:root {
  --ink: #121412;
  --muted: rgba(18, 20, 18, .62);
  --line: rgba(18, 20, 18, .12);
  --glass: rgba(255, 255, 255, .68);
  --green: #8ee0a1;
  --blue: #9fd5ff;
  --orange: #ffb46f;
  --purple: #cab7ff;
  --shadow: 0 30px 90px rgba(28, 42, 31, .16);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(circle at 20% 10%, rgba(154, 220, 174, .42), transparent 32rem),
    radial-gradient(circle at 90% 20%, rgba(159, 213, 255, .36), transparent 30rem),
    linear-gradient(135deg, #f7f5ee 0%, #eef5eb 50%, #f6f7fb 100%);
  overflow-x: hidden;
}

.grain {
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: .22;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 220 220' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='220' height='220' filter='url(%23n)' opacity='.22'/%3E%3C/svg%3E");
  mix-blend-mode: multiply;
}

.ambient {
  position: fixed;
  width: 34rem;
  aspect-ratio: 1;
  border-radius: 50%;
  filter: blur(18px);
  opacity: .42;
  pointer-events: none;
  animation: floaty 9s ease-in-out infinite alternate;
}

.ambient-a {
  left: -10rem;
  top: 10rem;
  background: radial-gradient(circle, #b7f1bb, transparent 68%);
}

.ambient-b {
  right: -8rem;
  bottom: 2rem;
  background: radial-gradient(circle, #b7cdfd, transparent 68%);
  animation-delay: -3s;
}

@keyframes floaty {
  from { transform: translate3d(0, 0, 0) scale(1); }
  to { transform: translate3d(2rem, -1.5rem, 0) scale(1.08); }
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem clamp(1rem, 4vw, 4rem);
  background: rgba(247, 248, 242, .72);
  backdrop-filter: blur(22px);
  border-bottom: 1px solid rgba(255, 255, 255, .52);
}

.brand, .topbar nav a {
  color: inherit;
  text-decoration: none;
}

.brand {
  display: inline-flex;
  gap: .7rem;
  align-items: center;
  letter-spacing: -.03em;
}

.brand span {
  display: grid;
  place-items: center;
  width: 2.25rem;
  height: 2.25rem;
  border-radius: 50%;
  color: white;
  background: #111;
  font-weight: 800;
}

.topbar nav {
  display: flex;
  gap: .5rem;
  padding: .35rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, .45);
}

.topbar nav a {
  padding: .62rem .95rem;
  border-radius: 999px;
  font-size: .92rem;
  color: var(--muted);
}

.topbar nav a.active {
  color: #111;
  background: white;
  box-shadow: 0 8px 24px rgba(20, 30, 20, .08);
}

.app-shell {
  position: relative;
  z-index: 1;
  width: min(1180px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 4rem 0 5rem;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 13rem;
  gap: 2rem;
  align-items: end;
  margin-bottom: 1.6rem;
}

.eyebrow, .mini-card > span, #questionMeta, .feedback span {
  margin: 0;
  color: rgba(18, 20, 18, .5);
  font-size: .76rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  font-weight: 800;
}

.hero h1 {
  max-width: 780px;
  margin: .5rem 0 .75rem;
  font-size: clamp(2.3rem, 6vw, 5.8rem);
  line-height: .92;
  letter-spacing: -.08em;
}

.hero-copy {
  max-width: 620px;
  margin: 0;
  color: var(--muted);
  font-size: 1.05rem;
  line-height: 1.8;
}

.score-orb {
  display: grid;
  place-items: center;
  min-height: 13rem;
  border-radius: 44px;
  background: rgba(18, 20, 18, .92);
  color: white;
  box-shadow: var(--shadow);
}

.score-orb span, .score-orb small {
  color: rgba(255, 255, 255, .62);
}

.score-orb strong {
  font-size: 3.6rem;
  letter-spacing: -.07em;
}

.trainer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 1.2rem;
  align-items: start;
}

.question-card, .mini-card {
  border: 1px solid rgba(255, 255, 255, .72);
  background: var(--glass);
  backdrop-filter: blur(26px);
  box-shadow: var(--shadow);
}

.question-card {
  position: relative;
  overflow: hidden;
  padding: clamp(1.2rem, 3vw, 2rem);
  border-radius: 38px;
}

.question-card::before {
  content: "";
  position: absolute;
  inset: 0 0 auto;
  height: .35rem;
  background: linear-gradient(90deg, var(--green), var(--blue), var(--orange), var(--purple));
}

.card-head {
  display: flex;
  gap: 1rem;
  align-items: start;
  justify-content: space-between;
}

.card-head h2 {
  margin: .3rem 0 0;
  font-size: clamp(1.35rem, 3vw, 2rem);
  letter-spacing: -.04em;
}

blockquote {
  margin: 2rem 0;
  padding: clamp(1.4rem, 3vw, 2.2rem);
  border: 1px solid var(--line);
  border-radius: 30px;
  background: rgba(255, 255, 255, .62);
  font-size: clamp(1.3rem, 2.8vw, 2.25rem);
  line-height: 1.35;
  letter-spacing: -.04em;
}

.choice-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: .8rem;
}

.choice-grid button {
  min-height: 10rem;
  padding: 1rem;
  text-align: left;
  border: 1px solid var(--line);
  border-radius: 28px;
  background: rgba(255, 255, 255, .52);
  color: inherit;
  cursor: pointer;
  transition: transform .22s ease, background .22s ease, border-color .22s ease;
}

.choice-grid button:hover {
  transform: translateY(-4px);
  background: white;
}

.choice-grid button span {
  display: grid;
  place-items: center;
  width: 2.3rem;
  height: 2.3rem;
  margin-bottom: 1rem;
  border-radius: 50%;
  background: #111;
  color: white;
  font-weight: 900;
}

.choice-grid button b {
  display: block;
  font-size: 1.05rem;
}

.choice-grid button small {
  display: block;
  margin-top: .4rem;
  color: var(--muted);
  line-height: 1.45;
}

.choice-grid button.correct {
  border-color: rgba(39, 151, 74, .58);
  background: rgba(188, 244, 195, .78);
}

.choice-grid button.wrong {
  border-color: rgba(218, 80, 66, .5);
  background: rgba(255, 208, 199, .72);
}

.choice-grid.answered button:not(.correct):not(.wrong) {
  opacity: .48;
}

.feedback {
  margin-top: 1rem;
  padding: 1rem 1.15rem;
  border-radius: 24px;
  background: rgba(18, 20, 18, .06);
  border: 1px solid var(--line);
}

.feedback p {
  margin: .35rem 0 0;
  color: var(--muted);
  line-height: 1.65;
}

.feedback.good {
  background: rgba(188, 244, 195, .55);
}

.feedback.bad {
  background: rgba(255, 222, 208, .62);
}

.card-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 1.2rem;
}

button, select {
  font: inherit;
}

.primary-button, .ghost-button, .text-button {
  border: 0;
  cursor: pointer;
}

.primary-button {
  display: inline-flex;
  gap: .5rem;
  align-items: center;
  padding: .95rem 1.25rem;
  border-radius: 999px;
  color: white;
  background: #111;
}

.primary-button:disabled {
  cursor: not-allowed;
  opacity: .35;
}

.ghost-button {
  padding: .78rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, .66);
}

.text-button {
  color: var(--muted);
  background: transparent;
}

.side-panel {
  display: grid;
  gap: 1rem;
}

.mini-card {
  padding: 1.2rem;
  border-radius: 30px;
}

.stat-row {
  display: flex;
  align-items: end;
  justify-content: space-between;
  padding: .8rem 0;
  border-bottom: 1px solid var(--line);
}

.stat-row:last-child {
  border-bottom: 0;
}

.stat-row b {
  font-size: 2.1rem;
  letter-spacing: -.06em;
}

.stat-row small {
  color: var(--muted);
}

.select-label {
  display: grid;
  gap: .6rem;
  margin-top: 1rem;
  color: var(--muted);
}

.mistake-card p {
  margin: .7rem 0 1rem;
  color: var(--muted);
  line-height: 1.55;
}

.mistake-count {
  display: flex;
  align-items: end;
  justify-content: space-between;
  margin-top: .7rem;
  padding-bottom: .75rem;
  border-bottom: 1px solid var(--line);
}

.mistake-count b {
  font-size: 2.4rem;
  letter-spacing: -.07em;
}

.mistake-count small {
  color: var(--muted);
}

.mistake-actions {
  display: grid;
  gap: .6rem;
}

.mistake-actions .ghost-button,
.mistake-actions .text-button {
  width: 100%;
}

select {
  width: 100%;
  padding: .85rem;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgba(255, 255, 255, .72);
  color: var(--ink);
}

.guide p {
  margin: .85rem 0 0;
  color: var(--muted);
  line-height: 1.55;
}

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

.guide h3 {
  margin: .45rem 0 .8rem;
  font-size: 1.05rem;
  letter-spacing: -.03em;
}

.clue-list {
  display: grid;
  gap: .65rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.clue-list li {
  display: grid;
  gap: .25rem;
  padding: .75rem;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgba(255, 255, 255, .46);
}

.clue-list b {
  font-size: .92rem;
}

.clue-list em {
  justify-self: start;
  padding: .16rem .45rem;
  border-radius: 999px;
  color: white;
  background: #111;
  font-style: normal;
  font-weight: 800;
}

.clue-list small {
  color: var(--muted);
  line-height: 1.35;
}

.tiny-tip {
  padding-top: .8rem;
  border-top: 1px solid var(--line);
}

.feedback-clues {
  display: grid;
  gap: .35rem;
  margin: .75rem 0 0;
  padding-left: 1.1rem;
  color: rgba(18, 20, 18, .72);
  line-height: 1.5;
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 1.5rem;
  z-index: 20;
  transform: translate(-50%, 1rem);
  padding: .85rem 1rem;
  border-radius: 999px;
  color: white;
  background: rgba(18, 20, 18, .9);
  opacity: 0;
  pointer-events: none;
  transition: opacity .22s ease, transform .22s ease;
}

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

@media (max-width: 940px) {
  .hero, .trainer-grid {
    grid-template-columns: 1fr;
  }

  .score-orb {
    min-height: 9rem;
  }

  .choice-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 620px) {
  .topbar {
    align-items: flex-start;
    gap: 1rem;
    flex-direction: column;
  }

  .topbar nav {
    width: 100%;
  }

  .topbar nav a {
    flex: 1;
    text-align: center;
  }

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

  .choice-grid button {
    min-height: 7.6rem;
  }
}