:root{--bg: #ffffff;--bg-surface: #f7f4ef;--bg-sidebar: #faf8f4;--bg-hover: #f1ece3;--bg-active: #e9e2d6;--text: #17150f;--text-muted: #57534b;--text-dim: #8a8479;--accent: #a2542a;--accent-dim: #c07743;--border: #e4ded2;--border-light: #d4ccbc;--code-bg: #f7f4ef;--success: #15803d;--warning: #b45309;--danger: #b91c1c;--radius: 8px;--sidebar-width: 280px;--max-content: 720px}*{margin:0;padding:0;box-sizing:border-box}html{font-size:16px;scroll-behavior:smooth}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,system-ui,sans-serif;background:var(--bg);color:var(--text);line-height:1.7;min-height:100vh}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}.layout{display:flex;min-height:100vh}.sidebar{width:var(--sidebar-width);background:var(--bg-sidebar);border-right:1px solid var(--border);padding:1.5rem 0;position:fixed;top:0;left:0;bottom:0;overflow-y:auto;z-index:10}.sidebar-header{padding:0 1.25rem 1.25rem;border-bottom:1px solid var(--border);margin-bottom:1rem}.sidebar-header h1{font-size:.875rem;font-weight:700;letter-spacing:.05em;text-transform:uppercase;color:var(--accent)}.sidebar-header p{font-size:.75rem;color:var(--text-dim);margin-top:.25rem}.sidebar-section{margin-bottom:.5rem}.sidebar-section-title{font-size:.7rem;font-weight:600;text-transform:uppercase;letter-spacing:.08em;color:var(--text-dim);padding:.5rem 1.25rem .25rem}.sidebar-link{display:flex;align-items:center;justify-content:space-between;padding:.4rem 1.25rem;font-size:.85rem;color:var(--text-muted);transition:all .15s;border-left:2px solid transparent}.sidebar-link:hover{color:var(--text);background:var(--bg-hover);text-decoration:none}.sidebar-link.active{color:var(--accent);background:var(--bg-active);border-left-color:var(--accent)}.menu-toggle{display:none;position:fixed;top:1rem;left:1rem;z-index:20;background:var(--bg-surface);border:1px solid var(--border);color:var(--text);padding:.5rem .75rem;border-radius:var(--radius);cursor:pointer;font-size:1.25rem}.main{margin-left:var(--sidebar-width);flex:1;padding:3rem 2rem;display:flex;justify-content:center}.content{max-width:var(--max-content);width:100%}.content h1{font-size:2rem;font-weight:700;margin-bottom:.5rem;color:var(--text);line-height:1.2}.content h2{font-size:1.4rem;font-weight:600;margin-top:2.5rem;margin-bottom:.75rem;color:var(--text);padding-bottom:.4rem;border-bottom:1px solid var(--border)}.content h3{font-size:1.1rem;font-weight:600;margin-top:1.75rem;margin-bottom:.5rem;color:var(--text)}.content p{margin-bottom:1rem;color:var(--text)}.content ul,.content ol{margin-bottom:1rem;padding-left:1.5rem}.content li{margin-bottom:.4rem}.content strong{color:var(--text);font-weight:600}.content hr{border:none;border-top:1px solid var(--border);margin:2rem 0}.content blockquote{border-left:3px solid var(--accent-dim);padding:.75rem 1rem;margin:1.25rem 0;background:var(--bg-surface);border-radius:0 var(--radius) var(--radius) 0;color:var(--text-muted)}.content blockquote p{margin-bottom:.5rem}.content blockquote p:last-child{margin-bottom:0}.content img{max-width:100%;height:auto;border-radius:var(--radius);border:1px solid var(--border);margin:1rem 0}.content code{font-family:SF Mono,Fira Code,Cascadia Code,monospace;font-size:.85em;background:#f0edf5;padding:.15em .4em;border-radius:3px;color:var(--accent)}.content pre{background:#faf9fc;border:1px solid #e8e0f0;border-radius:var(--radius);padding:1rem 1.25rem;overflow-x:auto;margin:1.25rem 0;line-height:1.5}.content pre code{background:none;padding:0;color:#333;font-size:.8rem}.copy-bar{display:flex;justify-content:flex-end;margin-bottom:1.5rem}.copy-btn{display:inline-flex;align-items:center;gap:.4rem;padding:.5rem 1rem;background:var(--accent);color:#fff;border:none;border-radius:var(--radius);font-size:.85rem;font-weight:500;cursor:pointer;transition:opacity .15s;font-family:inherit}.copy-btn:hover{opacity:.85}.copy-btn.copied{background:var(--success)}.code-copy-wrapper{position:relative}.code-copy-btn{display:block;margin:-.5rem auto 1.25rem;padding:.5rem 1.2rem;background:var(--accent);color:#fff;border:none;border-radius:var(--radius);font-size:.85rem;font-weight:500;cursor:pointer;transition:opacity .15s,background .15s;font-family:inherit}.code-copy-btn:hover{opacity:.85}.code-copy-btn.copied{background:var(--success)}.content table{width:100%;border-collapse:collapse;margin:1.25rem 0;font-size:.9rem}.content th{text-align:left;padding:.6rem .75rem;border-bottom:2px solid var(--border-light);font-weight:600;color:var(--text);font-size:.8rem;text-transform:uppercase;letter-spacing:.04em}.content td{padding:.6rem .75rem;border-bottom:1px solid var(--border);color:var(--text-muted)}.content tr:hover td{background:var(--bg-surface)}.content-header{display:flex;justify-content:space-between;align-items:flex-start;margin-bottom:2rem;gap:1rem}.lesson-meta{display:flex;gap:.5rem;flex-wrap:wrap}.lesson-meta-tag{font-size:.75rem;padding:.25rem .65rem;border-radius:100px;background:var(--bg-surface);border:1px solid var(--border);color:var(--text-muted)}.lesson-nav{display:flex;justify-content:space-between;margin-top:3rem;padding-top:1.5rem;border-top:1px solid var(--border);gap:1rem}.lesson-nav a{display:flex;flex-direction:column;padding:.75rem 1rem;border:1px solid var(--border);border-radius:var(--radius);transition:all .15s;max-width:48%}.lesson-nav a:hover{border-color:var(--accent-dim);background:var(--bg-surface);text-decoration:none}.lesson-nav-label{font-size:.7rem;text-transform:uppercase;letter-spacing:.06em;color:var(--text-dim);margin-bottom:.25rem}.lesson-nav-title{font-size:.9rem;color:var(--accent)}.lesson-nav .next{text-align:right;margin-left:auto}.content input[type=checkbox]{margin-right:.5rem;accent-color:var(--accent);cursor:pointer;width:1rem;height:1rem}.sidebar-link-text{flex:1;min-width:0}.sidebar-check{font-size:.7rem;color:var(--success);font-weight:700;margin-left:.5rem;flex-shrink:0}.sidebar-check.checked{color:var(--success)}.practice-time-bar{margin-top:2.5rem;padding:1.25rem;background:var(--bg-surface);border:1px solid var(--border);border-radius:var(--radius)}.practice-label{display:block;font-size:.85rem;font-weight:600;color:var(--text);margin-bottom:.5rem}.practice-input-row{display:flex;align-items:center;gap:.35rem}.practice-field{width:3.5rem;padding:.4rem .5rem;border:1px solid var(--border);border-radius:var(--radius);font-size:.9rem;font-family:inherit;text-align:center;background:var(--bg);color:var(--text)}.practice-field:focus{outline:none;border-color:var(--accent)}.practice-unit{font-size:.8rem;color:var(--text-muted);margin-right:.5rem}.practice-save{padding:.4rem 1rem;background:var(--accent);color:#fff;border:none;border-radius:var(--radius);font-size:.8rem;font-weight:600;cursor:pointer;font-family:inherit;margin-left:.5rem}.practice-save:hover{opacity:.85}.practice-hint{font-size:.75rem;color:var(--text-dim);margin-top:.35rem;margin-bottom:0}.lesson-done-bar{display:flex;justify-content:center;margin-top:2.5rem;padding-top:1.5rem;border-top:1px solid var(--border)}.done-btn{display:inline-flex;align-items:center;gap:.4rem;padding:.6rem 1.5rem;background:var(--bg-surface);color:var(--text-muted);border:1px solid var(--border);border-radius:var(--radius);font-size:.9rem;font-weight:500;cursor:pointer;transition:all .15s;font-family:inherit}.done-btn:hover{border-color:var(--success);color:var(--success)}.done-btn.is-done{background:var(--success);color:#fff;border-color:var(--success)}.done-btn.is-done:hover{opacity:.85}.sources{margin-top:2.5rem;padding-top:1rem;border-top:1px solid var(--border)}.sources h2{font-size:1rem;margin-top:0}.sources ul{list-style:none;padding-left:0}.sources li{margin-bottom:.4rem;font-size:.85rem}.sources a{color:var(--accent)}@media(max-width:768px){.menu-toggle{display:block}.sidebar{transform:translate(-100%);transition:transform .2s ease}.sidebar.open{transform:translate(0)}.main{margin-left:0;padding:4rem 1.25rem 2rem}.content h1{font-size:1.5rem}.lesson-nav{flex-direction:column}.lesson-nav a{max-width:100%}}
