.shell {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--zk-tint);
}

/* ── Masthead ─────────────────────────────────────────────────────────────── */
.shell__top {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  gap: 22px;
  height: 56px;
  padding: 0 24px;
  background: var(--zk-navy);
  color: #fff;
}

.mast__logo { display: flex; align-items: center; gap: 10px; }
.mast__z {
  width: 30px; height: 30px; border-radius: 50%;
  background: #fff; color: var(--zk-navy);
  font-weight: 700; font-size: 17px;
  display: grid; place-items: center;
}
.mast__word b { display: block; font-weight: 700; font-size: 17px; letter-spacing: .06em; line-height: 1.15; }
.mast__word b span { font-weight: 500; letter-spacing: 0; }
.mast__word small { display: block; font-size: 11.5px; opacity: .75; margin-top: -1px; letter-spacing: .02em; }

.mast__sep { width: 1px; height: 26px; background: rgba(255, 255, 255, .22); }

.mast__app { font-size: 17px; font-weight: 600; }
.mast__app span { font-weight: 400; opacity: .7; margin-left: 8px; font-size: 15px; }

.mast__user { margin-left: auto; }

/* ── Frame ────────────────────────────────────────────────────────────────── */
.shell__body { display: flex; flex: 1; min-height: 0; align-items: stretch; }

.shell__nav {
  position: sticky;
  top: 56px;
  align-self: flex-start;
  width: 232px;
  flex: none;
  min-height: calc(100vh - 56px);
  max-height: calc(100vh - 56px);
  overflow-y: auto;
  overscroll-behavior: contain;
  background: #fff;
  border-right: 1px solid var(--zk-line);
  padding: 20px 12px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.nav__h {
  margin: 0;
  padding: 18px 12px 6px;
  font-size: var(--fs-3xs);
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--zk-grey);
}
.nav__group { display: flex; flex-direction: column; gap: 2px; }

.nav__link {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 12px;
  border-radius: var(--r-sm);
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--zk-muted);
  text-decoration: none;
  cursor: pointer;
  transition: background var(--t-fast), color var(--t-fast);
}
.nav__link:hover { background: var(--zk-tint); color: var(--zk-ink); }
.nav__link.is-on {
  background: var(--zk-tint-blue);
  color: var(--zk-navy);
  font-weight: 600;
  box-shadow: inset 3px 0 0 var(--zk-blue);
}
.nav__name { min-width: 0; line-height: 1.35; }

/* The count is who is being waited on: red a person urgently, amber the
   customer, grey the calendar or history. */
.nav__n {
  margin-left: auto;
  font-size: var(--fs-2xs);
  font-weight: 600;
  padding: 1px 8px;
  border-radius: var(--r-pill);
  font-variant-numeric: tabular-nums;
  background: var(--zk-line-soft);
  color: var(--zk-muted);
}
.nav__n--red   { background: var(--zk-danger-tint); color: var(--zk-danger); }
.nav__n--amber { background: var(--zk-amber-tint);  color: var(--zk-amber); }
.nav__n--blue  { background: var(--zk-tint-blue);   color: var(--zk-blue); }

/* Closed folds. The summary IS a nav row; a chevron says it opens. */
.nav__fold > summary { list-style: none; }
.nav__fold > summary::-webkit-details-marker { display: none; }
.nav__fold > summary .nav__name::before {
  content: '';
  display: inline-block;
  width: 5px; height: 5px;
  margin: 0 8px 1px 0;
  border-right: 1.5px solid var(--zk-grey);
  border-bottom: 1.5px solid var(--zk-grey);
  transform: rotate(-45deg);
  transition: transform var(--t-fast);
}
.nav__fold[open] > summary .nav__name::before { transform: rotate(45deg); }
.nav__sub { display: flex; flex-direction: column; gap: 2px; padding-left: 12px; }

/* ── Canvas ───────────────────────────────────────────────────────────────── */
.shell__main {
  flex: 1;
  min-width: 0;
  width: 100%;
  background: var(--zk-tint);
  padding: 28px 32px 40px;
}

@media (max-width: 900px) {
  .shell__body { flex-direction: column; }
  .shell__nav {
    position: static; width: 100%; min-height: 0; max-height: none;
    border-right: 0; border-bottom: 1px solid var(--zk-line);
    flex-direction: row; flex-wrap: wrap; padding: 10px 12px;
  }
  .nav__h { display: none; }
  .nav__group { flex-direction: row; flex-wrap: wrap; }
  .shell__main { padding: 20px 16px 48px; }
}