:root {
  color-scheme: dark;
  --bg: #07111f;
  --panel: #0d1a2d;
  --panel-2: #12243b;
  --panel-3: #172c46;
  --line: #29425f;
  --line-strong: #416482;
  --text: #edf5ff;
  --muted: #9fb2ca;
  --input: #55d5ef;
  --output: #ffbd59;
  --green: #57d69b;
  --red: #ff7185;
  --shadow: 0 22px 60px rgb(0 4 15 / 38%);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }

html { min-width: 320px; background: var(--bg); }

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  background:
    radial-gradient(circle at 80% -10%, rgb(34 98 142 / 28%), transparent 38%),
    radial-gradient(circle at 0% 10%, rgb(30 86 120 / 18%), transparent 32%),
    var(--bg);
}

button,
input { font: inherit; }

button,
a { -webkit-tap-highlight-color: transparent; }

button:focus-visible,
a:focus-visible,
input:focus-visible {
  outline: 3px solid rgb(85 213 239 / 60%);
  outline-offset: 3px;
}

.trainer-shell {
  width: min(1580px, 100%);
  margin: 0 auto;
  padding: 24px clamp(14px, 2.3vw, 36px) 26px;
}

.trainer-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 28px;
  margin-bottom: 20px;
}

.eyebrow,
.section-kicker {
  margin: 0 0 6px;
  color: var(--input);
  font-size: 12px;
  font-weight: 750;
  letter-spacing: .14em;
  text-transform: uppercase;
}

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

h1 {
  margin-bottom: 8px;
  font-size: clamp(25px, 3vw, 39px);
  line-height: 1.1;
  letter-spacing: -.04em;
}

h2 {
  margin-bottom: 10px;
  font-size: clamp(22px, 2vw, 29px);
  line-height: 1.18;
  letter-spacing: -.025em;
}

h3 {
  margin-bottom: 12px;
  font-size: 17px;
  line-height: 1.35;
}

.lead {
  max-width: 760px;
  margin-bottom: 0;
  color: var(--muted);
}

.header-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 12px;
  flex: 0 0 auto;
}

.user-chip {
  max-width: 210px;
  overflow: hidden;
  padding: 9px 12px;
  border: 1px solid var(--line);
  border-radius: 12px;
  color: var(--muted);
  background: rgb(13 27 46 / 80%);
  font-size: 12px;
  font-weight: 700;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.score {
  min-width: 116px;
  padding: 9px 13px;
  border: 1px solid var(--line);
  border-radius: 13px;
  background: rgb(13 27 46 / 80%);
}

.score span {
  display: block;
  color: var(--muted);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: .09em;
}

.score strong {
  display: block;
  margin-top: 1px;
  color: var(--green);
  font-size: 18px;
  font-variant-numeric: tabular-nums;
}

.button,
.icon-button,
.tab {
  appearance: none;
  border: 1px solid var(--line-strong);
  color: var(--text);
  background: var(--panel-2);
  cursor: pointer;
  transition: background-color .16s ease, border-color .16s ease, transform .16s ease;
}

.button:hover,
.icon-button:hover,
.tab:hover {
  border-color: var(--input);
  background: var(--panel-3);
}

.button:active,
.icon-button:active,
.tab:active { transform: translateY(1px); }

.button {
  min-height: 42px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 9px 15px;
  border-radius: 11px;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}

.button-primary {
  color: #03131c;
  border-color: #6ee5fa;
  background: linear-gradient(135deg, #66e0f3, #43b9df);
}

.button-primary:hover {
  color: #03131c;
  background: linear-gradient(135deg, #82e9f8, #57c9e9);
}

.button-ghost { background: transparent; }

.mechanism-tabs {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
  margin-bottom: 14px;
}

.tab {
  min-height: 52px;
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 10px;
  padding: 9px 14px;
  border-radius: 13px;
  text-align: left;
  font-weight: 700;
}

.tab span {
  color: var(--muted);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
}

.tab.is-active {
  color: #061723;
  border-color: #76e4f6;
  background: linear-gradient(135deg, #75deef, #5abfe4);
}

.tab.is-active span { color: #17455a; }

.workspace {
  display: grid;
  grid-template-columns: minmax(560px, 1.55fr) minmax(360px, .8fr);
  gap: 14px;
  align-items: start;
}

.visual-column,
.study-column {
  min-width: 0;
  display: grid;
  gap: 14px;
}

.viewport-card,
.control-panel,
.study-card {
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgb(13 26 45 / 94%);
  box-shadow: var(--shadow);
}

.viewport-card { overflow: hidden; }

.viewport-toolbar {
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 0 14px 0 17px;
  border-bottom: 1px solid var(--line);
}

.viewport-toolbar > div:first-child {
  display: flex;
  align-items: center;
  gap: 9px;
  color: var(--muted);
  font-size: 13px;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--green);
  box-shadow: 0 0 14px rgb(87 214 155 / 70%);
}

.view-actions { display: flex; gap: 7px; }

.icon-button {
  min-height: 34px;
  padding: 6px 10px;
  border-radius: 9px;
  font-size: 12px;
}

.icon-button[aria-pressed="true"] {
  border-color: #62d5e9;
  background: #17465b;
}

.viewport {
  min-height: 520px;
  height: min(62vh, 660px);
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(circle at 50% 40%, rgb(43 78 111 / 68%), transparent 46%),
    linear-gradient(165deg, #12253d, #091526 75%);
}

.viewport canvas {
  width: 100%;
  height: 100%;
  display: block;
  touch-action: none;
}

.viewport-hint {
  padding: 9px 15px 11px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 12px;
}

.scene-label {
  position: absolute;
  z-index: 2;
  padding: 6px 9px;
  border: 1px solid currentColor;
  border-radius: 8px;
  background: rgb(5 15 28 / 86%);
  font-size: 11px;
  font-weight: 750;
  pointer-events: none;
  transition: opacity .15s ease;
}

.scene-label::after {
  content: "";
  position: absolute;
  top: 50%;
  width: 24px;
  border-top: 1px solid currentColor;
}

.input-label {
  left: 7%;
  top: 24%;
  color: var(--input);
}

.input-label::after { left: 100%; }

.output-label {
  right: 7%;
  top: 56%;
  color: var(--output);
}

.output-label::after { right: 100%; }

.viewport.hide-labels .scene-label { opacity: 0; }

.webgl-error {
  position: absolute;
  inset: 30px;
  z-index: 4;
  display: grid;
  place-items: center;
  padding: 24px;
  border: 1px solid var(--red);
  border-radius: 14px;
  color: #ffdbe0;
  background: rgb(66 15 29 / 94%);
  text-align: center;
}

.webgl-error[hidden] { display: none; }

.control-panel {
  display: grid;
  grid-template-columns: auto minmax(170px, 1fr) minmax(170px, 1fr) minmax(210px, .8fr);
  align-items: center;
  gap: 18px;
  padding: 15px;
}

.transport {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.range-field {
  min-width: 0;
  color: var(--muted);
  font-size: 12px;
}

.range-field span {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 6px;
}

.range-field strong {
  color: var(--text);
  font-variant-numeric: tabular-nums;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--input);
  cursor: pointer;
}

.experiment-control .range-field { display: block; }

.study-card { padding: 18px; }

.overview-card > p {
  margin-bottom: 14px;
  color: var(--muted);
  font-size: 14px;
}

.signal-path {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  margin: 14px 0;
  padding: 10px;
  border-radius: 12px;
  background: #091625;
}

.path-node {
  min-width: 58px;
  padding: 5px 7px;
  border: 1px solid var(--line-strong);
  border-radius: 7px;
  color: var(--muted);
  font-size: 11px;
  text-align: center;
}

.path-input { color: var(--input); border-color: rgb(85 213 239 / 55%); }
.path-output { color: var(--output); border-color: rgb(255 189 89 / 55%); }
.path-arrow { color: var(--line-strong); }

.live-values {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin: 0 0 12px;
}

.live-values > div {
  min-width: 0;
  padding: 9px 10px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #0a1728;
}

.live-values dt {
  margin-bottom: 2px;
  color: var(--muted);
  font-size: 11px;
}

.live-values dd {
  margin: 0;
  font-size: 15px;
  font-weight: 750;
  font-variant-numeric: tabular-nums;
  overflow-wrap: anywhere;
}

.formula-box {
  padding: 10px 12px;
  border-left: 3px solid var(--input);
  border-radius: 0 9px 9px 0;
  background: #091625;
}

.formula-box span {
  display: block;
  margin-bottom: 3px;
  color: var(--muted);
  font-size: 11px;
}

.formula-box code {
  color: #d9f7ff;
  font-family: "Cascadia Code", Consolas, monospace;
  font-size: 13px;
}

.card-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}

.card-heading h3 { margin-bottom: 0; }

.scheme-legend {
  display: flex;
  align-items: center;
  gap: 5px;
  color: var(--muted);
  font-size: 10px;
  white-space: nowrap;
}

.scheme-legend i {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--input);
}

.scheme-legend i:nth-child(2) {
  margin-left: 5px;
  background: var(--output);
}

.scheme-view {
  height: 172px;
  margin-top: 12px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 12px;
  background:
    linear-gradient(rgb(42 65 88 / 14%) 1px, transparent 1px),
    linear-gradient(90deg, rgb(42 65 88 / 14%) 1px, transparent 1px),
    #081524;
  background-size: 20px 20px;
}

.scheme-view svg { width: 100%; height: 100%; display: block; }
.scheme-view .scheme-line { fill: none; stroke: #aec1d5; stroke-width: 3; vector-effect: non-scaling-stroke; }
.scheme-view .scheme-thin { fill: none; stroke: #607b97; stroke-width: 1.5; vector-effect: non-scaling-stroke; }
.scheme-view .scheme-input { fill: rgb(85 213 239 / 10%); stroke: var(--input); stroke-width: 4; vector-effect: non-scaling-stroke; }
.scheme-view .scheme-output { fill: rgb(255 189 89 / 10%); stroke: var(--output); stroke-width: 4; vector-effect: non-scaling-stroke; }
.scheme-view .scheme-fill { fill: #aec1d5; }
.scheme-view text { fill: #dce9f6; font: 12px system-ui, sans-serif; }

.answers {
  display: grid;
  gap: 8px;
  min-width: 0;
  margin: 0;
  padding: 0;
  border: 0;
}

.answer {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 9px 10px;
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--muted);
  background: #0a1728;
  cursor: pointer;
}

.answer:hover { border-color: var(--line-strong); color: var(--text); }
.answer input { margin-top: 3px; accent-color: var(--input); }
.answer:has(input:checked) { color: var(--text); border-color: var(--input); background: #102b3c; }

.task-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-top: 13px;
}

.task-result {
  min-height: 21px;
  font-size: 13px;
  font-weight: 700;
}

.task-result.is-correct { color: var(--green); }
.task-result.is-error { color: var(--red); }

.save-state {
  min-height: 18px;
  margin-top: 11px;
  padding-top: 10px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 12px;
}

.save-state[data-status="saving"] { color: var(--input); }
.save-state[data-status="success"] { color: var(--green); }
.save-state[data-status="error"] { color: var(--red); }

.trainer-footer {
  margin-top: 15px;
  color: var(--muted);
  font-size: 12px;
  text-align: center;
}

@media (max-width: 1250px) {
  .workspace { grid-template-columns: minmax(520px, 1.35fr) minmax(340px, .9fr); }
  .control-panel { grid-template-columns: 1fr 1fr; }
  .transport { grid-column: 1 / -1; }
}

@media (max-width: 970px) {
  .trainer-header { flex-direction: column; }
  .header-actions { width: 100%; justify-content: space-between; }
  .mechanism-tabs { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .workspace { grid-template-columns: 1fr; }
  .study-column { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .overview-card { grid-column: 1 / -1; }
  .viewport { min-height: 460px; height: 58vh; }
}

@media (max-width: 650px) {
  .trainer-shell { padding-inline: 10px; }
  .header-actions { align-items: stretch; flex-direction: column; }
  .score { width: 100%; }
  .mechanism-tabs { grid-template-columns: 1fr; }
  .viewport-toolbar { height: auto; min-height: 52px; flex-wrap: wrap; padding-block: 8px; }
  .viewport { height: 55vh; min-height: 390px; }
  .viewport-hint { display: none; }
  .control-panel { grid-template-columns: 1fr; }
  .transport { grid-column: auto; }
  .transport .button { flex: 1 1 120px; }
  .study-column { grid-template-columns: 1fr; }
  .overview-card { grid-column: auto; }
  .scene-label { display: none; }
  .live-values { grid-template-columns: 1fr 1fr; }
}

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