/* Shared course footer and navigation. Uses each page's own colour tokens,
   so it follows the page's template and dark mode. */
.pbs-footer {
  max-width: 820px;
  margin: 0 auto;
  padding: 8px 0 40px;
  color: var(--slate, #5E6870);
  font-size: 13.5px;
  line-height: 1.6;
}
.pbs-footer.pbs-standalone { max-width: 760px; padding: 0 18px 40px; }
.pbs-footer p { margin: 0 0 4px; }
.pbs-footer a { color: var(--blue-d, #2B5A8C); font-weight: 800; text-decoration: none; }
.pbs-footer a:hover { text-decoration: underline; }
.pbs-author { color: var(--ink, #2D3439); font-weight: 800; }
.pbs-course b { color: var(--ink, #2D3439); font-weight: 900; }

/* The one bottom navigation row on every lesson: ← previous · Course map · next → */
.pbs-pn {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: baseline;
  gap: 8px 16px;
  padding: 26px 0 0;
  font-weight: 800;
  font-size: 14.5px;
  line-height: 1.4;
}
.pbs-pn a { color: var(--blue-d, #2B5A8C); text-decoration: none; }
.pbs-pn a:hover { text-decoration: underline; }
.pbs-pn .pbs-prev { text-align: left; min-width: 0; }
.pbs-pn .pbs-mid { text-align: center; white-space: nowrap; color: var(--slate, #5E6870); }
.pbs-pn .pbs-next { text-align: right; min-width: 0; }
.pbs-pn .gltrig { font-size: inherit; }

@media (max-width: 560px) {
  .pbs-pn { grid-template-columns: 1fr; gap: 10px; }
  .pbs-pn span.pbs-prev:empty, .pbs-pn span.pbs-next:empty { display: none; }
}

/* About button: right-hand end of every page's header bar */
.pbs-about {
  flex: none;
  display: inline-flex;
  align-items: center;
  font-family: var(--sans, "Nunito", system-ui, sans-serif);
  font-weight: 800;
  font-size: 13.5px;
  line-height: 1.2;
  color: var(--slate, #5E6870);
  background: transparent;
  border: 2px solid var(--line, #DEE3E6);
  border-radius: 12px;
  padding: 5px 10px;
  text-decoration: none;
  white-space: nowrap;
}
.pbs-about:hover { color: var(--blue-d, #2B5A8C); border-color: var(--blue-d, #2B5A8C); }
@media (max-width: 420px) {
  .pbs-about { font-size: 12.5px; padding: 4px 8px; }
}

/* Contract-work line at the end of the closing lessons */
.pbs-footer .pbs-work {
  margin: 0 0 16px;
  padding: 12px 16px;
  border: 2px solid var(--line, #DEE3E6);
  border-radius: 12px;
  color: var(--ink, #2D3439);
  font-size: 15px;
  font-weight: 700;
}

/* Files popup and glossary sheet: a centred box with a full border, not a sheet from the bottom.
   "html" outranks each page's own .gback / .gsheet rules, which load after this file. */
html .gback, .pbs-fback { align-items: center; padding: 24px 16px; }
html .gsheet, .pbs-fsheet {
  border: 2px solid var(--line, #DEE3E6);
  border-radius: 22px;
  max-height: calc(100vh - 48px);
  max-height: calc(100dvh - 48px);
  padding: 22px 20px;
}
@media (max-width: 520px) {
  html .gback, .pbs-fback { padding: 12px; }
  html .gsheet, .pbs-fsheet { max-height: calc(100vh - 24px); max-height: calc(100dvh - 24px); padding: 20px 16px; }
}

/* Files button and popup for the series whose template has none (build-site.py add_files, assets/js/files.js).
   Same look as the Tiles and Scaffolding popup, under pbs-f* names so the templates' own classes don't clash. */
.pbs-files {
  flex: none;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font: 900 14px var(--sans, "Nunito", system-ui, sans-serif);
  line-height: 1.2;
  color: var(--blue-d, #2B5A8C);
  background: var(--panel, #FFFFFF);
  border: 2px solid var(--line, #DEE3E6);
  border-bottom-width: 4px;
  border-radius: 12px;
  padding: 5px 10px;
  cursor: pointer;
  white-space: nowrap;
}
.pbs-files:active { transform: translateY(2px); border-bottom-width: 2px; }
.pbs-files svg { width: 18px; height: 18px; }
@media (max-width: 430px) {
  .pbs-files span { display: none; }
  .pbs-files { padding: 5px 7px; }
  /* the added button needs room: tighten only the headers that carry it */
  header .bar:has(.pbs-files) { gap: 8px; }
  header .bar:has(.pbs-files) .pbar { min-width: 24px; }
  header .bar:has(.pbs-files) .home span { display: none; }
  header.top .top-in:has(.pbs-files) { gap: 8px; padding-left: 12px; padding-right: 12px; }
  header.top .top-in:has(.pbs-files) .home { font-size: 13px; }
}
@media (max-width: 360px) {
  header .bar:has(.pbs-files), header.top .top-in:has(.pbs-files) { gap: 6px; padding-left: 10px; padding-right: 10px; }
}

.pbs-fback {
  position: fixed;
  inset: 0;
  z-index: 75;
  background: rgba(0, 0, 0, .35);
  display: none;
  justify-content: center;
  box-sizing: border-box;
}
.pbs-fback.show { display: flex; }
.pbs-fsheet {
  position: relative;
  box-sizing: border-box;
  background: var(--bg, #FFFFFF);
  color: var(--ink, #2D3439);
  font-family: var(--sans, "Nunito", system-ui, sans-serif);
  text-align: left;
  width: min(720px, 100%);
  overflow-y: auto;
  animation: pbs-fin .3s cubic-bezier(.3, 1.2, .5, 1);
}
@keyframes pbs-fin { from { transform: translateY(40px); opacity: 0; } }
.pbs-fx {
  position: absolute; top: 8px; right: 8px;
  width: 28px; height: 28px;
  border-radius: 10px;
  border: 2px solid var(--line, #DEE3E6);
  background: var(--panel, #FFFFFF);
  color: var(--slate, #5E6870);
  font: 900 14px var(--sans, "Nunito", system-ui, sans-serif);
  line-height: 1;
  cursor: pointer;
}
.pbs-fh { display: flex; align-items: center; gap: 10px; margin: 0 0 4px; font-size: 24px; font-weight: 900; line-height: 1.2; color: var(--ink, #2D3439); }
.pbs-ficn { width: 28px; height: 28px; flex: none; display: inline-block; vertical-align: middle; }
.pbs-fh .pbs-ficn { width: 30px; height: 30px; }
.pbs-fintro { margin: 0 0 6px; font-size: 14.5px; line-height: 1.45; color: var(--slate, #5E6870); }
.pbs-frow {
  display: flex; gap: 12px; align-items: flex-start; justify-content: space-between;
  border: 2px solid var(--line, #DEE3E6); border-bottom-width: 4px; border-radius: 14px;
  padding: 12px 14px; margin: 10px 0;
  background: var(--panel, #FFFFFF);
}
.pbs-frow > div { flex: 1; min-width: 0; }
.pbs-frow b { display: block; font-size: 16px; font-weight: 900; color: var(--ink, #2D3439); }
.pbs-frow p { margin: 2px 0 0; font-size: 14.5px; line-height: 1.45; color: var(--slate, #5E6870); }
.pbs-frow p b { display: inline; font-size: inherit; }
.pbs-fic {
  flex: none; width: 44px; height: 44px; border-radius: 14px;
  background: var(--soft, #F3F5F6);
  display: flex; align-items: center; justify-content: center;
}
.pbs-fbtn {
  flex: none;
  font-family: var(--sans, "Nunito", system-ui, sans-serif);
  font-weight: 800; font-size: 13.5px;
  color: var(--blue-d, #2B5A8C);
  background: var(--panel, #FFFFFF);
  border: 2px solid var(--line, #DEE3E6); border-bottom-width: 4px; border-radius: 12px;
  padding: 6px 11px;
  text-decoration: none;
  white-space: nowrap;
}
.pbs-fbtn:active { transform: translateY(2px); border-bottom-width: 2px; }
@media (max-width: 520px) { .pbs-frow { flex-direction: column; } .pbs-fbtn { align-self: flex-start; } }

/* Very narrow phones (320-360px): let each template's header shrink to make room for About */
@media (max-width: 360px) {
  header .bar { gap: 8px; }
  header .bar .pbar { min-width: 24px; }
  header .bar .home span { display: none; }
  header.top .top-in { gap: 8px; padding-left: 12px; padding-right: 12px; }
}