.shoulder-study {
  --study-paper: #f4f0e6;
  --study-muted: #b6cbd2;
  --study-accent: #9fdde9;
  --study-rule: #6594a44d;
  color: var(--study-paper);
  scroll-margin-top: 6rem;
  background: #10252c;
  border-color: #7aaab568;
}

.shoulder-study [hidden] { display: none !important; }
.shoulder-heading { padding: 19px 22px 17px; }
.shoulder-index {
  display: flex;
  gap: 8px;
  align-items: center;
  color: var(--study-accent);
  font-size: .68rem;
  font-weight: 650;
  letter-spacing: .11em;
  text-transform: uppercase;
}
.shoulder-index i {
  width: 7px;
  height: 7px;
  border: 1px solid currentColor;
  border-radius: 50%;
  box-shadow: 0 0 12px #a2e3f099;
}
.shoulder-heading h2 {
  color: var(--study-paper);
  font: 400 clamp(1.8rem, 3.6vw, 2.75rem)/1.04 Georgia, serif;
  letter-spacing: -.035em;
  margin: 8px 0 5px;
}
.shoulder-heading p, .shoulder-detail p { margin: 0; }
:root .shoulder-study .shoulder-heading p { color: var(--study-muted); font-size: .86rem; line-height: 1.5; }

.shoulder-canvas {
  position: relative;
  display: grid;
  isolation: isolate;
  overflow: hidden;
  aspect-ratio: 640 / 448;
  border-block: 1px solid var(--study-rule);
  background: #0c1723;
}
.shoulder-canvas :is(img, video) {
  display: block;
  grid-area: 1 / 1;
  width: 100%;
  height: 100%;
  object-fit: contain;
}
.shoulder-view-note {
  position: absolute;
  right: 10px;
  top: 10px;
  color: #c7dce5;
  background: #071820d9;
  padding: 4px 7px;
  border: 1px solid #a6cfd357;
  border-radius: 3px;
  font-size: .62rem;
  font-weight: 650;
  letter-spacing: .065em;
}
.shoulder-view-note b { margin-inline: 2px; }
.shoulder-callouts, .shoulder-leaders { position: absolute; inset: 0; width: 100%; height: 100%; pointer-events: none; }
.shoulder-leaders { overflow: visible; }
.shoulder-leaders line {
  stroke: #c2e9ee;
  stroke-opacity: .8;
  stroke-width: 1.05;
  vector-effect: non-scaling-stroke;
}
.shoulder-leaders circle { fill: #c2e9ee; }
.shoulder-marker {
  position: absolute;
  transform: translate(-50%, -50%);
  pointer-events: auto;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1px solid #a5d3dd;
  border-radius: 50%;
  color: var(--study-paper);
  background: #132a34;
  font: 650 .76rem/1 system-ui, sans-serif;
  letter-spacing: .07em;
  box-shadow: 0 0 0 4px #0b1b2699;
  cursor: pointer;
}
.shoulder-marker-one { left: 19%; top: 25%; }
.shoulder-marker-two { left: 23%; top: 55%; }
.shoulder-marker[aria-pressed="true"], .shoulder-marker:hover {
  background: #c0e7ed;
  color: #122b33;
}

.shoulder-control-bar { padding: 10px 17px 9px; border-bottom: 1px solid var(--study-rule); }
.shoulder-control-row, .shoulder-timeline { display: flex; align-items: center; gap: 9px; }
.shoulder-control-row { flex-wrap: wrap; justify-content: space-between; }
.shoulder-play, .shoulder-layers button {
  min-height: 44px;
  padding: 4px 9px;
  font: 650 .74rem/1.2 system-ui, sans-serif;
  cursor: pointer;
}
:root .shoulder-study .shoulder-play {
  border: 1px solid #99c8d37b;
  border-radius: 6px;
  color: var(--study-paper);
  background: #1a3a44;
}
:root .shoulder-study .shoulder-play:hover { background: #26505d; }
.shoulder-play-symbol {
  display: inline-block;
  margin-right: 3px;
  border: .27rem solid transparent;
  border-right: 0;
  border-left: .43rem solid var(--study-accent);
}
.shoulder-play[data-playing] .shoulder-play-symbol {
  width: .43rem;
  height: .54rem;
  border: solid var(--study-accent);
  border-width: 0 .13rem;
}
.shoulder-layers { display: flex; align-items: center; gap: 2px; min-width: 0; }
.shoulder-layers button {
  border: 1px solid transparent;
  border-radius: 6px;
  background: transparent;
  color: var(--study-muted);
}
.shoulder-layers button[aria-pressed="true"], .shoulder-layers button:hover {
  background: #1d3b43;
  border-color: #6ea3b48a;
  color: #e1f2f1;
}
.shoulder-timeline {
  min-height: 44px;
  color: var(--study-muted);
  font-size: .73rem;
}
.shoulder-timeline :is(label, span) { flex: none; }
:root .shoulder-study .shoulder-timeline input {
  appearance: auto;
  flex: 1;
  min-width: 60px;
  min-height: 44px;
  margin: 0;
  accent-color: var(--study-accent);
  cursor: ew-resize;
}
.shoulder-study :is(button, a, input):focus-visible {
  outline: 3px solid #f2d3a3;
  outline-offset: 3px;
}
:root .shoulder-study .shoulder-status { margin: 0; color: #ffe0af; font-size: .77rem; }
.shoulder-learning { padding: 13px 18px 14px; }
.shoulder-detail { min-height: 3.9rem; }
.shoulder-detail h3 {
  margin: 0 0 3px;
  color: var(--study-paper);
  font: 400 1.22rem/1.15 Georgia, serif;
}
:root .shoulder-study .shoulder-detail p { color: var(--study-muted); font-size: .84rem; line-height: 1.45; max-width: 60ch; }
.shoulder-link, .shoulder-note a { color: var(--study-accent); text-underline-offset: .19em; }
.shoulder-link {
  display: inline-flex;
  gap: 7px;
  align-items: center;
  min-height: 44px;
  font-size: .86rem;
  font-weight: 650;
}
:root .shoulder-study .shoulder-note { margin: 0; color: var(--study-muted); font-size: .71rem; line-height: 1.55; }

.shoulder-link-arrow {
  width: .5em;
  height: .5em;
  border-top: 1.5px solid currentColor;
  border-right: 1.5px solid currentColor;
  transform: rotate(45deg);
}

@media (max-width: 430px) {
  .shoulder-heading { padding: 15px 13px 13px; }
  .shoulder-learning, .shoulder-control-bar { padding-inline: 12px; }
  .shoulder-control-row { gap: 4px; }
  .shoulder-play, .shoulder-layers button { padding-inline: 6px; font-size: .7rem; }
  .shoulder-view-note { font-size: .56rem; }
}