body {
  min-height: 100vh;
  overflow: hidden;
  color: var(--text);
  background: radial-gradient(circle at 70% 12%, rgba(112, 77, 38, .16), transparent 27%), linear-gradient(180deg, #15100c, var(--bg) 72%);
  font-family: Georgia, 'Times New Roman', serif;
}

body::before { content: ''; position: fixed; inset: 0; pointer-events: none; opacity: .16; background: repeating-linear-gradient(90deg, rgba(255,255,255,.018) 0 1px, transparent 1px 4px); }
.app-shell { display: grid; grid-template-columns: var(--sidebar-width) minmax(0, 1fr); height: 100vh; }
.sidebar { position: relative; z-index: 2; display: flex; flex-direction: column; overflow-y: auto; padding: 28px 18px 20px; background: linear-gradient(180deg, rgba(37, 27, 18, .98), rgba(13, 10, 7, .98)); border-right: 1px solid var(--border); box-shadow: 18px 0 44px rgba(0,0,0,.25); }
.main-content { position: relative; overflow-y: auto; padding: 34px clamp(22px, 4vw, 68px) 54px; }
.main-content::-webkit-scrollbar, .zoom-stage::-webkit-scrollbar { width: 0; height: 0; }
.course-view, .intro-view { min-height: calc(100vh - 88px); }