:root {
  --bg: #fafafc;
  --paper: #fff;
  --text: #18181b;
  --text-2: #52525b;
  --muted: #71717a;
  --line: #e4e4e7;
  --soft: #f4f4f5;
  --purple: #5e5ce6;
  --purple-soft: #eef1ff;
  --red: #b42318;
  --red-soft: #fff1f0;
  --green: #047857;
  --green-soft: #ecfdf5;
  --amber: #a16207;
  --amber-soft: #fffbeb;
  --font: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
}
*,
*::before,
*::after {
  box-sizing: border-box;
}
html {
  -webkit-text-size-adjust: 100%;
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  line-height: 1.65;
  letter-spacing: 0;
}
button,
select {
  font: inherit;
  letter-spacing: 0;
}
button,
a {
  -webkit-tap-highlight-color: transparent;
}
[hidden] {
  display: none !important;
}
.learning-shell {
  width: min(920px, calc(100% - 40px));
  margin: 0 auto;
  padding: 42px 0 80px;
}
.learning-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  padding-bottom: 28px;
  border-bottom: 1px solid var(--line);
}
.learning-kicker {
  margin: 0 0 4px;
  color: var(--purple);
  font-size: 12px;
  font-weight: 700;
}
.learning-head h1 {
  margin: 0;
  font-size: 32px;
  line-height: 1.25;
  font-weight: 800;
  letter-spacing: 0;
}
.learning-head p:not(.learning-kicker) {
  max-width: 620px;
  margin: 8px 0 0;
  color: var(--text-2);
  font-size: 14px;
}
.learning-search-link,
.learning-button {
  display: inline-flex;
  min-height: 42px;
  align-items: center;
  justify-content: center;
  padding: 8px 15px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--text);
  font-size: 13px;
  font-weight: 650;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
}
.learning-search-link:hover,
.learning-button:hover {
  border-color: #c7d2fe;
  background: var(--purple-soft);
  color: #4f46e5;
}
.learning-search-link:focus-visible,
.learning-button:focus-visible,
.learning-tab:focus-visible,
.learning-toolbar select:focus-visible,
.learning-more button:focus-visible {
  outline: 3px solid rgba(94, 92, 230, 0.23);
  outline-offset: 2px;
}
.learning-tabs {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  margin-top: 24px;
  border-bottom: 1px solid var(--line);
}
.learning-tab {
  min-height: 64px;
  padding: 10px 12px;
  border: 0;
  border-bottom: 2px solid transparent;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  text-align: left;
}
.learning-tab span {
  display: block;
  font-size: 13px;
  font-weight: 650;
}
.learning-tab strong {
  display: block;
  margin-top: 1px;
  color: var(--text);
  font-size: 19px;
  font-weight: 750;
  font-variant-numeric: tabular-nums;
}
.learning-tab[aria-selected='true'] {
  border-bottom-color: var(--purple);
  color: var(--purple);
}
.learning-tab[aria-selected='true'] strong {
  color: var(--purple);
}
.learning-toolbar {
  min-height: 62px;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 9px;
}
.learning-toolbar label {
  color: var(--muted);
  font-size: 12px;
  font-weight: 650;
}
.learning-toolbar select {
  min-height: 38px;
  padding: 6px 34px 6px 11px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--text-2);
  font-size: 13px;
}
.learning-panel {
  min-height: 260px;
}
.learning-list {
  display: grid;
  gap: 12px;
}
.learning-card {
  padding: 19px 20px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  box-shadow: 0 1px 2px rgba(24, 24, 27, 0.025);
}
.learning-card-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
}
.learning-card-title {
  min-width: 0;
}
.learning-card-title h2 {
  margin: 0;
  color: var(--text);
  font-size: 16px;
  line-height: 1.45;
  font-weight: 750;
  letter-spacing: 0;
}
.learning-card-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  margin-top: 6px;
  color: var(--muted);
  font-size: 12px;
}
.learning-chip {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
  padding: 2px 8px;
  border-radius: 6px;
  background: var(--soft);
  color: var(--text-2);
  font-size: 11px;
  font-weight: 650;
}
.learning-chip--wrong {
  background: var(--red-soft);
  color: var(--red);
}
.learning-chip--reviewed {
  background: var(--green-soft);
  color: var(--green);
}
.learning-chip--improving {
  background: var(--amber-soft);
  color: var(--amber);
}
.learning-question {
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 4;
  overflow: hidden;
  margin: 14px 0 0;
  color: #27272a;
  font-size: 14px;
  line-height: 1.8;
  overflow-wrap: anywhere;
}
.learning-evidence {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px 22px;
  margin-top: 15px;
  padding-top: 14px;
  border-top: 1px solid var(--soft);
}
.learning-evidence-item span {
  display: block;
  color: var(--muted);
  font-size: 11px;
}
.learning-evidence-item strong {
  display: block;
  margin-top: 2px;
  color: var(--text-2);
  font-size: 13px;
  font-weight: 650;
}
.learning-note {
  margin-top: 12px;
  padding: 10px 12px;
  border-left: 3px solid #f59e0b;
  background: var(--amber-soft);
  color: #713f12;
  font-size: 12.5px;
  line-height: 1.65;
}
.learning-card-actions {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 8px;
  margin-top: 16px;
}
.learning-button--primary {
  border-color: var(--purple);
  background: var(--purple);
  color: #fff;
}
.learning-button--primary:hover {
  border-color: #4f46e5;
  background: #4f46e5;
  color: #fff;
}
.learning-button--danger {
  margin-right: auto;
  border-color: transparent;
  background: transparent;
  color: var(--muted);
}
.learning-button--danger:hover {
  border-color: #fecaca;
  background: #fff5f5;
  color: var(--red);
}
.learning-button:disabled {
  opacity: 0.55;
  cursor: wait;
}
.learning-progress {
  margin-top: 15px;
}
.learning-progress-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  color: var(--text-2);
  font-size: 12px;
}
.learning-progress-track {
  height: 5px;
  margin-top: 7px;
  overflow: hidden;
  border-radius: 4px;
  background: #ececf1;
}
.learning-progress-track i {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: var(--purple);
}
.learning-timeline {
  position: relative;
  display: grid;
  gap: 0;
  padding-left: 26px;
}
.learning-timeline::before {
  content: '';
  position: absolute;
  left: 8px;
  top: 12px;
  bottom: 12px;
  width: 1px;
  background: #d4d4d8;
}
.learning-history-item {
  position: relative;
  padding: 0 0 26px;
}
.learning-history-item::before {
  content: '';
  position: absolute;
  left: -22px;
  top: 8px;
  width: 9px;
  height: 9px;
  border: 2px solid #fff;
  border-radius: 50%;
  background: var(--purple);
  box-shadow: 0 0 0 1px #a5b4fc;
}
.learning-history-date {
  margin-bottom: 6px;
  color: var(--muted);
  font-size: 11.5px;
  font-weight: 650;
}
.learning-history-main {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  padding: 15px 17px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}
.learning-history-main h2 {
  margin: 0 0 4px;
  font-size: 15px;
  line-height: 1.45;
}
.learning-history-main p {
  margin: 0;
  color: var(--text-2);
  font-size: 12.5px;
}
.learning-history-main .learning-button {
  flex: 0 0 auto;
}
.learning-state {
  min-height: 260px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 34px;
  text-align: center;
  color: var(--muted);
}
.learning-state h2 {
  margin: 0 0 6px;
  color: var(--text);
  font-size: 17px;
}
.learning-state p {
  max-width: 480px;
  margin: 0;
  font-size: 13px;
}
.learning-state .learning-button {
  margin-top: 16px;
}
.learning-spinner {
  width: 26px;
  height: 26px;
  margin-bottom: 12px;
  border: 2px solid #dddde7;
  border-top-color: var(--purple);
  border-radius: 50%;
  animation: learning-spin 0.8s linear infinite;
}
.learning-more {
  display: flex;
  justify-content: center;
  padding-top: 22px;
}
.learning-more button {
  min-height: 44px;
  padding: 8px 20px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--text-2);
  font-weight: 650;
  cursor: pointer;
}
.learning-unavailable {
  color: var(--muted);
}
@keyframes learning-spin {
  to {
    transform: rotate(360deg);
  }
}
@media (max-width: 680px) {
  .learning-shell {
    width: calc(100% - 28px);
    padding: 28px 0 60px;
  }
  .learning-head {
    display: block;
    padding-bottom: 22px;
  }
  .learning-head h1 {
    font-size: 27px;
  }
  .learning-search-link {
    width: 100%;
    margin-top: 18px;
  }
  .learning-tabs {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    border: 1px solid var(--line);
    border-radius: 8px;
    overflow: hidden;
  }
  .learning-tab {
    min-height: 58px;
    border-right: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
  }
  .learning-tab:nth-child(2n) {
    border-right: 0;
  }
  .learning-tab:nth-child(n + 3) {
    border-bottom: 0;
  }
  .learning-tab[aria-selected='true'] {
    box-shadow: inset 0 -2px var(--purple);
  }
  .learning-toolbar {
    min-height: 58px;
  }
  .learning-toolbar select {
    min-height: 44px;
  }
  .learning-card {
    padding: 16px;
  }
  .learning-card-head {
    display: block;
  }
  .learning-evidence {
    grid-template-columns: 1fr;
  }
  .learning-card-actions {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }
  .learning-card-actions .learning-button {
    min-height: 44px;
  }
  .learning-button--danger {
    grid-column: 1/-1;
    grid-row: 2;
    width: 100%;
  }
  .learning-history-main {
    display: block;
  }
  .learning-history-main .learning-button {
    width: 100%;
    margin-top: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  * {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}