(--teal);
  padding: 8px 10px;
  color: #34312d;
  font-size: 0.86rem;
  background: #eef8f5;
}

.message {
  border-left: 3px solid var(--gold);
  padding: 7px 9px;
  font-size: 0.84rem;
  background: #fff8df;
}

.message.error {
  border-color: var(--danger);
  background: #fff0f1;
}

.matrix-grid {
  --cols: 3;
  display: grid;
  grid-template-columns: repeat(var(--cols), minmax(64px, 1fr));
  gap: 5px;
  overflow-x: auto;
  padding: 12px;
  border: 1px solid var(--line);
  background:
    linear-gradient(90deg, var(--ink) 2px, transparent 2px) left center / 10px calc(100% - 18px) no-repeat,
    linear-gradient(90deg, transparent calc(100% - 2px), var(--ink) calc(100% - 2px)) right center / 10px calc(100% - 18px) no-repeat,
    #fbfaf4;
}

.matrix-cell {
  min-width: 0;
  height: 42px;
  text-align: center;
  font-family: var(--mono);
  font-size: 0.92rem;
}

.matrix-cell.invalid {
  border-color: var(--danger);
  background: #fff0f1;
}

textarea.invalid {
  border-color: var(--danger);
  background: #fff0f1;
}

.paste-box {
  margin-top: 11px;
}

.quadratic-editor {
  display: grid;
  gap: 8px;
}

.quadratic-input-box {
  margin-top: 0;
}

.quadratic-input-box span {
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 700;
}

.quadratic-input-box textarea {
  min-height: 176px;
  line-height: 1.45;
}

.compact-control-grid {
  grid-template-columns: minmax(180px, 1fr) auto;
}

.tabs {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: 6px;
  margin-bottom: 12px;
}

.tabs.single-tab {
  grid-template-columns: minmax(0, 1fr);
}

.tab-btn[hidden] {
  display: none;
}

.tab-btn {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.tab-btn.active {
  border-color: var(--teal);
  color: #fffdfa;
  background: var(--teal);
}

.tab-panel {
  display: none;
}

.tab-panel.active {
  display: grid;
  gap: 12px;
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.result-card {
  min-width: 0;
  border: 1px solid var(--line);
  padding: 10px;
  background: #fffefa;
}

.result-card.wide {
  grid-column: 1 / -1;
}

.results-panel {
  position: relative;
  transition: opacity 160ms ease, border-color 160ms ease;
}

.results-panel.is-pending .tab-panels,
.results-panel.is-loading .tab-panels {
  opacity: 0.55;
}

.results-panel.is-pending,
.results-panel.is-loading {
  border-color: rgba(11, 106, 100, 0.45);
}

.results-panel.has-invalid-input {
  border-color: rgba(180, 35, 43, 0.5);
}

.card-head {
  margin-bottom: 8px;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
}

.math-line,
.text-block {
  padding: 10px;
  border: 1px solid var(--line);
  background: #f7f7ef;
}

.math-line {
  overflow-x: auto;
  font-family: var(--serif);
  font-size: 1.08rem;
}

.math-line .katex {
  font-size: 1.04em;
}

.math-inline {
  display: inline-block;
  max-width: 100%;
  overflow-wrap: normal;
  white-space: nowrap;
  vertical-align: baseline;
}

.math-inline .katex {
  font-size: 1em;
}

.math-render {
  font-family: var(--serif);
  text-transform: none;
}

.text-block {
  color: #34312d;
  font-family: var(--mono);
  font-size: 0.86rem;
}

.matrix-wrap {
  max-width: 100%;
  overflow-x: auto;
  padding-bottom: 2px;
}

.matrix-table {
  width: max-content;
  max-width: 100%;
  border-collapse: collapse;
  margin: 4px 0;
  font-family: var(--serif);
  font-size: 0.95rem;
}

.matrix-table td {
  min-width: 50px;
  max-width: 220px;
  border: 1px solid var(--line);
  padding: 9px 12px;
  text-align: center;
  vertical-align: middle;
  background: var(--panel);
  line-height: 1.2;
  white-space: nowrap;
}

.matrix-table .math-inline {
  min-width: max-content;
}

.matrix-table .katex {
  font-size: 1.04em;
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  margin: 8px 0;
  font-size: 0.88rem;
}

.data-table th,
.data-table td {
  border: 1px solid var(--line);
  padding: 7px 8px;
  text-align: left;
  vertical-align: top;
  background: var(--panel);
}

.data-table td {
  overflow-wrap: anywhere;
}

.data-table th {
  color: var(--muted);
  font-weight: 800;
  background: #f3f1e8;
}

.facts {
  display: grid;
  gap: 6px;
  margin: 0;
}

.fact-row {
  display: grid;
  grid-template-columns: minmax(110px, 0.55fr) 1fr;
  gap: 8px;
  border-bottom: 1px solid var(--line);
  padding-bottom: 5px;
}

.fact-row dt {
  color: var(--muted);
  font-weight: 700;
}

.fact-row dd {
  margin: 0;
  font-family: var(--mono);
}

.vector-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}

.vector {
  display: inline-grid;
  gap: 2px;
  padding: 6px 8px;
  border-left: 2px solid var(--ink);
  border-right: 2px solid var(--ink);
  font-family: var(--mono);
  background: var(--panel);
}

details {
  border: 1px solid var(--line);
  background: #fffefa;
}

summary {
  padding: 8px 10px;
  cursor: pointer;
  color: var(--burgundy);
  font-weight: 800;
}

.operation-list {
  display: grid;
  gap: 10px;
  margin: 0;
  padding: 0 10px 10px 30px;
}

.operation-step {
  padding-left: 4px;
}

.operation-code,
.step-title {
  display: inline-block;
  width: auto;
  max-width: 100%;
  margin-bottom: 5px;
  border: 1px solid var(--line);
  padding: 5px 7px;
  color: var(--teal);
  font-family: var(--mono);
  font-weight: 800;
  line-height: 1.25;
  overflow-wrap: anywhere;
  white-space: normal;
  background: #eef8f5;
}

.step-title {
  color: var(--burgundy);
  font-family: var(--sans);
  background: #fff0f4;
}

.operation-text {
  margin: 0 0 7px;
  color: #34312d;
  font-size: 0.9rem;
}

.equation-stack {
  display: grid;
  gap: 5px;
}

.completion-rows {
  display: grid;
  gap: 7px;
  margin: 8px 0;
}

.completion-row {
  display: grid;
  gap: 4px;
}

.verification-stack {
  display: grid;
  gap: 8px;
}

.conic-stack {
  display: grid;
  gap: 8px;
}

.conic-plot {
  width: 100%;
  min-height: 320px;
  border: 1px solid var(--line);
  background: #fffefa;
}

.plot-background rect {
  fill: #fbfaf2;
}

.plot-background line {
  stroke: rgba(167, 155, 136, 0.22);
  stroke-width: 1;
}

.axis {
  stroke-width: 1.4;
  vector-effect: non-scaling-stroke;
}

.old-axis {
  stroke: rgba(24, 23, 22, 0.34);
}

.principal-axis {
  stroke: var(--teal);
  stroke-dasharray: 7 5;
}

.helper-line {
  stroke: var(--gold);
  stroke-width: 1.6;
  stroke-dasharray: 9 5;
  vector-effect: non-scaling-stroke;
}

.conic-curve {
  fill: none;
  stroke: var(--burgundy);
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
  vector-effect: non-scaling-stroke;
}

.plot-point {
  fill: var(--teal);
  stroke: #fffefa;
  stroke-width: 1.4;
}

.plot-label,
.plot-note {
  fill: var(--ink);
  font-family: var(--mono);
  font-size: 12px;
  paint-order: stroke;
  stroke: #fffefa;
  stroke-width: 3px;
  stroke-linejoin: round;
}

.plot-note {
  fill: var(--danger);
  font-size: 14px;
}

.chain-list {
  display: grid;
  gap: 10px;
}

.chain-card {
  border: 1px solid var(--line);
  padding: 9px;
  background: #fffefa;
}

.chain-title {
  margin-bottom: 7px;
  color: var(--teal);
  font-weight: 800;
}

.mini-label {
  margin: 8px 0 5px;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 800;
}

.relation-list {
  margin: 8px 0 0;
  padding-left: 20px;
  font-family: var(--serif);
}

.empty-state {
  border: 1px dashed var(--line-strong);
  padding: 16px;
  color: var(--muted);
  background: #faf8ee;
}

@media (max-width: 980px) {
  .workspace,
  .result-grid,
  .control-grid,
  .compact-control-grid {
    grid-template-columns: 1fr;
  }

  .topbar {
    align-items: stretch;
    flex-direction: column;
  }

  .operation-list {
    padding-left: 24px;
    padding-right: 6px;
  }

  .operation-code,
  .step-title {
    display: block;
    width: 100%;
  }
}

@media (max-width: 560px) {
  .app-shell {
    width: min(100vw - 14px, 1480px);
    padding-top: 7px;
  }

  .tabs {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .mode-switch {
    grid-template-columns: 1fr;
  }

  .matrix-grid {
    overflow-x: auto;
    grid-template-columns: repeat(var(--cols), minmax(68px, 1fr));
  }
}