/* library/library.css — the Simulator Library. MechSimulator's library layout
   (animated hero, sticky search bar, subject map, drill columns, compact cards)
   in this site's materials: a lit rounded stage, glass controls, hairlines and
   each tool's own accent (guideline §5.14). On top of home.css. Scoped to .lib. */

.lib [hidden] { display: none !important; }
.lib { max-width: 1180px; padding-top: 64px; }
.lib .lbl-m { display: none; }

.lib-head { position: relative; z-index: 1; max-width: 620px; padding: 18px 28px 92px; pointer-events: none; }
.lib-head a, .lib-head button, .lib-head .site-nav { pointer-events: auto; }
.lib .lib-head .site-nav--hub { margin: 0 0 18px; }
.lib-head h1 {
  margin: 0 0 10px;
  font-size: clamp(2rem, 4.4vw, 3.1rem);
  font-weight: 800;
  line-height: 1.04;
  letter-spacing: -.035em;
}
.lib-head h1 em {
  font-style: normal;
  background: linear-gradient(100deg, #2dd4bf 0%, #7dd3fc 60%, #a5f3fc 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.lib-lede { max-width: 54ch; margin: 0; font-size: 1rem; line-height: 1.55; color: var(--home-ink); }
.lib-stats { display: flex; flex-wrap: wrap; gap: 6px 22px; margin: 16px 0 0; padding: 0; list-style: none; font-size: .85rem; color: var(--home-dim); }
.lib-stats b { margin-right: 4px; font-size: 1.15rem; font-weight: 750; color: var(--text); font-variant-numeric: tabular-nums; letter-spacing: -.02em; }
.lib-hero-req { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 14px; margin: 18px 0 0; font-size: .85rem; color: var(--home-dim); }
.lib-req-hero {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 42px;
  padding: 0 18px;
  border-radius: 999px;
  font-size: .9rem;
  font-weight: 650;
  text-decoration: none;
  color: var(--home-on-teal);
  background: var(--accent);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .35), 0 8px 22px -10px rgba(45, 212, 191, .7);
  transition: filter .15s, transform .1s ease-out;
}
.lib-req-hero span { font-size: 1.15rem; line-height: 1; }
.lib-req-hero:hover { filter: brightness(1.08); }
.lib-req-hero:active { transform: scale(.97); }
.lib-req-hero:focus-visible { outline: 2px solid #99f6e4; outline-offset: 3px; }

/* ── Sticky search bar ────────────────────────────────────────── */
.lib-sentinel { height: 1px; margin-top: -1px; }
.lib-bar {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin: 18px -12px 14px;
  padding: 10px 12px;
  border-radius: 0 0 16px 16px;
  background: rgba(13, 17, 23, .86);
  -webkit-backdrop-filter: blur(16px) saturate(160%);
  backdrop-filter: blur(16px) saturate(160%);
  border-bottom: 1px solid transparent;
  transition: box-shadow .2s, border-color .2s;
}
.lib-bar.is-stuck { border-bottom-color: var(--home-line); box-shadow: 0 12px 24px -18px rgba(0, 0, 0, .9); }
.lib-search { position: relative; flex: 1 1 260px; }
.lib-search input {
  width: 100%;
  min-height: 42px;
  padding: 0 40px 0 18px;
  border-radius: 999px;
  font: inherit;
  font-size: .95rem;
  color: var(--text);
  background: var(--home-glass);
  border: 1px solid rgba(255, 255, 255, .14);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .06);
  transition: border-color .2s, box-shadow .2s;
}
.lib-search input::placeholder { color: var(--home-dim); }
.lib-search input::-webkit-search-cancel-button { display: none; }
.lib-search input:focus { outline: none; border-color: color-mix(in srgb, var(--accent) 70%, transparent); box-shadow: 0 0 0 3px rgba(45, 212, 191, .18); }
.lib-kbd {
  position: absolute;
  top: 50%;
  right: 14px;
  display: grid;
  place-items: center;
  width: 22px;
  height: 22px;
  border-radius: 6px;
  font: 600 .74rem/1 inherit;
  color: var(--home-dim);
  border: 1px solid var(--home-line);
  transform: translateY(-50%);
  pointer-events: none;
}
.lib-search input:focus ~ .lib-kbd, .lib-search input:not(:placeholder-shown) ~ .lib-kbd { display: none; }
@media (pointer: coarse) { .lib-kbd { display: none; } }
.lib-q-clear {
  position: absolute;
  top: 50%;
  right: 6px;
  width: 32px;
  height: 32px;
  border: 0;
  border-radius: 50%;
  font-size: 1.2rem;
  color: var(--home-dim);
  background: none;
  transform: translateY(-50%);
  cursor: pointer;
}
.lib-q-clear:hover { color: var(--text); }
.lib-q-clear:focus-visible { outline: 2px solid var(--accent); }

/* Segmented controls: one glass track, a teal-tinted thumb. */
.lib-seg { display: flex; gap: 2px; padding: 3px; border-radius: 999px; background: var(--home-glass); border: 1px solid var(--home-line); }
.lib-seg button, .lib-3d {
  min-height: 34px;
  padding: 0 13px;
  border: 0;
  border-radius: 999px;
  font: inherit;
  font-size: .84rem;
  font-weight: 600;
  color: var(--home-ink);
  background: transparent;
  cursor: pointer;
  transition: background-color .2s, color .2s;
}
.lib-seg button:hover, .lib-3d:hover { color: var(--text); }
.lib-seg button[aria-pressed="true"] { color: var(--text); background: rgba(45, 212, 191, .16); box-shadow: inset 0 0 0 1px rgba(45, 212, 191, .45); }
.lib-3d { min-height: 42px; padding: 0 16px; background: var(--home-glass); border: 1px solid var(--home-line); }
.lib-3d[aria-pressed="true"] { color: var(--home-on-teal); background: var(--accent); border-color: transparent; }
.lib-seg button:focus-visible, .lib-3d:focus-visible { outline: 2px solid #99f6e4; outline-offset: 1px; }

/* ── Subject map: hairline tiles, a living glyph in each ──────── */
.lib-map {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  overflow: hidden;
  border-radius: 20px;
  background: var(--home-line);
  border: 1px solid var(--home-line);
}
.lib-tile {
  --tile: var(--accent);
  position: relative;
  display: flex;
  flex-direction: column;
  min-height: 132px;
  padding: 14px 16px 12px;
  border: 0;
  font: inherit;
  text-align: left;
  color: var(--text);
  background: var(--bg);
  cursor: pointer;
  transition: background-color .2s;
}
.lib-tile:hover:not(:disabled), .lib-tile[aria-pressed="true"] { background: color-mix(in srgb, var(--tile) 8%, var(--bg)); }
.lib-tile[aria-pressed="true"] { box-shadow: inset 0 -2px 0 var(--tile); }
.lib-tile:disabled { cursor: default; opacity: .45; }
.lib-tile:focus-visible { outline: 2px solid var(--tile); outline-offset: -4px; border-radius: 12px; }
.lib-tile-no { position: absolute; top: 12px; right: 14px; font-size: .68rem; font-weight: 600; color: #4a5470; font-variant-numeric: tabular-nums; }
.lib-tile-name { display: flex; align-items: center; gap: 9px; padding-right: 24px; font-size: .96rem; font-weight: 700; letter-spacing: -.01em; }
.lib-tile-name::before { content: ""; flex: none; width: 8px; height: 8px; border-radius: 50%; background: var(--tile); box-shadow: 0 0 0 3px color-mix(in srgb, var(--tile) 22%, transparent); }
.lib-tile-count { margin-top: 6px; font-size: 1.9rem; font-weight: 300; line-height: 1.1; color: color-mix(in srgb, var(--tile) 70%, #fff); font-variant-numeric: tabular-nums; }
.lib-tile-topics { margin-top: auto; padding-right: 78px; font-size: .74rem; line-height: 1.4; color: var(--home-dim); }
.lib-tile canvas { position: absolute; right: 12px; bottom: 10px; width: 68px; height: 44px; }

/* ── Drill columns ────────────────────────────────────────────── */
.lib-cols { display: grid; grid-template-columns: 1.1fr 1.2fr 1fr; gap: 10px; }
.lib-col { padding: 8px; border-radius: 16px; background: var(--surface); border: 1px solid var(--home-line); }
.lib-col-h { padding: 6px 10px 8px; font-size: .68rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--home-dim); }
.lib-col-list { max-height: 420px; overflow-y: auto; }
.lib-col-sub { padding: 10px 10px 4px; font-size: .66rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: #5d6884; }
.lib-opt {
  --opt: var(--accent);
  display: flex;
  justify-content: space-between;
  gap: 10px;
  width: 100%;
  min-height: 36px;
  padding: 8px 10px;
  border: 0;
  border-radius: 10px;
  font: inherit;
  font-size: .88rem;
  text-align: left;
  color: var(--home-ink);
  background: none;
  cursor: pointer;
}
.lib-opt:hover:not(:disabled) { color: var(--text); background: rgba(255, 255, 255, .04); }
.lib-opt[aria-pressed="true"] { color: var(--text); background: color-mix(in srgb, var(--opt) 15%, transparent); box-shadow: inset 2px 0 0 var(--opt); }
.lib-opt:disabled { opacity: .35; cursor: default; }
.lib-opt:focus-visible { outline: 2px solid var(--opt); outline-offset: -2px; }
.lib-opt-n { font-size: .8rem; color: var(--home-dim); font-variant-numeric: tabular-nums; }
.lib-steps, .lib-show { display: none; }

/* ── Results ──────────────────────────────────────────────────── */
.lib-results { margin-top: 20px; }
.lib-active { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 0 10px; }
.lib-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 32px;
  padding: 4px 6px 4px 12px;
  border-radius: 999px;
  font: inherit;
  font-size: .8rem;
  font-weight: 600;
  color: var(--text);
  background: rgba(45, 212, 191, .1);
  border: 1px solid rgba(45, 212, 191, .42);
  cursor: pointer;
}
.lib-chip:hover { background: rgba(45, 212, 191, .2); }
.lib-chip-x { display: inline-grid; place-items: center; width: 20px; height: 20px; border-radius: 50%; font-size: .9rem; line-height: 1; background: rgba(255, 255, 255, .08); }
.lib-chip-clear { min-height: 32px; padding: 4px 10px; border: 0; font: inherit; font-size: .8rem; color: var(--accent); background: none; text-decoration: underline; text-underline-offset: 2px; cursor: pointer; }
.lib-chip:focus-visible, .lib-chip-clear:focus-visible, .lib-count-wide:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.lib-count { margin: 0 0 10px; font-size: .86rem; color: var(--home-dim); font-variant-numeric: tabular-nums; }
.lib-count-wide { min-height: 28px; padding: 4px 2px; border: 0; font: inherit; color: var(--accent); background: none; text-decoration: underline; text-underline-offset: 3px; cursor: pointer; }
.lib-req-callout {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 18px;
  margin: 0 0 14px;
  padding: 14px 16px;
  border-radius: 16px;
  background: linear-gradient(100deg, rgba(45, 212, 191, .1), rgba(125, 211, 252, .04)), var(--surface);
  border: 1px solid rgba(45, 212, 191, .4);
}
.lib-req-callout p { flex: 1 1 320px; margin: 0; font-size: .9rem; line-height: 1.5; color: var(--home-dim); }
.lib-req-callout b { color: var(--text); }

.lib-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 10px; }
.lib-card {
  position: relative;
  display: flex;
  gap: 12px;
  padding: 12px;
  border-radius: 16px;
  background: linear-gradient(180deg, rgba(255, 255, 255, .03), transparent 70%), var(--surface);
  border: 1px solid var(--home-line);
  transition: border-color .2s, transform .15s ease-out, box-shadow .3s;
}
.lib-card:hover, .lib-card:focus-within {
  border-color: color-mix(in srgb, var(--tool) 50%, transparent);
  transform: translateY(-2px);
  box-shadow: 0 12px 28px -18px color-mix(in srgb, var(--tool) 60%, #000);
}
.lib-card-art {
  flex: none;
  display: grid;
  place-items: center;
  width: 64px;
  height: 64px;
  border-radius: 14px;
  background: radial-gradient(closest-side, var(--tool-lo), transparent), rgba(0, 0, 0, .2);
}
.lib-card-art img, .lib-card-art svg { width: 54px; height: 54px; }
.lib-card-body { min-width: 0; }
.lib-card h3 { margin: 0 0 4px; font-size: .96rem; font-weight: 700; line-height: 1.25; letter-spacing: -.01em; }
.lib-card-link { color: var(--text); text-decoration: none; }
.lib-card-link::after { content: ""; position: absolute; inset: 0; border-radius: 16px; }
.lib-card-link:focus-visible { outline: none; }
.lib-card-link:focus-visible::after { outline: 2px solid var(--tool-hi); outline-offset: 2px; }
.lib-card-desc { margin: 0 0 8px; font-size: .82rem; line-height: 1.45; color: var(--home-ink); }
.lib-tags { display: flex; flex-wrap: wrap; gap: 4px; margin: 0; }
.lib-tag { padding: 2px 8px; border-radius: 999px; font-size: .66rem; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; color: var(--home-dim); border: 1px solid var(--home-line); }
.lib-tag--view { color: var(--tool-hi); border-color: color-mix(in srgb, var(--tool) 35%, transparent); }
.lib-also { position: relative; z-index: 1; margin: 8px 0 0; font-size: .74rem; color: var(--home-dim); }
.lib-also span { display: block; margin-bottom: 2px; }
.lib-also button { display: block; min-height: 26px; padding: 3px 0; border: 0; font: inherit; text-align: left; color: var(--tool-hi); background: none; text-decoration: underline; text-underline-offset: 2px; text-decoration-color: color-mix(in srgb, var(--tool) 45%, transparent); cursor: pointer; }
.lib-also button:hover { color: var(--text); }
.lib-also button:focus-visible { outline: 2px solid var(--tool); outline-offset: 1px; border-radius: 4px; }

.lib-empty { padding: 32px 20px; border-radius: 16px; text-align: center; border: 1px dashed var(--home-line); }
.lib-empty-h { margin: 0; font-size: 1.02rem; color: var(--text); }
.lib-empty-sub { margin: 6px 0 0; font-size: .88rem; color: var(--home-dim); }
.lib-empty-actions { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px; margin-top: 14px; }
.lib-btn { display: inline-flex; align-items: center; min-height: 42px; padding: 0 18px; border: 0; border-radius: 999px; font: inherit; font-weight: 650; text-decoration: none; color: var(--home-on-teal); background: var(--accent); cursor: pointer; }
.lib-btn--ghost { color: var(--accent); background: transparent; border: 1px solid color-mix(in srgb, var(--accent) 55%, transparent); }
.lib-btn:focus-visible { outline: 2px solid #99f6e4; outline-offset: 2px; }
.lib-request {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 10px 14px;
  margin: 20px 0 4px;
  padding: 14px 16px;
  border-radius: 16px;
  font-size: .9rem;
  text-align: center;
  color: var(--home-dim);
  border: 1px dashed var(--home-line);
}
.lib-request-btn { display: inline-flex; align-items: center; min-height: 40px; padding: 0 16px; border-radius: 999px; font-weight: 600; font-size: .88rem; text-decoration: none; color: var(--accent); border: 1px solid color-mix(in srgb, var(--accent) 55%, transparent); transition: background-color .15s, color .15s; }
.lib-request-btn:hover { color: var(--home-on-teal); background: var(--accent); }
.lib-request-btn:focus-visible { outline: 2px solid #99f6e4; outline-offset: 2px; }

/* ── By course ────────────────────────────────────────────────── */
.lib-courses { margin-top: 56px; }
.lib-courses h2, .lib-index > h2 { margin: 0; font-size: 1.4rem; font-weight: 750; letter-spacing: -.025em; }
.lib-courses-lede, .lib-index-lede { margin: 6px 0 16px; font-size: .92rem; color: var(--home-dim); }
.lib-course-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 10px; }
.lib-course { display: flex; flex-direction: column; padding: 14px 16px 16px; border-radius: 16px; background: var(--surface); border: 1px solid var(--home-line); }
.lib-course h3 { margin: 0; font-size: .98rem; font-weight: 700; }
.lib-course p { margin: 6px 0 10px; font-size: .82rem; line-height: 1.5; color: var(--home-dim); }
.lib-course ul { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 0 12px; padding: 0; list-style: none; }
.lib-course ul a { display: inline-flex; align-items: center; min-height: 30px; padding: 0 11px; border-radius: 999px; font-size: .78rem; font-weight: 600; text-decoration: none; color: var(--home-ink); border: 1px solid var(--home-line); }
.lib-course ul a:hover, .lib-course ul a:focus-visible { color: var(--text); border-color: color-mix(in srgb, var(--accent) 55%, transparent); }
.lib-course-all { margin-top: auto; font-size: .84rem; font-weight: 600; text-decoration: none; color: var(--accent); }
.lib-course-all:hover { text-decoration: underline; }

/* ── Index: every link as plain HTML, folded by subject ───────── */
.lib-index { margin-top: 56px; }
.lib-index-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 10px; align-items: start; }
.lib-index-group { border-radius: 16px; background: var(--surface); border: 1px solid var(--home-line); }
.lib-index-group summary { display: flex; align-items: center; gap: 10px; min-height: 48px; padding: 10px 16px; border-radius: 16px; list-style: none; cursor: pointer; }
.lib-index-group summary::-webkit-details-marker { display: none; }
.lib-index-group summary::after { content: "+"; margin-left: 2px; font-size: 1.2rem; color: var(--accent); transition: transform .3s var(--home-ease); }
.lib-index-group[open] summary::after { transform: rotate(45deg); }
.lib-index-group summary:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.lib-index-group h3 { margin: 0; font-size: .94rem; font-weight: 700; }
.lib-index-n { margin-left: auto; font-size: .78rem; color: var(--home-dim); font-variant-numeric: tabular-nums; }
.lib-index-body { padding: 0 16px 14px; }
.lib-index-group h4 { margin: 12px 0 4px; font-size: .66rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--home-dim); }
.lib-index-group ul { margin: 0; padding: 0; list-style: none; }
.lib-index-group li a { display: block; padding: 3px 0; font-size: .86rem; text-decoration: none; color: var(--home-ink); }
.lib-index-group li a:hover { color: var(--text); text-decoration: underline; }
.lib-index-group p { margin: 10px 0 0; }
.lib-index-hub { font-size: .86rem; font-weight: 600; text-decoration: none; color: var(--accent); }

.lib-article { max-width: 72ch; margin-top: 48px; }
.lib-article h2 { margin: 0 0 12px; font-size: 1.4rem; font-weight: 750; letter-spacing: -.025em; }
.lib-article p { line-height: 1.7; color: var(--home-ink); }

/* ── Tablet ───────────────────────────────────────────────────── */
@media (max-width: 990px) {
  .lib-map { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* ── Phone (≤ 720 px): stepped drill, compact cards ───────────── */
@media (max-width: 720px) {
  .lib { padding-top: 60px; }
  .lib-head { padding: 14px 16px 78px; }
  .lib .lib-head .site-nav--hub { margin-bottom: 12px; }
  .lib-head h1 { font-size: 1.9rem; }
  .lib-lede { font-size: .94rem; line-height: 1.5; }
  .lib-stats { margin-top: 12px; gap: 4px 16px; font-size: .8rem; }
  .lib-stats b { font-size: 1.05rem; }
  .lib-hero-req > span { display: none; }

  .lib-bar { margin: 12px -16px 10px; padding: 8px 16px; gap: 8px; border-radius: 0; }
  .lib-search { flex-basis: 100%; }
  .lib-search input { min-height: 46px; font-size: 1rem; }
  .lib .lbl-d { display: none; }
  .lib .lbl-m { display: inline; }
  .lib-seg { flex: 1 1 auto; }
  .lib-seg button { flex: 1 1 auto; min-height: 38px; padding: 0 8px; }
  .lib-3d { min-height: 44px; }
  #lib-sort { flex: 1 1 100%; }

  .lib-tile { min-height: 96px; padding: 12px; }
  .lib-tile-name { font-size: .88rem; line-height: 1.2; }
  .lib-tile-count { font-size: 1.4rem; margin-top: 4px; }
  .lib-tile-topics { display: none; }
  .lib-tile-no { top: 10px; right: 10px; }
  .lib-tile canvas { width: 52px; height: 34px; right: 10px; bottom: 8px; }

  .lib-steps { display: flex; gap: 6px; margin-bottom: 8px; overflow-x: auto; scrollbar-width: none; }
  .lib-steps::-webkit-scrollbar { display: none; }
  .lib-steps button { flex: none; min-height: 40px; padding: 0 14px; border-radius: 999px; font: inherit; font-size: .82rem; font-weight: 600; color: var(--home-ink); background: var(--home-glass); border: 1px solid var(--home-line); }
  .lib-steps button[aria-current="step"] { color: var(--text); border-color: var(--accent); }
  .lib-cols { grid-template-columns: 1fr; }
  .lib-col { display: none; }
  .lib-col.is-step { display: block; }
  .lib-opt { min-height: 44px; }
  .lib-show {
    position: sticky;
    bottom: 12px;
    z-index: 4;
    display: block;
    width: 100%;
    min-height: 48px;
    margin-top: 10px;
    border: 0;
    border-radius: 999px;
    font: inherit;
    font-weight: 700;
    color: var(--home-on-teal);
    background: var(--accent);
    box-shadow: 0 12px 28px -12px rgba(0, 0, 0, .85);
    cursor: pointer;
  }

  .lib-grid { grid-template-columns: 1fr; gap: 8px; }
  .lib-card { padding: 10px; gap: 10px; }
  .lib-card-art { width: 52px; height: 52px; border-radius: 12px; }
  .lib-card-art img, .lib-card-art svg { width: 44px; height: 44px; }
  .lib-card-desc { display: -webkit-box; overflow: hidden; -webkit-line-clamp: 2; -webkit-box-orient: vertical; margin-bottom: 6px; }
  .lib-results[data-all="1"] .lib-also { display: none; }
  .lib-also span { display: inline; margin-right: 4px; }
  .lib-also button { display: inline; min-height: 32px; margin-right: 10px; }
  .lib-chip, .lib-chip-clear { min-height: 40px; }
  .lib-course ul a { min-height: 36px; }
  .lib-index-group li a { display: flex; align-items: center; min-height: 36px; font-size: .9rem; }
  .lib-courses, .lib-index { margin-top: 40px; }
}

@media (prefers-reduced-motion: reduce) {
  .lib-card, .lib-card:hover, .lib-card:focus-within { transition: none; transform: none; }
  .lib-index-group summary::after { transition: none; }
}
@media (prefers-reduced-transparency: reduce) {
  .lib-bar { background: var(--bg); -webkit-backdrop-filter: none; backdrop-filter: none; }
}
@media (prefers-contrast: more) {
  .lib-card, .lib-col, .lib-course, .lib-index-group, .lib-seg { border-color: rgba(255, 255, 255, .45); }
}