:root {
  color-scheme: light;
  --bg: #f6f7f9;
  --surface: #ffffff;
  --text: #17202a;
  --muted: #5f6b78;
  --line: #d9dee6;
  --accent: #0b7a75;
  --accent-dark: #075f5b;
  --accent-soft: #e7f4f2;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
}

.page {
  width: min(980px, calc(100% - 32px));
  margin: 0 auto;
  padding: 28px 0 40px;
}

.intro {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 20px;
  padding: 10px 0 22px;
}

.eyebrow {
  margin: 0 0 8px;
  color: var(--accent-dark);
  font-size: 15px;
  font-weight: 700;
}

h1 {
  margin: 0;
  font-size: clamp(28px, 5vw, 46px);
  line-height: 1.12;
  letter-spacing: 0;
}

.summary {
  max-width: 720px;
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 17px;
  line-height: 1.7;
}

.status {
  flex: 0 0 auto;
  min-width: 136px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.status span,
.status strong {
  display: block;
}

.status span {
  color: var(--muted);
  font-size: 13px;
}

.status strong {
  margin-top: 4px;
  font-size: 14px;
}

.video-shell,
.notes {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.video-shell {
  overflow: hidden;
}

.current-video {
  padding: 18px 20px;
  border-bottom: 1px solid var(--line);
}

.current-video span {
  display: inline-flex;
  margin-bottom: 8px;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-dark);
  font-size: 13px;
  font-weight: 700;
}

.current-video h2 {
  margin: 0;
  font-size: 22px;
  line-height: 1.35;
}

.video-frame {
  aspect-ratio: 16 / 9;
  min-height: 220px;
  background: #101820;
}

.video-frame iframe {
  width: 100%;
  height: 100%;
  border: 0;
}

.actions {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 18px;
  border-top: 1px solid var(--line);
}

.primary-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 18px;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}

.primary-button:hover {
  background: var(--accent-dark);
}

.actions p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
}

.steps {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 16px 0;
}

.step-button {
  display: grid;
  gap: 8px;
  min-height: 96px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  text-align: left;
  cursor: pointer;
  font: inherit;
}

.step-button span {
  color: var(--accent-dark);
  font-size: 13px;
  font-weight: 700;
}

.step-button strong {
  font-size: 17px;
  line-height: 1.35;
}

.step-button:hover,
.step-button.is-active {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.notes {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.notes div {
  padding: 20px;
}

.notes div + div {
  border-left: 1px solid var(--line);
}

.notes h2 {
  margin: 0 0 8px;
  font-size: 17px;
}

.notes p {
  margin: 0;
  color: var(--muted);
  line-height: 1.7;
}

@media (max-width: 760px) {
  .page {
    width: min(100% - 24px, 980px);
    padding-top: 18px;
  }

  .intro,
  .actions {
    display: block;
  }

  .status {
    margin-top: 18px;
  }

  .primary-button {
    width: 100%;
  }

  .actions p {
    margin-top: 12px;
  }

  .steps,
  .notes {
    grid-template-columns: 1fr;
  }

  .notes div + div {
    border-top: 1px solid var(--line);
    border-left: 0;
  }
}