:root {
  color-scheme: light;
  font-family:
    "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", system-ui, sans-serif;
  color: #203c2e;
  background: #f4f7f4;
  --ink: #123d2f;
  --accent: #d0ef8d;
  --line: #d6e0da;
  --muted: #536b5e;
}
* {
  box-sizing: border-box;
}
body {
  margin: 0;
  line-height: 1.65;
}
[hidden] {
  display: none !important;
}
a {
  color: inherit;
  text-underline-offset: 0.2em;
}
button {
  font: inherit;
  cursor: pointer;
}
::selection {
  color: var(--ink);
  background: var(--accent);
}
:focus-visible {
  outline: 3px solid #609b37;
  outline-offset: 4px;
}
.skip {
  position: absolute;
  top: -100px;
  left: 20px;
  background: white;
  padding: 12px;
  z-index: 2;
}
.skip:focus {
  top: 12px;
}
main {
  max-width: 1360px;
  margin: auto;
  padding-inline: 40px;
}
main {
  padding-block: 52px 64px;
}
.intro {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 28px;
}
h1 {
  margin: 0 0 10px;
  font-size: clamp(30px, 4vw, 44px);
  line-height: 1.25;
  letter-spacing: -0.025em;
}
.intro p {
  margin: 0;
  max-width: 65ch;
  color: var(--muted);
  font-size: 17px;
}
.watch-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 32px;
  align-items: start;
}
.player-frame {
  aspect-ratio: 16 / 9;
  background: #102e25;
  position: relative;
  overflow: hidden;
  border-radius: 6px;
}
video {
  width: 100%;
  height: 100%;
  display: block;
  background: #102e25;
}
.start-video {
  display: block;
  width: 100%;
  height: 100%;
  padding: 0;
  border: 0;
  background: #102e25;
  color: #fff;
  text-align: left;
}
.start-video img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.start-video span {
  position: absolute;
  inset: auto 0 0;
  display: block;
  text-align: center;
  padding: 16px;
  background: var(--accent);
  color: var(--ink);
  font-weight: 700;
  font-size: 18px;
}
.start-video:hover span {
  background: #bfe76a;
}
.player-frame:has(:focus-visible) {
  outline: 3px solid #609b37;
  outline-offset: 4px;
}
.player-frame :focus-visible {
  outline-offset: -4px;
}
.player-meta {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  margin-top: 12px;
  color: var(--muted);
  font-size: 14px;
}
.player-feedback {
  min-height: 28px;
  color: var(--muted);
  font-size: 14px;
}
#player-status {
  display: inline;
}
.retry {
  margin-left: 10px;
  min-height: 44px;
  background: white;
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 8px 16px;
  color: var(--ink);
}
.chapters h2 {
  margin: 0 0 6px;
  font-size: 21px;
  line-height: 1.4;
}
.chapters > p {
  margin: 0 0 18px;
  color: var(--muted);
  font-size: 14px;
}
.chapters ol {
  list-style: none;
  padding: 0;
  margin: 0;
  border-top: 1px solid var(--line);
}
.chapters li {
  border-bottom: 1px solid var(--line);
}
.chapter-link {
  display: block;
  padding: 22px 16px;
  text-decoration: none;
  transition: background 0.15s ease-out;
}
.chapter-link:hover {
  background: #e7efe8;
}
.chapter-link[aria-current] {
  background: #e5efd8;
}
.chapter-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
}
.chapter-heading strong {
  font-size: 18px;
  font-weight: 650;
}
.chapter-heading time {
  font-size: 14px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}
.chapter-link p {
  margin: 8px 0 0;
  font-size: 15px;
  color: var(--muted);
}
.help {
  margin-top: 32px;
  border-top: 1px solid var(--line);
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  gap: 24px;
}
.help p {
  margin: 0;
  max-width: 70ch;
  font-size: 15px;
  color: var(--muted);
}
.help a {
  white-space: nowrap;
}
@media (max-width: 1000px) {
  .watch-layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 20px;
  }
  .chapters ol {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .chapters li {
    border-bottom: 1px solid var(--line);
  }
  .chapter-heading {
    flex-direction: column;
    gap: 4px;
  }
}
@media (max-width: 620px) {
  main {
    padding-inline: 20px;
  }
  main {
    padding-block: 32px 40px;
  }
  .intro {
    display: block;
    margin-bottom: 20px;
  }
  .intro p {
    font-size: 16px;
  }
  .start-video span {
    padding: 10px;
    font-size: 16px;
  }
  .player-meta {
    font-size: 13px;
  }
  .chapters ol {
    display: block;
  }
  .chapter-heading {
    flex-direction: row;
  }
  .chapter-link {
    padding: 18px 12px;
  }
  .help {
    display: block;
  }
  .help a {
    display: inline-block;
    margin-top: 16px;
  }
}
@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
  }
}