:root {
  color-scheme: light;
  --bg: #f4f6fb;
  --surface: #ffffff;
  --surface-2: #fbfcff;
  --ink: #17203a;
  --muted: #5f6980;
  --faint: #66718a;
  --line: #e3e8f2;
  --primary: #3b5bdb;
  --primary-hover: #2f4ac4;
  --primary-strong: #2f4ac4;
  --primary-soft: #eef1fe;
  --primary-line: #c9d3f7;
  --green: #0f6b33;
  --green-soft: #e9f7ef;
  --green-line: #bfe4cd;
  --green-on: #ffffff;
  --red: #b42318;
  --red-soft: #fdecea;
  --red-line: #f4c4c0;
  --red-on: #ffffff;
  --amber: #b45309;
  --amber-soft: #fef4e6;
  --chip-bg: #eef1f8;
  --chip-ink: #4a5570;
  --letter-bg: #edf0f8;
  --letter-ink: #4a5570;
  --hover-bg: #f2f5fb;
  --opt-hover-bg: #f6f8ff;
  --track: #e9edf7;
  --progress-track: #e7ebf5;
  --progress-a: #5c7cfa;
  --progress-b: #3b5bdb;
  --rstat-bg: #f7f9fe;
  --topbar-bg: rgba(255, 255, 255, 0.82);
  --topbar-border: rgba(227, 232, 242, 0.9);
  --footer-bg: rgba(255, 255, 255, 0.6);
  --overlay: rgba(17, 24, 45, 0.5);
  --glow-a: #e4e9ff;
  --glow-b: #e2f5ec;
  --mix-a: #eef1fe;
  --mix-b: #f5f8ff;
  --mix-c: #e9f7f0;
  --badge-all-a: #e8edff;
  --badge-all-b: #e6f7ef;
  --chapter-stroke: #e6ebf7;
  --dot-blank: #d5dbe8;
  --shadow: 0 14px 40px rgba(23, 32, 58, 0.08);
  --radius-lg: 20px;
  --radius-md: 14px;
  --font: "Segoe UI", system-ui, -apple-system, Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
}

html[data-theme="dark"] {
  color-scheme: dark;
  --bg: #0c1220;
  --surface: #161e30;
  --surface-2: #1b2438;
  --ink: #e8edf8;
  --muted: #a9b4c9;
  --faint: #97a3ba;
  --line: #2a3550;
  --primary: #4a66e0;
  --primary-hover: #3d55c4;
  --primary-strong: #a9bcff;
  --primary-soft: #1e2a4d;
  --primary-line: #36477a;
  --green: #5fd68f;
  --green-soft: #10261a;
  --green-line: #245039;
  --green-on: #07150d;
  --red: #ff8f86;
  --red-soft: #2a1417;
  --red-line: #57292c;
  --red-on: #170504;
  --amber: #f2b45f;
  --amber-soft: #2a2011;
  --chip-bg: #222c42;
  --chip-ink: #bcc7db;
  --letter-bg: #232e46;
  --letter-ink: #c8d2e4;
  --hover-bg: #232e46;
  --opt-hover-bg: #202a41;
  --track: #2a3550;
  --progress-track: #232d44;
  --progress-a: #7a95ff;
  --progress-b: #4a66e0;
  --rstat-bg: #1b2438;
  --topbar-bg: rgba(12, 18, 32, 0.82);
  --topbar-border: rgba(42, 53, 80, 0.9);
  --footer-bg: rgba(12, 18, 32, 0.6);
  --overlay: rgba(3, 7, 16, 0.68);
  --glow-a: rgba(74, 102, 224, 0.2);
  --glow-b: rgba(34, 160, 105, 0.12);
  --mix-a: #1b2740;
  --mix-b: #182238;
  --mix-c: #142a24;
  --badge-all-a: #1c2848;
  --badge-all-b: #162a25;
  --chapter-stroke: #263250;
  --dot-blank: #3a4661;
  --shadow: 0 14px 40px rgba(0, 0, 0, 0.45);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  background: var(--bg);
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  color: var(--ink);
  background:
    radial-gradient(900px 480px at -10% -10%, var(--glow-a) 0%, transparent 60%),
    radial-gradient(800px 420px at 110% 0%, var(--glow-b) 0%, transparent 55%),
    var(--bg);
  display: flex;
  flex-direction: column;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--topbar-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--topbar-border);
}

.topbar-inner {
  max-width: 1040px;
  margin: 0 auto;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 11px;
  text-decoration: none;
  color: inherit;
}

.brand-mark {
  width: 40px;
  height: 40px;
  border-radius: 12px;
  background: linear-gradient(135deg, #4c6ef5, #2f4ac4);
  color: #fff;
  display: grid;
  place-items: center;
  box-shadow: 0 6px 16px rgba(59, 91, 219, 0.28);
  flex: none;
}

.brand-mark svg {
  width: 22px;
  height: 22px;
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand-text strong {
  font-size: 0.98rem;
  letter-spacing: -0.01em;
}

.brand-text small {
  color: var(--muted);
  font-size: 0.76rem;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.topbar-tag {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--primary-strong);
  background: var(--primary-soft);
  border: 1px solid var(--primary-line);
  padding: 6px 12px;
  border-radius: 999px;
  white-space: nowrap;
}

.theme-toggle {
  width: 38px;
  height: 38px;
  flex: none;
  display: grid;
  place-items: center;
  border-radius: 11px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--muted);
  cursor: pointer;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.theme-toggle:hover {
  background: var(--hover-bg);
  color: var(--ink);
  border-color: var(--primary-line);
}

.theme-toggle svg {
  width: 19px;
  height: 19px;
}

.theme-toggle .icon-sun {
  display: none;
}

html[data-theme="dark"] .theme-toggle .icon-sun {
  display: block;
}

html[data-theme="dark"] .theme-toggle .icon-moon {
  display: none;
}

.app {
  flex: 1;
  width: 100%;
  max-width: 1040px;
  margin: 0 auto;
  padding: 36px 24px 64px;
}

.hero {
  padding: 22px 0 34px;
  max-width: 760px;
}

.eyebrow {
  margin: 0;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--primary-strong);
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3rem);
  line-height: 1.12;
  letter-spacing: -0.03em;
  margin: 12px 0 16px;
  font-weight: 800;
}

.hero h1 span {
  color: var(--primary-strong);
}

.lede {
  font-size: 1.02rem;
  line-height: 1.65;
  color: var(--muted);
  margin: 0;
}

.lede strong {
  color: var(--ink);
}

.mix-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
  background: linear-gradient(120deg, var(--mix-a) 0%, var(--mix-b) 55%, var(--mix-c) 100%);
  border: 1px solid var(--primary-line);
  border-radius: var(--radius-lg);
  padding: 24px 26px;
  margin-bottom: 22px;
}

.mix-eyebrow {
  margin: 0 0 6px;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--primary-strong);
}

.mix-info h2 {
  margin: 0 0 4px;
  font-size: 1.3rem;
  letter-spacing: -0.01em;
}

.mix-info p:last-child {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.55;
}

.mix-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.chapter-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.chapter-card {
  position: relative;
  overflow: hidden;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 22px;
  box-shadow: 0 2px 6px rgba(23, 32, 58, 0.03);
  display: flex;
  flex-direction: column;
  gap: 16px;
  transition: transform 0.18s ease, box-shadow 0.18s ease;
}

.chapter-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
}

.chapter-num {
  position: absolute;
  top: -14px;
  right: 10px;
  font-size: 6rem;
  font-weight: 800;
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1.5px var(--chapter-stroke);
  pointer-events: none;
}

.chapter-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  position: relative;
}

.chapter-label {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary-strong);
  background: var(--primary-soft);
  padding: 5px 10px;
  border-radius: 999px;
}

.chapter-count {
  font-size: 0.8rem;
  color: var(--muted);
  font-weight: 600;
}

.chapter-card h2 {
  font-size: 1.06rem;
  line-height: 1.45;
  margin: 0;
  position: relative;
  flex: 1;
}

.chapter-actions {
  display: flex;
  gap: 10px;
  position: relative;
}

.chapter-actions .btn {
  flex: 1;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border-radius: 12px;
  border: 1.5px solid transparent;
  padding: 11px 16px;
  font: 600 0.92rem/1 var(--font);
  cursor: pointer;
  text-decoration: none;
  transition: background 0.15s, border-color 0.15s, color 0.15s, transform 0.05s;
  white-space: nowrap;
}

.btn:active:not(:disabled) {
  transform: translateY(1px);
}

.btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 6px 16px rgba(59, 91, 219, 0.22);
}

.btn-primary:hover:not(:disabled) {
  background: var(--primary-hover);
}

.btn-outline {
  background: var(--surface);
  border-color: var(--primary-line);
  color: var(--primary-strong);
}

.btn-outline:hover:not(:disabled) {
  background: var(--primary-soft);
}

.btn-ghost {
  background: transparent;
  border-color: transparent;
  color: var(--muted);
}

.btn-ghost:hover:not(:disabled) {
  background: var(--chip-bg);
  color: var(--ink);
}

.session {
  animation: fade 0.25s ease;
}

.session-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.back-link {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--muted);
  text-decoration: none;
  padding: 8px 0;
}

.back-link:hover {
  color: var(--primary-strong);
}

.badges {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.badge {
  font-size: 0.78rem;
  font-weight: 700;
  padding: 6px 12px;
  border-radius: 999px;
  background: var(--chip-bg);
  color: var(--chip-ink);
}

.badge.practice {
  background: var(--green-soft);
  color: var(--green);
}

.badge.exam {
  background: var(--amber-soft);
  color: var(--amber);
}

.badge.all {
  background: linear-gradient(120deg, var(--badge-all-a), var(--badge-all-b));
  color: var(--primary-strong);
  border: 1px solid var(--primary-line);
}

.progress {
  height: 6px;
  border-radius: 999px;
  background: var(--progress-track);
  overflow: hidden;
  margin-bottom: 18px;
}

.progress > div {
  height: 100%;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--progress-a), var(--progress-b));
  transition: width 0.25s ease;
}

.session-stats {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.stat-pill {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--muted);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 7px 12px;
}

.stat-pill b {
  color: var(--ink);
}

.stat-pill.ok b {
  color: var(--green);
}

.qcard {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 28px;
  box-shadow: var(--shadow);
}

.qcard-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.qindex {
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--muted);
}

.qindex b {
  color: var(--primary-strong);
  font-size: 1rem;
}

.qid {
  font-size: 0.72rem;
  color: var(--faint);
  font-weight: 600;
  margin-left: 8px;
}

.sheet-link {
  border: 1px solid var(--primary-line);
  color: var(--primary-strong);
  background: var(--primary-soft);
  font: 600 0.82rem var(--font);
  cursor: pointer;
  padding: 7px 12px;
  border-radius: 9px;
}

.sheet-link:hover {
  border-color: var(--primary);
}

.qtext {
  font-size: 1.12rem;
  line-height: 1.7;
  font-weight: 600;
  margin: 16px 0 22px;
  letter-spacing: -0.005em;
}

.opts {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.opt {
  display: flex;
  align-items: flex-start;
  gap: 13px;
  width: 100%;
  text-align: left;
  background: var(--surface-2);
  border: 1.5px solid var(--line);
  border-radius: var(--radius-md);
  padding: 13px 16px;
  font: 500 0.98rem/1.55 var(--font);
  color: var(--ink);
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s, box-shadow 0.15s;
}

.opt:hover:not(:disabled) {
  border-color: var(--primary-line);
  background: var(--opt-hover-bg);
}

.opt .letter {
  flex: none;
  width: 30px;
  height: 30px;
  border-radius: 9px;
  background: var(--letter-bg);
  color: var(--letter-ink);
  display: grid;
  place-items: center;
  font-weight: 700;
  font-size: 0.86rem;
  margin-top: 1px;
  transition: background 0.15s, color 0.15s;
}

.opt .otext {
  flex: 1;
  min-width: 0;
}

.opt .otag {
  flex: none;
  font-size: 0.7rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 999px;
  margin-top: 2px;
  background: var(--surface);
  border: 1px solid currentColor;
  white-space: nowrap;
}

.opt.sel {
  border-color: var(--primary);
  background: var(--primary-soft);
  box-shadow: 0 0 0 3px rgba(59, 91, 219, 0.09);
}

.opt.sel .letter {
  background: var(--primary);
  color: #fff;
}

.opt.correct {
  border-color: var(--green);
  background: var(--green-soft);
}

.opt.correct .letter {
  background: var(--green);
  color: var(--green-on);
}

.opt.correct .otag {
  color: var(--green);
}

.opt.wrong {
  border-color: var(--red);
  background: var(--red-soft);
}

.opt.wrong .letter {
  background: var(--red);
  color: var(--red-on);
}

.opt.wrong .otag {
  color: var(--red);
}

.opt.dim {
  opacity: 0.62;
}

.opt:disabled {
  cursor: default;
}

.feedback {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  margin-top: 16px;
  padding: 14px 16px;
  border-radius: var(--radius-md);
  font-size: 0.93rem;
  font-weight: 600;
  line-height: 1.5;
}

.feedback .fb-icon {
  flex: none;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-size: 0.75rem;
  font-weight: 800;
}

.feedback.ok {
  background: var(--green-soft);
  border: 1px solid var(--green-line);
  color: var(--green);
}

.feedback.ok .fb-icon {
  background: var(--green);
  color: var(--green-on);
}

.feedback.bad {
  background: var(--red-soft);
  border: 1px solid var(--red-line);
  color: var(--red);
}

.feedback.bad .fb-icon {
  background: var(--red);
  color: var(--red-on);
}

.feedback b {
  font-weight: 800;
}

.exambar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 22px;
  padding-top: 20px;
  border-top: 1px dashed var(--line);
}

.exambar-note {
  font-size: 0.9rem;
  color: var(--muted);
}

.exambar-note b {
  color: var(--ink);
}

.qnav {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  margin-top: 18px;
  flex-wrap: wrap;
}

.overlay {
  position: fixed;
  inset: 0;
  z-index: 80;
  background: var(--overlay);
  display: flex;
  align-items: flex-end;
  justify-content: center;
  padding: 0;
  animation: fade 0.15s ease;
}

.sheet {
  width: 100%;
  max-width: 720px;
  max-height: 86vh;
  overflow: auto;
  background: var(--surface);
  border-radius: 22px 22px 0 0;
  padding: 22px 22px 28px;
  box-shadow: 0 -20px 60px rgba(17, 24, 45, 0.25);
}

.sheet-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
}

.sheet-head h3 {
  margin: 0;
  font-size: 1.05rem;
}

.close-x {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--muted);
  font: 600 0.9rem var(--font);
  cursor: pointer;
  flex: none;
}

.close-x:hover {
  background: var(--hover-bg);
  color: var(--ink);
}

.legend {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  font-size: 0.78rem;
  color: var(--muted);
  margin-bottom: 14px;
}

.legend span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.dot {
  width: 10px;
  height: 10px;
  border-radius: 3px;
  background: var(--dot-blank);
}

.dot.ok {
  background: var(--green);
}

.dot.bad {
  background: var(--red);
}

.dot.done {
  background: var(--primary);
}

.numgrid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(46px, 1fr));
  gap: 8px;
}

.num {
  height: 46px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: var(--surface);
  font: 600 0.86rem var(--font);
  color: var(--muted);
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

.num:hover {
  border-color: var(--primary-line);
  color: var(--primary-strong);
  background: var(--primary-soft);
}

.num.ok {
  background: var(--green-soft);
  border-color: var(--green-line);
  color: var(--green);
}

.num.bad {
  background: var(--red-soft);
  border-color: var(--red-line);
  color: var(--red);
}

.num.done {
  background: var(--primary-soft);
  border-color: var(--primary-line);
  color: var(--primary-strong);
}

.num.cur {
  outline: 2px solid var(--primary);
  outline-offset: 1px;
}

.modal {
  width: calc(100% - 32px);
  max-width: 440px;
  background: var(--surface);
  border-radius: 18px;
  padding: 24px;
  margin: auto;
  box-shadow: var(--shadow);
}

.modal h3 {
  margin: 0 0 10px;
  font-size: 1.15rem;
}

.modal p {
  margin: 0 0 20px;
  color: var(--muted);
  line-height: 1.6;
  font-size: 0.95rem;
}

.modal p b {
  color: var(--ink);
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 10px;
  flex-wrap: wrap;
}

.result {
  animation: fade 0.25s ease;
}

.result-hero {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 34px 26px;
  box-shadow: var(--shadow);
  text-align: center;
}

.score-ring {
  width: 168px;
  height: 168px;
  border-radius: 50%;
  background: conic-gradient(var(--primary) calc(var(--p) * 1%), var(--track) 0);
  display: grid;
  place-items: center;
  margin: 18px auto 20px;
}

.score-inner {
  width: 132px;
  height: 132px;
  border-radius: 50%;
  background: var(--surface);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  box-shadow: inset 0 0 0 1px var(--line);
}

.score-inner b {
  font-size: 1.45rem;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.score-inner span {
  font-size: 0.76rem;
  color: var(--muted);
  font-weight: 600;
}

.result-stats {
  display: flex;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
  margin: 18px 0 6px;
}

.rstat {
  min-width: 96px;
  padding: 12px 16px;
  border-radius: 14px;
  background: var(--rstat-bg);
  border: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.rstat b {
  font-size: 1.3rem;
}

.rstat span {
  font-size: 0.76rem;
  color: var(--muted);
  font-weight: 600;
}

.rstat.ok b {
  color: var(--green);
}

.rstat.bad b {
  color: var(--red);
}

.rstat.blank b {
  color: var(--muted);
}

.result-sub {
  color: var(--muted);
  font-size: 0.88rem;
  margin: 10px 0 0;
}

.result-actions {
  display: flex;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 22px;
}

.review-title {
  font-size: 1.25rem;
  margin: 36px 0 6px;
  letter-spacing: -0.01em;
}

.review-sub {
  color: var(--muted);
  font-size: 0.88rem;
  margin: 0 0 16px;
}

.filterbar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin: 16px 0;
}

.filter-btn {
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--muted);
  font: 600 0.84rem var(--font);
  padding: 8px 14px;
  border-radius: 999px;
  cursor: pointer;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}

.filter-btn:hover {
  border-color: var(--primary-line);
  color: var(--primary-strong);
}

.filter-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

.review-list {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.review-item {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 22px;
}

.review-head {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.tag {
  font-size: 0.72rem;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 999px;
  margin-left: auto;
}

.tag.ok {
  background: var(--green-soft);
  color: var(--green);
  border: 1px solid var(--green-line);
}

.tag.bad {
  background: var(--red-soft);
  color: var(--red);
  border: 1px solid var(--red-line);
}

.tag.blank {
  background: var(--chip-bg);
  color: var(--chip-ink);
  border: 1px solid var(--line);
}

.review-item .qtext {
  font-size: 1rem;
  margin: 12px 0 16px;
}

.review-item .opt {
  padding: 11px 14px;
  font-size: 0.93rem;
  cursor: default;
}

.review-item .opt:hover {
  border-color: var(--line);
  background: var(--surface-2);
}

.review-item .opt.correct:hover {
  border-color: var(--green);
  background: var(--green-soft);
}

.review-item .opt.wrong:hover {
  border-color: var(--red);
  background: var(--red-soft);
}

.review-item .opt .letter {
  width: 26px;
  height: 26px;
  font-size: 0.78rem;
}

.review-empty {
  background: var(--surface);
  border: 1px dashed var(--line);
  border-radius: var(--radius-md);
  padding: 28px;
  text-align: center;
  color: var(--muted);
  font-size: 0.92rem;
}

.footer {
  border-top: 1px solid var(--line);
  background: var(--footer-bg);
}

.footer-inner {
  max-width: 1040px;
  margin: 0 auto;
  padding: 20px 24px;
  font-size: 0.8rem;
  color: var(--muted);
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.footer p {
  margin: 0;
}

.footer-note {
  opacity: 0.85;
}

@keyframes fade {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@media (min-width: 640px) {
  .overlay {
    align-items: center;
    padding: 24px;
  }

  .sheet {
    border-radius: 22px;
  }
}

@media (max-width: 900px) {
  .chapter-grid {
    grid-template-columns: 1fr;
  }

  .chapter-card {
    padding: 20px;
  }

  .chapter-num {
    font-size: 5rem;
  }
}

@media (max-width: 640px) {
  .topbar-inner {
    padding: 10px 16px;
  }

  .brand-text strong {
    font-size: 0.9rem;
  }

  .brand-text small {
    font-size: 0.7rem;
  }

  .topbar-tag {
    display: none;
  }

  .app {
    padding: 24px 16px 48px;
  }

  .hero {
    padding: 12px 0 26px;
  }

  .mix-card {
    padding: 20px;
  }

  .mix-actions {
    width: 100%;
  }

  .mix-actions .btn {
    flex: 1;
  }

  .qcard {
    padding: 20px 16px;
  }

  .qtext {
    font-size: 1.03rem;
  }

  .opt {
    padding: 12px 13px;
    font-size: 0.94rem;
  }

  .qnav .btn {
    flex: 1;
  }

  .sheet {
    padding: 18px 16px 24px;
  }

  .numgrid {
    grid-template-columns: repeat(auto-fill, minmax(42px, 1fr));
  }

  .result-hero {
    padding: 26px 18px;
  }

  .review-item {
    padding: 18px 16px;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }
}