/* ===== П2 Испити — mobile-first styles ===== */
:root {
  --bg: #f5f6f8;
  --surface: #ffffff;
  --surface-2: #eef0f4;
  --text: #1c2128;
  --text-dim: #5b6472;
  --border: #dde1e7;
  --accent: #2563eb;
  --accent-soft: #dbe7ff;
  --green: #16803c;
  --green-soft: #d9f2e2;
  --red: #c22f2f;
  --red-soft: #fbe1e1;
  --amber: #92600a;
  --amber-soft: #fdf0d4;
  --code-bg: #f1f3f6;
  --shadow: 0 1px 3px rgba(15, 23, 42, .08), 0 4px 14px rgba(15, 23, 42, .06);
  --radius: 14px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101418;
    --surface: #181e26;
    --surface-2: #212934;
    --text: #e6e9ee;
    --text-dim: #9aa4b2;
    --border: #2c3542;
    --accent: #5b8def;
    --accent-soft: #1e2c47;
    --green: #4cc276;
    --green-soft: #15301f;
    --red: #ef6c6c;
    --red-soft: #3a1c1c;
    --amber: #e0a83f;
    --amber-soft: #33270f;
    --code-bg: #12171d;
    --shadow: 0 1px 3px rgba(0, 0, 0, .4);
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: baseline;
  gap: .75rem;
  padding: .8rem 1rem calc(.8rem);
  padding-left: max(1rem, env(safe-area-inset-left));
  padding-right: max(1rem, env(safe-area-inset-right));
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
.brand {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text);
  text-decoration: none;
  letter-spacing: .01em;
}
.brand span { color: var(--accent); }
.brand-sub { font-size: .72rem; color: var(--text-dim); }

main {
  flex: 1;
  width: 100%;
  max-width: 860px;
  margin: 0 auto;
  padding: 1rem;
  padding-left: max(1rem, env(safe-area-inset-left));
  padding-right: max(1rem, env(safe-area-inset-right));
}
.site-footer {
  max-width: 860px;
  margin: 0 auto;
  padding: 1rem 1.25rem 2rem;
  font-size: .74rem;
  color: var(--text-dim);
  text-align: center;
}
.loading { text-align: center; color: var(--text-dim); padding: 3rem 0; }

/* ===== Home ===== */
.hero {
  background: linear-gradient(135deg, var(--accent) 0%, color-mix(in srgb, var(--accent) 60%, #7c3aed) 100%);
  color: #fff;
  border-radius: var(--radius);
  padding: 1.25rem 1.25rem 1.4rem;
  margin-bottom: 1.4rem;
  box-shadow: var(--shadow);
}
.hero h1 { margin: 0 0 .3rem; font-size: 1.35rem; }
.hero p { margin: 0 0 1rem; font-size: .92rem; opacity: .92; }
.hero .btn { background: #fff; color: #1d4ed8; border: none; font-weight: 700; }
.hero .btn:active { transform: scale(.97); }

.section-title {
  font-size: .8rem;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--text-dim);
  margin: 1.5rem 0 .6rem;
  font-weight: 700;
}
.exam-grid { display: grid; grid-template-columns: 1fr; gap: .7rem; }
@media (min-width: 620px) { .exam-grid { grid-template-columns: 1fr 1fr; } }

.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: .6rem;
}
.topic-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: .7rem .9rem;
  text-decoration: none;
  color: var(--text);
  font-weight: 600;
  font-size: .9rem;
  display: flex;
  flex-direction: column;
  gap: .15rem;
  box-shadow: var(--shadow);
  transition: transform .06s ease;
}
.topic-card:active { transform: scale(.98); }
.topic-count { font-size: .75rem; color: var(--text-dim); font-weight: 500; }

.exam-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: .9rem 1rem;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: .55rem;
}
.exam-card .row1 { display: flex; align-items: center; justify-content: space-between; gap: .5rem; }
.exam-card h3 { margin: 0; font-size: 1.02rem; }
.exam-card .meta { font-size: .78rem; color: var(--text-dim); }
.badge {
  font-size: .68rem;
  font-weight: 700;
  padding: .15rem .5rem;
  border-radius: 99px;
  white-space: nowrap;
}
.badge.ai { background: var(--amber-soft); color: var(--amber); }
.badge.prev { background: var(--accent-soft); color: var(--accent); }
.exam-card .actions { display: flex; gap: .5rem; }

/* ===== Buttons ===== */
.btn {
  appearance: none;
  border: 1px solid var(--border);
  background: var(--surface-2);
  color: var(--text);
  font: inherit;
  font-size: .92rem;
  font-weight: 600;
  padding: .55rem 1rem;
  border-radius: 10px;
  cursor: pointer;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .4rem;
  min-height: 44px;
  transition: transform .06s ease, background .15s ease;
  touch-action: manipulation;
}
.btn:active { transform: scale(.97); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.ghost { background: transparent; }
.btn.danger { background: var(--red); border-color: var(--red); color: #fff; }
.btn.block { width: 100%; }
.btn:disabled { opacity: .45; cursor: default; }
.btn-row { display: flex; gap: .6rem; margin-top: 1rem; }
.btn-row .btn { flex: 1; }

/* ===== Question rendering ===== */
.q-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  box-shadow: var(--shadow);
  margin-bottom: .9rem;
}
.q-head { display: flex; gap: .6rem; align-items: baseline; margin-bottom: .4rem; }
.q-head > div { min-width: 0; flex: 1; }
.q-num {
  flex-shrink: 0;
  font-weight: 800;
  color: var(--accent);
  font-size: .95rem;
}
.q-text { margin: 0; font-size: .95rem; }
pre.code {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: .7rem .8rem;
  overflow-x: auto;
  font-family: ui-monospace, "Cascadia Code", Consolas, Menlo, monospace;
  font-size: .8rem;
  line-height: 1.45;
  margin: .7rem 0;
  -webkit-overflow-scrolling: touch;
}
.options { list-style: none; margin: .7rem 0 0; padding: 0; display: flex; flex-direction: column; gap: .5rem; }
.opt {
  display: flex;
  gap: .65rem;
  align-items: flex-start;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  padding: .6rem .7rem;
  font-size: .92rem;
  background: var(--surface);
  width: 100%;
  text-align: left;
  color: var(--text);
  font-family: inherit;
  cursor: pointer;
  transition: border-color .12s ease, background .12s ease;
}
button.opt:active { background: var(--surface-2); }
.opt .letter {
  flex-shrink: 0;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--surface-2);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .8rem;
  font-weight: 700;
  color: var(--text-dim);
}
.opt .opt-body { flex: 1; min-width: 0; }
.opt pre.code { margin: .1rem 0 0; }
.opt.selected { border-color: var(--accent); background: var(--accent-soft); }
.opt.selected .letter { background: var(--accent); border-color: var(--accent); color: #fff; }
.opt.correct { border-color: var(--green); background: var(--green-soft); }
.opt.correct .letter { background: var(--green); border-color: var(--green); color: #fff; }
.opt.wrong { border-color: var(--red); background: var(--red-soft); }
.opt.wrong .letter { background: var(--red); border-color: var(--red); color: #fff; }

.explain {
  margin-top: .7rem;
  background: var(--surface-2);
  border-left: 3px solid var(--accent);
  border-radius: 8px;
  padding: .6rem .8rem;
  font-size: .87rem;
}
.explain b { color: var(--accent); }

/* ===== Overview toolbar ===== */
.toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: .8rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}
.toolbar h2 { margin: 0; font-size: 1.15rem; flex: 1; }
.back-link { color: var(--accent); text-decoration: none; font-weight: 600; font-size: .9rem; }
.switch-label { display: inline-flex; align-items: center; gap: .5rem; font-size: .85rem; font-weight: 600; cursor: pointer; user-select: none; }
.switch-label input { position: absolute; opacity: 0; }
.switch-ui {
  width: 44px; height: 26px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 99px;
  position: relative;
  transition: background .15s ease;
}
.switch-ui::after {
  content: "";
  position: absolute;
  top: 2px; left: 2px;
  width: 20px; height: 20px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 1px 3px rgba(0,0,0,.3);
  transition: transform .15s ease;
}
.switch-label input:checked + .switch-ui { background: var(--green); border-color: var(--green); }
.switch-label input:checked + .switch-ui::after { transform: translateX(18px); }

.notes-box {
  background: var(--amber-soft);
  color: var(--amber);
  border-radius: 10px;
  padding: .6rem .8rem;
  font-size: .8rem;
  margin-bottom: 1rem;
}

/* ===== Take mode ===== */
.take-top { display: flex; align-items: center; gap: .7rem; margin-bottom: .8rem; }
.progressbar {
  flex: 1;
  height: 8px;
  background: var(--surface-2);
  border-radius: 99px;
  overflow: hidden;
}
.progressbar > div { height: 100%; background: var(--accent); border-radius: 99px; transition: width .2s ease; }
.take-count { font-size: .82rem; font-weight: 700; color: var(--text-dim); white-space: nowrap; }
.timer { font-size: .82rem; color: var(--text-dim); font-variant-numeric: tabular-nums; }

.dots { display: flex; gap: .35rem; flex-wrap: wrap; margin: .8rem 0 1rem; justify-content: center; }
.dot {
  width: 34px; height: 34px;
  border-radius: 50%;
  border: 1.5px solid var(--border);
  background: var(--surface);
  color: var(--text-dim);
  font-size: .8rem;
  font-weight: 700;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  font-family: inherit;
}
.dot.answered { background: var(--accent-soft); border-color: var(--accent); color: var(--accent); }
.dot.ok { background: var(--green-soft); border-color: var(--green); color: var(--green); }
.dot.bad { background: var(--red-soft); border-color: var(--red); color: var(--red); }
.dot.seen { background: var(--surface-2); border-color: var(--text-dim); color: var(--text-dim); }
.dot.current { border-color: var(--accent); background: var(--accent); color: #fff; }

/* Practice with instant feedback */
.practice-bar { display: flex; justify-content: flex-end; margin: -.2rem 0 .2rem; }
.practice-bar .switch-label { font-size: .8rem; color: var(--text-dim); }
button.opt:disabled { cursor: default; opacity: 1; }
.verdict-row { display: flex; margin-top: .7rem; }
.verdict-row .result-tag { margin-left: 0; }

.modal-back {
  position: fixed; inset: 0;
  background: rgba(0,0,0,.5);
  display: flex; align-items: center; justify-content: center;
  padding: 1.5rem;
  z-index: 50;
}
.modal {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 1.2rem;
  max-width: 380px;
  width: 100%;
  box-shadow: var(--shadow);
}
.modal h3 { margin: 0 0 .5rem; }
.modal p { margin: 0 0 1rem; font-size: .9rem; color: var(--text-dim); }

/* ===== Results ===== */
.score-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.3rem 1rem;
  text-align: center;
  margin-bottom: 1.2rem;
}
.score-big { font-size: 2.4rem; font-weight: 800; margin: .2rem 0; }
.score-big small { font-size: 1.1rem; color: var(--text-dim); font-weight: 600; }
.score-sub { color: var(--text-dim); font-size: .85rem; }
.score-pills { display: flex; justify-content: center; gap: .5rem; margin-top: .9rem; flex-wrap: wrap; }
.pill { font-size: .78rem; font-weight: 700; padding: .25rem .7rem; border-radius: 99px; }
.pill.ok { background: var(--green-soft); color: var(--green); }
.pill.bad { background: var(--red-soft); color: var(--red); }
.pill.skip { background: var(--surface-2); color: var(--text-dim); }

.result-tag { font-size: .78rem; font-weight: 700; margin-left: auto; white-space: nowrap; }
.result-tag.ok { color: var(--green); }
.result-tag.bad { color: var(--red); }
.result-tag.skip { color: var(--text-dim); }

.reveal-btn {
  background: none; border: none; color: var(--accent);
  font: inherit; font-size: .83rem; font-weight: 600;
  cursor: pointer; padding: .3rem 0; margin-top: .3rem;
}

@media (max-width: 480px) {
  .brand-sub { display: none; }
  main { padding: .75rem; }
  .q-card { padding: .85rem; }
}