:root {
  color-scheme: light;
  --bg: #edf2ef;
  --surface: #ffffff;
  --surface-soft: #f5f8f6;
  --surface-deep: #e3ebe6;
  --ink: #172320;
  --muted: #66746e;
  --faint: #8c9993;
  --line: #d8e1dc;
  --line-strong: #b7c7bf;
  --traditional: #df6b4f;
  --traditional-soft: #fff0eb;
  --model: #4d7eb3;
  --model-soft: #edf4fc;
  --success: #2d8066;
  --warning: #b7782e;
  --danger: #b34c50;
  --shadow: 0 18px 50px rgba(23, 35, 32, 0.1);
  --safe-top: env(safe-area-inset-top, 0px);
  --safe-bottom: env(safe-area-inset-bottom, 0px);
  font-family: "Avenir Next", "PingFang SC", "Microsoft YaHei", sans-serif;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #111a18;
  --surface: #1b2925;
  --surface-soft: #22332e;
  --surface-deep: #2a3e37;
  --ink: #edf5f1;
  --muted: #adbbb5;
  --faint: #7e9088;
  --line: #334941;
  --line-strong: #4a6258;
  --traditional: #ff9075;
  --traditional-soft: #3a2825;
  --model: #8db9ed;
  --model-soft: #243548;
  --success: #70c9a7;
  --warning: #e2aa63;
  --danger: #ff9a9a;
  --shadow: 0 22px 60px rgba(0, 0, 0, 0.3);
}

* {
  box-sizing: border-box;
}

html,
body {
  width: 100%;
  height: 100%;
  margin: 0;
  overflow: hidden;
  background: var(--bg);
  color: var(--ink);
  -webkit-tap-highlight-color: transparent;
}

body {
  min-height: 100dvh;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

button,
input {
  font: inherit;
}

button,
a {
  color: inherit;
}

button:focus-visible,
a:focus-visible,
input:focus-visible,
summary:focus-visible,
.feed:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--traditional) 70%, transparent);
  outline-offset: 3px;
}

button {
  cursor: pointer;
}

.app-shell {
  display: grid;
  grid-template-rows: auto auto auto minmax(0, 1fr);
  width: 100%;
  height: 100dvh;
  max-width: 1160px;
  margin: 0 auto;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: calc(13px + var(--safe-top)) clamp(14px, 3vw, 34px) 10px;
}

.brand-button {
  display: flex;
  min-width: 0;
  align-items: center;
  gap: 11px;
  padding: 0;
  border: 0;
  background: transparent;
  text-align: left;
}

.brand-mark {
  display: grid;
  width: 46px;
  height: 46px;
  flex: 0 0 auto;
  place-items: center;
  border-radius: 8px;
  background: var(--ink);
  color: var(--bg);
  font: 800 18px/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.brand-copy {
  display: flex;
  min-width: 0;
  flex-direction: column;
  gap: 4px;
}

.brand-copy strong {
  overflow: hidden;
  font-size: 16px;
  line-height: 1.1;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.brand-copy small {
  overflow: hidden;
  color: var(--muted);
  font-size: 11px;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.top-actions {
  display: flex;
  align-items: center;
  gap: 7px;
}

.text-link {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  padding: 0 9px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
  text-decoration: none;
}

.text-link:hover {
  color: var(--ink);
}

.icon-button {
  display: grid;
  width: 40px;
  height: 40px;
  padding: 0;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--ink);
  font-size: 21px;
  line-height: 1;
}

.icon-button:hover {
  border-color: var(--line-strong);
  background: var(--surface-soft);
}

.icon-button.quiet {
  border-color: transparent;
  background: var(--surface-soft);
}

.track-switch {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  width: min(560px, calc(100% - 28px));
  margin: 0 auto 10px;
  padding: 3px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface-deep);
}

.track-switch button {
  display: flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--muted);
}

.track-switch button strong {
  font-size: 14px;
}

.track-switch button span {
  font: 700 11px/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.track-switch button[aria-pressed="true"] {
  background: var(--surface);
  color: var(--ink);
  box-shadow: 0 3px 10px rgba(23, 35, 32, 0.08);
}

.track-switch button[data-track="traditional"][aria-pressed="true"] strong {
  color: var(--traditional);
}

.track-switch button[data-track="model"][aria-pressed="true"] strong {
  color: var(--model);
}

.chapter-strip {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding: 2px clamp(14px, 3vw, 34px) 11px;
  scrollbar-width: none;
  scroll-snap-type: x proximity;
}

.chapter-strip::-webkit-scrollbar,
.feed::-webkit-scrollbar,
.detail-content::-webkit-scrollbar,
.explore-panel::-webkit-scrollbar,
.stack-inline::-webkit-scrollbar {
  display: none;
}

.chapter-chip {
  flex: 0 0 auto;
  min-height: 34px;
  padding: 7px 11px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
  color: var(--muted);
  font-size: 11px;
  font-weight: 700;
  scroll-snap-align: start;
}

.chapter-chip:hover,
.chapter-chip[aria-pressed="true"] {
  border-color: var(--ink);
  background: var(--ink);
  color: var(--bg);
}

.feed {
  position: relative;
  min-height: 0;
  overflow-x: hidden;
  overflow-y: auto;
  padding: 2px clamp(12px, 3vw, 34px) calc(22px + var(--safe-bottom));
  scroll-behavior: smooth;
  scroll-snap-type: y mandatory;
  scrollbar-width: none;
  overscroll-behavior-y: contain;
}

.feed-card {
  --accent: var(--traditional);
  --accent-soft: var(--traditional-soft);
  position: relative;
  display: flex;
  width: min(100%, 760px);
  min-height: min(660px, calc(100dvh - 158px - var(--safe-top) - var(--safe-bottom)));
  margin: 4px auto 16px;
  overflow: hidden;
  flex-direction: column;
  border: 1px solid color-mix(in srgb, var(--accent) 22%, var(--line));
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
  scroll-snap-align: start;
  scroll-snap-stop: always;
}

.feed-card.track-model {
  --accent: var(--model);
  --accent-soft: var(--model-soft);
}

.feed-card::before {
  position: absolute;
  top: 0;
  right: 0;
  left: 0;
  height: 4px;
  background: var(--accent);
  content: "";
}

.card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 14px;
  padding: 23px 24px 12px;
}

.card-kicker {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  align-items: center;
  color: var(--muted);
  font: 700 10px/1.3 ui-monospace, SFMono-Regular, Consolas, monospace;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.card-kicker .priority {
  color: var(--accent);
}

.card-header h2 {
  margin: 8px 0 0;
  font-size: clamp(1.45rem, 3vw, 2.15rem);
  font-weight: 760;
  line-height: 1.15;
  letter-spacing: 0;
}

.primer-mark {
  display: inline-flex;
  min-height: 29px;
  align-items: center;
  padding: 5px 8px;
  border: 1px solid color-mix(in srgb, var(--accent) 35%, var(--line));
  border-radius: 5px;
  background: var(--accent-soft);
  color: var(--accent);
  font: 750 10px/1 ui-monospace, SFMono-Regular, Consolas, monospace;
  white-space: nowrap;
}

.bookmark-button {
  display: grid;
  width: 38px;
  height: 38px;
  flex: 0 0 auto;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: transparent;
  color: var(--muted);
  font-size: 20px;
}

.bookmark-button:hover,
.bookmark-button[aria-pressed="true"] {
  border-color: var(--accent);
  color: var(--accent);
}

.card-body {
  display: grid;
  gap: 0;
  min-height: 0;
  padding: 0 24px;
  overflow: auto;
}

.card-section {
  padding: 15px 0;
  border-top: 1px solid var(--line);
}

.card-section:first-child {
  border-top: 0;
}

.section-label {
  display: block;
  margin-bottom: 7px;
  color: var(--accent);
  font: 750 10px/1.2 ui-monospace, SFMono-Regular, Consolas, monospace;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.card-section p {
  margin: 0;
  color: var(--ink);
  font-size: 0.96rem;
  line-height: 1.65;
}

.card-section .muted-copy {
  color: var(--muted);
}

.concept-preview {
  color: var(--ink);
  font-size: 1.02rem;
  line-height: 1.7;
}

.visual-preview {
  margin: 0;
  max-height: 155px;
  overflow: hidden;
  border-left: 3px solid var(--accent);
  padding: 9px 12px;
  background: var(--surface-soft);
  color: var(--muted);
  font: 600 0.75rem/1.5 ui-monospace, SFMono-Regular, Consolas, monospace;
  white-space: pre-wrap;
}

.shape-preview {
  display: inline-block;
  color: var(--accent);
  font: 650 0.78rem/1.5 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  margin-top: auto;
  padding: 14px 24px 20px;
  border-top: 1px solid var(--line);
}

.card-meta {
  display: flex;
  min-width: 0;
  flex-wrap: wrap;
  gap: 8px 14px;
  color: var(--muted);
  font: 650 0.72rem/1.4 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.card-meta .status-text {
  color: var(--accent);
}

.card-actions {
  display: flex;
  flex: 0 0 auto;
  gap: 8px;
}

.primary-button,
.secondary-button,
.status-button,
.text-button {
  min-height: 40px;
  border-radius: 6px;
  font-size: 0.82rem;
  font-weight: 750;
}

.primary-button {
  border: 1px solid var(--ink);
  background: var(--ink);
  color: var(--bg);
  padding: 9px 14px;
}

.primary-button:hover {
  opacity: 0.86;
}

.secondary-button,
.status-button {
  border: 1px solid var(--line-strong);
  background: var(--surface);
  color: var(--ink);
  padding: 9px 12px;
}

.secondary-button:hover,
.status-button:hover {
  border-color: var(--ink);
  background: var(--surface-soft);
}

.status-button[data-status="mastered"] {
  border-color: var(--success);
  color: var(--success);
}

.status-button[data-status="learning"] {
  border-color: var(--warning);
  color: var(--warning);
}

.text-button {
  border: 0;
  background: transparent;
  color: var(--muted);
  padding: 9px 0;
}

.text-button:hover {
  color: var(--ink);
}

.empty-state {
  align-self: center;
  justify-self: center;
  padding: 42px 18px;
  text-align: center;
}

.empty-symbol {
  display: block;
  color: var(--faint);
  font-size: 30px;
}

.empty-state h2 {
  margin: 12px 0 5px;
  font-size: 1.2rem;
}

.empty-state p {
  margin: 0 0 18px;
  color: var(--muted);
}

.feed-position {
  position: fixed;
  right: 18px;
  bottom: calc(14px + var(--safe-bottom));
  z-index: 3;
  padding: 7px 9px;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: color-mix(in srgb, var(--surface) 90%, transparent);
  color: var(--muted);
  font: 700 0.7rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
  backdrop-filter: blur(9px);
}

dialog {
  padding: 0;
  border: 0;
  background: transparent;
  color: var(--ink);
}

dialog::backdrop {
  background: rgba(6, 14, 12, 0.6);
  backdrop-filter: blur(4px);
}

.detail-dialog {
  width: min(940px, calc(100% - 22px));
  max-width: 940px;
  height: min(92dvh, 900px);
  max-height: 92dvh;
}

.detail-panel {
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
  width: 100%;
  height: 100%;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.detail-header {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr) 40px;
  align-items: center;
  gap: 10px;
  padding: 12px 14px;
  border-bottom: 1px solid var(--line);
}

.detail-heading {
  min-width: 0;
  text-align: center;
}

.detail-heading strong,
.detail-heading small {
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.detail-heading strong {
  font-size: 0.94rem;
}

.detail-heading small {
  margin-top: 3px;
  color: var(--muted);
  font-size: 0.7rem;
}

.detail-content {
  overflow-y: auto;
  padding: 22px clamp(16px, 4vw, 42px) 38px;
}

.detail-content h1,
.detail-content h2,
.detail-content h3,
.detail-content h4 {
  color: var(--ink);
  line-height: 1.25;
}

.detail-content h1 {
  margin: 0 0 18px;
  font-size: 2rem;
}

.detail-content h2 {
  margin: 30px 0 10px;
  border-bottom: 1px solid var(--line);
  padding-bottom: 8px;
  font-size: 1.25rem;
}

.detail-content h3 {
  margin: 22px 0 8px;
  font-size: 1.05rem;
}

.detail-content h4 {
  margin: 15px 0 6px;
  color: var(--muted);
  font-size: 0.9rem;
}

.detail-content p,
.detail-content li {
  color: var(--ink);
  font-size: 0.93rem;
  line-height: 1.75;
}

.detail-content p {
  margin: 10px 0;
}

.detail-content ul,
.detail-content ol {
  margin: 8px 0 14px;
  padding-left: 22px;
}

.detail-content li + li {
  margin-top: 5px;
}

.detail-content blockquote {
  margin: 0 0 18px;
  border-left: 3px solid var(--traditional);
  padding: 8px 14px;
  background: var(--traditional-soft);
  color: var(--muted);
  font-size: 0.96rem;
  line-height: 1.65;
}

.detail-content code:not(pre code) {
  border-radius: 3px;
  background: var(--surface-deep);
  padding: 2px 4px;
  font: 0.86em ui-monospace, SFMono-Regular, Consolas, monospace;
}

.code-block {
  margin: 14px 0 18px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #101b19;
}

.code-toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 7px 10px;
  border-bottom: 1px solid #2a3b36;
  color: #adc0b8;
  font: 700 0.68rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.copy-button {
  border: 0;
  background: transparent;
  color: #d5e3de;
  font-size: 0.72rem;
}

.copy-button:hover {
  color: var(--orange);
}

.detail-content pre {
  max-width: 100%;
  margin: 12px 0;
  overflow-x: auto;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}

.code-block pre {
  margin: 0;
  padding: 13px;
  color: #dbe9e4;
  font: 0.78rem/1.6 ui-monospace, SFMono-Regular, Consolas, monospace;
  white-space: pre;
  overflow-wrap: normal;
}

.detail-content .visual-block {
  border-left: 3px solid var(--model);
  background: var(--model-soft);
  padding: 12px 14px;
  color: var(--muted);
  font: 0.8rem/1.6 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.detail-content table {
  width: 100%;
  margin: 14px 0;
  border-collapse: collapse;
  font-size: 0.82rem;
}

.detail-content th,
.detail-content td {
  border: 1px solid var(--line);
  padding: 8px 9px;
  text-align: left;
  vertical-align: top;
}

.detail-content th {
  background: var(--surface-soft);
  font-weight: 750;
}

.detail-content a {
  color: var(--model);
}

.detail-content details {
  margin: 14px 0;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 8px 12px;
}

.detail-content summary {
  cursor: pointer;
  font-weight: 750;
}

.detail-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 10px 14px calc(10px + var(--safe-bottom));
  border-top: 1px solid var(--line);
  background: var(--surface);
}

.detail-footer > * {
  min-width: 0;
}

.explore-dialog {
  width: min(680px, calc(100% - 22px));
  max-width: 680px;
  max-height: 88dvh;
}

.explore-panel {
  max-height: 88dvh;
  overflow-y: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.sheet-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  padding: 20px 20px 12px;
}

.eyebrow {
  color: var(--traditional);
  font: 750 0.68rem/1.2 ui-monospace, SFMono-Regular, Consolas, monospace;
  letter-spacing: 0.12em;
}

.sheet-header h2 {
  margin: 7px 0 0;
  font-size: 1.45rem;
}

.progress-overview {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  margin: 5px 20px 15px;
  border: 1px solid var(--line);
  border-radius: 6px;
  overflow: hidden;
  background: var(--line);
}

.progress-stat {
  min-height: 74px;
  padding: 12px 10px;
  background: var(--surface-soft);
}

.progress-stat strong,
.progress-stat span {
  display: block;
}

.progress-stat strong {
  font: 800 1.35rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.progress-stat span {
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.7rem;
}

.search-field {
  display: block;
  margin: 0 20px 16px;
  color: var(--muted);
  font-size: 0.74rem;
  font-weight: 700;
}

.search-control {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 7px;
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  padding: 0 10px;
  background: var(--surface);
}

.search-control input {
  width: 100%;
  min-height: 43px;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--ink);
  font-size: 16px;
}

.search-control button {
  border: 0;
  background: transparent;
  color: var(--muted);
}

.filter-group {
  margin: 0 20px 15px;
  border: 0;
  padding: 0;
}

.filter-group legend,
.chapter-grid-section h3 {
  margin-bottom: 8px;
  color: var(--ink);
  font-size: 0.78rem;
  font-weight: 800;
}

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

.filter-chip {
  min-height: 32px;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: var(--surface-soft);
  color: var(--muted);
  padding: 6px 10px;
  font-size: 0.72rem;
  font-weight: 700;
}

.filter-chip[aria-pressed="true"] {
  border-color: var(--ink);
  background: var(--ink);
  color: var(--bg);
}

.chapter-grid-section {
  margin: 0 20px 18px;
}

.chapter-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 7px;
}

.chapter-tile {
  display: flex;
  min-height: 47px;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: var(--surface-soft);
  color: var(--ink);
  padding: 8px 10px;
  text-align: left;
}

.chapter-tile strong {
  overflow: hidden;
  font-size: 0.74rem;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.chapter-tile span {
  flex: 0 0 auto;
  color: var(--muted);
  font: 650 0.68rem/1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.chapter-tile[aria-pressed="true"] {
  border-color: var(--traditional);
  background: var(--traditional-soft);
}

.sheet-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 11px 20px calc(13px + var(--safe-bottom));
  border-top: 1px solid var(--line);
}

.wide {
  min-width: 150px;
}

.toast {
  position: fixed;
  bottom: calc(18px + var(--safe-bottom));
  left: 50%;
  z-index: 10;
  max-width: min(360px, calc(100% - 32px));
  transform: translate(-50%, 16px);
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  background: var(--ink);
  color: var(--bg);
  padding: 10px 13px;
  font-size: 0.8rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity 160ms ease, transform 160ms ease;
}

.toast.visible {
  transform: translate(-50%, 0);
  opacity: 1;
}

@media (max-width: 760px) {
  .feed-card {
    min-height: min(630px, calc(100dvh - 158px - var(--safe-top) - var(--safe-bottom)));
  }

  .card-header,
  .card-body,
  .card-footer {
    padding-right: 17px;
    padding-left: 17px;
  }

  .card-footer {
    align-items: flex-end;
  }

  .card-actions {
    flex-direction: column;
  }

  .detail-content h1 {
    font-size: 1.65rem;
  }
}

@media (max-width: 500px) {
  .app-shell {
    grid-template-rows: auto auto auto minmax(0, 1fr);
  }

  .text-link {
    display: none;
  }

  .track-switch {
    width: calc(100% - 18px);
  }

  .chapter-strip {
    padding-right: 9px;
    padding-left: 9px;
  }

  .feed {
    padding-right: 9px;
    padding-left: 9px;
  }

  .feed-card {
    min-height: calc(100dvh - 150px - var(--safe-top) - var(--safe-bottom));
  }

  .card-header h2 {
    font-size: 1.4rem;
  }

  .card-section p {
    font-size: 0.88rem;
  }

  .card-footer {
    gap: 10px;
  }

  .card-meta {
    max-width: 45%;
  }

  .primary-button,
  .status-button {
    font-size: 0.75rem;
  }

  .progress-overview {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .chapter-grid {
    grid-template-columns: 1fr;
  }

  .sheet-footer {
    align-items: stretch;
    flex-direction: column-reverse;
  }

  .wide {
    width: 100%;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}