:root {
  --ink: #121412;
  --muted: rgba(18, 20, 18, .62);
  --line: rgba(18, 20, 18, .12);
  --glass: rgba(255, 255, 255, .68);
  --green: #a6efb7;
  --blue: #9fd5ff;
  --orange: #ffc06f;
  --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 16% 12%, rgba(166, 239, 183, .42), transparent 32rem),
    radial-gradient(circle at 88% 16%, rgba(159, 213, 255, .34), transparent 30rem),
    linear-gradient(135deg, #f7f5ee 0%, #eef5eb 52%, #f7f8fb 100%);
  overflow-x: hidden;
}

.grain {
  position: fixed;
  inset: 0;
  pointer-events: none;
  opacity: .18;
  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, #b9f2c4, 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, .word-card 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: 820px;
  margin: .5rem 0 .75rem;
  font-size: clamp(2.3rem, 6vw, 5.6rem);
  line-height: .92;
  letter-spacing: -.08em;
}

.hero-copy {
  max-width: 640px;
  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));
}

.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;
}

.word-card {
  margin: 1.8rem 0 1rem;
  padding: clamp(1.4rem, 3vw, 2.2rem);
  border: 1px solid var(--line);
  border-radius: 32px;
  background: rgba(255, 255, 255, .64);
}

.word-card h3 {
  margin: .2rem 0 0;
  font-size: clamp(3rem, 8vw, 7rem);
  line-height: .95;
  letter-spacing: -.08em;
}

.choice-list {
  display: grid;
  gap: .8rem;
}

.choice-list button {
  display: grid;
  grid-template-columns: 2.2rem 1fr;
  gap: .9rem;
  align-items: start;
  width: 100%;
  min-height: 4.8rem;
  padding: 1rem;
  text-align: left;
  border: 1px solid var(--line);
  border-radius: 24px;
  color: inherit;
  background: rgba(255, 255, 255, .52);
  cursor: pointer;
  transition: transform .22s ease, background .22s ease, border-color .22s ease;
}

.choice-list button:hover { transform: translateY(-2px); background: white; }

.choice-list i {
  display: grid;
  place-items: center;
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 50%;
  color: white;
  background: #111;
  font-style: normal;
  font-weight: 900;
}

.choice-list b {
  display: block;
  font-size: 1rem;
  line-height: 1.55;
}

.choice-list.answered button:not(.correct):not(.wrong) { opacity: .48; }
.choice-list button.correct { border-color: rgba(39, 151, 74, .58); background: rgba(188, 244, 195, .78); }
.choice-list button.wrong { border-color: rgba(218, 80, 66, .5); background: rgba(255, 208, 199, .72); }

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

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

button { 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, .mistake-count b { font-size: 2.1rem; letter-spacing: -.06em; }
.stat-row small, .mistake-count small { color: var(--muted); }

.mistake-card p, .guide p {
  margin: .8rem 0 0;
  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-actions {
  display: grid;
  gap: .6rem;
  margin-top: 1rem;
}

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

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

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

.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; }
}

@media (max-width: 620px) {
  .topbar { align-items: flex-start; gap: 1rem; flex-direction: column; }
  .topbar nav { width: 100%; flex-wrap: wrap; }
  .topbar nav a { flex: 1; text-align: center; }
  .choice-list button { grid-template-columns: 1fr; }
}