/*! tailwindcss v4.2.1 | MIT License | https://tailwindcss.com */
@layer theme, base, components, utilities;
@layer theme {
  :root, :host {
    --font-sans: ui-sans-serif, system-ui, sans-serif, "Apple Color Emoji",
      "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono",
      "Courier New", monospace;
    --spacing: 0.25rem;
    --default-font-family: var(--font-sans);
    --default-mono-font-family: var(--font-mono);
  }
}
@layer base {
  *, ::after, ::before, ::backdrop, ::file-selector-button {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    border: 0 solid;
  }
  html, :host {
    line-height: 1.5;
    -webkit-text-size-adjust: 100%;
    tab-size: 4;
    font-family: var(--default-font-family, ui-sans-serif, system-ui, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji");
    font-feature-settings: var(--default-font-feature-settings, normal);
    font-variation-settings: var(--default-font-variation-settings, normal);
    -webkit-tap-highlight-color: transparent;
  }
  hr {
    height: 0;
    color: inherit;
    border-top-width: 1px;
  }
  abbr:where([title]) {
    -webkit-text-decoration: underline dotted;
    text-decoration: underline dotted;
  }
  h1, h2, h3, h4, h5, h6 {
    font-size: inherit;
    font-weight: inherit;
  }
  a {
    color: inherit;
    -webkit-text-decoration: inherit;
    text-decoration: inherit;
  }
  b, strong {
    font-weight: bolder;
  }
  code, kbd, samp, pre {
    font-family: var(--default-mono-font-family, ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace);
    font-feature-settings: var(--default-mono-font-feature-settings, normal);
    font-variation-settings: var(--default-mono-font-variation-settings, normal);
    font-size: 1em;
  }
  small {
    font-size: 80%;
  }
  sub, sup {
    font-size: 75%;
    line-height: 0;
    position: relative;
    vertical-align: baseline;
  }
  sub {
    bottom: -0.25em;
  }
  sup {
    top: -0.5em;
  }
  table {
    text-indent: 0;
    border-color: inherit;
    border-collapse: collapse;
  }
  :-moz-focusring {
    outline: auto;
  }
  progress {
    vertical-align: baseline;
  }
  summary {
    display: list-item;
  }
  ol, ul, menu {
    list-style: none;
  }
  img, svg, video, canvas, audio, iframe, embed, object {
    display: block;
    vertical-align: middle;
  }
  img, video {
    max-width: 100%;
    height: auto;
  }
  button, input, select, optgroup, textarea, ::file-selector-button {
    font: inherit;
    font-feature-settings: inherit;
    font-variation-settings: inherit;
    letter-spacing: inherit;
    color: inherit;
    border-radius: 0;
    background-color: transparent;
    opacity: 1;
  }
  :where(select:is([multiple], [size])) optgroup {
    font-weight: bolder;
  }
  :where(select:is([multiple], [size])) optgroup option {
    padding-inline-start: 20px;
  }
  ::file-selector-button {
    margin-inline-end: 4px;
  }
  ::placeholder {
    opacity: 1;
  }
  @supports (not (-webkit-appearance: -apple-pay-button))  or (contain-intrinsic-size: 1px) {
    ::placeholder {
      color: currentcolor;
      @supports (color: color-mix(in lab, red, red)) {
        color: color-mix(in oklab, currentcolor 50%, transparent);
      }
    }
  }
  textarea {
    resize: vertical;
  }
  ::-webkit-search-decoration {
    -webkit-appearance: none;
  }
  ::-webkit-date-and-time-value {
    min-height: 1lh;
    text-align: inherit;
  }
  ::-webkit-datetime-edit {
    display: inline-flex;
  }
  ::-webkit-datetime-edit-fields-wrapper {
    padding: 0;
  }
  ::-webkit-datetime-edit, ::-webkit-datetime-edit-year-field, ::-webkit-datetime-edit-month-field, ::-webkit-datetime-edit-day-field, ::-webkit-datetime-edit-hour-field, ::-webkit-datetime-edit-minute-field, ::-webkit-datetime-edit-second-field, ::-webkit-datetime-edit-millisecond-field, ::-webkit-datetime-edit-meridiem-field {
    padding-block: 0;
  }
  ::-webkit-calendar-picker-indicator {
    line-height: 1;
  }
  :-moz-ui-invalid {
    box-shadow: none;
  }
  button, input:where([type="button"], [type="reset"], [type="submit"]), ::file-selector-button {
    appearance: button;
  }
  ::-webkit-inner-spin-button, ::-webkit-outer-spin-button {
    height: auto;
  }
  [hidden]:where(:not([hidden="until-found"])) {
    display: none !important;
  }
}
@layer utilities {
  .start {
    inset-inline-start: var(--spacing);
  }
  .end {
    inset-inline-end: var(--spacing);
  }
  .block {
    display: block;
  }
}
:root {
  --ink: #152338;
  --muted: #66758b;
  --line: #e3e9f1;
  --paper: #ffffff;
  --canvas: #eef2f7;
  --blue: #1e5bbd;
  --blue-deep: #16499a;
  --blue-soft: #ebf2ff;
  --green: #1f7a58;
  --gold: #f0b429;
  --nav: #102038;
  --nav-2: #173150;
  --danger: #b14d43;
  --shadow: 0 14px 40px rgba(16, 32, 56, .08);
  --shadow-soft: 0 8px 24px rgba(16, 32, 56, .05);
  --radius: 18px;
  --safe-top: env(safe-area-inset-top, 0px);
  --safe-right: env(safe-area-inset-right, 0px);
  --safe-bottom: env(safe-area-inset-bottom, 0px);
  --safe-left: env(safe-area-inset-left, 0px);
  --mobile-nav: 0px;
}
* {
  box-sizing: border-box;
}
html {
  text-size-adjust: 100%;
  -webkit-text-size-adjust: 100%;
  scrollbar-width: thin;
  scrollbar-color: #a8b8cf transparent;
}
html::-webkit-scrollbar {
  width: 10px;
}
html::-webkit-scrollbar-thumb {
  background: #b3c1d6;
  border-radius: 99px;
  border: 2px solid transparent;
  background-clip: content-box;
}
html::-webkit-scrollbar-track {
  background: transparent;
}
::selection {
  background: rgba(240, 180, 41, .35);
}
html, body {
  min-height: 100%;
  min-height: 100dvh;
}
body {
  margin: 0;
  background: radial-gradient(1200px 420px at 12% -8%, #dce7f7 0%, transparent 58%),
    radial-gradient(900px 380px at 110% 0%, #e7eef8 0%, transparent 52%),
    var(--canvas);
  color: var(--ink);
  font-family: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", system-ui, sans-serif;
  line-height: 1.55;
  text-rendering: optimizeLegibility;
}
button, textarea, input {
  font: inherit;
}
button {
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}
:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 2px;
}
.visually-hidden {
  position: fixed;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
}
.study-shell {
  min-height: 100vh;
  min-height: 100dvh;
  display: grid;
  grid-template-columns: 288px minmax(0, 1fr);
  padding-left: var(--safe-left);
}
.study-sidebar {
  position: sticky;
  top: 0;
  z-index: 20;
  align-self: start;
  height: 100vh;
  height: 100dvh;
  overflow: auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
  scrollbar-color: rgba(255, 255, 255, .30) transparent;
  padding: calc(28px + var(--safe-top)) 22px 24px;
  background: linear-gradient(180deg, rgba(240, 180, 41, .08), transparent 28%),
    linear-gradient(180deg, var(--nav-2), var(--nav));
  color: white;
  box-shadow: inset -1px 0 0 rgba(255,255,255,.04);
}
.study-sidebar::-webkit-scrollbar {
  width: 8px;
}
.study-sidebar::-webkit-scrollbar-thumb {
  background: rgba(255,255,255,.28);
  border-radius: 99px;
}
.study-sidebar::-webkit-scrollbar-track {
  background: transparent;
}
.brand-row {
  display: flex;
  align-items: center;
  gap: 12px;
}
.brand-mark {
  width: 44px;
  height: 44px;
  flex: 0 0 44px;
  display: grid;
  place-items: center;
  border-radius: 14px;
  background: linear-gradient(180deg, #ffd36a, var(--gold));
  color: var(--nav);
  font-weight: 900;
  font-size: 20px;
  box-shadow: 0 8px 18px rgba(240, 180, 41, .28);
}
.eyebrow {
  margin: 0 0 6px;
  color: #93a6c0;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .14em;
}
.study-sidebar h1 {
  margin: 0;
  font-size: 22px;
  letter-spacing: .02em;
}
.study-sidebar nav {
  display: grid;
  gap: 6px;
  margin: 36px 0 28px;
}
.nav-item {
  display: grid;
  grid-template-columns: 30px 1fr auto;
  align-items: center;
  gap: 8px;
  width: 100%;
  min-height: 46px;
  border: 0;
  border-radius: 13px;
  padding: 10px 12px;
  background: transparent;
  color: #c5d0de;
  text-align: left;
  cursor: pointer;
  transition: background .16s ease, color .16s ease, transform .16s ease;
}
.nav-item:hover {
  background: rgba(255,255,255,.06);
  color: white;
}
.nav-item.active {
  background: rgba(255,255,255,.12);
  color: white;
  box-shadow: inset 0 0 0 1px rgba(240,180,41,.18);
}
.nav-item b {
  min-width: 22px;
  color: var(--gold);
  text-align: right;
}
.nav-icon {
  width: 26px;
  height: 26px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: rgba(255,255,255,.08);
  color: var(--gold);
  font-size: 12px;
  font-weight: 900;
}
.chapter-card {
  display: grid;
  gap: 5px;
  border: 1px solid rgba(255,255,255,.1);
  border-radius: 16px;
  padding: 16px;
  background: rgba(255,255,255,.05);
}
.chapter-card p, .chapter-card span {
  margin: 0;
  color: #a8b7ca;
  font-size: 13px;
}
.chapter-card strong {
  font-size: 20px;
}
.chapter-card em {
  margin-top: 5px;
  color: #f5c66d;
  font-size: 12px;
  font-style: normal;
}
.sidebar-note {
  margin: 16px 3px 0;
  color: #8293aa;
  font-size: 12px;
  line-height: 1.7;
}
.free-use-note {
  margin: 16px 3px 0;
  padding: 12px 13px;
  border: 1px solid rgba(246, 193, 119, .32);
  border-radius: 12px;
  color: #f6d49e;
  background: rgba(246, 193, 119, .08);
  font-size: 12px;
  line-height: 1.7;
}
.free-use-note a {
  color: #ffe3b7;
  text-decoration: underline;
  text-underline-offset: 2px;
  word-break: break-word;
}
.study-content {
  width: min(980px, calc(100% - 48px));
  margin: 0 auto;
  padding: 42px 0 calc(36px + var(--mobile-nav) + var(--safe-bottom));
  padding-right: var(--safe-right);
}
.topbar {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 18px;
}
.topbar h2 {
  margin: 0;
  font-size: 28px;
  letter-spacing: -.02em;
  line-height: 1.25;
}
.progress-copy {
  color: var(--muted);
  font-size: 16px;
}
.progress-copy strong {
  color: var(--blue);
  font-size: 28px;
}
.progress-copy small {
  display: block;
  margin-top: 3px;
  font-size: 11px;
  text-align: right;
}
.question-topbar {
  align-items: flex-start;
}
.back-link {
  margin: 0 0 14px;
  border: 0;
  padding: 0;
  background: transparent;
  color: var(--blue);
  cursor: pointer;
  font-weight: 700;
}
.autosave-label {
  display: inline-flex;
  margin-top: 10px;
  border-radius: 999px;
  padding: 6px 11px;
  background: #eaf6f0;
  color: var(--green);
  font-size: 12px;
  font-weight: 700;
}
.chapter-total {
  display: flex;
  align-items: baseline;
  gap: 7px;
  color: var(--muted);
}
.chapter-total strong {
  color: var(--blue);
  font-size: 32px;
}
.chapter-total span {
  font-size: 13px;
}
.progress-track {
  height: 8px;
  overflow: hidden;
  margin: 20px 0 26px;
  border-radius: 999px;
  background: #dfe4ec;
}
.progress-track span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--blue), #4d86e6);
  border-radius: inherit;
}
.question-picker {
  margin: -8px 0 20px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: rgba(255,255,255,.86);
  overflow: hidden;
  backdrop-filter: blur(10px);
}
.question-picker-toggle {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 46px;
  border: 0;
  padding: 13px 16px;
  background: white;
  color: var(--blue);
  cursor: pointer;
  text-align: left;
  font-weight: 800;
}
.question-picker-toggle:hover {
  background: var(--blue-soft);
}
.question-picker-toggle b {
  width: 26px;
  height: 26px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: var(--blue-soft);
  font-size: 19px;
}
.question-picker-panel {
  border-top: 1px solid var(--line);
  padding: 15px 16px 18px;
}
.question-picker-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 13px;
  color: var(--muted);
  font-size: 12px;
}
.question-picker-legend span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.question-picker-legend span::before {
  content: "";
  width: 10px;
  height: 10px;
  border-radius: 3px;
  background: #edf0f4;
}
.question-picker-legend .legend-current::before {
  background: var(--blue);
}
.question-picker-legend .legend-done::before {
  background: #83bea3;
}
.question-picker-legend .legend-wrong::before {
  background: #cf756b;
}
.question-picker-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(42px, 1fr));
  gap: 7px;
}
.question-picker-item {
  min-height: 40px;
  border: 1px solid #dfe4eb;
  border-radius: 10px;
  padding: 5px 3px;
  background: white;
  color: #536178;
  cursor: pointer;
  font-size: 12px;
  font-weight: 800;
}
.question-picker-item:hover {
  border-color: #8aa9e6;
  color: var(--blue);
}
.question-picker-item.done {
  border-color: #a9d2bf;
  background: #eff8f4;
  color: var(--green);
}
.question-picker-item.marked-wrong {
  border-color: #e2aaa4;
  background: #fff1ef;
  color: #a8463d;
}
.question-picker-item.current {
  border-color: var(--blue);
  background: var(--blue);
  color: white;
  box-shadow: 0 0 0 2px rgba(30,91,189,.16);
}
.question-card {
  border: 1px solid var(--line);
  border-radius: 22px;
  padding: 30px;
  background: var(--paper);
  box-shadow: var(--shadow);
  contain: layout style;
  scroll-margin-top: 16px;
}
.question-meta {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
}
.question-meta > div:first-child {
  display: grid;
  gap: 5px;
}
.question-number {
  color: var(--blue);
  font-weight: 800;
}
.chapter-order {
  color: var(--muted);
}
.question-type {
  border-radius: 999px;
  padding: 6px 11px;
  background: var(--blue-soft);
  color: var(--blue);
  font-size: 13px;
}
.meta-tags {
  display: flex;
  gap: 7px;
}
.meta-tags span {
  border-radius: 999px;
  padding: 6px 11px;
  background: var(--blue-soft);
  color: var(--blue);
  font-size: 13px;
}
.question-card h3 {
  margin: 26px 0 22px;
  font-size: 22px;
  line-height: 1.65;
  font-weight: 750;
}
.option-list {
  display: grid;
  gap: 10px;
}
.option {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  width: 100%;
  min-height: 52px;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 12px 14px;
  background: white;
  color: var(--ink);
  text-align: left;
  cursor: pointer;
  transition: border-color .08s ease, background .08s ease;
}
.option-content {
  flex: 1;
  min-width: 0;
}
.option:hover {
  border-color: #9bb7ee;
  background: #f8fbff;
}
.option .option-letter {
  width: 30px;
  height: 30px;
  flex: 0 0 30px;
  display: grid;
  place-items: center;
  margin-top: 1px;
  border-radius: 9px;
  background: #eef1f5;
  font-weight: 800;
}
.option.selected {
  border-color: var(--blue);
  background: #f2f6ff;
  box-shadow: 0 0 0 2px rgba(30,91,189,.08);
}
.option.selected .option-letter {
  background: var(--blue);
  color: white;
}
.option.correct {
  border-color: #5aaa87;
  background: #eff9f4;
}
.option.correct .option-letter {
  background: var(--green);
  color: white;
}
.option.wrong {
  border-color: #dc7a72;
  background: #fff5f4;
}
.option.wrong .option-letter {
  background: #b5463e;
  color: white;
}
.formula-text {
  white-space: pre-wrap;
}
.formula-script {
  position: relative;
  font-family: "Cambria Math", "STIX Two Math", "Times New Roman", serif;
  font-size: .72em;
  line-height: 0;
  vertical-align: baseline;
}
sub.formula-script {
  bottom: -.24em;
}
sup.formula-script {
  top: -.48em;
}
.question-actions {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 26px;
}
.ghost-button, .primary-button {
  min-height: 44px;
  border-radius: 12px;
  padding: 11px 20px;
  cursor: pointer;
  transition: transform .12s ease, box-shadow .16s ease, background .16s ease, border-color .16s ease;
}
.ghost-button {
  border: 1px solid var(--line);
  background: white;
  color: var(--ink);
}
.ghost-button:hover:not(:disabled) {
  border-color: #b7c6db;
  background: #f7f9fc;
}
.primary-button {
  border: 1px solid var(--blue);
  background: linear-gradient(180deg, #2b6fd0, var(--blue));
  color: white;
  font-weight: 700;
  box-shadow: 0 8px 18px rgba(30, 91, 189, .18);
}
.primary-button:hover:not(:disabled) {
  background: var(--blue-deep);
}
.ghost-button:disabled, .primary-button:disabled {
  cursor: not-allowed;
  opacity: .45;
  box-shadow: none;
}
.action-right {
  display: flex;
  gap: 10px;
}
.privacy-note {
  margin: 18px 4px 0;
  color: var(--muted);
  font-size: 13px;
}
.instruction-strip {
  display: flex;
  align-items: center;
  gap: 14px;
  margin: 22px 0 20px;
  border: 1px solid #d8e3f7;
  border-radius: 15px;
  padding: 14px 16px;
  background: linear-gradient(180deg, #f5f8ff, var(--blue-soft));
  color: #52627c;
}
.instruction-strip strong {
  flex: 0 0 auto;
  color: var(--blue);
}
.instruction-strip span {
  line-height: 1.6;
}
.filter-panel {
  display: grid;
  gap: 12px;
  margin: 26px 0 20px;
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 15px 18px;
  background: rgba(255,255,255,.75);
}
.filter-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}
.filter-row > span {
  width: 46px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
}
.filter-chip {
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 7px 12px;
  background: transparent;
  color: #536178;
  cursor: pointer;
  font-size: 13px;
}
.filter-chip:hover {
  background: #edf1f6;
}
.filter-chip.active {
  border-color: #c7d7f5;
  background: var(--blue-soft);
  color: var(--blue);
  font-weight: 800;
}
.chapter-select-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 14px;
}
.chapter-select-card {
  min-height: 172px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 10px;
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 18px;
  background: white;
  color: var(--ink);
  text-align: left;
  cursor: pointer;
  box-shadow: var(--shadow-soft);
  transition: transform .16s ease, border-color .16s ease, box-shadow .16s ease;
}
.chapter-select-card:hover:not(:disabled) {
  transform: translateY(-2px);
  border-color: #9eb9eb;
  box-shadow: 0 16px 32px rgba(30,91,189,.1);
}
.chapter-select-card:disabled {
  cursor: not-allowed;
  opacity: .48;
  box-shadow: none;
}
.chapter-select-card strong {
  min-height: 44px;
  font-size: 17px;
  line-height: 1.45;
}
.chapter-select-card > div {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.chapter-select-card > div span {
  border-radius: 999px;
  padding: 5px 9px;
  background: #f0f3f7;
  color: #647187;
  font-size: 12px;
}
.chapter-select-card small {
  margin-top: auto;
  color: var(--blue);
  font-weight: 700;
  line-height: 1.5;
}
.chapter-select-card:disabled small {
  color: var(--muted);
}
.chapter-index {
  color: var(--blue);
  font-size: 12px;
  font-weight: 900;
  letter-spacing: .04em;
}
.type-select-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 14px;
}
.type-select-card {
  display: grid;
  grid-template-columns: 52px 1fr;
  gap: 8px 14px;
  align-items: center;
  min-height: 118px;
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 18px;
  background: white;
  color: var(--ink);
  text-align: left;
  cursor: pointer;
  box-shadow: var(--shadow-soft);
}
.type-select-card:hover:not(:disabled) {
  border-color: #9eb9eb;
  box-shadow: 0 12px 30px rgba(30,91,189,.08);
}
.type-select-card:disabled {
  cursor: not-allowed;
  opacity: .48;
}
.type-icon {
  grid-row: 1 / 3;
  width: 52px;
  height: 52px;
  display: grid;
  place-items: center;
  border-radius: 15px;
  background: var(--blue-soft);
  color: var(--blue);
  font-size: 22px;
  font-weight: 900;
}
.type-select-card > div {
  display: grid;
  gap: 4px;
}
.type-select-card strong {
  font-size: 18px;
}
.type-select-card > div span {
  color: var(--muted);
  font-size: 13px;
}
.type-select-card small {
  grid-column: 2;
  color: var(--blue);
  font-weight: 700;
}
.type-select-card:disabled small {
  color: var(--muted);
}
.selection-topbar {
  align-items: flex-end;
}
.segment-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 14px;
}
.segment-card {
  display: grid;
  gap: 14px;
  border: 1px solid var(--line);
  border-radius: 17px;
  padding: 18px;
  background: white;
  color: var(--ink);
  text-align: left;
  cursor: pointer;
  box-shadow: var(--shadow-soft);
}
.segment-card:hover:not(:disabled) {
  border-color: #9eb9eb;
  box-shadow: 0 12px 30px rgba(30,91,189,.08);
}
.segment-card:disabled {
  cursor: not-allowed;
  opacity: .48;
}
.segment-card > div:first-child {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
}
.segment-card > div:first-child span {
  color: var(--blue);
  font-weight: 900;
}
.segment-card > div:first-child b {
  color: #3d4c64;
}
.segment-card small {
  color: var(--muted);
  line-height: 1.5;
}
.segment-track {
  height: 7px;
  overflow: hidden;
  border-radius: 99px;
  background: #e8ecf2;
}
.segment-track span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: var(--blue);
}
.wrong-chapter-card {
  min-height: 160px;
}
.wrong-count {
  align-items: baseline;
}
.chapter-select-card .wrong-count b {
  color: var(--danger);
  font-size: 26px;
}
.chapter-select-card .wrong-count span {
  padding: 0;
  background: transparent;
}
.sync-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 9px;
}
.sync-strip {
  justify-content: space-between;
}
.sync-strip > div {
  display: flex;
  align-items: center;
  gap: 14px;
}
.sync-strip > div span {
  line-height: 1.6;
}
.sync-strip > b {
  flex: 0 0 auto;
  color: var(--danger);
}
.sync-notice {
  margin: -8px 0 20px;
  border: 1px solid #c9deef;
  border-radius: 12px;
  padding: 11px 14px;
  background: #f2f8fc;
  color: #36597a;
  font-size: 13px;
  line-height: 1.6;
}
.sync-code-card {
  display: grid;
  gap: 14px;
  margin: 20px 0 24px;
  border: 1px solid #cbd9ee;
  border-radius: 17px;
  padding: 18px;
  background: #f8fbff;
}
.sync-code-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.sync-code-heading > div {
  display: grid;
  gap: 5px;
}
.sync-code-heading strong {
  color: var(--blue);
}
.sync-code-heading small {
  color: var(--muted);
  line-height: 1.6;
}
.sync-code-area {
  width: 100%;
  min-height: 100px;
  resize: vertical;
  border: 1px solid #cdd8e7;
  border-radius: 12px;
  padding: 12px;
  background: white;
  color: #31415a;
  font: 12px/1.6 ui-monospace, SFMono-Regular, Consolas, monospace;
  outline: none;
}
.sync-code-area:focus {
  border-color: #8aa9e6;
  box-shadow: 0 0 0 3px rgba(30,91,189,.08);
}
.sync-code-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}
.sync-code-actions span {
  color: var(--muted);
  font-size: 12px;
}
.exam-builder-card {
  display: grid;
  gap: 22px;
  margin-top: 24px;
  border: 1px solid var(--line);
  border-radius: 20px;
  padding: 22px;
  background: white;
  box-shadow: var(--shadow-soft);
}
.exam-builder-section {
  display: grid;
  gap: 13px;
}
.exam-section-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
}
.exam-section-heading strong {
  color: #30415b;
  font-size: 16px;
}
.exam-chip-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
}
.exam-chip {
  border: 1px solid #d7dee8;
  border-radius: 11px;
  padding: 10px 13px;
  background: #fafbfd;
  color: #536178;
  cursor: pointer;
  font-size: 13px;
}
.exam-chip:hover {
  border-color: #9eb9eb;
  background: #f5f8ff;
}
.exam-chip.active {
  border-color: #9eb9eb;
  background: var(--blue-soft);
  color: var(--blue);
  font-weight: 800;
}
.exam-blueprint {
  display: grid;
  gap: 10px;
  border: 1px solid #e0e7f1;
  border-radius: 14px;
  padding: 16px;
  background: #fbfcfe;
}
.exam-blueprint > div {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.exam-blueprint span {
  border-radius: 999px;
  padding: 6px 10px;
  background: #edf2f9;
  color: #536178;
  font-size: 12px;
}
.exam-blueprint small {
  color: var(--muted);
  line-height: 1.6;
}
.exam-create-button {
  justify-self: start;
  min-width: 190px;
}
.exam-record-list {
  display: grid;
  gap: 14px;
  margin-top: 26px;
}
.exam-record-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  border: 1px solid var(--line);
  border-radius: 17px;
  padding: 18px;
  background: white;
  box-shadow: var(--shadow-soft);
}
.exam-record-main {
  display: grid;
  gap: 7px;
  min-width: 0;
}
.exam-record-main h3 {
  margin: 0;
  font-size: 18px;
}
.exam-record-main p {
  margin: 0;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.6;
}
.exam-record-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}
.exam-record-tags span {
  border-radius: 999px;
  padding: 5px 9px;
  background: #eef2f7;
  color: #5e6c80;
  font-size: 12px;
}
.exam-record-tags .danger-tag {
  background: #fff0ed;
  color: var(--danger);
}
.exam-record-tags .good-tag {
  background: #edf8f2;
  color: var(--green);
}
.exam-record-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 8px;
  flex: 0 0 auto;
}
.subparts {
  margin: -6px 0 24px 24px;
  padding: 0;
  color: #33425a;
  line-height: 1.8;
}
.hint {
  margin: 2px 2px 0;
  color: var(--muted);
  font-size: 12px;
}
.draft-area {
  display: grid;
  gap: 9px;
}
.draft-area label {
  color: #536178;
  font-size: 14px;
  font-weight: 700;
}
.draft-area textarea {
  min-height: 132px;
  resize: vertical;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 15px;
  background: #fafbfd;
  color: var(--ink);
  font: inherit;
  line-height: 1.65;
  outline: none;
}
.draft-area textarea:focus {
  border-color: #8aa9e6;
  box-shadow: 0 0 0 3px rgba(30,91,189,.08);
}
.inline-notice {
  margin: 16px 0 0;
  color: #ad4a42;
  font-size: 14px;
}
.image-gallery {
  display: grid;
  gap: 18px;
  margin: 24px 0;
}
.image-gallery figure {
  margin: 0;
  text-align: center;
}
.image-button {
  display: inline-flex;
  max-width: 100%;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 10px;
  background: white;
  cursor: zoom-in;
}
.image-button img {
  display: block;
  width: auto;
  max-width: 100%;
  max-height: min(440px, 58vh);
  object-fit: contain;
}
.image-gallery figcaption {
  margin-top: 7px;
  color: var(--muted);
  font-size: 12px;
}
.answer-panel {
  margin-top: 24px;
  border: 1px solid #d9e3ed;
  border-radius: 17px;
  padding: 20px;
  background: #f7fafc;
}
.answer-panel.answer-good {
  border-color: #bddfce;
  background: #f0f8f4;
}
.answer-panel.answer-review {
  border-color: #efd1cd;
  background: #fff8f7;
}
.answer-heading {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
}
.answer-heading > div {
  display: grid;
  gap: 3px;
}
.answer-kicker {
  color: var(--green);
  font-size: 12px;
  font-weight: 900;
  letter-spacing: .08em;
}
.answer-heading strong {
  font-size: 20px;
}
.answer-panel > p {
  margin: 15px 0 0;
  line-height: 1.8;
}
.correct-answer-content strong {
  margin-right: 6px;
  color: var(--green);
}
.link-button {
  border: 0;
  background: transparent;
  color: var(--blue);
  cursor: pointer;
}
.self-grade {
  display: grid;
  gap: 10px;
  margin-top: 18px;
  border-top: 1px solid rgba(23,36,59,.1);
  padding-top: 18px;
}
.self-grade > span {
  font-weight: 700;
}
.self-grade > div {
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
}
.self-grade button {
  min-height: 40px;
  border: 1px solid #ced7e3;
  border-radius: 10px;
  padding: 9px 16px;
  background: white;
  cursor: pointer;
}
.self-grade button:hover, .self-grade button.chosen {
  border-color: var(--blue);
  background: var(--blue-soft);
  color: var(--blue);
}
.self-grade button:disabled:not(.chosen) {
  opacity: .45;
  cursor: not-allowed;
}
.self-grade small {
  color: var(--muted);
}
.empty-state {
  margin-top: 30px;
  border: 1px dashed #cad3df;
  border-radius: 22px;
  padding: 64px 24px;
  background: white;
  text-align: center;
}
.empty-state > div {
  width: 58px;
  height: 58px;
  display: grid;
  place-items: center;
  margin: 0 auto 18px;
  border-radius: 50%;
  background: #edf8f2;
  color: var(--green);
  font-size: 28px;
}
.empty-state h3 {
  margin: 0;
  font-size: 22px;
}
.empty-state p {
  max-width: 540px;
  margin: 12px auto 24px;
  color: var(--muted);
  line-height: 1.7;
}
.stat-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
  margin-top: 26px;
}
.stat-card {
  display: grid;
  gap: 7px;
  border: 1px solid var(--line);
  border-radius: 17px;
  padding: 20px;
  background: white;
  box-shadow: var(--shadow-soft);
}
.stat-card span {
  color: var(--muted);
  font-size: 13px;
}
.stat-card strong {
  color: var(--blue);
  font-size: 32px;
}
.stat-card small {
  color: #8b96a8;
}
.stat-card.warning strong {
  color: var(--danger);
}
.settings-card {
  margin-top: 26px;
  border: 1px solid var(--line);
  border-radius: 17px;
  padding: 22px;
  background: white;
  box-shadow: var(--shadow-soft);
}
.settings-heading {
  display: grid;
  gap: 5px;
  margin-bottom: 16px;
}
.settings-heading strong {
  color: var(--ink);
  font-size: 17px;
}
.settings-heading span {
  color: var(--muted);
  font-size: 13px;
  line-height: 1.6;
}
.setting-list {
  display: grid;
  gap: 12px;
}
.setting-row {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 24px;
  padding: 17px 18px;
  border: 1px solid #e3e9f1;
  border-radius: 14px;
  background: #f8fafc;
  cursor: pointer;
  transition: border-color .2s ease, background .2s ease;
}
.setting-row:hover {
  border-color: #b9cbe0;
  background: #f4f8fc;
}
.danger-button {
  border-color: #e7b7ad;
  color: #a84d40;
  background: #fffafa;
}
.danger-button:hover {
  border-color: #c97969;
  background: #fff0ed;
}
.setting-row span {
  display: grid;
  min-width: 0;
  gap: 7px;
}
.setting-row strong {
  font-size: 15px;
}
.setting-row small {
  max-width: 680px;
  color: var(--muted);
  line-height: 1.65;
}
.setting-row input {
  width: 24px;
  height: 24px;
  flex: 0 0 auto;
  margin-top: 1px;
  accent-color: var(--blue);
}
.chapter-progress-card {
  margin-top: 20px;
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 22px;
  background: white;
  box-shadow: var(--shadow-soft);
}
.chapter-progress-card h3 {
  margin: 0 0 20px;
}
.chapter-progress-row {
  display: grid;
  grid-template-columns: minmax(140px, 230px) 1fr minmax(120px, 165px);
  align-items: center;
  gap: 18px;
  padding: 14px 0;
  border-top: 1px solid #edf0f4;
}
.chapter-progress-row:first-of-type {
  border-top: 0;
}
.chapter-progress-row > div:first-child {
  display: grid;
  gap: 3px;
}
.chapter-progress-row span {
  color: var(--muted);
  font-size: 13px;
}
.chapter-progress-row b {
  text-align: right;
}
.mini-track {
  height: 8px;
  overflow: hidden;
  border-radius: 99px;
  background: #e8ecf2;
}
.mini-track span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: var(--blue);
}
.image-modal {
  position: fixed;
  inset: 0;
  z-index: 50;
  display: grid;
  place-items: center;
  padding: 30px;
  background: rgba(8,18,34,.86);
  cursor: zoom-out;
}
.image-modal img {
  max-width: min(1100px, 94vw);
  max-height: 88vh;
  border-radius: 10px;
  background: white;
  object-fit: contain;
}
.image-modal button {
  position: fixed;
  top: calc(16px + var(--safe-top));
  right: calc(18px + var(--safe-right));
  width: 42px;
  height: 42px;
  border: 1px solid rgba(255,255,255,.35);
  border-radius: 50%;
  background: rgba(255,255,255,.12);
  color: white;
  font-size: 27px;
  cursor: pointer;
}
.mobile-nav {
  display: none;
}
@media (max-width: 1100px) {
  .study-shell {
    grid-template-columns: 250px minmax(0, 1fr);
  }
  .study-content {
    width: min(100% - 36px, 980px);
  }
  .stat-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}
@media (max-width: 860px) {
  :root {
    --mobile-nav: 64px;
  }
  .study-shell {
    grid-template-columns: 1fr;
    padding-left: 0;
  }
  .study-sidebar {
    position: sticky;
    top: 0;
    z-index: 40;
    height: auto;
    min-height: 0;
    overflow: visible;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: calc(10px + var(--safe-top)) 16px 12px;
    box-shadow: 0 8px 24px rgba(10, 22, 40, .18);
  }
  .study-sidebar nav,
  .chapter-card,
  .sidebar-note,
  .free-use-note {
    display: none;
  }
  .study-sidebar h1 {
    font-size: 17px;
  }
  .eyebrow {
    margin-bottom: 2px;
    font-size: 9px;
  }
  .brand-mark {
    width: 36px;
    height: 36px;
    flex-basis: 36px;
    font-size: 16px;
    border-radius: 11px;
  }
  .study-content {
    width: min(100% - 28px, 980px);
    padding-top: 22px;
  }
  .question-card {
    scroll-margin-top: calc(72px + var(--safe-top));
  }
  .topbar h2 {
    font-size: 22px;
  }
  .question-card {
    padding: 20px 16px;
    border-radius: 18px;
  }
  .question-card h3 {
    font-size: 18px;
  }
  .filter-row > span {
    width: 100%;
  }
  .instruction-strip {
    align-items: flex-start;
  }
  .chapter-progress-row {
    grid-template-columns: 1fr auto;
  }
  .chapter-progress-row .mini-track {
    grid-column: 1 / -1;
    grid-row: 2;
  }
  .question-meta {
    align-items: flex-start;
  }
  .meta-tags {
    flex-wrap: wrap;
    justify-content: flex-end;
  }
  .sync-strip > div {
    align-items: flex-start;
  }
  .sync-code-heading {
    align-items: flex-start;
    flex-direction: column;
  }
  .exam-record-card {
    align-items: flex-start;
    flex-direction: column;
  }
  .exam-record-actions {
    justify-content: flex-start;
  }
  .exam-create-button {
    width: 100%;
    justify-self: stretch;
  }
  .mobile-nav {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 45;
    display: grid;
    grid-template-columns: repeat(6, minmax(0, 1fr));
    gap: 2px;
    padding: 6px 6px calc(6px + var(--safe-bottom));
    border-top: 1px solid #dce2ea;
    background: rgba(255,255,255,.96);
    box-shadow: 0 -8px 24px rgba(16, 32, 56, .08);
    backdrop-filter: blur(16px);
  }
  .mobile-nav .nav-item {
    grid-template-columns: 1fr;
    justify-items: center;
    min-height: 52px;
    gap: 3px;
    padding: 6px 2px;
    color: #6d7b8e;
    font-size: 10px;
    line-height: 1.2;
    text-align: center;
  }
  .mobile-nav .nav-item b {
    display: none;
  }
  .mobile-nav .nav-icon {
    background: #eef1f5;
    color: #6d7b8e;
  }
  .mobile-nav .nav-item.active {
    background: var(--blue-soft);
    color: var(--blue);
  }
  .mobile-nav .nav-item.active .nav-icon {
    background: white;
    color: var(--blue);
  }
}
@media (max-width: 560px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
  }
  .progress-copy {
    font-size: 14px;
  }
  .progress-copy strong {
    font-size: 22px;
  }
  .question-actions, .action-right {
    align-items: stretch;
  }
  .question-actions {
    flex-wrap: wrap;
  }
  .ghost-button, .primary-button {
    flex: 1 1 auto;
    padding: 11px 14px;
  }
  .instruction-strip {
    display: grid;
  }
  .chapter-total {
    display: none;
  }
  .stat-grid {
    grid-template-columns: 1fr;
  }
  .setting-row {
    gap: 14px;
    padding: 15px;
  }
  .sync-topbar {
    display: grid;
  }
  .sync-actions {
    justify-content: flex-start;
  }
  .sync-strip {
    align-items: flex-start;
  }
  .sync-strip > div {
    display: grid;
    gap: 6px;
  }
  .mobile-nav {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  :root {
    --mobile-nav: 112px;
  }
}
@media (max-width: 380px) {
  .brand-row {
    gap: 8px;
  }
  .study-content {
    width: calc(100% - 20px);
  }
  .chapter-select-card, .question-card {
    padding: 16px 13px;
  }
}
@media (hover: none) {
  .chapter-select-card:hover:not(:disabled),
  .type-select-card:hover:not(:disabled),
  .segment-card:hover:not(:disabled) {
    transform: none;
    box-shadow: var(--shadow-soft);
  }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation: none !important;
    transition: none !important;
  }
}
.home-shell {
  min-height: 100vh;
  min-height: 100dvh;
  max-width: 1020px;
  margin: 0 auto;
  padding: 56px 28px 44px;
}
.home-hero .brand-row {
  gap: 16px;
}
.home-mark {
  width: 54px;
  height: 54px;
  flex-basis: 54px;
  font-size: 26px;
  border-radius: 17px;
}
.home-hero h1 {
  margin: 0;
  font-size: 30px;
  letter-spacing: .02em;
  color: var(--ink);
}
.home-sub {
  color: var(--muted);
  margin: 16px 0 36px;
  font-size: 15px;
  max-width: 640px;
}
.home-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 22px;
}
.subject-card {
  position: relative;
  display: grid;
  gap: 14px;
  height: 100%;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: var(--paper);
  box-shadow: var(--shadow-soft);
  padding: 28px;
  text-decoration: none;
  color: var(--ink);
  transition: transform .16s ease, box-shadow .16s ease, border-color .16s ease;
}
.subject-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
  border-color: #c9d8f0;
}
.subject-last-badge {
  position: absolute;
  top: 20px;
  right: 20px;
  background: var(--gold);
  color: var(--nav);
  font-size: 11px;
  font-weight: 900;
  padding: 4px 11px;
  border-radius: 99px;
}
.subject-card-head {
  display: flex;
  gap: 15px;
  align-items: center;
}
.subject-card-head .brand-mark {
  width: 50px;
  height: 50px;
  flex-basis: 50px;
  font-size: 23px;
}
.subject-card-head h2 {
  margin: 0;
  font-size: 24px;
}
.subject-tagline {
  margin: 0;
  color: var(--muted);
  font-size: 13.5px;
}
.subject-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 20px;
}
.subject-stats div {
  display: flex;
  align-items: baseline;
  gap: 5px;
}
.subject-stats strong {
  font-size: 22px;
  color: var(--blue-deep);
}
.subject-stats div.warn strong {
  color: var(--danger);
}
.subject-stats span {
  color: var(--muted);
  font-size: 12px;
}
.subject-resume {
  margin: 0;
  font-size: 13px;
  color: #4a5c78;
  background: var(--blue-soft);
  border-radius: 10px;
  padding: 9px 13px;
}
.subject-enter {
  color: var(--accent, var(--blue));
  font-weight: 800;
  font-size: 14px;
}
.home-note {
  color: #93a1b5;
  font-size: 12.5px;
  margin-top: 30px;
}
@media (max-width: 920px) {
  .home-shell {
    padding: 34px 18px 40px;
  }
  .home-hero h1 {
    font-size: 24px;
  }
  .home-sub {
    margin-bottom: 26px;
  }
}
.brand-home {
  display: block;
  text-decoration: none;
  color: inherit;
}
@media (pointer: coarse) {
  .sync-code-area {
    font-size: 16px;
  }
  .filter-chip {
    padding: 9px 14px;
  }
  .exam-chip {
    padding: 12px 14px;
  }
  .chapter-select-card, .type-select-card, .segment-card, .subject-card, .filter-chip, .exam-chip {
    touch-action: manipulation;
  }
  .chapter-select-card:active:not(:disabled), .type-select-card:active:not(:disabled), .segment-card:active {
    transform: scale(.99);
  }
  .subject-card:active {
    transform: scale(.985);
  }
  .ghost-button:active, .primary-button:active {
    transform: scale(.98);
  }
  .nav-item:active {
    opacity: .8;
  }
}