:root {
  --blueprint: #123b5d;
  --blueprint-deep: #0b283f;
  --signal: #d84b3f;
  --signal-soft: #ffe4df;
  --mist: #e9f1f4;
  --paper: #f9fbfc;
  --ink: #14232d;
  --muted: #667681;
  --line: #c8d8df;
  --success: #18765b;
  --warning: #a76812;
  --shadow: 0 18px 50px rgba(18, 59, 93, 0.12);
  --display: "STZhongsong", "Songti SC", "Noto Serif CJK SC", serif;
  --body: "Microsoft YaHei", "PingFang SC", "Noto Sans CJK SC", sans-serif;
  --mono: "Cascadia Code", "SFMono-Regular", Consolas, monospace;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(rgba(18, 59, 93, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(18, 59, 93, 0.035) 1px, transparent 1px),
    var(--mist);
  background-size: 24px 24px;
  font-family: var(--body);
}

button,
input,
textarea {
  font: inherit;
}

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

a {
  color: inherit;
}

:focus-visible {
  outline: 3px solid rgba(216, 75, 63, 0.55);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 100;
  transform: translateY(-180%);
  padding: 0.7rem 1rem;
  color: white;
  background: var(--signal);
  text-decoration: none;
}

.skip-link:focus {
  transform: none;
}

.app-shell {
  min-height: 100vh;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  min-height: 78px;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0 2rem;
  color: white;
  background: var(--blueprint-deep);
  border-bottom: 4px solid var(--signal);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.8rem;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  color: var(--blueprint-deep);
  background: white;
  font: 800 1.35rem/1 var(--mono);
  transform: rotate(-4deg);
}

.brand strong,
.brand small {
  display: block;
}

.brand strong {
  font-family: var(--display);
  font-size: 1.08rem;
  letter-spacing: 0.04em;
}

.brand small {
  margin-top: 0.12rem;
  color: #b7cbd5;
  font-size: 0.7rem;
  letter-spacing: 0.08em;
}

.top-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.text-button,
.icon-button,
.primary-button,
.secondary-button,
.rating-button,
.chapter-row {
  border: 0;
  cursor: pointer;
}

.text-button {
  padding: 0.7rem 0.9rem;
  color: #d6e4ea;
  background: transparent;
}

.primary-button,
.secondary-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0.8rem 1.15rem;
  font-weight: 700;
  text-decoration: none;
}

.primary-button {
  color: white;
  background: var(--signal);
  box-shadow: 4px 4px 0 #7b281f;
}

.primary-button:hover {
  transform: translate(1px, 1px);
  box-shadow: 3px 3px 0 #7b281f;
}

.primary-button.compact {
  min-height: 40px;
  padding: 0.55rem 0.9rem;
  font-size: 0.86rem;
}

.secondary-button {
  color: var(--blueprint);
  background: transparent;
  border: 1px solid var(--blueprint);
}

.workspace {
  display: grid;
  grid-template-columns: 270px minmax(0, 1fr) 270px;
  min-height: calc(100vh - 82px);
}

.rail,
.evidence-panel {
  position: sticky;
  top: 82px;
  align-self: start;
  height: calc(100vh - 82px);
  overflow: auto;
}

.rail {
  padding: 1.5rem 0.85rem 2rem;
  background: rgba(249, 251, 252, 0.94);
  border-right: 1px solid var(--line);
}

.rail-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  padding: 0 0.65rem 1rem;
  color: var(--muted);
  font-size: 0.76rem;
  letter-spacing: 0.08em;
}

.rail-heading strong {
  color: var(--signal);
  font: 800 1.15rem/1 var(--mono);
}

.chapter-track {
  position: relative;
}

.chapter-track::before {
  position: absolute;
  top: 18px;
  bottom: 18px;
  left: 24px;
  width: 2px;
  content: "";
  background: var(--line);
}

.chapter-row {
  position: relative;
  display: grid;
  width: 100%;
  grid-template-columns: 31px 1fr auto;
  gap: 0.65rem;
  align-items: center;
  padding: 0.66rem 0.6rem;
  color: var(--ink);
  text-align: left;
  background: transparent;
}

.chapter-row:hover,
.chapter-row.active {
  background: #dfebf0;
}

.chapter-row.active::after {
  position: absolute;
  top: 15%;
  right: -0.85rem;
  width: 4px;
  height: 70%;
  content: "";
  background: var(--signal);
}

.track-node {
  position: relative;
  z-index: 1;
  display: grid;
  width: 28px;
  height: 28px;
  place-items: center;
  color: var(--blueprint);
  background: var(--paper);
  border: 2px solid var(--blueprint);
  border-radius: 50%;
  font: 700 0.65rem/1 var(--mono);
}

.chapter-row.touched .track-node {
  color: white;
  background: var(--blueprint);
}

.chapter-row.verified .track-node {
  background: var(--success);
  border-color: var(--success);
}

.chapter-name {
  overflow: hidden;
  font-size: 0.79rem;
  font-weight: 650;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.chapter-meter {
  color: var(--muted);
  font: 0.65rem/1 var(--mono);
}

main {
  min-width: 0;
  padding: 3.2rem clamp(1.5rem, 4vw, 4.5rem) 6rem;
}

.evidence-panel {
  padding: 2rem 1.5rem;
  color: white;
  background: var(--blueprint);
  border-left: 1px solid #0c2d47;
}

.eyebrow {
  margin: 0 0 0.9rem;
  color: #b7cfda;
  font: 700 0.7rem/1 var(--mono);
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.evidence-panel h2 {
  margin: 0;
  font: 700 1.65rem/1.35 var(--display);
}

.evidence-list {
  margin: 2rem 0;
}

.evidence-list div {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  padding: 1rem 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.18);
}

.evidence-list dt {
  color: #bdd1da;
  font-size: 0.78rem;
}

.evidence-list dd {
  margin: 0;
  font: 800 1.7rem/1 var(--mono);
}

.evidence-note {
  padding: 1rem;
  color: #d9e6eb;
  background: rgba(8, 34, 52, 0.45);
  font-size: 0.78rem;
  line-height: 1.7;
}

.evidence-note span {
  display: inline-block;
  margin-right: 0.35rem;
  color: #ffb7ad;
}

.loading-state,
.empty-state {
  display: grid;
  min-height: 45vh;
  place-items: center;
  color: var(--muted);
}

.loading-pulse {
  width: 12px;
  height: 12px;
  background: var(--signal);
  border-radius: 50%;
  animation: pulse 1.2s infinite;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(250px, 0.65fr);
  gap: clamp(2rem, 5vw, 5rem);
  align-items: end;
  padding-bottom: 3rem;
  border-bottom: 1px solid var(--line);
}

.hero-kicker,
.section-kicker {
  color: var(--signal);
  font: 800 0.72rem/1 var(--mono);
  letter-spacing: 0.15em;
}

.hero h1 {
  max-width: 760px;
  margin: 0.7rem 0 1.2rem;
  font: 700 clamp(2.7rem, 4.1vw, 5rem)/0.98 var(--display);
  letter-spacing: -0.04em;
}

.hero h1 span,
.hero h1 em {
  display: block;
  width: max-content;
  white-space: nowrap;
}

.hero h1 em {
  position: relative;
  color: var(--blueprint);
  font-style: normal;
}

.hero h1 em::after {
  position: absolute;
  right: 0;
  bottom: -0.1em;
  left: 0;
  height: 0.11em;
  content: "";
  background: var(--signal);
  transform: rotate(-1deg);
}

.hero-copy {
  max-width: 640px;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.9;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  margin-top: 1.6rem;
}

.brief-card {
  padding: 1.5rem;
  background: var(--paper);
  border: 1px solid var(--line);
  box-shadow: 8px 8px 0 rgba(18, 59, 93, 0.13);
  transform: rotate(1deg);
}

.brief-card p {
  margin: 0 0 1.2rem;
  color: var(--muted);
  font-size: 0.75rem;
}

.brief-card strong {
  display: block;
  margin-bottom: 1rem;
  font: 700 1.15rem/1.45 var(--display);
}

.brief-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5rem;
}

.brief-stats span {
  padding-top: 0.7rem;
  color: var(--muted);
  border-top: 2px solid var(--blueprint);
  font-size: 0.68rem;
}

.brief-stats b {
  display: block;
  margin-bottom: 0.25rem;
  color: var(--ink);
  font: 800 1.25rem/1 var(--mono);
}

.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 1rem;
  margin: 3.5rem 0 1.25rem;
}

.section-heading h2 {
  margin: 0.4rem 0 0;
  font: 700 2rem/1.2 var(--display);
}

.section-heading p {
  max-width: 410px;
  margin: 0;
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.7;
}

.chapter-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.chapter-card {
  position: relative;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1rem;
  min-height: 145px;
  padding: 1.35rem;
  background: var(--paper);
  text-decoration: none;
  transition: background 160ms ease, transform 160ms ease;
}

.chapter-card:hover {
  z-index: 2;
  background: white;
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.chapter-index {
  color: var(--signal);
  font: 800 0.85rem/1 var(--mono);
}

.chapter-card h3 {
  margin: 0 0 0.55rem;
  font: 700 1.08rem/1.45 var(--display);
}

.chapter-card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.74rem;
}

.mini-progress {
  position: absolute;
  right: 1.35rem;
  bottom: 1.25rem;
  left: 3.9rem;
  height: 4px;
  background: var(--mist);
}

.mini-progress span {
  display: block;
  height: 100%;
  background: var(--blueprint);
}

.chapter-header {
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--line);
}

.back-link {
  display: inline-flex;
  margin-bottom: 1.5rem;
  color: var(--muted);
  font-size: 0.8rem;
  text-decoration: none;
}

.chapter-header h1 {
  max-width: 820px;
  margin: 0.55rem 0 1rem;
  font: 700 clamp(2.2rem, 4vw, 4.3rem)/1.08 var(--display);
  letter-spacing: -0.03em;
}

.chapter-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 1.2rem;
  color: var(--muted);
  font-size: 0.76rem;
}

.chapter-actions {
  display: flex;
  gap: 0.8rem;
  margin-top: 1.5rem;
}

.question-list {
  display: grid;
  gap: 0.65rem;
  margin-top: 2rem;
}

.question-link {
  display: grid;
  grid-template-columns: 62px minmax(0, 1fr) auto;
  gap: 1rem;
  align-items: center;
  padding: 1rem 1.1rem;
  background: rgba(249, 251, 252, 0.85);
  border: 1px solid var(--line);
  text-decoration: none;
}

.question-link:hover {
  background: white;
  border-color: var(--blueprint);
}

.question-link .q-number {
  color: var(--signal);
  font: 800 0.72rem/1 var(--mono);
}

.question-link .q-title {
  font-size: 0.88rem;
  line-height: 1.55;
}

.question-status {
  min-width: 68px;
  color: var(--muted);
  font-size: 0.68rem;
  text-align: right;
}

.question-status.done {
  color: var(--success);
}

.question-status.due {
  color: var(--warning);
}

.practice-shell {
  max-width: 900px;
  margin: 0 auto;
}

.practice-topline {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.4rem;
  color: var(--muted);
  font: 0.72rem/1 var(--mono);
}

.practice-card {
  background: var(--paper);
  border: 1px solid var(--line);
  box-shadow: 10px 10px 0 rgba(18, 59, 93, 0.12);
}

.question-face {
  padding: clamp(1.5rem, 4vw, 3.2rem);
  border-top: 6px solid var(--signal);
}

.question-type {
  display: inline-flex;
  padding: 0.35rem 0.55rem;
  color: var(--blueprint);
  background: #dceaf0;
  font: 700 0.68rem/1 var(--mono);
}

.question-face h1 {
  margin: 1.1rem 0 1.8rem;
  font: 700 clamp(1.7rem, 3.4vw, 3rem)/1.34 var(--display);
}

.answer-frame {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  margin: 0 0 1.5rem;
  background: var(--line);
  border: 1px solid var(--line);
}

.answer-frame span {
  padding: 0.8rem;
  color: var(--muted);
  background: var(--mist);
  font-size: 0.74rem;
  text-align: center;
}

.confidence-fieldset {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin: 1.2rem 0;
  padding: 0;
  border: 0;
}

.confidence-fieldset legend {
  float: left;
  margin-right: 0.5rem;
  color: var(--muted);
  font-size: 0.75rem;
}

.confidence-option {
  position: relative;
}

.confidence-option input {
  position: absolute;
  opacity: 0;
}

.confidence-option span {
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  color: var(--muted);
  background: white;
  border: 1px solid var(--line);
  cursor: pointer;
  font: 700 0.78rem/1 var(--mono);
}

.confidence-option input:checked + span {
  color: white;
  background: var(--blueprint);
  border-color: var(--blueprint);
}

.spoken-answer {
  width: 100%;
  min-height: 150px;
  padding: 1rem;
  color: var(--ink);
  background: white;
  border: 1px solid var(--line);
  resize: vertical;
  line-height: 1.75;
}

.spoken-answer:focus {
  border-color: var(--blueprint);
  outline: 2px solid rgba(18, 59, 93, 0.16);
}

.practice-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 1rem;
}

.answer-sheet {
  display: none;
  padding: clamp(1.5rem, 4vw, 3rem);
  background: #eef5f7;
  border-top: 1px solid var(--line);
}

.answer-sheet.revealed {
  display: block;
  animation: reveal 240ms ease-out;
}

.answer-sheet h2 {
  margin: 0 0 0.8rem;
  font: 700 1.45rem/1.3 var(--display);
}

.answer-copy {
  max-height: 55vh;
  overflow: auto;
  padding: 1.2rem;
  color: #273943;
  background: white;
  border-left: 4px solid var(--blueprint);
  font-size: 0.86rem;
  line-height: 1.85;
  white-space: pre-wrap;
}

.rating-area {
  margin-top: 1.5rem;
}

.rating-area > p {
  margin: 0 0 0.8rem;
  font-weight: 700;
}

.rating-buttons {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.65rem;
}

.rating-button {
  min-height: 54px;
  padding: 0.7rem;
  color: var(--ink);
  background: white;
  border: 1px solid var(--line);
}

.rating-button:hover {
  border-color: var(--blueprint);
}

.rating-button[data-rating="again"] {
  color: #a2352c;
}

.rating-button[data-rating="good"] {
  color: var(--success);
}

.practice-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 1.5rem;
}

.practice-nav a {
  color: var(--blueprint);
  font-size: 0.8rem;
}

.mock-intro {
  max-width: 760px;
  margin: 4vh auto 0;
}

.mock-intro h1 {
  margin: 0.5rem 0 1rem;
  font: 700 clamp(2.7rem, 6vw, 5.5rem)/1 var(--display);
}

.mock-intro > p {
  color: var(--muted);
  line-height: 1.8;
}

.mock-settings {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  margin: 2rem 0;
}

.mock-settings label {
  display: grid;
  gap: 0.5rem;
  color: var(--muted);
  font-size: 0.78rem;
}

.mock-settings select {
  min-height: 48px;
  padding: 0 0.8rem;
  color: var(--ink);
  background: white;
  border: 1px solid var(--line);
}

.search-dialog {
  width: min(760px, calc(100vw - 2rem));
  max-height: min(740px, calc(100vh - 2rem));
  padding: 0;
  background: var(--paper);
  border: 0;
  box-shadow: 0 30px 100px rgba(8, 34, 52, 0.35);
}

.search-dialog::backdrop {
  background: rgba(8, 34, 52, 0.72);
  backdrop-filter: blur(3px);
}

.dialog-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.1rem 1.25rem 0.6rem;
}

.dialog-head label {
  font: 700 1.1rem/1.3 var(--display);
}

.icon-button {
  width: 38px;
  height: 38px;
  color: var(--muted);
  background: transparent;
  font-size: 1.7rem;
}

#search-input {
  width: calc(100% - 2.5rem);
  margin: 0.4rem 1.25rem 1rem;
  padding: 0.9rem 1rem;
  color: var(--ink);
  background: white;
  border: 1px solid var(--line);
}

.search-results {
  max-height: 55vh;
  overflow: auto;
  border-top: 1px solid var(--line);
}

.search-result {
  display: block;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
}

.search-result:hover {
  background: var(--mist);
}

.search-result small {
  display: block;
  margin-bottom: 0.3rem;
  color: var(--signal);
}

.search-result strong {
  font-size: 0.86rem;
}

.toast {
  position: fixed;
  right: 1.25rem;
  bottom: 1.25rem;
  z-index: 80;
  max-width: 340px;
  padding: 0.9rem 1.1rem;
  color: white;
  background: var(--blueprint-deep);
  box-shadow: var(--shadow);
  opacity: 0;
  pointer-events: none;
  transform: translateY(12px);
  transition: 180ms ease;
}

.toast.show {
  opacity: 1;
  transform: none;
}

@keyframes pulse {
  50% { opacity: 0.25; transform: scale(0.75); }
}

@keyframes reveal {
  from { opacity: 0; transform: translateY(-8px); }
}

@media (max-width: 1180px) {
  .workspace {
    grid-template-columns: 230px minmax(0, 1fr);
  }

  .evidence-panel {
    display: none;
  }
}

@media (max-width: 820px) {
  .topbar {
    min-height: 68px;
    padding: 0 1rem;
  }

  .brand small,
  .text-button {
    display: none;
  }

  .workspace {
    display: block;
  }

  .rail {
    position: static;
    height: auto;
    padding: 0.7rem;
    overflow-x: auto;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .rail-heading {
    display: none;
  }

  .chapter-track {
    display: flex;
    width: max-content;
  }

  .chapter-track::before,
  .chapter-name,
  .chapter-meter,
  .chapter-row.active::after {
    display: none;
  }

  .chapter-row {
    display: block;
    width: auto;
    padding: 0.25rem;
  }

  main {
    padding: 2rem 1rem 4rem;
  }

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

  .hero h1 {
    font-size: clamp(2.5rem, 13vw, 4.5rem);
  }

  .brief-card {
    transform: none;
  }

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

  .section-heading {
    display: block;
  }

  .section-heading p {
    margin-top: 0.8rem;
  }

  .question-link {
    grid-template-columns: 50px minmax(0, 1fr);
  }

  .question-status {
    grid-column: 2;
    text-align: left;
  }

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

  .confidence-fieldset {
    flex-wrap: wrap;
  }

  .confidence-fieldset legend {
    width: 100%;
    margin-bottom: 0.5rem;
  }

  .rating-buttons,
  .mock-settings {
    grid-template-columns: 1fr;
  }

  .practice-actions {
    align-items: stretch;
    flex-direction: column;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}