:root {
  --bg: #f4f6fb;
  --card: #ffffff;
  --ink: #16202e;
  --muted: #667389;
  --line: #dde3ec;
  --brand: #2f6df6;
  --brand-dark: #1f52c4;
  --brand-soft: #eaf0ff;
  --green: #11845b;
  --green-soft: #e6f6ee;
  --red: #c93535;
  --red-soft: #fdeaea;
  --amber: #a76900;
  --amber-soft: #fff4dd;
  --radius: 14px;
  --shadow: 0 8px 28px rgba(22, 32, 46, .08);
}

* { box-sizing: border-box; }

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

button, input, select { font: inherit; }

/* ---------- общие блоки ---------- */
.wrap { width: min(1080px, 100% - 32px); margin: 0 auto; }

.topbar {
  background: #fff;
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 20;
}
.topbar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 0;
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; letter-spacing: -.2px; }
.brand__mark {
  width: 32px; height: 32px; border-radius: 9px;
  background: linear-gradient(135deg, var(--brand), #6f9bff);
  color: #fff; display: grid; place-items: center; font-size: 15px; font-weight: 800;
}
.brand__sub { color: var(--muted); font-size: 12px; font-weight: 500; }

.who { display: flex; align-items: center; gap: 12px; font-size: 14px; }
.who__name { font-weight: 600; }
.who__class { color: var(--muted); font-size: 13px; }

.btn {
  border: 1px solid transparent;
  border-radius: 10px;
  padding: 9px 16px;
  background: var(--brand);
  color: #fff;
  font-weight: 600;
  cursor: pointer;
  transition: .15s ease;
}
.btn:hover { background: var(--brand-dark); }
.btn:disabled { opacity: .55; cursor: not-allowed; }
.btn--ghost { background: #fff; border-color: var(--line); color: var(--ink); }
.btn--ghost:hover { background: #f7f9fc; }
.btn--danger { background: var(--red); }
.btn--danger:hover { background: #a92a2a; }
.btn--sm { padding: 6px 12px; font-size: 13px; border-radius: 8px; }

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

/* ---------- вход ---------- */
.login-page {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
  background:
    radial-gradient(900px 500px at 15% -10%, #dfe8ff 0%, transparent 60%),
    radial-gradient(700px 500px at 110% 110%, #e4f7ee 0%, transparent 55%),
    var(--bg);
}
.login {
  width: min(420px, 100%);
  padding: 34px 32px 30px;
}
.login h1 { margin: 0 0 6px; font-size: 24px; letter-spacing: -.4px; }
.login p.sub { margin: 0 0 24px; color: var(--muted); font-size: 14px; }
.field { margin-bottom: 14px; }
.field label { display: block; font-size: 13px; font-weight: 600; margin-bottom: 6px; color: #3d4a5c; }
.field input, .field select {
  width: 100%;
  padding: 11px 13px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fbfcfe;
  outline: none;
  transition: .15s;
}
.field input:focus, .field select:focus { border-color: var(--brand); background: #fff; box-shadow: 0 0 0 3px rgba(47, 109, 246, .12); }
.login .btn { width: 100%; padding: 12px; margin-top: 6px; }
.hint { margin-top: 16px; font-size: 12.5px; color: var(--muted); line-height: 1.6; }
.error {
  display: none;
  background: var(--red-soft);
  color: var(--red);
  border: 1px solid #f3cccc;
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 13.5px;
  margin-bottom: 14px;
}
.error.show { display: block; }

/* ---------- список уроков ---------- */
.page-head { padding: 26px 0 6px; }
.page-head h1 { margin: 0 0 4px; font-size: 26px; letter-spacing: -.5px; }
.page-head p { margin: 0; color: var(--muted); font-size: 14px; }

.progress-summary {
  margin: 18px 0 22px;
  padding: 18px 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 22px 34px;
  align-items: center;
}
.stat__value { font-size: 22px; font-weight: 700; letter-spacing: -.5px; }
.stat__label { font-size: 12.5px; color: var(--muted); }
.bar { height: 9px; border-radius: 99px; background: #e9edf5; overflow: hidden; flex: 1 1 180px; }
.bar__fill { height: 100%; border-radius: 99px; background: linear-gradient(90deg, var(--brand), #57a0ff); transition: width .4s ease; }

.lesson-list { display: grid; gap: 12px; padding-bottom: 40px; }
.lesson {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 18px;
  cursor: pointer;
  transition: .15s ease;
}
.lesson:hover { border-color: #c3d3f5; transform: translateY(-1px); }
.lesson__num {
  width: 38px; height: 38px; flex: 0 0 auto;
  border-radius: 10px;
  background: var(--brand-soft);
  color: var(--brand-dark);
  display: grid; place-items: center;
  font-weight: 700; font-size: 14px;
}
.lesson__body { flex: 1 1 auto; min-width: 0; }
.lesson__title { font-weight: 600; font-size: 15px; }
.lesson__meta { color: var(--muted); font-size: 12.5px; margin-top: 2px; }
.lesson__score { flex: 0 0 auto; text-align: right; }
.pill {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 99px;
  font-size: 12px;
  font-weight: 600;
}
.pill--none { background: #eef1f7; color: var(--muted); }
.pill--ok { background: var(--green-soft); color: var(--green); }
.pill--mid { background: var(--amber-soft); color: var(--amber); }
.pill--bad { background: var(--red-soft); color: var(--red); }

/* ---------- задание ---------- */
.quiz-head { padding: 22px 0 10px; }
.backlink {
  background: none; border: 0; padding: 0; color: var(--brand-dark);
  font-size: 13.5px; font-weight: 600; cursor: pointer; margin-bottom: 10px;
}
.quiz-head h1 { margin: 0 0 6px; font-size: 22px; letter-spacing: -.4px; }

.theory {
  background: var(--brand-soft);
  border: 1px solid #d3e0ff;
  border-left: 4px solid var(--brand);
  border-radius: 0 10px 10px 0;
  padding: 14px 18px;
  margin: 12px 0 20px;
  font-size: 14.5px;
}

.q {
  padding: 18px 20px;
  margin-bottom: 12px;
}
.q__text { font-weight: 600; margin-bottom: 12px; font-size: 15px; }
.opt {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  margin-bottom: 8px;
  cursor: pointer;
  transition: .12s;
  background: #fbfcfe;
}
.opt:hover { border-color: #b9cbf1; background: #f6f9ff; }
.opt input { margin-top: 3px; accent-color: var(--brand); }
.opt.selected { border-color: var(--brand); background: var(--brand-soft); }
.opt.correct { border-color: var(--green); background: var(--green-soft); }
.opt.wrong { border-color: var(--red); background: var(--red-soft); }
.opt__mark { margin-left: auto; font-size: 13px; font-weight: 700; }
.explain {
  margin-top: 10px;
  font-size: 13.5px;
  color: #40506a;
  background: #f7f9fc;
  border-radius: 8px;
  padding: 9px 12px;
}

.actions { display: flex; gap: 10px; align-items: center; padding: 6px 0 40px; flex-wrap: wrap; }
.actions .spacer { flex: 1 1 auto; }

.result {
  padding: 26px;
  text-align: center;
  margin-bottom: 16px;
}
.result__score { font-size: 44px; font-weight: 800; letter-spacing: -1.5px; line-height: 1; }
.result__score span { font-size: 20px; color: var(--muted); font-weight: 600; }
.result__msg { margin: 8px 0 0; color: var(--muted); }

/* ---------- учитель ---------- */
.tabs { display: flex; gap: 6px; margin: 18px 0 18px; flex-wrap: wrap; }
.tab {
  border: 1px solid var(--line);
  background: #fff;
  color: var(--muted);
  padding: 8px 15px;
  border-radius: 99px;
  cursor: pointer;
  font-size: 13.5px;
  font-weight: 600;
}
.tab.active { background: var(--brand); border-color: var(--brand); color: #fff; }

.panel { display: none; padding-bottom: 40px; }
.panel.active { display: block; }

.table-wrap { overflow-x: auto; }
table.data { width: 100%; border-collapse: collapse; font-size: 13.5px; background: #fff; }
table.data th, table.data td { padding: 10px 12px; border-bottom: 1px solid var(--line); text-align: left; vertical-align: middle; }
table.data th { background: #f7f9fc; font-size: 12.5px; color: var(--muted); text-transform: uppercase; letter-spacing: .04em; }
table.data tr:last-child td { border-bottom: 0; }
.mini-bar { width: 90px; height: 6px; border-radius: 99px; background: #e9edf5; overflow: hidden; display: inline-block; vertical-align: middle; }
.mini-bar i { display: block; height: 100%; background: var(--brand); }
.muted { color: var(--muted); }
.chips { display: flex; flex-wrap: wrap; gap: 4px; }
.chip {
  font-size: 11px; padding: 2px 7px; border-radius: 6px;
  background: #eef1f7; color: var(--muted); font-weight: 600;
}
.chip.ok { background: var(--green-soft); color: var(--green); }
.chip.mid { background: var(--amber-soft); color: var(--amber); }
.chip.bad { background: var(--red-soft); color: var(--red); }

.form-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 12px; }
.form-card { padding: 22px; max-width: 620px; }
.form-row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin-top: 12px; }

.notice {
  padding: 12px 16px;
  border-radius: 10px;
  font-size: 13.5px;
  margin: 12px 0;
  background: var(--amber-soft);
  color: #6b4a00;
  border: 1px solid #f0dcae;
}
.notice.ok { background: var(--green-soft); color: var(--green); border-color: #c4e6d5; }

.empty { padding: 30px; text-align: center; color: var(--muted); font-size: 14px; }

.toast {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: #1b2637;
  color: #fff;
  padding: 11px 18px;
  border-radius: 10px;
  font-size: 13.5px;
  opacity: 0;
  pointer-events: none;
  transition: .2s ease;
  z-index: 100;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

@media (max-width: 640px) {
  .lesson { flex-wrap: wrap; }
  .lesson__score { width: 100%; text-align: left; }
  .who__class { display: none; }
  .result__score { font-size: 36px; }
}