:root {
  --paper: #fbfaf6;
  --white: #ffffff;
  --ink: #17191e;
  --ink-2: #474c56;
  --ink-3: #8a8e97;
  --rule: #e5e2d9;
  --rule-2: #d2cec2;
  --pen: #2346b0;
  --pen-soft: #eef1fb;
  --red: #c63b2f;
  --red-soft: #fcefed;
  --margin-line: #eab0aa;
  --green: #1d7346;
  --green-soft: #e9f4ed;
  --marker: #ffe57a;
  --code-bg: #1b1d22;
  --code-ink: #e9e7e1;
  --serif: 'Literata', Georgia, 'Times New Roman', serif;
  --sans: 'Golos Text', -apple-system, 'Segoe UI', Roboto, Arial, sans-serif;
  --mono: 'JetBrains Mono', Menlo, Consolas, monospace;
  --cell: 22px;
}

* {
  box-sizing: border-box;
}
html,
body {
  margin: 0;
}
body {
  font-family: var(--sans);
  background: var(--paper);
  color: var(--ink);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
h1,
h2,
h3 {
  font-family: var(--serif);
  font-weight: 600;
  line-height: 1.18;
  margin: 0 0 0.45em;
  letter-spacing: -0.01em;
}
h4 {
  font-size: 16px;
  margin: 0 0 0.4em;
}
p {
  margin: 0 0 0.8em;
}
a {
  color: var(--pen);
  text-underline-offset: 3px;
}
code,
pre,
kbd,
textarea {
  font-variant-ligatures: none;
  font-feature-settings:
    'liga' 0,
    'calt' 0;
}
code,
pre,
kbd {
  font-family: var(--mono);
}
:not(pre) > code {
  font-size: 0.88em;
  background: var(--pen-soft);
  color: #1b2f73;
  padding: 0.08em 0.35em;
  border-radius: 4px;
}
pre {
  background: var(--code-bg);
  color: var(--code-ink);
  padding: 14px 16px;
  border-radius: 6px;
  overflow-x: auto;
  margin: 0.6em 0 1em;
  font-size: 14px;
  line-height: 1.55;
}
ul,
ol {
  margin: 0.2em 0 0.8em;
  padding-left: 1.3em;
}
.muted {
  color: var(--ink-3);
}
.small {
  font-size: 14px;
}
.row {
  display: flex;
  gap: 12px;
  align-items: center;
  flex-wrap: wrap;
}
.spacer {
  flex: 1;
}
.hidden {
  display: none !important;
}
.mark {
  background: linear-gradient(transparent 55%, var(--marker) 55%, var(--marker) 92%, transparent 92%);
  padding: 0 0.08em;
}
.grid-paper {
  background-color: var(--white);
  background-image:
    linear-gradient(rgba(35, 70, 176, 0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(35, 70, 176, 0.07) 1px, transparent 1px);
  background-size: var(--cell) var(--cell);
}

/* шапка */
.topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  gap: 36px;
  height: 60px;
  padding: 0 32px;
  background: var(--paper);
  border-bottom: 1px solid var(--rule);
}
.brand {
  display: flex;
  align-items: baseline;
  gap: 10px;
  text-decoration: none;
  color: var(--ink);
}
.brand-name {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 23px;
  letter-spacing: -0.02em;
}
.brand-name::after {
  content: '.';
  color: var(--red);
}
.brand-sub {
  font-size: 13px;
  color: var(--ink-3);
}
.topnav {
  display: flex;
  gap: 22px;
}
.topnav a {
  text-decoration: none;
  color: var(--ink-2);
  font-size: 15px;
  padding: 18px 0 16px;
  border-bottom: 2px solid transparent;
}
.topnav a:hover {
  color: var(--ink);
}
.topnav a.active {
  color: var(--ink);
  border-bottom-color: var(--pen);
}
.topbar-right {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 18px;
  font-size: 14px;
}
.mode {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  color: var(--ink-2);
}
.mode::before {
  content: '';
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--ink-3);
}
.mode.on::before {
  background: var(--green);
}
.mode.demo::before {
  background: #d9a520;
}

/* кнопки и поля */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font: inherit;
  font-weight: 600;
  font-size: 15px;
  padding: 10px 18px;
  border-radius: 6px;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: #fff;
  cursor: pointer;
  text-decoration: none;
  transition:
    background 0.12s,
    border-color 0.12s;
}
.btn:hover {
  background: var(--pen);
  border-color: var(--pen);
}
.btn:disabled {
  background: var(--rule-2);
  border-color: var(--rule-2);
  color: #fff;
  cursor: not-allowed;
}
.btn-line {
  background: var(--white);
  color: var(--ink);
  border-color: var(--rule-2);
}
.btn-line:hover {
  background: var(--white);
  color: var(--pen);
  border-color: var(--pen);
}
.btn-lg {
  padding: 13px 24px;
  font-size: 16px;
}
.btn-sm {
  padding: 6px 12px;
  font-size: 14px;
}
.link-btn {
  background: none;
  border: none;
  padding: 0;
  font: inherit;
  font-size: 14px;
  color: var(--ink-3);
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 3px;
}
.link-btn:hover {
  color: var(--ink);
}
input.field,
textarea.field {
  width: 100%;
  font: inherit;
  font-size: 15px;
  color: var(--ink);
  background: var(--white);
  border: 1px solid var(--rule-2);
  border-radius: 6px;
  padding: 10px 12px;
}
textarea.field {
  resize: vertical;
  min-height: 96px;
  line-height: 1.55;
}
input.field:focus,
textarea.field:focus,
.editor textarea:focus {
  outline: 2px solid var(--pen);
  outline-offset: -1px;
}

/* каркас страниц */
.page {
  max-width: 1100px;
  margin: 0 auto;
  padding: 48px 32px 90px;
}
.page-narrow {
  max-width: 860px;
}
.kicker {
  font-size: 14px;
  color: var(--red);
  font-weight: 600;
  margin-bottom: 10px;
}
.sheet {
  background: var(--white);
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 24px 26px;
}
.note {
  border-left: 3px solid #d9a520;
  background: #fdf6dd;
  padding: 10px 14px;
  font-size: 14.5px;
  margin: 14px 0;
  border-radius: 0 4px 4px 0;
}
.note.red {
  border-color: var(--red);
  background: var(--red-soft);
}
.footer {
  margin-top: 80px;
  padding-top: 18px;
  border-top: 1px solid var(--rule);
  color: var(--ink-3);
  font-size: 14px;
}

/* главная */
.hero {
  display: grid;
  grid-template-columns: 1.15fr 1fr;
  gap: 56px;
  align-items: center;
  padding: 24px 0 64px;
}
.hero h1 {
  font-size: 54px;
  font-weight: 600;
  letter-spacing: -0.025em;
}
.hero .lead {
  font-size: 19px;
  color: var(--ink-2);
  max-width: 32em;
  margin: 18px 0 28px;
}
.notebook {
  position: relative;
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 26px 26px 26px 66px;
  transform: rotate(0.6deg);
  box-shadow: 0 18px 40px -24px rgba(23, 25, 30, 0.35);
}
.notebook::before {
  content: '';
  position: absolute;
  top: 0;
  bottom: 0;
  left: 46px;
  width: 1px;
  background: var(--margin-line);
}
.nb-line {
  margin-bottom: 14px;
  font-size: 15.5px;
}
.nb-line .who {
  display: block;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--ink-3);
}
.nb-line.bot .who {
  color: var(--pen);
}
.nb-line.user {
  font-family: var(--serif);
  font-style: italic;
  color: #1b2f73;
  font-size: 17px;
}
.nb-stamp {
  display: inline-block;
  color: var(--red);
  border: 1.5px solid var(--red);
  border-radius: 4px;
  padding: 1px 8px;
  font-size: 12.5px;
  font-weight: 600;
  transform: rotate(-2deg);
  margin-top: 4px;
}

.numbers {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border-top: 1px solid var(--ink);
  border-bottom: 1px solid var(--rule);
  margin-bottom: 20px;
}
.numbers > div {
  padding: 22px 24px 20px 0;
}
.numbers > div + div {
  padding-left: 24px;
  border-left: 1px solid var(--rule);
}
.numbers .n {
  font-family: var(--serif);
  font-size: 52px;
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.03em;
}
.numbers .n small {
  font-size: 22px;
  color: var(--ink-3);
  font-weight: 400;
}
.numbers p {
  margin: 10px 0 0;
  color: var(--ink-2);
  max-width: 17em;
}
.numbers-cap {
  font-size: 14px;
  color: var(--ink-3);
  margin-bottom: 10px;
}

/* загрузка задания */
.task-layout {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  gap: 28px;
  align-items: start;
  margin-top: 26px;
}
.task-paper {
  position: relative;
  padding: 0;
  overflow: hidden;
}
.task-paper textarea {
  display: block;
  width: 100%;
  min-height: 330px;
  border: none;
  resize: vertical;
  font: inherit;
  font-size: 16px;
  color: var(--ink);
  background: transparent;
  padding: 11px 22px 22px 66px;
  line-height: var(--cell);
  background-image: linear-gradient(rgba(35, 70, 176, 0.1) 1px, transparent 1px);
  background-size: 100% var(--cell);
  background-position: 0 10px;
}
.task-paper::before {
  content: '';
  position: absolute;
  top: 0;
  bottom: 0;
  left: 46px;
  width: 1px;
  background: var(--margin-line);
  z-index: 1;
  pointer-events: none;
}
.task-paper textarea:focus {
  outline: none;
}
.task-actions {
  display: flex;
  gap: 12px;
  align-items: center;
  padding: 14px 22px;
  border-top: 1px solid var(--rule);
  background: var(--white);
}
.drop {
  display: block;
  border: 1.5px dashed var(--rule-2);
  border-radius: 6px;
  padding: 26px 20px;
  text-align: center;
  cursor: pointer;
  background: var(--white);
  transition:
    border-color 0.12s,
    background 0.12s;
}
.drop:hover,
.drop.drag {
  border-color: var(--pen);
  background: var(--pen-soft);
}
.drop b {
  display: block;
  font-size: 16px;
  margin-bottom: 2px;
}
.steps-preview {
  margin-top: 18px;
}
.steps-preview li {
  margin-bottom: 6px;
  color: var(--ink-2);
}
.progress-list {
  list-style: none;
  padding: 0;
  margin: 14px 0 0;
}
.progress-list li {
  padding: 6px 0 6px 28px;
  position: relative;
  color: var(--ink-3);
}
.progress-list li::before {
  content: '';
  position: absolute;
  left: 4px;
  top: 13px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  border: 1.5px solid var(--rule-2);
}
.progress-list li.active {
  color: var(--ink);
}
.progress-list li.active::before {
  border-color: var(--pen);
  border-top-color: transparent;
  animation: spin 0.7s linear infinite;
}
.progress-list li.done {
  color: var(--ink);
}
.progress-list li.done::before {
  content: '✓';
  border: none;
  width: auto;
  height: auto;
  top: 6px;
  left: 3px;
  color: var(--green);
  font-weight: 700;
}
@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.field-label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  margin: 18px 0 6px;
}
select.field {
  width: 100%;
  font: inherit;
  font-size: 16px;
  padding: 10px 12px;
  border: 1px solid var(--rule-2);
  border-radius: 6px;
  background: var(--white);
  color: var(--ink);
}
.task-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 8px;
  margin-top: 10px;
}
.task-card {
  font: inherit;
  text-align: left;
  padding: 12px 14px;
  border: 1px solid var(--rule-2);
  border-radius: 6px;
  background: var(--white);
  cursor: pointer;
  color: var(--ink);
}
.task-card:hover {
  border-color: var(--pen);
}
.task-card.sel {
  border-color: var(--pen);
  background: var(--pen-soft);
  box-shadow: inset 3px 0 0 var(--pen);
}
.task-card .lvl {
  display: block;
  font-size: 12.5px;
  color: var(--ink-3);
  margin-bottom: 2px;
}
.task-card b {
  font-weight: 600;
  font-size: 15px;
}

/* рабочее пространство */
.workspace {
  display: grid;
  grid-template-columns: 236px minmax(0, 1fr) 350px;
  height: calc(100vh - 60px);
}
.ws-side {
  border-right: 1px solid var(--rule);
  padding: 26px 20px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 26px;
}
.ws-main {
  overflow-y: auto;
  padding: 34px 40px 80px;
}
.ws-margin {
  position: relative;
  background: var(--paper);
  border-left: 1px solid var(--rule);
  display: flex;
  flex-direction: column;
  min-height: 0;
}
.ws-margin::before {
  content: '';
  position: absolute;
  top: 0;
  bottom: 0;
  left: 18px;
  width: 1px;
  background: var(--margin-line);
}

.task-mini h4 {
  font-family: var(--serif);
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 2px;
}
.task-mini .meta {
  font-size: 13.5px;
  color: var(--ink-3);
}
.steps {
  list-style: none;
  padding: 0;
  margin: 0;
  counter-reset: s;
}
.steps li {
  margin: 0;
}
.steps a {
  display: grid;
  grid-template-columns: 28px 1fr;
  align-items: center;
  gap: 10px;
  padding: 9px 0;
  text-decoration: none;
  color: var(--ink-2);
  font-size: 15.5px;
}
.steps a .d {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  border: 1.5px solid var(--rule-2);
  display: grid;
  place-items: center;
  font-size: 13px;
  font-weight: 600;
  color: var(--ink-3);
}
.steps a:hover {
  color: var(--ink);
}
.steps a.cur {
  color: var(--ink);
  font-weight: 600;
}
.steps a.cur .d {
  border-color: var(--pen);
  background: var(--pen);
  color: #fff;
}
.steps a.done .d {
  border-color: var(--green);
  color: var(--green);
}
.steps a.cur.done .d {
  background: var(--green);
  border-color: var(--green);
  color: #fff;
}
.steps a.locked {
  color: var(--ink-3);
  cursor: not-allowed;
}
.steps a.locked .d {
  border-style: dashed;
}

.own-meter .lbl {
  font-size: 13.5px;
  color: var(--ink-3);
}
.own-meter .val {
  font-family: var(--serif);
  font-size: 36px;
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.02em;
}
.own-meter .bar {
  height: 6px;
  background: var(--rule);
  margin: 8px 0 6px;
}
.own-meter .bar div {
  height: 100%;
  background: var(--green);
  transition:
    width 0.4s,
    background 0.4s;
}
.own-meter .hint {
  font-size: 13px;
  color: var(--ink-3);
  line-height: 1.45;
}

.stage-h {
  margin-bottom: 24px;
  max-width: 760px;
}
.stage-h .step-no {
  font-size: 14px;
  color: var(--red);
  font-weight: 600;
}
.stage-h h2 {
  font-size: 34px;
  margin: 2px 0 6px;
}
.stage-h p {
  color: var(--ink-2);
  margin: 0;
  font-size: 16.5px;
}
.content {
  max-width: 760px;
}
.block {
  margin-bottom: 18px;
}

.summary-strip {
  display: grid;
  grid-template-columns: repeat(4, auto);
  justify-content: start;
  gap: 0;
  border: 1px solid var(--rule);
  border-radius: 6px;
  background: var(--white);
  margin-bottom: 22px;
}
.summary-strip > div {
  padding: 12px 20px;
}
.summary-strip > div + div {
  border-left: 1px solid var(--rule);
}
.summary-strip .k {
  font-size: 12.5px;
  color: var(--ink-3);
}
.summary-strip .v {
  font-weight: 600;
}

.concept {
  background: var(--white);
  border: 1px solid var(--rule);
  border-radius: 6px;
  margin-bottom: 10px;
}
.concept summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 15px 20px;
}
.concept summary::-webkit-details-marker {
  display: none;
}
.concept summary::after {
  content: '+';
  margin-left: auto;
  font-size: 22px;
  color: var(--ink-3);
  line-height: 1;
}
.concept[open] summary::after {
  content: '−';
}
.concept summary h3 {
  font-size: 19px;
  margin: 0;
}
.concept .body {
  padding: 0 20px 18px;
  border-top: 1px solid var(--rule);
  padding-top: 14px;
}
.tick {
  color: var(--green);
  font-weight: 700;
}

.q {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px dashed var(--rule-2);
}
.q-title {
  font-weight: 600;
  margin-bottom: 8px;
}
.opts {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.opts.inline {
  flex-direction: row;
  flex-wrap: wrap;
}
.opt {
  font: inherit;
  font-size: 15px;
  text-align: left;
  padding: 9px 14px;
  border-radius: 6px;
  border: 1px solid var(--rule-2);
  background: var(--white);
  color: var(--ink);
  cursor: pointer;
  position: relative;
}
.opt:hover:not(:disabled) {
  border-color: var(--pen);
  color: var(--pen);
}
.opt:disabled {
  cursor: default;
}
.opt.right {
  border-color: var(--green);
  background: var(--green-soft);
  color: #134d2f;
}
.opt.right::after {
  content: '✓';
  position: absolute;
  right: 12px;
  color: var(--green);
  font-weight: 700;
}
.opt.wrong {
  border-color: var(--red);
  color: var(--red);
  text-decoration: line-through;
  text-decoration-thickness: 1.5px;
  background: var(--white);
}
.fb {
  margin-top: 8px;
  font-size: 14.5px;
  padding-left: 12px;
  border-left: 2px solid;
}
.fb.ok {
  border-color: var(--green);
  color: #134d2f;
}
.fb.bad {
  border-color: var(--red);
  color: #8b261d;
  font-family: var(--serif);
  font-style: italic;
  font-size: 15.5px;
}

.plan-step {
  background: var(--white);
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 18px 20px;
  margin-bottom: 10px;
}
.plan-step.locked {
  opacity: 0.4;
  pointer-events: none;
}
.plan-step .no {
  font-size: 13.5px;
  color: var(--ink-3);
}
.plan-step h3 {
  font-size: 19px;
  margin: 2px 0 10px;
}
.my-plan {
  padding: 18px 22px 16px 62px;
  position: relative;
  border: 1px solid var(--rule);
  border-radius: 6px;
  margin-top: 18px;
}
.my-plan::before {
  content: '';
  position: absolute;
  top: 0;
  bottom: 0;
  left: 44px;
  width: 1px;
  background: var(--margin-line);
}
.my-plan h4 {
  font-family: var(--serif);
  font-size: 18px;
  font-weight: 600;
}
.my-plan ol {
  font-family: var(--serif);
  color: #1b2f73;
  font-size: 16.5px;
  margin: 0;
}
.plan-mini {
  border: 1px solid var(--rule);
  background: var(--white);
  border-radius: 6px;
  padding: 10px 16px;
  margin-bottom: 14px;
  font-size: 14.5px;
}
.plan-mini summary {
  cursor: pointer;
  font-weight: 600;
}
.plan-mini ol {
  margin: 8px 0 2px;
  color: var(--ink-2);
}

/* редактор */
.editor-wrap {
  border-radius: 6px;
  overflow: hidden;
  background: var(--code-bg);
  border: 1px solid #2a2d33;
}
.editor-bar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 14px;
  background: #24272d;
  color: #9aa0aa;
  font: 13px var(--mono);
}
.editor-bar .dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #6b7078;
  display: inline-block;
  margin-right: 6px;
}
.editor-bar .dot.ok {
  background: #49b97a;
}
.editor {
  display: flex;
  font: 15px/1.65 var(--mono);
}
.gutter {
  padding: 14px 10px 14px 16px;
  text-align: right;
  color: #5c616a;
  user-select: none;
  white-space: pre;
  min-width: 44px;
}
.editor textarea {
  flex: 1;
  min-height: 280px;
  resize: none;
  border: none;
  background: transparent;
  color: var(--code-ink);
  font: inherit;
  padding: 14px 16px 14px 6px;
  tab-size: 4;
  white-space: pre;
  overflow-x: auto;
  overflow-y: hidden;
  caret-color: #fff;
}
.editor textarea::selection {
  background: #3b4f8f;
}
.run-row {
  display: flex;
  gap: 14px;
  align-items: center;
  margin: 12px 0 14px;
  flex-wrap: wrap;
}
.result {
  background: var(--white);
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 14px 18px;
}
.result h4 {
  margin-bottom: 6px;
}
.t-row {
  display: grid;
  grid-template-columns: 20px 1fr;
  gap: 6px;
  padding: 5px 0;
  font: 13.5px/1.5 var(--mono);
  border-bottom: 1px dotted var(--rule);
}
.t-row:last-child {
  border-bottom: none;
}
.t-row .i {
  font-weight: 700;
}
.t-row.pass .i {
  color: var(--green);
}
.t-row.fail .i {
  color: var(--red);
}
.t-row .exp {
  color: var(--ink-3);
}
.err {
  margin-top: 8px;
  color: #8b261d;
  font-family: var(--serif);
  font-style: italic;
  font-size: 15.5px;
  padding-left: 12px;
  border-left: 2px solid var(--red);
}

.hints-h {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-top: 30px;
}
.hints-h h3 {
  font-size: 21px;
  margin: 0;
}
.ladder {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border: 1px solid var(--rule);
  border-radius: 6px;
  overflow: hidden;
  margin-top: 10px;
  background: var(--white);
}
.rung {
  font: inherit;
  text-align: left;
  padding: 11px 14px;
  border: none;
  background: var(--white);
  cursor: pointer;
  color: var(--ink);
}
.rung + .rung {
  border-left: 1px solid var(--rule);
}
.rung .lv {
  display: block;
  font-size: 12.5px;
  color: var(--ink-3);
}
.rung b {
  font-size: 14.5px;
  font-weight: 600;
}
.rung:hover:not(:disabled) {
  background: var(--pen-soft);
}
.rung:disabled {
  cursor: not-allowed;
  color: var(--ink-3);
  background: repeating-linear-gradient(-45deg, var(--white), var(--white) 6px, #f6f5f1 6px, #f6f5f1 12px);
}
.rung.open {
  background: var(--pen-soft);
}
.rung.open b {
  color: var(--pen);
}
.hint-text {
  margin-top: 12px;
  background: var(--white);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--pen);
  border-radius: 0 6px 6px 0;
  padding: 14px 18px;
}
.hint-text .t {
  font-size: 13px;
  font-weight: 600;
  color: var(--pen);
  margin-bottom: 4px;
}

/* проверка ИИ */
.ai-code {
  background: var(--code-bg);
  color: var(--code-ink);
  border-radius: 6px;
  padding: 10px 0;
  font: 15px/1.6 var(--mono);
}
.ai-code .ln-row {
  display: flex;
  padding: 1px 16px;
  cursor: pointer;
  white-space: pre;
  border-left: 3px solid transparent;
}
.ai-code .ln-row:hover {
  background: #262a31;
}
.ai-code .ln {
  width: 30px;
  color: #5c616a;
  user-select: none;
  flex: none;
}
.ai-code .ln-row.miss {
  background: #3a2222;
  border-left-color: var(--red);
}
.ai-code .ln-row.hit {
  background: #1f3a2b;
  border-left-color: #49b97a;
}
.ai-code.locked .ln-row {
  cursor: default;
}
.ai-head {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: var(--ink-3);
  margin-bottom: 8px;
}
.ai-head b {
  color: var(--ink);
}

/* защита */
.scale {
  display: flex;
  gap: 6px;
  margin: 10px 0 4px;
}
.scale button {
  width: 50px;
  height: 50px;
  border-radius: 6px;
  font: 600 20px var(--serif);
  border: 1px solid var(--rule-2);
  background: var(--white);
  cursor: pointer;
  color: var(--ink);
}
.scale button:hover:not(:disabled) {
  border-color: var(--pen);
  color: var(--pen);
}
.scale button.sel {
  background: var(--pen);
  color: #fff;
  border-color: var(--pen);
}
.scale button:disabled:not(.sel) {
  color: var(--ink-3);
  cursor: default;
}
.scale-cap {
  display: flex;
  justify-content: space-between;
  width: 274px;
  font-size: 12.5px;
  color: var(--ink-3);
}
.def-q {
  background: var(--white);
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 18px 20px;
  margin-bottom: 10px;
}
.def-q .no {
  font-size: 13.5px;
  color: var(--ink-3);
}
.def-q .text {
  font-size: 16.5px;
  margin: 2px 0 10px;
}
.grade {
  font-family: var(--serif);
  color: var(--red);
  font-size: 17px;
  font-weight: 600;
}
.def-result {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 28px;
  align-items: center;
  padding: 22px 24px;
  border: 1px solid var(--ink);
  border-radius: 6px;
  background: var(--white);
  margin-top: 14px;
}
.def-result .score {
  font-family: var(--serif);
  font-size: 64px;
  font-weight: 600;
  color: var(--red);
  line-height: 1;
}
.def-result .score small {
  font-size: 24px;
  color: var(--ink-3);
  font-weight: 400;
}
.loading {
  color: var(--ink-3);
  display: flex;
  gap: 10px;
  align-items: center;
  padding: 10px 0;
}
.loading::before {
  content: '';
  width: 14px;
  height: 14px;
  border: 2px solid var(--pen);
  border-top-color: transparent;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

.next-row {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-top: 30px;
  padding-top: 18px;
  border-top: 1px solid var(--rule);
  max-width: 760px;
}

/* поля: наставник */
.mg-head {
  padding: 18px 20px 14px 36px;
  border-bottom: 1px solid var(--rule);
}
.mg-head b {
  font-family: var(--serif);
  font-size: 19px;
  font-weight: 600;
}
.mg-head span {
  display: block;
  font-size: 13px;
  color: var(--ink-3);
  line-height: 1.4;
}
.mg-log {
  flex: 1;
  overflow-y: auto;
  padding: 18px 20px 10px 36px;
  min-height: 0;
}
.mg-msg {
  margin-bottom: 16px;
  font-size: 14.8px;
  line-height: 1.55;
}
.mg-msg .who {
  display: block;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--pen);
  margin-bottom: 1px;
}
.mg-msg.user .who {
  color: var(--ink-3);
}
.mg-msg.user .tx {
  font-family: var(--serif);
  font-style: italic;
  color: #1b2f73;
  font-size: 15.5px;
}
.mg-msg p:last-child {
  margin-bottom: 0;
}
.mg-msg pre {
  font-size: 12.5px;
  padding: 10px 12px;
}
.mg-msg .guard {
  display: inline-block;
  margin-top: 6px;
  color: var(--red);
  border: 1.3px solid var(--red);
  border-radius: 4px;
  padding: 0 7px;
  font-size: 12px;
  font-weight: 600;
  transform: rotate(-1.5deg);
}
.mg-msg.typing {
  color: var(--ink-3);
  font-style: italic;
}
.mg-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  padding: 4px 20px 10px 36px;
}
.chip {
  font: inherit;
  font-size: 13px;
  padding: 4px 10px;
  border-radius: 20px;
  border: 1px solid var(--rule-2);
  background: var(--white);
  cursor: pointer;
  color: var(--ink-2);
}
.chip:hover {
  border-color: var(--pen);
  color: var(--pen);
}
.mg-form {
  display: flex;
  gap: 8px;
  padding: 12px 20px 18px 36px;
  border-top: 1px solid var(--rule);
}
.mg-form input {
  flex: 1;
  font: inherit;
  font-size: 14.5px;
  padding: 9px 12px;
  border-radius: 6px;
  border: 1px solid var(--rule-2);
  background: var(--white);
}
.mg-form input:focus {
  outline: 2px solid var(--pen);
  outline-offset: -1px;
}

@media (max-width: 1150px) {
  .workspace {
    grid-template-columns: 210px minmax(0, 1fr);
    height: auto;
  }
  .ws-margin {
    grid-column: 1 / -1;
    height: 540px;
    border-left: none;
    border-top: 1px solid var(--rule);
  }
  .hero,
  .split {
    grid-template-columns: 1fr;
  }
}
@media (max-width: 780px) {
  .workspace {
    grid-template-columns: 1fr;
  }
  .ws-side {
    border-right: none;
    border-bottom: 1px solid var(--rule);
  }
  .ws-main {
    padding: 26px 20px 60px;
  }
  .topnav,
  .brand-sub {
    display: none;
  }
  .hero h1 {
    font-size: 38px;
  }
  .numbers,
  .task-layout {
    grid-template-columns: 1fr;
  }
  .numbers > div + div {
    border-left: none;
    border-top: 1px solid var(--rule);
    padding-left: 0;
  }
  .ladder {
    grid-template-columns: 1fr 1fr;
  }
  .summary-strip {
    grid-template-columns: 1fr 1fr;
  }
}

.task-summary {
  font-size: 17px;
}
.sub-h {
  font-size: 22px;
  margin: 0 0 10px;
}
pre.cond {
  white-space: pre-wrap;
  background: none;
  color: var(--ink);
  padding: 8px 0 0;
  font-size: 13.5px;
}
.lead-s {
  color: var(--ink-2);
  font-size: 16.5px;
  margin: -10px 0 18px;
}
.review {
  margin-top: 12px;
  background: var(--white);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--red);
  border-radius: 0 6px 6px 0;
  padding: 14px 18px;
}
.review .t {
  font-size: 13px;
  font-weight: 600;
  color: var(--red);
  margin-bottom: 4px;
}
.review p:last-of-type {
  margin-bottom: 0;
}
.guard {
  display: inline-block;
  margin-top: 6px;
  color: var(--red);
  border: 1.3px solid var(--red);
  border-radius: 4px;
  padding: 0 7px;
  font-size: 12px;
  font-weight: 600;
  transform: rotate(-1.5deg);
}
pre.compiler {
  background: #2a1f1f;
  color: #f3d6d2;
  font-size: 12.5px;
  max-height: 220px;
}

/* без лигатур, чтобы != не превращалось в ≠ */
.editor,
.editor textarea,
pre,
code,
.ai-code,
.t-row {
  font-variant-ligatures: none;
  font-feature-settings:
    'liga' 0,
    'calt' 0;
}

[hidden] {
  display: none !important;
}

/* телефон */
@media (max-width: 780px) {
  .topbar {
    padding: 0 16px;
  }
  .page {
    padding: 28px 16px 60px;
  }
  .ws-side {
    position: sticky;
    top: 60px;
    z-index: 10;
    background: var(--paper);
    padding: 10px 16px 12px;
    gap: 8px;
  }
  .task-mini h4 {
    font-size: 15px;
    margin: 0;
  }
  .task-mini .meta {
    display: none;
  }
  .steps {
    display: flex;
    gap: 4px;
  }
  .steps li {
    flex: 1;
  }
  .steps a {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 3px;
    padding: 2px 0;
    font-size: 12px;
    text-align: center;
  }
  .steps a .d {
    width: 24px;
    height: 24px;
  }
  .own-meter {
    display: flex;
    align-items: center;
    gap: 10px;
  }
  .own-meter .lbl {
    font-size: 12px;
    white-space: nowrap;
  }
  .own-meter .val {
    font-size: 17px;
  }
  .own-meter .bar {
    flex: 1;
    margin: 0;
  }
  .own-meter .hint {
    display: none;
  }
  .ws-main {
    padding: 22px 16px 40px;
  }
  .stage-h h2 {
    font-size: 28px;
  }
  .summary-strip {
    grid-template-columns: 1fr 1fr 1fr;
  }
  .summary-strip > div {
    padding: 10px 12px;
  }
  .editor {
    font-size: 13px;
  }
  .ws-margin {
    height: auto;
    min-height: 0;
  }
  .mg-log {
    max-height: none;
  }
  .ladder {
    grid-template-columns: 1fr 1fr;
  }
  .rung:nth-child(3) {
    border-left: none;
  }
  .rung:nth-child(n + 3) {
    border-top: 1px solid var(--rule);
  }
}

@media (max-width: 780px) {
  .topbar-right {
    gap: 12px;
    font-size: 13px;
  }
  .mode,
  .link-btn {
    white-space: nowrap;
  }
}

/* ввод/вывод и проверочные примеры */
.io-box {
  border: 1px solid var(--rule);
  border-radius: 6px;
  background: var(--white);
  padding: 10px 16px;
  margin: 0 0 22px;
  font-size: 15px;
  display: grid;
  gap: 6px;
}
.io-box .k {
  display: inline-block;
  min-width: 64px;
  font-size: 12.5px;
  color: var(--ink-3);
}
.gen-note {
  margin-top: 10px;
}
.gen-note[hidden] {
  display: none;
}
.gen-note .dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #d9a520;
  display: inline-block;
  margin-right: 6px;
  animation: gen-pulse 1.2s ease-in-out infinite;
}
@keyframes gen-pulse {
  50% {
    opacity: 0.25;
  }
}
.gen-tag {
  font: 600 10.5px var(--sans);
  color: var(--pen);
  background: var(--pen-soft);
  border-radius: 3px;
  padding: 1px 5px;
  vertical-align: 1px;
}