/* Question navigator: sticky side panel on wide screens, compact bar + bottom sheet on small screens. */

.nav-progress {
  display: flex;
  height: 6px;
  overflow: hidden;
  border-radius: 6px;
  background: var(--track);
}
.nav-progress i { display: block; height: 100%; transition: width .3s ease; }
.nav-progress .is-correct { background: var(--success); }
.nav-progress .is-wrong { background: var(--danger); }

/* ---------- Panel ---------- */
.exam-nav {
  display: grid;
  gap: 14px;
  align-content: start;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: var(--surface);
  box-shadow: 0 5px 20px rgba(22, 32, 61, .03);
}
.nav-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 10px; }
.nav-head h2 { margin: 0; font-size: 1rem; }
.nav-head p { margin: 2px 0 0; color: var(--muted); font-size: .76rem; }
.nav-close {
  display: none;
  place-items: center;
  flex: none;
  width: 34px;
  height: 34px;
  border: 1px solid var(--line);
  border-radius: 11px;
  color: var(--muted);
  background: var(--surface);
  cursor: pointer;
  font: inherit;
  font-size: 1.25rem;
  line-height: 1;
}

.nav-filters { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 6px; }
.nav-filter {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 6px;
  min-width: 0;
  padding: 6px 7px 6px 11px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--ink-2);
  background: var(--surface);
  cursor: pointer;
  font: inherit;
  font-size: .74rem;
  font-weight: 700;
  transition: border-color .15s, background .15s, color .15s;
}
.nav-filter b {
  min-width: 22px;
  padding: 0 6px;
  border-radius: 999px;
  color: var(--ink-3);
  background: var(--fill);
  font-size: .68rem;
  line-height: 19px;
  text-align: center;
}
.nav-filter:hover:not(:disabled) { border-color: var(--primary-line-strong); }
.nav-filter.is-important:not(.is-active) { color: var(--danger-ink); }
.nav-filter.is-active { border-color: var(--primary); color: var(--primary); background: var(--primary-bg); }
.nav-filter.is-active b { color: #fff; background: var(--primary-solid); }
.nav-filter:disabled { opacity: .45; cursor: default; }

.nav-grid { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 7px; }
.nav-cell {
  position: relative;
  display: grid;
  place-items: center;
  height: 42px;
  padding-top: 7px;
  border: 1px solid var(--line);
  border-radius: 11px;
  color: var(--ink-3);
  background: var(--surface);
  cursor: pointer;
  font: inherit;
  font-size: .82rem;
  font-weight: 700;
  transition: transform .15s, border-color .15s, box-shadow .15s;
}
/* Importance level badge: solid red ★ for level 1, tinted number for levels 2–5. */
.level-mark {
  display: inline-grid;
  place-items: center;
  min-width: 15px;
  height: 15px;
  padding: 0 3px;
  border: 1px solid var(--tier-line);
  border-radius: 5px;
  color: var(--tier);
  background: var(--tier-bg);
  font-size: 9px;
  font-style: normal;
  font-weight: 800;
  line-height: 1;
}
.level-mark.tier-1 { border-color: var(--tier-1-solid); color: #fff; background: var(--tier-1-solid); }
.nav-cell .level-mark { position: absolute; top: 3px; left: 3px; }
.nav-cell:hover { border-color: var(--primary-line-strong); transform: translateY(-1px); }
.nav-cell.is-correct { border-color: var(--success-line); color: var(--success); background: var(--success-bg); }
.nav-cell.is-wrong { border-color: var(--danger-line); color: var(--danger); background: var(--danger-bg); }
.nav-cell.is-missed { border-style: dashed; border-color: var(--warn-line); color: var(--warn-ink); background: var(--warn-bg); }
.nav-cell.is-current { z-index: 1; box-shadow: 0 0 0 2px var(--surface), 0 0 0 4px var(--primary); }
.nav-cell.is-current.is-unanswered { border-color: var(--primary); color: var(--primary); background: var(--primary-bg); }

.nav-empty {
  margin: 0;
  padding: 18px 10px;
  border: 1px dashed var(--line);
  border-radius: 12px;
  color: var(--muted);
  font-size: .8rem;
  text-align: center;
}

.nav-pager { display: flex; align-items: center; justify-content: space-between; gap: 8px; color: var(--muted); font-size: .76rem; }
.nav-pager button {
  width: 34px;
  height: 30px;
  border: 1px solid var(--line);
  border-radius: 9px;
  color: var(--ink);
  background: var(--surface);
  cursor: pointer;
  font: inherit;
}
.nav-pager button:disabled { opacity: .4; cursor: default; }

.nav-jump {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--primary-line);
  border-radius: 12px;
  color: var(--primary);
  background: var(--primary-bg-soft);
  cursor: pointer;
  font: inherit;
  font-size: .82rem;
  font-weight: 700;
  transition: background .15s;
}
.nav-jump:hover:not(:disabled) { background: var(--primary-bg); }
.nav-jump:disabled { border-color: var(--line); color: var(--muted); background: var(--fill-soft); cursor: default; }

.nav-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 7px 12px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: .7rem;
}
.nav-legend span { display: inline-flex; align-items: center; gap: 5px; white-space: nowrap; }
.swatch { display: inline-block; width: 11px; height: 11px; border: 1px solid var(--line); border-radius: 4px; background: var(--surface); }
.swatch.is-correct { border-color: var(--success-line); background: var(--success-bg); }
.swatch.is-wrong { border-color: var(--danger-line); background: var(--danger-bg); }
.swatch.is-missed { border: 1px dashed var(--warn-line); background: var(--warn-bg); }
.nav-legend .legend-levels { flex-basis: 100%; gap: 4px; flex-wrap: wrap; }
.nav-legend .legend-levels small { margin-right: 2px; font-size: .66rem; }

/* ---------- Compact bar (small screens) ---------- */
.nav-bar { display: none; }

@media (min-width: 821px) {
  .exam-layout { grid-template-columns: minmax(0, 1fr) 292px; }
  .exam-nav {
    position: sticky;
    top: 164px;
    align-self: start;
    max-height: calc(100vh - 184px);
    overflow-y: auto;
    scrollbar-width: thin;
  }
  .nav-backdrop { display: none; }
}

@media (max-width: 820px) {
  .nav-bar {
    position: sticky;
    top: 8px;
    z-index: 20;
    display: grid;
    gap: 9px;
    padding: 11px 13px 12px;
    border: 1px solid var(--line);
    border-radius: 16px;
    background: rgba(var(--glass), .95);
    box-shadow: 0 8px 22px rgba(22, 32, 61, .07);
    backdrop-filter: blur(12px);
  }
  .nav-bar-row { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
  .nav-bar-text { display: grid; min-width: 0; }
  .nav-bar-text strong { font-size: .9rem; white-space: nowrap; }
  .nav-bar-text em { color: var(--muted); font-size: .76rem; font-style: normal; font-weight: 600; }
  .nav-bar-text span { color: var(--muted); font-size: .7rem; white-space: nowrap; }
  .nav-bar-actions { display: flex; flex: none; gap: 6px; }
  .nav-bar-jump,
  .nav-bar-open {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    min-height: 36px;
    padding: 0 11px;
    border: 1px solid transparent;
    border-radius: 11px;
    cursor: pointer;
    font: inherit;
    font-size: .75rem;
    font-weight: 700;
    white-space: nowrap;
  }
  .nav-bar-jump { border-color: var(--primary-line); color: var(--primary); background: var(--primary-bg-soft); }
  .nav-bar-jump:disabled { border-color: var(--line); color: var(--muted); background: var(--fill-soft); cursor: default; }
  .nav-bar-open { color: #fff; background: var(--primary-solid); box-shadow: 0 6px 14px rgba(69, 89, 230, .22); }
  .grid-icon {
    width: 12px;
    height: 12px;
    background:
      linear-gradient(currentColor, currentColor) 0 0 / 5px 5px no-repeat,
      linear-gradient(currentColor, currentColor) 100% 0 / 5px 5px no-repeat,
      linear-gradient(currentColor, currentColor) 0 100% / 5px 5px no-repeat,
      linear-gradient(currentColor, currentColor) 100% 100% / 5px 5px no-repeat;
  }

  /* Bottom sheet */
  .exam-nav {
    position: fixed;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 40;
    max-height: min(86vh, 660px);
    overflow-y: auto;
    overscroll-behavior: contain;
    padding: 10px 18px calc(18px + env(safe-area-inset-bottom));
    border-width: 1px 0 0;
    border-radius: 22px 22px 0 0;
    box-shadow: 0 -18px 50px rgba(22, 32, 61, .18);
    transform: translateY(calc(100% + 24px));
    visibility: hidden;
    transition: transform .28s ease, visibility 0s linear .28s;
  }
  .exam-nav::before {
    content: "";
    justify-self: center;
    width: 42px;
    height: 5px;
    border-radius: 5px;
    background: var(--line-strong);
  }
  .exam-nav.is-open { transform: none; visibility: visible; transition: transform .28s ease; }
  .nav-close { display: grid; }
  .nav-filters { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .nav-filter { flex-direction: column; justify-content: center; gap: 3px; padding: 7px 4px; border-radius: 12px; }
  .nav-grid { grid-template-columns: repeat(auto-fill, minmax(44px, 1fr)); gap: 8px; }
  .nav-cell { height: 46px; }

  .nav-backdrop {
    position: fixed;
    inset: 0;
    z-index: 35;
    background: rgba(15, 22, 42, .42);
    opacity: 0;
    pointer-events: none;
    transition: opacity .25s ease;
  }
  .nav-backdrop.is-open { opacity: 1; pointer-events: auto; }
  html.nav-sheet-open,
  html.nav-sheet-open body { overflow: hidden; }
}

@media (max-width: 340px) {
  .nav-bar-row { flex-wrap: wrap; }
  .nav-bar-actions { width: 100%; }
  .nav-bar-jump, .nav-bar-open { flex: 1; justify-content: center; }
}

@media (prefers-reduced-motion: reduce) {
  .exam-nav, .nav-backdrop, .nav-progress i, .nav-cell { transition: none; }
}