:root {
  --bg: #f6f4ff;
  --bg-soft: #f0ecff;
  --panel: #ffffff;
  --panel-soft: #faf8ff;
  --line: #e5dcff;
  --text: #191437;
  --muted: #655f86;
  --v1: #6933e7;
  --v2: #8639eb;
  --v3: #a03feb;
  --v4: #ba46ec;
  --v5: #d64ded;
  --shadow: 0 12px 28px rgba(105, 51, 231, 0.14);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  width: 100%;
  overflow-x: hidden;
  color: var(--text);
  font-family: "Manrope", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
}

.page-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(850px 380px at 8% -5%, rgba(166, 70, 236, 0.14), transparent 68%),
    radial-gradient(700px 360px at 100% 18%, rgba(105, 51, 231, 0.12), transparent 65%),
    linear-gradient(180deg, #f6f4ff 0%, #f8f6ff 50%, #f2eeff 100%);
}

.shell {
  width: 100vw;
  max-width: none;
  padding-left: 10px;
  padding-right: 10px;
  margin: 0 auto;
}

.panel {
  background: linear-gradient(160deg, var(--panel) 0%, var(--panel-soft) 100%);
  border: 1px solid var(--line);
  border-radius: 18px;
  box-shadow: var(--shadow);
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 9;
  margin-top: 10px;
  margin-bottom: 12px;
  padding: 10px 14px;
  background: rgba(255, 255, 255, 0.86);
  border: 1px solid var(--line);
  border-radius: 14px;
  backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  text-decoration: none;
  font-size: 24px;
  font-weight: 800;
}

.logo-dot {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: linear-gradient(140deg, var(--v1), var(--v5));
}

.topnav {
  display: inline-flex;
  gap: 8px;
}

.topnav a {
  text-decoration: none;
  color: #5c5680;
  font-size: 14px;
  padding: 8px 14px;
  border-radius: 999px;
  border: 1px solid transparent;
  transition: all 0.18s ease;
}

.topnav a:hover,
.topnav a.active {
  color: #fff;
  border-color: rgba(105, 51, 231, 0.4);
  background: linear-gradient(110deg, var(--v1), var(--v4));
}

.main-grid,
.course-main {
  display: grid;
  gap: 14px;
  padding-bottom: 54px;
}

.hero {
  display: block;
  padding: 20px;
}

.eyebrow {
  margin: 0;
  color: #7a73a0;
  letter-spacing: 0.15em;
  font-size: 12px;
}

.hero h1 {
  margin: 10px 0;
  font-size: clamp(34px, 4vw, 56px);
  line-height: 1.14;
}

.hero-desc,
.course-hero p {
  margin: 0;
  color: var(--muted);
  line-height: 1.78;
  font-size: 17px;
}

.hero-cta {
  margin-top: 18px;
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 42px;
  padding: 0 18px;
  border-radius: 12px;
  text-decoration: none;
  font-size: 14px;
  font-weight: 700;
}

.btn-primary {
  color: #fff;
  border: 1px solid rgba(105, 51, 231, 0.34);
  background: linear-gradient(110deg, var(--v1), var(--v4));
}

.btn-ghost {
  color: #564f7e;
  border: 1px solid #d9ccff;
  background: #fff;
}

.course-spotlight {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
  padding: 24px;
}

.course-spotlight h2 {
  margin: 8px 0;
  font-size: clamp(28px, 2.5vw, 40px);
}

.course-spotlight p,
.course-spotlight li {
  color: var(--muted);
  line-height: 1.75;
}

.spotlight-visual {
  min-height: 260px;
  border-radius: 16px;
  overflow: hidden;
  border: 1px solid #d9ccff;
  box-shadow: 0 10px 24px rgba(105, 51, 231, 0.18);
}

.spotlight-visual img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.library-layout {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 14px;
}

.sidebar {
  padding: 16px;
  max-height: 78vh;
  overflow: auto;
  background: linear-gradient(180deg, #efe9ff, #f8f5ff);
}

.sidebar-head h2 {
  margin: 0;
  font-size: 24px;
}

.sidebar-head p {
  margin: 5px 0 14px;
  color: #726b98;
  font-size: 13px;
}

.brand {
  display: inline-block;
  text-decoration: none;
  color: #2b1f5f;
  font-size: 18px;
  font-weight: 800;
  margin-bottom: 10px;
}

.menu-group {
  margin-bottom: 12px;
}

.group-title {
  display: block;
  text-decoration: none;
  color: #25195d;
  font-size: 30px;
  font-weight: 800;
  margin-bottom: 4px;
}

.sub-list {
  margin: 0;
  padding-left: 20px;
}

.sub-list li {
  margin: 6px 0;
}

.sub-list a {
  color: #52497f;
  font-size: 28px;
  text-decoration: none;
}

.sub-list a:hover,
.group-title:hover,
.brand:hover {
  color: var(--v1);
  text-decoration: underline;
}

.content {
  padding: 18px;
}

.content-head h2 {
  margin: 0;
  font-size: 30px;
}

.content-head p {
  margin: 8px 0 0;
  color: #776fa0;
  display: flex;
  align-items: center;
  gap: 7px;
}

.avatar {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  background: linear-gradient(120deg, var(--v1), var(--v5));
}

.sep {
  opacity: 0.52;
}

.category {
  margin-top: 18px;
}

.category > h2 {
  margin: 0 0 8px;
  font-size: 39px;
}

.subcategory h3 {
  margin: 12px 0;
  font-size: 30px;
  color: #2c1f66;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(175px, 1fr));
  gap: 14px;
}

.video-card {
  position: relative;
  border-radius: 14px;
  overflow: hidden;
  background: #efe9ff;
  border: 1px solid #d9ccff;
  aspect-ratio: 9 / 16;
  box-shadow: 0 10px 20px rgba(105, 51, 231, 0.16);
  cursor: pointer;
}

.video-card::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 46%, rgba(28, 16, 60, 0.34) 100%);
}

.video-card video {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.play-btn {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 56px;
  height: 56px;
  border: 0;
  border-radius: 50%;
  color: #fff;
  background: linear-gradient(120deg, rgba(105, 51, 231, 0.92), rgba(186, 70, 236, 0.92));
  font-size: 28px;
  z-index: 1;
  pointer-events: none;
}

.duration {
  position: absolute;
  right: 7px;
  bottom: 7px;
  z-index: 1;
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 8px;
  background: rgba(42, 26, 92, 0.58);
}

.caption {
  margin: 8px 0 0;
  color: #665d8a;
  font-size: 13px;
  line-height: 1.5;
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 2;
  overflow: hidden;
}

#playerDialog {
  width: min(460px, 92vw);
  border: 1px solid #d7c9ff;
  border-radius: 16px;
  padding: 14px;
  background: #fbf9ff;
  color: #20174b;
}

#playerDialog::backdrop {
  background: rgba(32, 18, 70, 0.32);
}

.dialog-actions {
  display: flex;
  justify-content: flex-end;
  margin-bottom: 8px;
}

.dialog-actions button {
  width: 30px;
  height: 30px;
  border-radius: 50%;
  border: 0;
  background: #ece2ff;
  color: #2b1f5f;
}

#dialogVideo {
  width: 100%;
  border-radius: 10px;
  background: #000;
}

#dialogTitle {
  margin: 8px 0 0;
  color: #5f5785;
  font-size: 13px;
}

.course-hero {
  padding: 26px;
}

.course-hero h1 {
  margin: 10px 0;
  font-size: clamp(34px, 4vw, 54px);
}

.course-kpis {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}

.kpi {
  padding: 14px;
}

.kpi span {
  color: #776fa0;
  font-size: 13px;
}

.kpi strong {
  display: block;
  margin-top: 8px;
  font-size: 21px;
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.course-card {
  padding: 18px;
}

.course-card.wide {
  grid-column: 1 / -1;
}

.course-card h2 {
  margin: 0 0 10px;
  font-size: 24px;
}

.course-card p,
.course-card li {
  color: #655d89;
  line-height: 1.75;
}

.course-card ul,
.course-card ol {
  margin: 0;
  padding-left: 22px;
}

.outline {
  columns: 2;
  column-gap: 24px;
}

.price {
  margin: 0 0 8px;
  color: #2e1f6a;
  font-size: 34px;
  font-weight: 800;
}

@media (max-width: 1100px) {
  .course-spotlight {
    grid-template-columns: 1fr;
  }

  .library-layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    max-height: none;
  }

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

  .course-grid {
    grid-template-columns: 1fr;
  }

  .outline {
    columns: 1;
  }
}

@media (max-width: 760px) {
  .topbar {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  .topnav {
    width: 100%;
    flex-wrap: wrap;
  }

  .hero,
  .course-spotlight,
  .content,
  .sidebar,
  .course-hero,
  .course-card,
  .kpi {
    padding: 14px;
  }

  .group-title,
  .category > h2,
  .subcategory h3,
  .sub-list a {
    font-size: 24px;
  }

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

  .course-kpis {
    grid-template-columns: 1fr;
  }
}