:root {
  --color-pos: #0877bd;
  --color-neg: #f59322;
  --color-border: #d3d6da;
  --color-border-filled: #878a8c;
  --color-text: #1a1a1b;
  --color-muted: #555;
  --color-bg: #ffffff;
  --color-panel: #f6f7f8;
  --color-accent: #3a7ca5;
  --color-wrong: #c0392b;
  --color-right: #2e8b57;
}

* { box-sizing: border-box; }

html { font-size: 17px; scroll-behavior: smooth; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: "Helvetica Neue", Arial, "Segoe UI", sans-serif;
}

/* sticky footer: main grows to fill short pages, pushing the footer down */
body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.mono { font-family: "SF Mono", Menlo, Consolas, monospace; }
.muted { color: #888; font-weight: 400; font-size: 0.85rem; }

/* ---------- Header ---------- */

#app-header {
  flex: none;
  border-bottom: 1px solid var(--color-border);
}

.header-inner {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px;
}

.header-inner h1 {
  font-size: 1.9rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  margin: 0;
}

.subtitle {
  font-size: 1.1rem;
  font-weight: 400;
  color: var(--color-muted);
  letter-spacing: normal;
}

.header-buttons { display: flex; gap: 8px; }

/* ---------- Buttons ---------- */

.btn {
  display: inline-block;
  padding: 9px 16px;
  border-radius: 4px;
  border: 1px solid var(--color-text);
  background: var(--color-text);
  color: white;
  font-weight: 600;
  cursor: pointer;
  font-size: 0.95rem;
  text-decoration: none;
  font-family: inherit;
  line-height: 1.2;
}

.btn:hover { opacity: 0.85; }

.btn:disabled,
.btn:disabled:hover {
  background: #eceef0;
  color: #9aa0a6;
  border-color: #dfe2e5;
  opacity: 1;
  cursor: not-allowed;
}

.btn-secondary {
  background: white;
  color: var(--color-text);
  border: 1px solid var(--color-border-filled);
}

.btn-secondary:hover { background: #f4f4f5; opacity: 1; }

.btn-small { padding: 6px 12px; font-size: 0.85rem; }

.btn-play { min-width: 110px; }
.btn-play.running { background: var(--color-accent); border-color: var(--color-accent); }

/* ---------- Control bar ---------- */

#control-bar {
  flex: none;
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.96);
  border-bottom: 1px solid var(--color-border);
  backdrop-filter: blur(4px);
}

.control-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 10px 16px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 24px;
}

.control-group { display: flex; align-items: center; gap: 8px; }
.control-group input[type="range"] { width: 100px; margin-left: 8px; }
.speed-label { font-size: 0.78rem; color: #888; min-width: 58px; font-variant-numeric: tabular-nums; }

.counters {
  display: flex;
  gap: 20px;
  font-size: 0.85rem;
  color: #777;
}

.counters b {
  color: var(--color-text);
  font-size: 1.05rem;
  margin-left: 4px;
  font-variant-numeric: tabular-nums;
}

.status-line {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 16px 10px;
  font-size: 0.88rem;
  font-weight: 600;
}

.status-line.good { color: var(--color-right); }
.status-line.bad { color: var(--color-wrong); }

/* ---------- Layout ---------- */

#app-main {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  flex: 1 0 auto;
  padding: 20px 16px 48px;
  display: grid;
  grid-template-columns: minmax(0, 560px) minmax(0, 1fr);
  gap: 40px;
  align-items: start;
}

#plot-col, #model-col { min-width: 0; }

.muted { color: #888; font-weight: 400; }

.sub-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin: 22px 0 8px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: #777;
}

.link-buttons { display: flex; gap: 10px; text-transform: none; letter-spacing: 0; }

.link-btn {
  border: none;
  background: none;
  padding: 0;
  font-family: inherit;
  font-size: 0.8rem;
  color: var(--color-accent);
  cursor: pointer;
}

.link-btn:hover { text-decoration: underline; }

/* chips: data presets */
.chips {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
}

.chips-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: #777;
  margin-right: 4px;
}

.chip {
  border: 1px solid var(--color-border);
  background: white;
  border-radius: 999px;
  padding: 5px 12px;
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
}

.chip:hover { border-color: var(--color-border-filled); }
.chip.active { background: var(--color-text); border-color: var(--color-text); color: white; }

.tool-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 14px;
  margin-top: 14px;
}

.tool-row .segmented { flex: none; }
.tool-row .seg-btn { flex: none; padding: 6px 12px; }
.hint { font-size: 0.78rem; color: #888; }

details.fold {
  margin-top: 16px;
  border-top: 1px solid var(--color-border);
  padding-top: 10px;
}

details.fold summary {
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-muted);
}

details.fold[open] summary { margin-bottom: 10px; }

.settings .check { display: flex; }

.model-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 14px;
}

.model-row label {
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: #777;
}

.model-row select, .model-row input { width: 100%; text-transform: none; letter-spacing: 0; }

/* ---------- Data controls ---------- */

.segmented {
  display: flex;
  border: 1px solid var(--color-border-filled);
  border-radius: 4px;
  overflow: hidden;
}

.seg-btn {
  flex: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 5px;
  padding: 7px 6px;
  border: none;
  border-right: 1px solid var(--color-border);
  background: white;
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  color: var(--color-text);
}

.seg-btn:last-child { border-right: none; }
.seg-btn:hover { background: #f4f4f5; }
.seg-btn.active { background: var(--color-text); color: white; }

.dot {
  display: inline-block;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  border: 1.5px solid white;
  box-shadow: 0 0 0 1px rgba(0,0,0,0.25);
  flex-shrink: 0;
}

.dot-pos { background: var(--color-pos); }
.dot-neg { background: var(--color-neg); }

.field-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin: 8px 0;
  font-size: 0.88rem;
}

.field-row label { font-weight: 600; }

select, input[type="number"] {
  font-family: inherit;
  font-size: 0.88rem;
  padding: 5px 6px;
  border: 1px solid var(--color-border-filled);
  border-radius: 4px;
  background: white;
  color: var(--color-text);
}

#max-epochs { width: 70px; }

.table-wrap {
  max-height: 340px;
  overflow-y: auto;
  border: 1px solid var(--color-border);
  border-radius: 4px;
}

#data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}

#data-table th {
  position: sticky;
  top: 0;
  background: var(--color-panel);
  font-weight: 600;
  text-align: left;
  padding: 5px 6px;
  border-bottom: 1px solid var(--color-border);
  z-index: 1;
}

#data-table td {
  padding: 2px 4px;
  border-bottom: 1px solid #eef0f2;
}

#data-table td:first-child {
  color: #888;
  font-variant-numeric: tabular-nums;
  padding-left: 8px;
  width: 30px;
}

#data-table input {
  width: 62px;
  padding: 3px 4px;
  font-size: 0.82rem;
}

#data-table select {
  padding: 3px 2px;
  font-size: 0.82rem;
  font-weight: 700;
}

#data-table select.cls-pos { color: var(--color-pos); }
#data-table select.cls-neg { color: var(--color-neg); }

#data-table tr.current td { background: #fff7d6; }
#data-table tr.wrong td:first-child { color: var(--color-wrong); font-weight: 700; }

.row-del {
  border: none;
  background: none;
  color: #999;
  cursor: pointer;
  font-size: 1rem;
  padding: 0 4px;
}

.row-del:hover { color: var(--color-wrong); }

.table-empty {
  text-align: center;
  color: #888;
  padding: 14px 6px !important;
  font-style: italic;
}

.table-buttons { display: flex; gap: 8px; margin-top: 8px; }

/* ---------- Model column ---------- */

#diagram-wrap {
  background: var(--color-panel);
  border-radius: 6px;
  padding: 8px 4px;
}

#diagram { display: block; width: 100%; height: auto; }

.check {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.88rem;
  cursor: pointer;
  margin: 3px 0;
}

.weight-row {
  display: grid;
  grid-template-columns: 26px minmax(60px, 1fr) auto;
  align-items: center;
  gap: 10px;
  margin: 6px 0;
}

.weight-row .wlabel { font-weight: 600; font-size: 0.95rem; }
.weight-row input[type="range"] { width: 100%; }
.weight-row.disabled { opacity: 0.4; }

.stepper { display: inline-flex; align-items: stretch; }

.stepper input[type="number"] {
  width: 64px;
  border-radius: 0;
  text-align: center;
  -moz-appearance: textfield;
}

.stepper input::-webkit-outer-spin-button,
.stepper input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }

.step-btn-small {
  width: 28px;
  border: 1px solid var(--color-border-filled);
  background: white;
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  padding: 0;
}

.step-btn-small:first-child { border-radius: 4px 0 0 4px; border-right: none; }
.step-btn-small:last-child { border-radius: 0 4px 4px 0; border-left: none; }
.step-btn-small:hover:not(:disabled) { background: #f4f4f5; }
.step-btn-small:disabled { cursor: not-allowed; }

.wstep { display: inline-flex; align-items: center; gap: 4px; font-size: 0.8rem; color: #777; }
.wstep select { padding: 1px 2px; font-size: 0.8rem; }

.lede {
  font-size: 0.92rem;
  color: var(--color-muted);
  line-height: 1.45;
  margin: 0 0 12px;
}

.ub-grid {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 3px 12px;
  align-items: baseline;
  margin-top: 6px;
}

.ub-label {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: #888;
  white-space: nowrap;
}

/* ---------- Output column ---------- */

#plot-wrap {
  position: relative;
  width: 100%;
  max-width: 560px;
  margin-top: 12px;
}

/* height is set from the width in JS so the data area stays square */
#plot {
  width: 100%;
  display: block;
  cursor: crosshair;
  touch-action: none;
}

.boundary-eq {
  font-size: 0.9rem;
  margin-top: 6px;
  line-height: 1.5;
}

.plot-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 14px;
  font-size: 0.78rem;
  color: var(--color-muted);
  margin-top: 8px;
}

.plot-legend > span { display: inline-flex; align-items: center; gap: 5px; }

.ring {
  display: inline-block;
  width: 13px;
  height: 13px;
  border-radius: 50%;
  border: 2px solid var(--color-text);
}

.ring-current { border: 2.5px solid var(--color-wrong); }

.swatch { display: inline-block; width: 18px; height: 0; }
.swatch-line { border-top: 3px solid var(--color-text); }
.swatch-trail { border-top: 2px dashed #888; }

.update-box {
  background: var(--color-panel);
  border-radius: 6px;
  padding: 10px 12px;
  font-size: 0.85rem;
  line-height: 1.6;
  min-height: 60px;
}

.update-box .ub-line { white-space: nowrap; overflow-x: auto; }
.update-box .ub-head { font-weight: 700; margin-bottom: 2px; }
.update-box .ub-head .muted { font-weight: 400; font-size: 0.8rem; }
.update-box .ok { color: var(--color-right); font-weight: 700; }
.update-box .bad { color: var(--color-wrong); font-weight: 700; }
.update-box .changed { font-weight: 700; }
.update-box .placeholder { color: #888; font-style: italic; }

#chart {
  width: 100%;
  height: 110px;
  display: block;
}

.chart-legend {
  display: flex;
  gap: 16px;
  font-size: 0.78rem;
  color: var(--color-muted);
  margin-top: 4px;
}

.chart-legend span::before {
  content: "";
  display: inline-block;
  width: 14px;
  height: 0;
  border-top: 2px solid currentColor;
  vertical-align: middle;
  margin-right: 5px;
}

.chart-legend .lg-err { color: var(--color-text); }
.chart-legend .lg-mse { color: var(--color-accent); }
.chart-legend .lg-mse::before { border-top-style: dashed; }

/* ---------- How it works ---------- */

#how-it-works {
  border-top: 1px solid var(--color-border);
  background: var(--color-panel);
}

.how-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 28px 16px 36px;
}

.how-inner h2 { margin: 0 0 8px; font-size: 1.35rem; }
.how-inner h3 { font-size: 1rem; margin: 18px 0 6px; }

.how-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  font-size: 0.9rem;
  line-height: 1.55;
}

.how-grid p { margin: 6px 0; }
.how-grid ul { padding-left: 20px; margin: 6px 0; }
.how-grid li { margin: 4px 0; }

.formula {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.05rem;
  background: white;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 8px 12px;
  text-align: center;
}

.formula-inline { font-family: Georgia, "Times New Roman", serif; }

/* ---------- Toasts ---------- */

#toast-container {
  position: fixed;
  top: 16px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1000;
  display: flex;
  flex-direction: column;
  gap: 8px;
  align-items: center;
}

.toast {
  background: var(--color-text);
  color: white;
  padding: 10px 16px;
  border-radius: 6px;
  font-weight: 600;
  font-size: 0.95rem;
  box-shadow: 0 2px 8px rgba(0,0,0,0.2);
  animation: toast-in 0.15s ease;
}

@keyframes toast-in {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ---------- Footer ---------- */

#app-footer {
  flex: none;
  border-top: 1px solid var(--color-border);
}

.footer-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 18px 16px 28px;
  font-size: 0.8rem;
  color: #777;
  text-align: center;
}

.footer-inner p { margin: 3px 0; }
.footer-inner a { color: var(--color-muted); }

/* ---------- Responsive ---------- */

@media (max-width: 900px) {
  #app-main { grid-template-columns: minmax(0, 1fr); gap: 24px; }
  #plot-wrap { margin-left: auto; margin-right: auto; }
}

@media (max-width: 720px) {
  .how-grid { grid-template-columns: 1fr; gap: 8px; }
  .header-inner h1 { font-size: 1.5rem; }
  .counters { gap: 14px; }
}

.nocase { text-transform: none; }
.btn { white-space: nowrap; }
.control-group { flex-wrap: wrap; }
.formula { overflow-x: auto; white-space: nowrap; font-size: 0.98rem; }

/* ---------- Tabs: Full / Simple ---------- */

.tab-bar { border-bottom: 1px solid var(--color-border); }

.tab-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 8px 16px 0;
  display: flex;
  gap: 4px;
}

.tab-btn {
  padding: 9px 18px;
  border: none;
  background: transparent;
  color: var(--color-muted);
  font-family: inherit;
  font-weight: 600;
  font-size: 0.92rem;
  cursor: pointer;
  border-bottom: 3px solid transparent;
  border-radius: 4px 4px 0 0;
  margin-bottom: -1px;
}

.tab-btn:hover { background: #f4f4f5; color: var(--color-text); }
.tab-btn.active { color: var(--color-text); border-bottom-color: var(--color-accent); }

/* Simple view: plot on the left; training data and the update log on the right */
#side-col { display: none; min-width: 0; }

body.simple #side-col { display: block; }
body.simple #model-col,
body.simple #how-it-works,
body.simple .lede,
body.simple #boundary-eq,
body.simple #data-slot details.fold summary,
body.simple .header-buttons { display: none; }

body.simple #app-main {
  max-width: 1240px;
  grid-template-columns: minmax(0, 540px) minmax(0, 1fr);
}

body.simple .tab-inner,
body.simple .control-inner,
body.simple .status-line,
body.simple .header-inner { max-width: 1240px; }

body.simple #data-slot details.fold { margin-top: 0; border-top: none; padding-top: 0; }
body.simple #data-slot .table-wrap { max-height: 190px; }

.side-head {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: #777;
  margin: 0 0 8px;
}

.side-head .muted { text-transform: none; letter-spacing: 0; }
#data-slot + .side-head { margin-top: 22px; }

.log-wrap {
  max-height: 440px;
  overflow: auto;
  border: 1px solid var(--color-border);
  border-radius: 4px;
}

#log-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
  font-variant-numeric: tabular-nums;
}

#log-table th {
  position: sticky;
  top: 0;
  background: var(--color-panel);
  font-weight: 600;
  text-align: right;
  padding: 6px 8px;
  border-bottom: 1px solid var(--color-border);
  white-space: nowrap;
}

#log-table td {
  text-align: right;
  padding: 4px 8px;
  border-bottom: 1px solid #eef0f2;
  white-space: nowrap;
}

#log-table th:nth-child(-n+3), #log-table td:nth-child(-n+3) { text-align: left; }
#log-table th:nth-child(9), #log-table td:nth-child(9) { border-left: 1px solid var(--color-border); }

#log-table td.ok { color: var(--color-right); font-weight: 700; }
#log-table td.bad { color: var(--color-wrong); font-weight: 700; }
#log-table tr.miss td { background: #fdf0ee; }
#log-table tr.miss td:nth-child(n+9) { font-weight: 700; }
#log-table tr.nochange td:nth-child(n+9) { color: #999; }
#log-table tr.epoch-start td { border-top: 2px solid var(--color-border-filled); }
#log-table tr.latest td { box-shadow: inset 0 -2px 0 var(--color-accent); }
#log-table tr.log-start td { color: var(--color-muted); font-style: italic; background: #fafafa; }
#log-table tr.log-start td:nth-child(n+2) { font-style: normal; }

.log-empty {
  margin: 0;
  padding: 16px 12px;
  font-size: 0.85rem;
  color: #888;
  font-style: italic;
}

@media (max-width: 900px) {
  body.simple #app-main { grid-template-columns: minmax(0, 1fr); }
}
body.simple #data-slot .table-wrap,
body.simple #data-slot .table-buttons { max-width: 380px; }

/* borrowed panels in the Simple view */
body.simple #weights-slot { margin-top: 4px; }
body.simple #weights-slot .sub-head { margin-top: 18px; }
body.simple #update-slot .sub-head { margin: 22px 0 8px; }
body.simple #update-slot .update-box { font-size: 0.9rem; }
#update-slot + .side-head { margin-top: 22px; }