.system-topbar .edu-topbar__inner {
  max-width: none;
}

.system-version {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--edu-ink-muted);
  font-size: 12px;
  font-weight: 620;
}

.system-version::before {
  content: "";
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--edu-success);
}

.system-layout {
  width: min(100%, 1536px);
  min-height: calc(100vh - var(--edu-header-height));
  margin-inline: auto;
  display: grid;
  grid-template-columns: 248px minmax(0, 1fr);
}

.system-sidebar {
  position: sticky;
  top: var(--edu-header-height);
  height: calc(100vh - var(--edu-header-height));
  align-self: start;
  overflow-y: auto;
  border-right: 1px solid var(--edu-border);
  background: var(--edu-surface);
  padding: 28px 20px;
  scrollbar-width: none;
}

.system-sidebar::-webkit-scrollbar {
  display: none;
}

.system-nav-group + .system-nav-group {
  margin-top: 28px;
}

.system-nav-label {
  margin: 0 0 8px 10px;
  color: var(--edu-ink-subtle);
  font-size: 12px;
  font-weight: 680;
}

.system-nav {
  display: grid;
  gap: 2px;
}

.system-nav a {
  min-height: 36px;
  display: flex;
  align-items: center;
  padding: 7px 10px;
  border-radius: var(--edu-radius-control);
  color: var(--edu-ink-muted);
  font-size: 13px;
  font-weight: 590;
  text-decoration: none;
}

.system-nav a:hover,
.system-nav a[aria-current="true"] {
  background: var(--edu-accent-soft);
  color: var(--edu-accent-strong);
}

.system-main {
  min-width: 0;
  background: var(--edu-canvas);
}

.system-main .edu-page {
  max-width: 1160px;
}

.system-intro {
  padding: 4px 0 44px;
  border-bottom: 1px solid var(--edu-border);
}

.system-intro h1 {
  max-width: 760px;
  margin-bottom: 12px;
  font-size: 38px;
  font-weight: 770;
  line-height: 48px;
}

.system-intro p {
  max-width: 760px;
  margin-bottom: 24px;
  color: var(--edu-ink-muted);
  font-size: 17px;
  line-height: 28px;
}

.system-principles {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0;
  border-block: 1px solid var(--edu-border);
}

.system-principle {
  min-height: 120px;
  padding: 20px;
  border-right: 1px solid var(--edu-border);
  background: var(--edu-surface);
}

.system-principle:first-child {
  box-shadow: inset 3px 0 0 var(--edu-brand);
}

.system-principle:last-child {
  border-right: 0;
}

.system-principle strong {
  display: block;
  margin-bottom: 6px;
  font-size: 15px;
}

.system-principle span {
  color: var(--edu-ink-muted);
  font-size: 13px;
  line-height: 20px;
}

.system-theme-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 24px;
}

.system-theme-note {
  color: var(--edu-ink-muted);
  font-size: 13px;
}

.system-specimen {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(300px, .75fr);
  gap: 24px;
  align-items: start;
}

.system-learning-pane {
  overflow: hidden;
  border: 1px solid var(--edu-border);
  border-radius: var(--edu-radius-panel);
  background: var(--edu-surface);
}

.system-learning-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 18px;
  border-bottom: 1px solid var(--edu-border);
}

.system-learning-head strong {
  font-size: 14px;
}

.system-learning-body {
  display: grid;
  gap: 20px;
  padding: 24px;
}

.system-question {
  margin-bottom: 0;
  font-size: 21px;
  font-weight: 680;
  line-height: 30px;
}

.system-answer {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.system-answer .edu-choice {
  grid-template-columns: 28px minmax(0, 1fr);
}

.system-token-note {
  display: grid;
  gap: 16px;
}

.system-rule-list {
  display: grid;
}

.system-rule {
  display: grid;
  grid-template-columns: 96px minmax(0, 1fr);
  gap: 16px;
  padding: 13px 0;
  border-bottom: 1px solid var(--edu-border);
}

.system-rule:last-child {
  border-bottom: 0;
}

.system-rule dt {
  color: var(--edu-ink-muted);
  font-size: 12px;
  font-weight: 650;
}

.system-rule dd {
  margin: 0;
  font-size: 13px;
}

.system-type-row {
  display: grid;
  grid-template-columns: 120px minmax(0, 1fr) 120px;
  align-items: baseline;
  gap: 20px;
  padding: 18px 0;
  border-bottom: 1px solid var(--edu-border);
}

.system-type-row:last-child {
  border-bottom: 0;
}

.system-type-name,
.system-type-meta {
  color: var(--edu-ink-muted);
  font-size: 12px;
}

.system-type-sample--page {
  font-size: 32px;
  font-weight: 760;
  line-height: 40px;
}

.system-type-sample--section {
  font-size: 22px;
  font-weight: 720;
  line-height: 30px;
}

.system-type-sample--component {
  font-size: 16px;
  font-weight: 680;
  line-height: 24px;
}

.system-type-sample--body {
  font-size: 15px;
  line-height: 24px;
}

.system-component-board {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0;
}

.system-component-cell {
  min-height: 180px;
  display: grid;
  align-content: start;
  gap: 16px;
  padding: 20px;
  border-top: 1px solid var(--edu-border);
  background: var(--edu-surface);
}

.system-component-cell:nth-child(odd) {
  border-right: 1px solid var(--edu-border);
}

.system-component-cell h3 {
  margin-bottom: 0;
  font-size: 14px;
  font-weight: 680;
}

.system-component-cell p {
  margin-bottom: 0;
  color: var(--edu-ink-muted);
  font-size: 12px;
}

.system-shell-diagram {
  overflow: hidden;
  border: 1px solid var(--edu-border-strong);
  border-radius: var(--edu-radius-panel);
  background: var(--edu-surface);
}

.system-shell-top {
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-inline: 18px;
  border-bottom: 1px solid var(--edu-border);
}

.system-shell-mark {
  width: 120px;
  height: 12px;
  border-radius: 2px;
  background: var(--edu-brand);
}

.system-shell-tools {
  display: flex;
  gap: 8px;
}

.system-shell-tools span {
  width: 28px;
  height: 28px;
  border: 1px solid var(--edu-border);
  border-radius: var(--edu-radius-control);
}

.system-shell-body {
  min-height: 290px;
  display: grid;
  grid-template-columns: 160px minmax(0, 1fr);
}

.system-shell-rail {
  padding: 18px;
  border-right: 1px solid var(--edu-border);
  background: var(--edu-surface-subtle);
}

.system-shell-rail span,
.system-shell-content span {
  display: block;
  border-radius: 2px;
  background: var(--edu-border);
}

.system-shell-rail span {
  height: 9px;
  margin-bottom: 14px;
}

.system-shell-rail span:nth-child(2) {
  width: 72%;
  background: var(--edu-accent);
}

.system-shell-content {
  padding: 28px;
}

.system-shell-content span:nth-child(1) {
  width: 46%;
  height: 18px;
  margin-bottom: 14px;
  background: var(--edu-ink);
}

.system-shell-content span:nth-child(2) {
  width: 72%;
  height: 9px;
  margin-bottom: 28px;
}

.system-shell-task {
  height: 150px;
  border: 1px solid var(--edu-border);
  border-left: 3px solid var(--edu-accent);
  border-radius: var(--edu-radius-control);
}

.system-do-dont {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.system-guidance {
  padding: 20px;
  border-top: 3px solid var(--edu-success);
  background: var(--edu-surface);
}

.system-guidance--dont {
  border-top-color: var(--edu-danger);
}

.system-guidance h3 {
  margin-bottom: 12px;
  font-size: 15px;
}

.system-guidance ul {
  margin: 0;
  padding-left: 20px;
  color: var(--edu-ink-muted);
}

.system-guidance li + li {
  margin-top: 8px;
}

.system-copy-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 10px;
}

.system-copy-row h3 {
  margin-bottom: 0;
  font-size: 15px;
}

.system-footer {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-top: 32px;
  color: var(--edu-ink-muted);
  font-size: 12px;
}

@media (max-width: 1120px) {
  .system-principles {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .system-principle:nth-child(2) {
    border-right: 0;
  }

  .system-principle:nth-child(-n + 2) {
    border-bottom: 1px solid var(--edu-border);
  }

  .system-specimen {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 840px) {
  .system-layout {
    grid-template-columns: 1fr;
  }

  .system-sidebar {
    position: sticky;
    top: var(--edu-header-height);
    z-index: 40;
    height: auto;
    display: flex;
    gap: 8px;
    overflow-x: auto;
    border-right: 0;
    border-bottom: 1px solid var(--edu-border);
    padding: 8px 16px;
  }

  .system-nav-group,
  .system-nav {
    display: contents;
  }

  .system-nav-group + .system-nav-group {
    margin-top: 0;
  }

  .system-nav-label,
  .system-nav--secondary {
    display: none;
  }

  .system-nav a {
    flex: 0 0 auto;
  }
}

@media (max-width: 720px) {
  .system-topbar .system-version {
    display: none;
  }

  .system-topbar .edu-topbar__actions .edu-button {
    display: none;
  }

  .system-intro h1 {
    font-size: 30px;
    line-height: 38px;
  }

  .system-principles,
  .system-component-board,
  .system-do-dont {
    grid-template-columns: 1fr;
  }

  .system-principle,
  .system-principle:nth-child(2),
  .system-component-cell:nth-child(odd) {
    border-right: 0;
    border-bottom: 1px solid var(--edu-border);
  }

  .system-principle:last-child {
    border-bottom: 0;
  }

  .system-answer {
    grid-template-columns: 1fr;
  }

  .system-type-row {
    grid-template-columns: 86px minmax(0, 1fr);
  }

  .system-type-meta {
    display: none;
  }

  .system-shell-body {
    grid-template-columns: 88px minmax(0, 1fr);
  }

  .system-shell-content {
    padding: 18px;
  }
}