:root {
  color-scheme: dark;
  --bg: #090c12;
  --panel: #121826;
  --panel-2: #192235;
  --text: #e8edf8;
  --muted: #9da9c2;
  --accent: #5ea0ff;
  --accent-2: #8f6bff;
  --border: #25304a;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
  background: radial-gradient(circle at 20% 0%, #162038 0%, var(--bg) 45%);
  color: var(--text);
}

.app {
  display: grid;
  grid-template-columns: 360px 1fr;
  min-height: 100vh;
}

.sidebar {
  border-right: 1px solid var(--border);
  background: rgba(7, 12, 20, 0.75);
  backdrop-filter: blur(8px);
  padding: 20px 16px;
  overflow-y: auto;
}

.brand h1 {
  margin: 0;
  font-size: 1.2rem;
}

.brand p {
  margin: 4px 0 0;
  color: var(--muted);
}

.search-wrap {
  margin: 16px 0;
}

#searchInput {
  width: 100%;
  background: var(--panel);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 10px;
  padding: 10px 12px;
}

.course-nav {
  display: grid;
  gap: 10px;
}

.module {
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}

.module summary {
  cursor: pointer;
  background: var(--panel);
  padding: 10px 12px;
  font-weight: 600;
  list-style: none;
}

.module summary::-webkit-details-marker {
  display: none;
}

.lesson-list {
  margin: 0;
  padding: 6px;
  list-style: none;
  background: #0f1727;
}

.lesson-btn {
  width: 100%;
  border: 0;
  background: transparent;
  text-align: left;
  color: var(--text);
  padding: 10px;
  border-radius: 10px;
  cursor: pointer;
}

.lesson-btn:hover {
  background: #202c44;
}

.lesson-btn.active {
  background: linear-gradient(90deg, rgba(94, 160, 255, 0.25), rgba(143, 107, 255, 0.2));
  border: 1px solid rgba(94, 160, 255, 0.35);
}

.lesson-meta {
  display: block;
  color: var(--muted);
  font-size: 0.8rem;
  margin-top: 4px;
}

.content {
  padding: 24px;
  display: grid;
  gap: 18px;
  align-content: start;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.topbar h2 {
  margin: 0;
}

.muted {
  color: var(--muted);
  margin: 8px 0 0;
}

.btn {
  border: 1px solid #4067c7;
  color: #dbe8ff;
  background: #294588;
  padding: 10px 14px;
  border-radius: 10px;
  cursor: pointer;
}

.btn:disabled {
  opacity: 0.4;
  cursor: default;
}

.player-wrap {
  border: 1px solid var(--border);
  border-radius: 16px;
  background: #060a12;
  overflow: hidden;
  position: relative;
}

video {
  width: 100%;
  max-height: 68vh;
  background: black;
  display: none;
}

.empty-state {
  min-height: 320px;
  display: grid;
  place-items: center;
  color: var(--muted);
}

.legal-inline {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: rgba(18, 24, 38, 0.7);
  padding: 10px 12px;
}

.legal-inline p {
  margin: 0;
  color: var(--muted);
  font-size: 0.86rem;
  line-height: 1.4;
}

.resources {
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
  padding: 14px 16px;
}

.resources h3 {
  margin: 0 0 10px;
}

.resource-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 8px;
}

.resource-list a {
  color: #b8d1ff;
  text-decoration: none;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px;
  display: block;
  background: var(--panel-2);
}

.resource-list a:hover {
  border-color: #4c74c8;
}

.site-footer {
  margin-top: 6px;
  color: var(--muted);
  font-size: 0.9rem;
  display: flex;
  gap: 10px;
  align-items: center;
}

.site-footer a {
  color: #b8d1ff;
  text-decoration: none;
}

.site-footer a:hover {
  text-decoration: underline;
}

@media (max-width: 980px) {
  .app {
    grid-template-columns: 1fr;
  }

  .sidebar {
    border-right: 0;
    border-bottom: 1px solid var(--border);
    max-height: 45vh;
  }
}