:root{--ink: #111;--muted: #888;--rule: #e6e6e6;--hover: #000;--bg: #fff;--max: 1180px;--sb: 240px;--sans: "Helvetica Neue", Helvetica, Arial, sans-serif;--mono: "IBM Plex Mono", ui-monospace, Menlo, monospace}*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}html,body{height:100%}body{background:var(--bg);color:var(--ink);font-family:var(--sans);font-size:13px;line-height:1.55;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}a{color:inherit;text-decoration:none}a:hover{text-decoration:underline}.muted{color:var(--muted)}.frame{display:grid;grid-template-columns:var(--sb) 1fr;max-width:var(--max);min-height:100vh;margin:0 auto}nav.sidebar{border-right:1px solid var(--rule);padding:28px 22px 28px 28px;position:sticky;top:0;align-self:start;height:100vh;overflow-y:auto}.brand{font-weight:700;letter-spacing:-.01em;font-size:14px;display:block}.brand-sub{font-family:var(--mono);font-size:11px;color:var(--muted);margin:2px 0 30px}ul.spine{list-style:none}ul.spine>li{margin:9px 0;line-height:1.4}ul.spine>li a{display:flex;gap:8px;align-items:baseline;color:var(--muted)}ul.spine>li .n{font-family:var(--mono);font-size:11px;color:#c2c0b8}ul.spine>li.done a{color:var(--ink)}ul.spine>li.done .n{color:var(--muted)}ul.spine>li.active a{color:var(--hover);font-weight:600}ul.spine>li.active .n{color:var(--hover)}ul.spine>li.locked a{color:#c7c5bd;pointer-events:none;cursor:default}ul.spine>li.locked .n{color:#d8d6cf}ul.spine>li .tick{margin-left:auto;font-family:var(--mono);font-size:11px;color:var(--muted)}.toolkit-foot{margin-top:30px;padding-top:14px;border-top:1px solid var(--rule);font-family:var(--mono);font-size:11px;color:var(--muted);line-height:1.8}.toolkit-foot .count{color:var(--ink)}.toolkit-actions{margin-top:12px;display:flex;flex-direction:column;gap:6px}.toolkit-actions button{font-family:var(--mono);font-size:11px;color:var(--ink);background:#fff;border:1px solid #cfcdc6;border-radius:0;padding:5px 10px;text-align:left;cursor:pointer}.toolkit-actions button:hover{background:#f4f3ef}main.content{padding:60px 56px 96px;max-width:760px}.intro{font-size:16px;line-height:1.65;color:var(--ink);max-width:620px;margin-bottom:40px}.intro a{text-decoration:underline;text-decoration-thickness:1px;text-underline-offset:2px}h1.lesson-title{font-size:24px;font-weight:600;letter-spacing:-.01em;margin-bottom:18px}.eyebrow{font-family:var(--mono);font-size:11px;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);margin-bottom:8px}.content p{margin:14px 0}.content h2{font-size:16px;font-weight:600;margin:36px 0 10px;padding-top:16px;border-top:1px solid var(--rule)}figure.frontispiece{margin:0 0 36px}figure.frontispiece img{display:block;width:100%;max-width:720px;height:auto;background:var(--rule)}figure.frontispiece figcaption{margin-top:12px;max-width:620px;font-size:13px;line-height:1.55;color:var(--muted);font-style:italic}figure.frontispiece figcaption em{font-style:normal}figure.frontispiece figcaption a{text-decoration:underline}figure.frontispiece.home{margin-top:8px}figure.frontispiece.home img{max-width:380px;margin-left:auto;margin-right:auto}figure.frontispiece.home figcaption{max-width:540px;margin:12px auto 0}.callout{margin:22px 0;padding:14px 16px;background:#faf9f6;border-top:1px solid var(--rule)}.callout .callout-title{font-family:var(--mono);font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin-bottom:6px}.callout p{margin:0}.cell-embed{margin:24px 0;border:1px solid var(--rule)}.cell-embed iframe{display:block;width:100%;border:0;background:#fff}.cell-fallback{border-top:1px solid var(--rule);font-size:12px}.cell-fallback summary{padding:8px 12px;font-family:var(--mono);font-size:11px;color:var(--muted);cursor:pointer}.cell-fallback pre{margin:0;padding:0 14px 12px;font-family:var(--mono);font-size:12px;line-height:1.6;white-space:pre-wrap;color:var(--ink)}.cell-fallback .out{color:#444}.pycell{border:1px solid var(--rule);margin:24px 0;background:#fff}.pycell-sublabel{font-family:var(--mono);font-size:11px;color:var(--muted);padding:8px 12px 0}.pycell-input{display:block;width:100%;border:0;border-bottom:1px solid var(--rule);resize:vertical;padding:6px 14px 12px;font-family:var(--mono);font-size:13px;line-height:1.6;color:var(--ink);background:#fff;outline:none}.pycell-num{display:inline-block;field-sizing:content;width:58px;min-width:38px;max-width:130px;margin:2px 14px 12px;border:1px solid var(--rule);border-radius:0;padding:5px 8px;font-family:var(--mono);font-size:13px;color:var(--ink);background:#fff;outline:none}.pycell-coderow{display:flex;align-items:center;justify-content:space-between;padding:8px 12px 0}.pycell-run{font-family:var(--mono);font-size:11px;color:var(--ink);background:#fff;border:1px solid #cfcdc6;border-radius:0;padding:4px 14px;cursor:pointer}.pycell-run:hover:not(:disabled){background:#f4f3ef}.pycell-run:disabled{color:var(--muted);cursor:default}.pycell-code{margin:4px 0 0;padding:6px 14px 14px;font-family:var(--mono);font-size:13px;line-height:1.6;color:var(--ink);background:#fff;white-space:pre-wrap}.pycell-code .tok-comment{color:#9a9a93;font-style:italic}.pycell-code .tok-str{color:#3b6d11}.pycell-code .tok-kw{color:#185fa5}.pycell-code .tok-fn{color:#712b13}.pycell-out{margin:0;padding:12px 14px;border-top:1px solid var(--rule);font-family:var(--mono);font-size:13px;line-height:1.6;color:#333;white-space:pre-wrap;background:#faf9f6}.prompt{margin-top:30px;padding-top:16px;border-top:1px solid var(--rule);font-style:italic;font-size:14px;line-height:1.6;color:#444}.prompt .lab{font-style:normal;font-family:var(--mono);font-size:11px;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);margin-right:10px}.deposit{margin-top:28px;padding-top:16px;border-top:1px solid var(--rule);display:flex;align-items:center;gap:14px}.deposit button{font-family:var(--mono);font-size:12px;color:var(--ink);background:#fff;border:1px solid var(--ink);border-radius:0;padding:8px 14px;cursor:pointer}.deposit button:hover{background:var(--ink);color:#fff}.deposit button[disabled]{color:var(--muted);border-color:var(--rule);background:#fff;cursor:default}.deposit .state{font-family:var(--mono);font-size:11px;color:var(--muted)}ul.lesson-index{list-style:none;margin:24px 0}ul.lesson-index>li{padding:14px 0;border-top:1px solid var(--rule)}ul.lesson-index>li .n{font-family:var(--mono);font-size:11px;color:var(--muted);margin-right:10px}ul.lesson-index>li a{font-size:15px}ul.lesson-index>li p{color:var(--muted);margin:4px 0 0}.further{margin-top:30px;padding-top:16px;border-top:1px solid var(--rule);font-size:14px}.further a{text-decoration:underline;text-decoration-thickness:1px;text-underline-offset:2px}a.spine-extra{display:block;margin-top:18px;font-family:var(--mono);font-size:11px;color:var(--muted)}a.spine-extra:hover{color:var(--hover)}a.spine-extra.here{color:var(--ink)}a.spine-top{display:block;margin:0 0 16px;font-family:var(--mono);font-size:11px;color:var(--muted)}a.spine-top:hover{color:var(--hover)}a.spine-top.here{color:var(--ink)}ul.reading-list{list-style:none;margin:12px 0 4px}ul.reading-list>li{padding:13px 0;border-top:1px solid var(--rule)}ul.reading-list>li:first-child{border-top:0}.reading-title{font-size:14px;line-height:1.5}.reading-title cite{font-style:italic}.reading-title a{text-decoration:underline;text-decoration-thickness:1px;text-underline-offset:2px}.reading-meta{font-family:var(--mono);font-size:11px;color:var(--muted);margin-top:4px;line-height:1.7}.reading-meta a{text-decoration:underline}.reading-note{font-size:13px;color:#444;margin-top:4px}.verdict{display:inline-block;font-family:var(--mono);font-size:10px;letter-spacing:.06em;text-transform:uppercase;color:var(--muted);border:1px solid var(--rule);padding:1px 6px;margin-left:8px;vertical-align:middle;white-space:nowrap}ul.gaps{list-style:none;margin:12px 0}ul.gaps>li{position:relative;padding:7px 0 7px 20px;line-height:1.6}ul.gaps>li:before{content:"—";position:absolute;left:0;color:var(--muted)}ul.gaps>li b{font-weight:600}.exercise{padding-top:2px}.exercise p{margin:0 0 10px}.exercise .exercise-foot{font-family:var(--mono);font-size:11px;color:var(--muted);margin:0;line-height:1.9}.exercise-foot .skill{display:inline-block;color:var(--ink);border:1px solid var(--ink);padding:0 6px;margin-left:2px;font-size:10px;letter-spacing:.06em;text-transform:uppercase;vertical-align:middle}.callout.feature{border:1px solid var(--ink);background:#faf9f6;padding:16px 18px}.callout.feature .callout-title{color:var(--ink)}.callout.feature p+p{margin-top:10px}table.cheatsheet{width:100%;border-collapse:collapse;margin:16px 0 4px;font-size:13px}table.cheatsheet th,table.cheatsheet td{text-align:left;vertical-align:top;padding:9px 16px 9px 0;border-top:1px solid var(--rule);line-height:1.5}table.cheatsheet thead th{border-top:0;font-family:var(--mono);font-weight:500;font-size:11px;letter-spacing:.04em;text-transform:uppercase;color:var(--muted)}table.cheatsheet tbody td:first-child{color:var(--ink);width:30%}table.cheatsheet b{font-weight:600}table.cheatsheet code{font-family:var(--mono);font-size:12px}a.spine-extra+a.spine-extra{margin-top:8px}.gofurther{margin:30px 0 0;padding:14px 16px;background:#faf9f6;border-top:1px solid var(--rule)}.gofurther .gf-title{font-family:var(--mono);font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin-bottom:6px}.gofurther p{margin:0;line-height:1.6}.gofurther p+p{margin-top:8px}.gofurther .gf-foot{font-family:var(--mono);font-size:11px;color:var(--muted);line-height:1.8}.gofurther .gf-foot .skill{display:inline-block;color:var(--ink);border:1px solid var(--ink);padding:0 6px;margin-left:2px;font-size:10px;letter-spacing:.06em;text-transform:uppercase;vertical-align:middle}.gofurther .gf-foot a{text-decoration:underline}#preview-gate[data-astro-cid-b7jmyspo]{position:fixed;inset:0;z-index:99999;background:#000;display:flex;align-items:center;justify-content:center}#preview-gate[data-astro-cid-b7jmyspo] form[data-astro-cid-b7jmyspo]{display:flex;flex-direction:column;align-items:center;gap:14px}#preview-gate[data-astro-cid-b7jmyspo] input[data-astro-cid-b7jmyspo]{width:260px;padding:12px 16px;border:0;border-radius:0;background:#fff;color:#111;font-family:IBM Plex Mono,ui-monospace,Menlo,monospace;font-size:14px;text-align:center;outline:none}#preview-gate[data-astro-cid-b7jmyspo] input[data-astro-cid-b7jmyspo]::placeholder{color:#888}#preview-gate[data-astro-cid-b7jmyspo] #preview-gate-error[data-astro-cid-b7jmyspo]{margin:0;font-family:IBM Plex Mono,ui-monospace,Menlo,monospace;font-size:11px;letter-spacing:.04em;color:#fff}