/* ==========================================================================
   Whitepapers (/whitepapers/ and /whitepapers/<slug>)
   Markup comes from tools/build-whitepapers.py. These pages also load
   learn.css, for the figure frames, the full-size viewer, the share row and
   the feedback strip, so only what is particular to the papers is here.
   ========================================================================== */

/* A word with a hyphen in it (ESP32-C3) stays on one line. */
.nb { white-space: nowrap; }

/* ---------------- Tags: domains and readiness level ---------------- */

.wp-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  list-style: none;
  margin: 0;
  padding: 0;
}
.wp-tags li {
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  padding: 0.22rem 0.7rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--navy-border);
  color: var(--text-soft);
  background: transparent;
}
.wp-tags .wp-tag-trl {
  border-color: transparent;
  background: var(--brand-navy);
  color: #fff;
}
.ground-night .wp-tags li { border-color: rgba(185, 192, 218, 0.28); }
.ground-night .wp-tags .wp-tag-trl { background: var(--copper-ground); }

/* ---------------- The list ---------------- */

.wp-list-wrap { max-width: 64rem; }

/* The filters sit on a navy panel so the site's own form fields (and the
   styled dropdown interactive.js builds from each select) look as they do in
   the contact form. Hidden until whitepapers.js runs: without it they could
   not do anything, and every paper is listed anyway. */
.wp-filters {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr)) auto;
  align-items: end;
  gap: 1rem;
  padding: 1.1rem 1.25rem 1.25rem;
  margin-bottom: 2rem;
  border-radius: var(--radius-lg);
  background: var(--brand-navy);
  box-shadow: 0 6px 20px rgba(14, 22, 63, 0.14);
  /* The panel is navy on a cotton ground, so it takes the dark palette back. */
  --text-strong: #ffffff;
  --text-soft: #b9c0da;
  --text-muted: #838cae;
  --copper-light: #d68a4c;
  --copper: #b96e37;
  --navy-border: rgba(185, 192, 218, 0.15);
  color: var(--text-strong);
}
.wp-filters[hidden] { display: none; }
.wp-filter { min-width: 0; }
.wp-filter .form-label { margin-bottom: 0.45rem; }
.wp-clear {
  font: inherit;
  font-size: 0.85rem;
  color: var(--copper-light);
  background: none;
  border: 0;
  padding: 0.85rem 0.25rem;
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 0.18em;
  white-space: nowrap;
}
.wp-clear:hover, .wp-clear:focus-visible { color: #fff; }
.wp-clear[hidden] { display: none; }

.wp-year + .wp-year { margin-top: 2.5rem; }
.wp-year-title {
  display: flex;
  align-items: center;
  gap: 1rem;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--text-muted);
  margin-bottom: 1rem;
}
.wp-year-title::after { content: ''; flex: 1; height: 1px; background: var(--navy-border); }

.wp-cards { display: grid; gap: 1.25rem; }

.wp-card {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.4fr);
  background: var(--cotton-raised);
  border: 1px solid var(--navy-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: 0 2px 10px rgba(14, 22, 63, 0.07);
  transition: box-shadow var(--transition-normal), border-color var(--transition-normal);
}
.wp-card:hover { box-shadow: 0 10px 28px rgba(14, 22, 63, 0.11); border-color: rgba(143, 78, 28, 0.4); }
.wp-card[hidden] { display: none; }

.wp-card-media { display: block; position: relative; background: var(--brand-navy); min-height: 100%; }
.wp-card-media img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-smooth);
}
.wp-card:hover .wp-card-media img { transform: scale(1.03); }

.wp-card-body { padding: clamp(1.25rem, 2.5vw, 1.75rem); display: flex; flex-direction: column; gap: 0.7rem; }
.wp-card-meta { margin: 0; font-size: 0.78rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--text-muted); }
.wp-card-title { margin: 0; font-size: clamp(1.1rem, 0.9rem + 0.7vw, 1.35rem); font-weight: 600; line-height: 1.3; letter-spacing: -0.01em; }
.wp-card-title a { color: var(--text-strong); text-decoration: none; }
.wp-card-title a:hover, .wp-card-title a:focus-visible { color: var(--copper); }
.wp-card-summary { margin: 0; font-size: 0.95rem; line-height: 1.65; color: var(--text-soft); }

.wp-card-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.6rem 1.5rem;
  margin: 0.35rem 0 0;
  padding-top: 0.9rem;
  border-top: 1px solid var(--navy-border);
  font-size: 0.92rem;
}
.wp-card-pdf {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--text-strong);
  text-decoration: none;
  font-weight: 500;
}
.wp-card-pdf svg { width: 1.05rem; height: 1.05rem; color: var(--copper); flex: none; }
.wp-card-pdf-meta { font-weight: 400; color: var(--text-muted); font-size: 0.85rem; }
.wp-card-pdf:hover span:first-of-type, .wp-card-pdf:focus-visible span:first-of-type { color: var(--copper); text-decoration: underline; text-underline-offset: 0.18em; }

/* "Opens in a new tab" mark, which whitepapers.js adds on computers only. */
.wp-newtab-icon, .wp-card-pdf .wp-newtab-icon, .wp-cta .btn .wp-newtab-icon, .wp-read .btn .wp-newtab-icon {
  width: 0.8em; height: 0.8em; flex: none; opacity: 0.85;
}
.btn .wp-newtab-icon { margin-left: -0.3rem; }
.wp-cover-hint .wp-newtab-icon { margin-left: 0.35em; vertical-align: -0.08em; }

.wp-empty {
  text-align: center;
  padding: 2.5rem 1rem;
  border: 1px dashed rgba(14, 22, 63, 0.25);
  border-radius: var(--radius-lg);
  color: var(--text-soft);
}
.wp-empty p { margin: 0 0 1rem; }
.wp-empty[hidden] { display: none; }

/* ---------------- One paper: hero ---------------- */

.wp-hero { padding-bottom: 2.5rem; }
.wp-hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) clamp(12rem, 22vw, 17rem);
  align-items: center;
  gap: clamp(2rem, 5vw, 4.5rem);
  max-width: 64rem;
}
.wp-title { font-size: clamp(1.65rem, 1.15rem + 2vw, 2.6rem); margin-bottom: 0; }
.wp-hero .divider-copper { margin: 1.25rem 0; }
.wp-byline { margin: 0 0 1rem; font-size: 0.85rem; letter-spacing: 0.06em; text-transform: uppercase; color: var(--text-soft); }

.wp-cta { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-top: 1.75rem; }
.wp-cta .btn svg, .wp-read .btn svg { width: 1.1rem; height: 1.1rem; flex: none; }
.wp-file { margin: 0.75rem 0 0; font-size: 0.82rem; color: var(--text-muted); }

/* The cover is a link to the PDF too: it is what a reader expects to press. */
.wp-cover {
  position: relative;
  display: block;
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid rgba(214, 138, 76, 0.45);
  box-shadow: 0 24px 50px rgba(0, 0, 0, 0.45), 0 0 0 6px rgba(214, 138, 76, 0.08);
  transform: rotate(2deg);
  transition: transform var(--transition-smooth), box-shadow var(--transition-normal);
}
.wp-cover img { display: block; width: 100%; height: auto; }
.wp-cover:hover, .wp-cover:focus-visible { transform: rotate(0deg) translateY(-4px); box-shadow: 0 30px 60px rgba(0, 0, 0, 0.5), 0 0 0 6px rgba(214, 138, 76, 0.18); }
.wp-cover:focus-visible { outline: 2px solid var(--copper-light); outline-offset: 4px; }
.wp-cover-hint {
  position: absolute;
  left: 50%;
  bottom: 1rem;
  transform: translateX(-50%) translateY(6px);
  padding: 0.4rem 0.9rem;
  border-radius: var(--radius-full);
  background: rgba(6, 9, 30, 0.85);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.05em;
  white-space: nowrap;
  opacity: 0;
  transition: opacity var(--transition-fast), transform var(--transition-fast);
}
.wp-cover:hover .wp-cover-hint, .wp-cover:focus-visible .wp-cover-hint { opacity: 1; transform: translateX(-50%); }

/* ---------------- One paper: body ---------------- */

.wp-summary { margin: 0; line-height: 1.75; color: var(--text-soft); }

.wp-findings { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.85rem; }
.wp-findings li {
  position: relative;
  padding-left: 1.4rem;
  line-height: 1.65;
  color: var(--text-soft);
}
.wp-findings li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0.62em;
  width: 0.5rem;
  height: 0.5rem;
  border-radius: 50%;
  background: var(--brand-copper);
}
.wp-findings strong { color: var(--text-strong); font-weight: 600; }

.wp-gallery-wrap { max-width: 72rem; margin: 1rem auto 2.5rem; }
.wp-gallery-head { max-width: 46rem; margin: 0 auto 1.5rem; }
.wp-gallery-head p { margin: 0; color: var(--text-muted); font-size: 0.95rem; }
.wp-gallery {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.75rem 1.5rem;
  align-items: start;
}
.wp-figure { margin: 0; }
.wp-figure .fig-scroll { overflow: hidden; }
.wp-figure .fig-svg { padding: 0.35rem; }
.wp-figure figcaption { font-size: 0.88rem; }
.wp-fig-no { font-weight: 600; color: var(--text-strong); margin-right: 0.15rem; }
@media (hover: hover) {
  .wp-figure .fig-scroll { cursor: zoom-in; }
}

.wp-details dl { margin: 0; display: grid; gap: 0; }
.wp-details dl > div {
  display: grid;
  grid-template-columns: 9rem minmax(0, 1fr);
  gap: 1rem;
  padding: 0.7rem 0;
  border-top: 1px solid var(--navy-border);
}
.wp-details dl > div:first-child { border-top: 0; padding-top: 0; }
.wp-details dt { font-size: 0.8rem; font-weight: 600; letter-spacing: 0.05em; text-transform: uppercase; color: var(--text-muted); padding-top: 0.15rem; }
.wp-details dd { margin: 0; color: var(--text-strong); line-height: 1.6; }

.wp-read {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem 1.5rem;
  margin: 0.5rem 0 1.5rem;
  padding: 1.5rem 1.75rem;
  border-radius: var(--radius-lg);
  background: var(--brand-navy);
  color: #fff;
}
.wp-read p { margin: 0; flex: 1 1 18rem; color: #c3c9e0; line-height: 1.6; }

/* ---------------- Small screens ---------------- */

@media (max-width: 900px) {
  .wp-filters { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .wp-clear { grid-column: 1 / -1; justify-self: start; padding: 0; }
  .wp-gallery { grid-template-columns: minmax(0, 1fr); }
  .wp-gallery-head { margin-left: 0; }
}

@media (max-width: 720px) {
  .wp-hero-grid { grid-template-columns: minmax(0, 1fr); }
  /* The buttons already open the paper; the cover would only push the summary down. */
  .wp-cover { display: none; }
  .wp-card { grid-template-columns: minmax(0, 1fr); }
  .wp-card-media { aspect-ratio: 16 / 9; min-height: 0; }
  .wp-filters { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0.85rem 0.75rem; padding: 1rem; }
  .wp-filter:nth-child(3) { grid-column: 1 / -1; }
  .wp-details dl > div { grid-template-columns: minmax(0, 1fr); gap: 0.2rem; }
  .wp-cta .btn { flex: 1 1 auto; }
  .wp-read .btn { width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  .wp-cover, .wp-cover:hover, .wp-cover:focus-visible { transform: none; }
  .wp-card-media img, .wp-card:hover .wp-card-media img { transition: none; transform: none; }
}