:root {
  --blue: #0D5EAF;
  --blue-dark: #094a8a;
  --bg: #f5f8fb;
  --card: #ffffff;
  --text: #1c2733;
  --muted: #5b6b7a;
  --green: #1a9c5b;
  --red: #c0392b;
  --border: #e1e8ef;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}

.wrap { max-width: 880px; margin: 0 auto; padding: 0 20px; }

.site-header { background: var(--blue); color: #fff; }
.header-inner { display: flex; align-items: center; justify-content: space-between; padding: 14px 20px; flex-wrap: wrap; gap: 10px; }
.brand { color: #fff; font-weight: 700; font-size: 1.2rem; text-decoration: none; }
.nav { display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }
.nav a { color: #eaf2fb; text-decoration: none; font-size: 0.95rem; }
.nav a:hover { text-decoration: underline; }
.nav .btn-nav { background: #fff; color: var(--blue); padding: 6px 12px; border-radius: 6px; font-weight: 600; }
.nav .btn-nav:hover { text-decoration: none; opacity: .9; }

main.wrap { padding: 32px 20px 60px; min-height: 60vh; }

.hero { text-align: center; padding: 40px 0 20px; }
.hero h1 { font-size: 2rem; margin-bottom: 8px; }
.hero p { color: var(--muted); font-size: 1.1rem; }
.cta-row { display: flex; gap: 12px; justify-content: center; margin-top: 20px; flex-wrap: wrap; }

.btn { display: inline-block; background: var(--blue); color: #fff; padding: 10px 20px; border-radius: 8px; text-decoration: none; font-weight: 600; border: none; cursor: pointer; font-size: 1rem; }
.btn:hover { background: var(--blue-dark); }
.btn.secondary { background: #fff; color: var(--blue); border: 1px solid var(--blue); }
.btn.secondary:hover { background: #eef4fb; }

.card { background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 20px 24px; margin-bottom: 18px; }

.level-badge { display: inline-block; background: #eaf2fb; color: var(--blue); padding: 3px 10px; border-radius: 12px; font-size: 0.8rem; font-weight: 700; margin-bottom: 10px; }
.level-badge.soon { background: #f0f1f2; color: var(--muted); }

.lesson-list { list-style: none; padding: 0; margin: 0; display: grid; gap: 12px; }
.lesson-item { display: flex; justify-content: space-between; align-items: center; background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 16px 20px; text-decoration: none; color: var(--text); }
.lesson-item:hover { border-color: var(--blue); }
.lesson-item .title { font-weight: 600; }
.lesson-item .status { font-size: 0.85rem; color: var(--muted); }
.lesson-item .status.done { color: var(--green); font-weight: 600; }

table.vocab { width: 100%; border-collapse: collapse; margin: 14px 0; }
table.vocab th, table.vocab td { border: 1px solid var(--border); padding: 8px 10px; text-align: left; }
table.vocab th { background: #f0f5fa; }

form.stack { display: grid; gap: 14px; max-width: 420px; }
form.stack label { font-weight: 600; font-size: 0.9rem; display: block; margin-bottom: 4px; }
form.stack input[type=text], form.stack input[type=email], form.stack input[type=password] {
  width: 100%; padding: 10px 12px; border: 1px solid var(--border); border-radius: 8px; font-size: 1rem;
}

.exercise { border-top: 1px solid var(--border); padding-top: 16px; margin-top: 16px; }
.exercise .prompt { font-weight: 600; margin-bottom: 8px; }
.options label { display: block; margin: 6px 0; cursor: pointer; }
.result-ok { color: var(--green); font-weight: 600; }
.result-bad { color: var(--red); font-weight: 600; }

.alert { padding: 12px 16px; border-radius: 8px; margin-bottom: 16px; }
.alert.error { background: #fdecea; color: var(--red); border: 1px solid #f5c6cb; }
.alert.success { background: #eafaf1; color: var(--green); border: 1px solid #b7ebc6; }

.progress-bar { background: #e1e8ef; border-radius: 8px; height: 14px; overflow: hidden; margin: 8px 0 4px; }
.progress-bar-fill { background: var(--green); height: 100%; }

.stat-row { display: flex; gap: 20px; flex-wrap: wrap; }
.stat { background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 16px 20px; text-align: center; flex: 1; min-width: 140px; }
.stat .num { font-size: 1.6rem; font-weight: 700; color: var(--blue); }
.stat .label { color: var(--muted); font-size: 0.85rem; }

@media (max-width: 600px) {
  .hero h1 { font-size: 1.5rem; }
}