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solid #da3633}.output-error pre{color:#ff7b72}.completion-message{margin:32px 0;padding:24px;background:linear-gradient(135deg,#1f6feb,#1f3a6f);border-radius:8px;text-align:center}.completion-message h3{font-size:24px;margin-bottom:8px;color:#fff}.completion-message p{font-size:16px;color:#c9d1d9}.navigation-buttons{display:flex;justify-content:space-between;gap:16px;padding:24px 48px;border-top:1px solid #30363d;background-color:#161b22}::-webkit-scrollbar{width:12px;height:12px}::-webkit-scrollbar-track{background:#0d1117}::-webkit-scrollbar-thumb{background:#30363d;border-radius:6px}::-webkit-scrollbar-thumb:hover{background:#484f58}@media(max-width:1024px){.sidebar{width:280px}.lesson-viewer{padding:24px 32px}.navigation-buttons{padding:20px 32px}}@media(max-width:768px){.app{flex-direction:column}.sidebar{width:100%;max-height:50vh;border-right:none;border-bottom:1px solid #30363d}.lesson-viewer{padding:20px 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