* { box-sizing: border-box; }
:root {
  --bg: #070b14;
  --panel: rgba(15, 23, 42, .92);
  --soft: rgba(255,255,255,.06);
  --border: rgba(255,255,255,.13);
  --text: #eef4ff;
  --muted: #94a3b8;
  --green: #32d583;
  --blue: #5b8cff;
  --purple: #9b7cff;
  --red: #ff5c7a;
  --yellow: #ffd166;
}
body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, Arial, sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 15% 15%, rgba(91,140,255,.25), transparent 28rem),
    radial-gradient(circle at 85% 10%, rgba(50,213,131,.16), transparent 26rem),
    var(--bg);
}
.page { width: min(1120px, 100%); margin: 0 auto; padding: 34px 22px 80px; }
.back {
  display: inline-flex;
  margin-bottom: 24px;
  padding: 12px 18px;
  border-radius: 999px;
  color: var(--text);
  text-decoration: none;
  background: rgba(255,255,255,.075);
  border: 1px solid var(--border);
  font-weight: 900;
}
.panel {
  margin-bottom: 24px;
  padding: 32px;
  border: 1px solid var(--border);
  border-radius: 30px;
  background: linear-gradient(145deg, rgba(15,23,42,.95), rgba(17,24,39,.84));
  box-shadow: 0 28px 80px rgba(0,0,0,.35);
}
.hero h1 { font-size: clamp(44px, 8vw, 82px); line-height: .92; letter-spacing: -.07em; }
.hero h1 span { color: var(--green); }
.eyebrow { margin: 0 0 10px; color: var(--green); font-size: 12px; font-weight: 900; letter-spacing: .15em; text-transform: uppercase; }
h1, h2, h3 { margin-top: 0; }
h2 { font-size: clamp(30px, 5vw, 48px); letter-spacing: -.045em; }
p, li { line-height: 1.7; }
.lead, .muted, .translation { color: var(--muted); }
.hero-grid, .explain-grid, .mistake-grid, .choice-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}
.explain-grid { grid-template-columns: repeat(2, 1fr); }
.hero-grid > div, .explain-grid article, .mistake-grid article, .choice-card {
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: var(--soft);
}
.example { color: var(--text); font-size: 20px; font-weight: 900; }
.correct { color: var(--green); font-weight: 900; }
.notice {
  margin-top: 18px;
  padding: 18px;
  border-radius: 18px;
  border: 1px solid rgba(50,213,131,.28);
  background: rgba(50,213,131,.08);
}
.warning { border-color: rgba(255,209,102,.32); background: rgba(255,209,102,.08); }
.formula {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin: 22px 0;
}
.formula span {
  padding: 18px;
  border-radius: 16px;
  text-align: center;
  font-weight: 900;
  color: #06130f;
  background: linear-gradient(135deg, var(--green), #9ff3d0);
}
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; overflow: hidden; border-radius: 18px; }
th, td { padding: 15px; border-bottom: 1px solid var(--border); text-align: left; }
th { color: var(--green); background: rgba(255,255,255,.06); }
.exercise-list { display: grid; gap: 14px; margin: 22px 0; }
.exercise-item {
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: rgba(255,255,255,.045);
}
.sentence { margin-bottom: 12px; font-weight: 800; }
input {
  width: 100%;
  height: 52px;
  padding: 0 15px;
  border-radius: 14px;
  border: 1px solid var(--border);
  outline: none;
  color: var(--text);
  background: rgba(7,11,20,.72);
  font-size: 16px;
}
input.correct-input { border-color: var(--green); box-shadow: 0 0 0 3px rgba(50,213,131,.13); }
input.wrong-input { border-color: var(--red); box-shadow: 0 0 0 3px rgba(255,92,122,.13); }
button {
  min-height: 50px;
  margin: 6px 8px 0 0;
  padding: 13px 18px;
  border: 0;
  border-radius: 14px;
  cursor: pointer;
  font-weight: 900;
}
.primary { color: #06130f; background: linear-gradient(135deg, var(--green), #8df0c8); }
.secondary { color: var(--text); background: rgba(255,255,255,.08); border: 1px solid var(--border); }
.action-link {
  display: inline-flex;
  min-height: 52px;
  align-items: center;
  padding: 14px 20px;
  border-radius: 14px;
  text-decoration: none;
  font-weight: 900;
}
.result-box { margin-top: 16px; color: var(--muted); font-weight: 800; }
.choice-card button { width: 100%; }
.steps { padding-left: 22px; }
.solution { margin-top: 10px; color: var(--green); font-weight: 900; }
.pill {
  display: inline-flex;
  margin: 0 0 16px;
  padding: 8px 14px;
  border-radius: 999px;
  color: #b9ccff;
  background: rgba(91,140,255,.16);
  font-size: 14px;
  font-weight: 900;
}
#quizBox, #resultBox {
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: 26px;
  background: rgba(255,255,255,.045);
}
.prompt-box {
  margin: 18px 0;
  padding: 24px;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: rgba(7,11,20,.55);
  font-size: clamp(24px, 5vw, 42px);
  font-weight: 900;
  line-height: 1.25;
}
.choice-buttons {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin-bottom: 16px;
}
.choice-option {
  width: 100%;
  color: var(--text);
}
.choice-option.primary {
  color: #06130f;
}
.solution-line {
  min-height: 26px;
  color: var(--muted);
  font-weight: 800;
}
.score-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  margin: 18px 0 24px;
}
.score-grid div {
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: rgba(7,11,20,.45);
}
.score-grid strong {
  display: block;
  font-size: 42px;
  color: var(--green);
}
#rightList, #wrongList {
  padding: 0;
  list-style: none;
}
#rightList li, #wrongList li {
  margin: 10px 0;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: rgba(7,11,20,.45);
}
@media (max-width: 850px) {
  .hero-grid, .explain-grid, .mistake-grid, .choice-grid, .formula { grid-template-columns: 1fr; }
  .panel { padding: 22px; }
}