:root {
  --bg: #f5f5f7;
  --card-bg: #ffffff;
  --text: #1d1d1f;
  --muted: #6e6e73;
  --accent: #0071e3;
  --border: #d2d2d7;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

.layout {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.topbar {
  display: none;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}

.topbar .brand {
  font-size: 15px;
  font-weight: 600;
}

.menu-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--card-bg);
  cursor: pointer;
  padding: 0;
  flex-shrink: 0;
}

.menu-btn svg {
  width: 20px;
  height: 20px;
  color: var(--text);
}

.body-row {
  flex: 1;
  display: flex;
}

main {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px 24px;
}

.content {
  width: 100%;
  max-width: 760px;
}

.video-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 16px;
  box-shadow: 0 20px 40px -20px rgba(0, 0, 0, 0.15);
}

.video-wrap {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  border-radius: 12px;
  overflow: hidden;
  background: #000;
}

video {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: contain;
  background: #000;
}

.mute-toggle {
  position: absolute;
  top: 12px;
  right: 12px;
  z-index: 2;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: none;
  background: rgba(0, 0, 0, 0.55);
  color: #fff;
  cursor: pointer;
  padding: 0;
}

.mute-toggle svg {
  width: 18px;
  height: 18px;
}

.fallback-link {
  text-align: center;
  margin-top: 16px;
  font-size: 13px;
  color: var(--muted);
}

.fallback-link a {
  color: var(--accent);
  text-decoration: none;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 16px;
  font-size: 14px;
  font-weight: 500;
  color: var(--accent);
  text-decoration: none;
}

.page-title {
  font-size: 22px;
  font-weight: 600;
  margin: 0 0 4px;
}

.page-subtitle {
  font-size: 14px;
  color: var(--muted);
  margin: 0 0 24px;
}

.list-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 8px;
  box-shadow: 0 20px 40px -20px rgba(0, 0, 0, 0.15);
}

.list-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 16px 18px;
  border-radius: 12px;
  color: var(--text);
  text-decoration: none;
}

.list-link + .list-link {
  border-top: 1px solid var(--border);
}

.list-link:hover {
  background: var(--bg);
}

.list-link .title {
  font-size: 15px;
  font-weight: 600;
}

.list-link .desc {
  font-size: 13px;
  color: var(--muted);
  margin-top: 2px;
}

.list-link .chevron {
  color: var(--muted);
  flex-shrink: 0;
}

aside {
  width: 240px;
  flex-shrink: 0;
  background: var(--card-bg);
  border-left: 1px solid var(--border);
  padding: 32px 20px;
}

aside nav {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

aside .nav-link {
  display: block;
  padding: 12px 14px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text);
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
}

aside .nav-link:hover {
  background: var(--bg);
}

aside .nav-link.active {
  background: rgba(0, 113, 227, 0.1);
  color: var(--accent);
  border-color: rgba(0, 113, 227, 0.25);
}

@media (max-width: 720px) {
  .topbar {
    display: flex;
  }

  aside {
    display: none;
    width: 100%;
    border-left: none;
    border-top: 1px solid var(--border);
  }

  aside.open {
    display: block;
  }

  main {
    padding: 24px 16px;
  }
}