:root {
  color-scheme: light;
  --bg: #f5f7f8;
  --surface: #ffffff;
  --surface-alt: #eef2f4;
  --text: #172126;
  --muted: #5e6b73;
  --border: #d7dfe3;
  --accent: #205f73;
  --accent-hover: #174b5b;
  --focus: #0f6f91;
  --error-bg: #fff2f0;
  --error-border: #e2aaa2;
  --error-text: #8b261c;
  --radius: 14px;
  --shadow: 0 8px 24px rgba(18, 42, 52, 0.08);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
html { min-height: 100%; background: var(--bg); }
body { margin: 0; min-height: 100vh; color: var(--text); background: var(--bg); }

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

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

.app-header {
  padding: 44px 0 28px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1, h2, h3, p { margin-top: 0; }
h1 { margin-bottom: 10px; font-size: clamp(1.8rem, 4vw, 3rem); line-height: 1.08; }
h2 { margin-bottom: 6px; font-size: 1.1rem; }
h3 { font-size: 0.95rem; }

.subtitle { margin-bottom: 0; max-width: 760px; color: var(--muted); line-height: 1.6; }
.muted { color: var(--muted); line-height: 1.6; }
.compact { margin-bottom: 0; font-size: 0.9rem; }

.app-main { padding-block: 28px 48px; }

.mode-tabs {
  display: inline-flex;
  gap: 6px;
  margin-bottom: 20px;
  padding: 5px;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: 12px;
}

.mode-tab {
  border: 0;
  border-radius: 8px;
  padding: 10px 16px;
  color: var(--muted);
  background: transparent;
  font-weight: 650;
}

.mode-tab:hover { color: var(--text); }
.mode-tab:focus-visible, .button:focus-visible, input:focus-visible, select:focus-visible, summary:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--focus) 28%, transparent);
  outline-offset: 2px;
}

.mode-tab.is-active { color: #fff; background: var(--accent); }

.workspace {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(320px, 0.75fr);
  gap: 20px;
  align-items: start;
}

.panel, .about-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.panel { padding: 24px; }
.mode-panel[hidden] { display: none; }

.section-heading {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  align-items: flex-start;
  margin-bottom: 20px;
}

.field {
  display: grid;
  gap: 7px;
  margin-bottom: 16px;
}

.field-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(130px, 0.42fr);
  gap: 12px;
}

.field label, .field-label {
  font-size: 0.9rem;
  font-weight: 650;
}

input, select {
  width: 100%;
  min-height: 42px;
  padding: 9px 11px;
  color: var(--text);
  background: #fff;
  border: 1px solid #bec9cf;
  border-radius: 9px;
}

input:invalid[aria-invalid="true"], select[aria-invalid="true"] {
  border-color: var(--error-border);
}

.hint {
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.45;
}

.radio-group {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 16px;
}

.radio-option {
  display: inline-flex;
  gap: 7px;
  align-items: center;
  color: var(--text);
  font-size: 0.9rem;
}

.radio-option input {
  width: auto;
  min-height: auto;
}

.assumption-box, .placeholder-box {
  display: grid;
  gap: 5px;
  margin-top: 6px;
  padding: 16px;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--muted);
  line-height: 1.5;
}

.assumption-box strong, .placeholder-box strong { color: var(--text); }

.form-message {
  margin-top: 16px;
  padding: 12px 14px;
  border: 1px solid var(--error-border);
  border-radius: 9px;
  color: var(--error-text);
  background: var(--error-bg);
  line-height: 1.45;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}

.button {
  min-height: 40px;
  padding: 9px 15px;
  border-radius: 9px;
  font-weight: 650;
}

.button.primary {
  border: 1px solid var(--accent);
  color: #fff;
  background: var(--accent);
}

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

.button.secondary, .button.tertiary {
  color: var(--text);
  background: #fff;
  border: 1px solid var(--border);
}

.button.secondary:hover, .button.tertiary:hover { background: var(--surface-alt); }
.button.small { min-height: 34px; padding: 6px 10px; font-size: 0.84rem; }
.button:disabled { opacity: 0.45; cursor: not-allowed; }

.formula-panel {
  margin-top: 20px;
  border-top: 1px solid var(--border);
  padding-top: 16px;
}

.formula-panel summary {
  color: var(--accent);
  font-weight: 700;
  cursor: pointer;
}

.formula-content {
  padding-top: 14px;
  color: var(--muted);
  line-height: 1.65;
}

.formula-display {
  overflow-x: auto;
  margin: 12px 0;
  padding: 14px;
  border-radius: 8px;
  background: var(--surface-alt);
  color: var(--text);
  font-family: "Cambria Math", "Times New Roman", serif;
  font-size: 1.05rem;
}

.result-placeholder {
  display: grid;
  justify-items: center;
  gap: 12px;
  padding: 28px 12px;
  text-align: center;
  color: var(--muted);
}

.result-placeholder p { margin-bottom: 0; line-height: 1.5; }

.result-symbol {
  display: grid;
  place-items: center;
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background: var(--surface-alt);
  color: var(--accent);
  font-size: 2rem;
  font-weight: 700;
}

.result-primary {
  display: grid;
  gap: 4px;
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface-alt);
}

.result-primary strong {
  font-size: clamp(1.8rem, 5vw, 2.7rem);
  line-height: 1.05;
}

.result-label, .result-unit {
  color: var(--muted);
  font-size: 0.86rem;
}

.result-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 12px;
}

.metric-card {
  display: grid;
  gap: 4px;
  padding: 14px;
  border: 1px solid var(--border);
  border-radius: 10px;
}

.metric-card span, .metric-card small { color: var(--muted); }
.metric-card span { font-size: 0.82rem; }
.metric-card strong { font-size: 1.08rem; }
.metric-card small { font-size: 0.75rem; }

.interpretation-card {
  margin-top: 12px;
  padding: 15px;
  border: 1px solid var(--border);
  border-radius: 10px;
}

.interpretation-card h3 { margin-bottom: 6px; }
.interpretation-card p { margin-bottom: 0; color: var(--muted); line-height: 1.55; }

.version-card {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.9rem;
}

.version-card strong { color: var(--text); }

.about-card { margin-top: 20px; padding: 22px 24px; }
.about-card p { margin-bottom: 0; color: var(--muted); line-height: 1.65; }

.app-footer {
  padding: 20px 0;
  border-top: 1px solid var(--border);
  background: var(--surface);
  color: var(--muted);
  font-size: 0.9rem;
}

.app-footer .app-shell { display: flex; justify-content: space-between; gap: 20px; }
body.is-embed .app-main { padding-top: 16px; }

@media (max-width: 820px) {
  .workspace { grid-template-columns: 1fr; }
  .mode-tabs { display: grid; width: 100%; grid-template-columns: 1fr 1fr; }
}

@media (max-width: 560px) {
  .app-shell { width: min(100% - 20px, 1180px); }
  .app-header { padding-top: 28px; }
  .mode-tabs { grid-template-columns: 1fr; }
  .panel, .about-card { padding: 18px; border-radius: 10px; }
  .field-row, .result-grid { grid-template-columns: 1fr; }
  .section-heading { flex-direction: column; }
  .app-footer .app-shell { flex-direction: column; gap: 5px; }
}


/* Spatial / GIS Calculator */
.fieldset {
  margin: 0 0 18px;
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: 11px;
}

.fieldset legend {
  padding: 0 7px;
  font-weight: 750;
}

.field-row.three {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.subpanel {
  margin: 8px 0 18px;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface-alt);
}

.vertex-table-wrap {
  overflow-x: auto;
  margin-top: 14px;
}

.vertex-table {
  width: 100%;
  min-width: 590px;
  border-collapse: collapse;
}

.vertex-table th,
.vertex-table td {
  padding: 8px;
  border-bottom: 1px solid var(--border);
  text-align: left;
  vertical-align: middle;
}

.vertex-table th {
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 700;
}

.vertex-table td:first-child {
  font-weight: 700;
}

.vertex-table input {
  min-width: 110px;
}

.vertex-actions {
  display: flex;
  gap: 4px;
}

.icon-button {
  width: 30px;
  height: 30px;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 7px;
  background: #fff;
  color: var(--text);
}

.icon-button:hover {
  background: var(--surface-alt);
}

.icon-button.danger {
  font-size: 1.15rem;
}

.compact-row {
  margin-top: 12px;
}

.warning-box,
.diagnostic-box,
.map-status {
  margin-top: 14px;
  padding: 13px 14px;
  border-radius: 9px;
  line-height: 1.5;
}

.warning-box {
  border: 1px solid #dccb8a;
  background: #fffbea;
}

.warning-box ul {
  margin: 8px 0 0;
  padding-left: 20px;
}

.diagnostic-box {
  border: 1px solid var(--border);
  background: var(--surface-alt);
}

.diagnostic-grid {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 7px 16px;
  margin-top: 10px;
  font-size: 0.88rem;
}

.diagnostic-grid span {
  color: var(--muted);
}

.map-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-bottom: 12px;
}

.map-height-field {
  max-width: 310px;
}

.spatial-map {
  width: 100%;
  height: 390px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: #e8ecef;
  overflow: hidden;
}

.map-status {
  margin: 0 0 10px;
  border: 1px solid var(--border);
  background: #fff;
  color: var(--muted);
}

.map-symbol {
  display: grid;
  place-items: center;
  border: 2px solid #fff;
  border-radius: 50%;
  box-shadow: 0 1px 5px rgba(0,0,0,.35);
  font-family: system-ui, sans-serif;
  font-size: 12px;
  font-weight: 800;
}

.map-symbol-observer {
  width: 28px;
  height: 28px;
  background: #172126;
  color: #fff;
}

.map-symbol-target {
  width: 26px;
  height: 26px;
  background: #fff;
  color: #172126;
  border-color: #172126;
}

.observer-div-icon,
.target-div-icon {
  background: transparent;
  border: 0;
}

@media (max-width: 680px) {
  .field-row.three {
    grid-template-columns: 1fr;
  }

  .spatial-map {
    height: 320px;
  }
}


/* v1.0 stable additions */
.toolbox-link { display:inline-block; margin-bottom:18px; color:var(--accent); font-weight:650; text-decoration:none; }
.toolbox-link:hover { text-decoration:underline; }
.startup-message { margin:0 0 18px; }
.result-heading { align-items:end; }
.precision-field { margin:0; min-width:130px; }
.precision-field select { min-height:34px; padding:6px 8px; font-size:.84rem; }
.result-actions { display:flex; flex-wrap:wrap; gap:7px; margin:-8px 0 14px; }
.action-status { margin:0 0 12px; padding:8px 10px; border-radius:8px; background:var(--surface-alt); color:var(--muted); font-size:.84rem; }
.scene-panel { margin-top:14px; padding-top:14px; border-top:1px solid var(--border); }
.scene-heading { display:flex; justify-content:space-between; align-items:flex-start; gap:12px; margin-bottom:10px; }
.scene-heading h3 { margin-bottom:3px; }
.scene-heading .button-row { margin-top:0; }
.scene-canvas { width:100%; height:360px; display:block; border:1px solid var(--border); border-radius:10px; background:#f7f9fa; touch-action:none; }
.scene-canvas:focus-visible { outline:3px solid color-mix(in srgb, var(--focus) 28%, transparent); outline-offset:2px; }
.about-card details { margin-top:14px; }
.about-card summary { cursor:pointer; color:var(--accent); font-weight:700; }
.about-card details p { margin-top:10px; }
@media (max-width:560px) { .result-heading, .scene-heading { flex-direction:column; align-items:stretch; } .precision-field { width:100%; } .scene-canvas { height:300px; } }