.practice{padding:32px 0 38px;background:#eef2ef;border-bottom:1px solid var(--line);scroll-margin-top:18px}
.practice-heading{margin-bottom:20px}.practice-heading .section-kicker{margin-bottom:7px}.practice-heading h2{font:600 31px/1.2 var(--display);letter-spacing:-.5px;margin:0}
.practice-app{background:#fff;border:1px solid #c4cfd2;padding:20px;outline-offset:4px}.practice-workspace{display:grid;grid-template-columns:190px minmax(300px,1fr) minmax(285px,1fr);gap:25px;align-items:start}.practice-workspace[hidden]{display:none}.practice-board-column,.practice-study{min-width:0}.practice-index{border-right:1px solid var(--line);padding-right:15px}.practice-index summary{font-size:14px;font-weight:700;list-style:none;margin:0 0 13px}.practice-index summary span{display:none}.chapter-link{display:flex;gap:10px;width:100%;padding:11px 8px;border:0;border-left:3px solid transparent;background:transparent;text-align:left;color:var(--ink);font:14px/1.45 'Segoe UI',sans-serif}.chapter-link span{font-size:13px;color:#637c8a;font-variant-numeric:tabular-nums;padding-top:1px}.study-chapter.active>.chapter-link{border-color:var(--gold);background:#edf3f6;font-weight:600}.chapter-variants{display:none;border-left:1px solid #cbd6dc;margin:3px 0 10px 19px;padding-left:8px}.study-chapter.active .chapter-variants{display:block}.chapter-variants button{display:block;width:100%;text-align:left;background:transparent;border:0;font:13px/1.5 'Segoe UI',sans-serif;color:#426079;padding:8px 4px}.chapter-variants button.active{font-weight:700;color:#103e60;text-decoration:underline;text-underline-offset:3px}.chapter-link:hover,.chapter-variants button:hover{background:#f1f5f7}
.practice-board-top{display:flex;justify-content:space-between;align-items:center;gap:10px;margin:0 4px 6px}.practice-board-top strong{font:600 21px var(--display)}.practice-board-top span{font:13px/1.4 'Segoe UI',sans-serif;color:var(--muted);text-align:right;max-width:65%}.practice-board{position:relative;width:100%;aspect-ratio:1;outline-offset:2px}.practice-board>svg{display:block;width:100%;height:100%}.practice-board.interactive{touch-action:none}.square-grid{position:absolute;inset:5.22388%;display:grid;grid-template-columns:repeat(8,1fr);grid-template-rows:repeat(8,1fr)}.square-grid button{padding:0;border:0;background:transparent;position:relative;touch-action:none;border-radius:0;cursor:grab}.square-grid button.selected{box-shadow:inset 0 0 0 4px #12628a;background:#18587933}.square-grid button.legal::after{content:'';position:absolute;inset:34%;border-radius:50%;background:#103e6099;box-shadow:0 0 0 2px #fff9}.square-grid button:hover{box-shadow:inset 0 0 0 3px #164d77aa}.square-grid button:focus-visible{outline:3px solid #102d48;outline-offset:-3px}.drag-piece{position:fixed;top:0;left:0;width:60px;height:60px;z-index:1000;pointer-events:none;filter:drop-shadow(0 3px 4px #0007)}
.practice-controls{display:grid;grid-template-columns:38px 42px 1fr 42px 38px;gap:3px;align-items:center;background:var(--navy);padding:6px;color:#fff}.practice-controls button{background:transparent;border:1px solid #ffffff44;color:inherit;min-height:40px;font-size:22px;padding:0}.practice-controls button:hover:not(:disabled){background:#ffffff22}.practice-controls button:disabled{opacity:.35}.practice-controls span{text-align:center;font-size:13px;font-variant-numeric:tabular-nums}.practice-keyboard{text-align:center;font:13px/1.4 'Segoe UI',sans-serif;color:var(--muted);margin:8px 0}.practice-keyboard>span{white-space:nowrap}kbd{font:13px 'Segoe UI',sans-serif;background:#f2f5f7;border:1px solid #c5cfd5;padding:1px 4px;border-radius:3px}.practice-tools{display:flex;flex-wrap:wrap;justify-content:space-between;gap:3px 12px;padding-top:7px;border-top:1px solid var(--line)}.practice-tools button{font-size:13px;background:none;border:0;color:#33576c;padding:8px 0;text-decoration:underline;text-underline-offset:3px}.practice-tools button[aria-pressed=true]{font-weight:600}.practice-feedback{font:14px/1.5 'Segoe UI',sans-serif;color:#24566b;margin:10px 4px 0;min-height:21px}
.practice-modes{display:flex;border-bottom:1px solid #bdcbd3;margin-bottom:18px;gap:2px}.practice-modes button{font:14px 'Segoe UI',sans-serif;flex:1;min-height:42px;border:0;border-bottom:3px solid transparent;background:transparent;color:#34566c;padding:8px 6px}.practice-modes button[aria-pressed=true]{border-bottom-color:var(--blue);color:#173c57;font-weight:700;background:#edf3f6}.practice-kind{font:13px 'Segoe UI',sans-serif;color:var(--muted);margin:0 0 6px}.practice-comment h3{font:600 23px/1.25 var(--display);margin:0 0 12px}.practice-comment #practice-text p{font:16px/1.65 'Segoe UI',sans-serif;margin:0 0 12px}.practice-note-tabs{display:flex;gap:6px;margin-bottom:12px}.practice-note-tabs:empty{display:none}.practice-note-tabs button{border:0;background:#eef2f4;font:13px 'Segoe UI',sans-serif;min-height:32px;padding:6px 10px;color:#32536a}.practice-note-tabs button[aria-pressed=true]{background:#224e6b;color:#fff}.practice-video-link{font-size:13px;margin:2px 0 14px;text-underline-offset:4px}.practice-history{border-top:1px solid var(--line);padding-top:13px}.practice-history h4,.practice-branches h4{font:600 13px 'Segoe UI',sans-serif;color:var(--muted);margin:0 0 9px}.practice-history #practice-moves{max-height:280px;overflow:auto;scrollbar-gutter:stable;padding-right:4px}.move-table{display:grid;gap:0}.move-row{display:grid;grid-template-columns:32px 1fr 1fr;align-items:center;border-bottom:1px solid #ecf0f2;min-height:32px;font-size:14px}.move-row>span{color:#627b8b;text-align:center;font-size:13px}.move-row button,.initial-move{font:15px 'Segoe UI',sans-serif;text-align:left;background:transparent;border:0;padding:6px 9px;min-height:32px;color:var(--ink)}.move-row button:hover,.initial-move:hover{background:#eff4f6}.move-row button[aria-current],.initial-move[aria-current]{background:#dfeaf1;box-shadow:inset 3px 0 #20658b;font-weight:700}.move-segment+ .move-segment{margin-top:14px;padding-left:10px;border-left:2px solid #b9cbd7}.move-segment>p{font:13px/1.45 'Segoe UI',sans-serif;margin:0 0 6px;color:#4f6777}.practice-branches{margin-bottom:16px}.practice-branches>div{display:flex;gap:8px}.practice-branches button{background:#eff4f6;border:1px solid #b8cbd8;padding:7px 13px;min-height:35px;font-size:14px;color:var(--ink)}.empty-moves,#practice-free-help p{font:15px/1.6 'Segoe UI',sans-serif;color:#4f6573;margin:0 0 12px}.practice-return{background:none;border:0;padding:0;margin:0 0 18px;font:14px 'Segoe UI',sans-serif;color:#225f81;text-decoration:underline;text-underline-offset:4px;min-height:30px}
.practice-engine{border-top:1px solid var(--line);margin-top:18px;padding-top:14px}.engine-heading{display:flex;align-items:center;justify-content:space-between;gap:12px}.engine-heading h4{font:600 14px/1.4 'Segoe UI',sans-serif;margin:0}.engine-heading button{background:#edf3f5;border:1px solid #b6cad4;padding:7px 9px;min-height:35px;font:13px 'Segoe UI',sans-serif;color:#174563;white-space:nowrap}.engine-heading button[aria-pressed=true]{background:#1d506e;color:white}.practice-engine>p{font:13px/1.5 'Segoe UI',sans-serif;color:var(--muted);margin:8px 0}.practice-engine small,.practice-engine small a{font:13px/1.5 'Segoe UI',sans-serif;color:#607785}.engine-line{display:grid;grid-template-columns:64px 1fr;gap:7px;font:14px/1.65 'Segoe UI',sans-serif;margin:7px 0}.engine-line strong{font-variant-numeric:tabular-nums;color:#153e59}.practice-app button{cursor:pointer}.practice-app button:disabled{cursor:default}.practice-app :focus-visible{outline:3px solid #c98c29;outline-offset:2px}.promotion-dialog{border:1px solid #9fb3c1;padding:24px;max-width:calc(100vw - 32px);color:var(--ink)}.promotion-dialog::backdrop{background:#102535aa}.promotion-dialog h2{font:600 23px var(--display);margin:0 0 20px}.promotion-dialog div{display:flex;gap:8px;flex-wrap:wrap}.promotion-dialog button{min-height:42px;padding:8px 15px;font-size:15px;background:#edf3f7;border:1px solid #bacbd6;cursor:pointer}.promotion-dialog>button{margin-top:17px;background:transparent}
.lesson-figure.diagram-figure{display:grid;grid-template-columns:minmax(230px,1fr) minmax(180px,.75fr);gap:20px;align-items:center;background:#f0f4f5;padding:20px;border:1px solid #d7e1e5;margin:30px 0}.diagram-figure>a{min-width:0}.lesson-figure.diagram-figure img{border:0;aspect-ratio:1;background:white}.lesson-figure.diagram-figure figcaption{padding:0 0 0 16px;margin:0;font-size:15px;border-left:3px solid var(--gold)}.diagram-figure figcaption .figure-zoom{font-size:13px;color:#476378;font-weight:400;margin-top:9px}.diagram-figure .diagram-practice{display:inline-block;font:600 14px/1.4 'Segoe UI',sans-serif;margin-top:14px;color:#1e5b7e;text-underline-offset:4px}
@media(min-width:1101px){.practice-index summary{pointer-events:none}.practice-index{position:sticky;top:18px}.practice-board-column{position:sticky;top:18px}}
@media(max-width:1100px){.practice-workspace{grid-template-columns:minmax(270px,1fr) minmax(280px,1fr);gap:20px}.practice-index{grid-column:1/-1;border:1px solid var(--line);padding:0}.practice-index summary{cursor:pointer;padding:12px 14px;margin:0;display:flex;justify-content:space-between}.practice-index summary span{display:block}.practice-index[open] summary{border-bottom:1px solid var(--line)}.practice-index nav{display:grid;grid-template-columns:1fr 1fr;padding:8px}.practice-app{padding:18px}.practice-comment h3{font-size:24px}}
@media(max-width:700px){.practice{padding-block:27px}.practice-heading h2{font-size:27px}.practice-app{padding:12px}.practice-workspace{display:flex;flex-direction:column;gap:17px}.practice-index{width:100%}.practice-index nav{display:block}.practice-board-column,.practice-study{width:100%}.practice-board-column{max-width:470px;align-self:center}.practice-history #practice-moves{max-height:330px}.practice-comment #practice-text p{font-size:17px}.practice-modes button{font-size:14px}.practice-tools{gap:3px 9px}.practice-controls{grid-template-columns:32px 36px 1fr 36px 32px}.practice-controls span{font-size:13px}.practice-keyboard{margin-top:8px}.lesson-figure.diagram-figure{grid-template-columns:1fr;gap:14px;padding:13px}.diagram-figure>a{max-width:460px;width:100%;margin:auto}.lesson-figure.diagram-figure figcaption{font-size:14px}.practice-feedback:empty{display:none}}
@media(min-width:1101px){.practice-index,.practice-board-column{top:104px}}
@media(max-width:700px){.practice-workspace{gap:0}.practice-board-column,.practice-study{display:contents}.practice-index{order:0;margin-bottom:13px}.practice-modes{order:1;width:100%;margin-bottom:14px}.practice-board-top{order:3;width:100%;margin:0 0 5px}.practice-board{order:4;max-width:470px;align-self:center}.practice-controls{order:5;width:100%;max-width:470px;align-self:center}.practice-keyboard{order:6;width:100%}.practice-tools{order:7;width:100%;margin-bottom:8px}.practice-feedback{order:8;width:100%;margin:0 0 14px}.practice-comment{order:9;margin-top:9px}.practice-video-link{order:10;align-self:flex-start}.practice-branches{order:11;width:100%}.practice-history{order:12;width:100%;margin-top:7px}.practice-engine{order:13;width:100%}#practice-free-help{order:2;width:100%;margin-bottom:10px}#practice-free-help p{font-size:14px;margin-bottom:4px}.practice-return{margin-bottom:3px}}

.practice-controls>span{white-space:nowrap}
@media(max-width:360px){.practice-controls .counter-prefix{display:none}.practice-board>svg text{font-size:31px}}
/* Evaluación de la posición y profundidad del motor. */
.practice-board-frame{display:grid;grid-template-columns:38px minmax(0,1fr);gap:6px;align-items:stretch;width:100%}.board-evaluation{position:relative;display:flex;align-items:center;justify-content:center;padding:5.22388% 0;min-width:0}.evaluation-score{position:absolute;top:-19px;left:50%;transform:translateX(-50%);font:600 13px/1.3 'Segoe UI',sans-serif;white-space:nowrap;color:var(--ink);font-variant-numeric:tabular-nums}.evaluation-track{position:relative;height:100%;width:15px;border:1px solid #79909e;background:#17364a;overflow:hidden;border-radius:2px}.evaluation-white{position:absolute;top:0;left:0;right:0;height:50%;background:#fff;transition:height .25s ease}.white-bottom .evaluation-white{top:auto;bottom:0}.evaluation-middle{position:absolute;top:50%;left:0;right:0;border-top:1px solid #aabac5}.board-evaluation.pending .evaluation-track{opacity:.35}.engine-footer{display:flex;align-items:baseline;justify-content:space-between;flex-wrap:wrap;gap:10px;margin-top:10px}.engine-depth{position:relative;margin-left:auto}.engine-depth summary{list-style:none;cursor:pointer;text-decoration:underline;text-decoration-style:dotted;text-underline-offset:4px;font:13px/1.5 'Segoe UI',sans-serif;color:#335b75}.engine-depth summary::-webkit-details-marker{display:none}.engine-depth form{position:absolute;right:0;top:28px;z-index:5;background:white;border:1px solid #a7bbc9;box-shadow:0 8px 24px #143c5726;padding:14px;width:245px;max-width:calc(100vw - 60px)}.engine-depth label{display:block;font:600 14px/1.5 'Segoe UI',sans-serif;margin-bottom:8px}.engine-depth form>div{display:flex;gap:8px}.engine-depth input{min-width:0;width:100%;padding:8px;border:1px solid #8fa7b7;font:16px 'Segoe UI',sans-serif}.engine-depth form button{border:1px solid #295977;background:#214d69;color:white;padding:8px 12px;font:14px 'Segoe UI',sans-serif}.engine-depth form p{font:13px/1.5 'Segoe UI',sans-serif;margin:9px 0 0;color:#4d6676}
@media(max-width:700px){.practice-board-frame{order:4;max-width:470px;align-self:center}.practice-board-frame .practice-board{max-width:none}.practice-board-top{padding-left:44px;margin-bottom:8px}.evaluation-score{top:-20px}}
@media(max-width:360px){.practice .az-wrap{width:calc(100% - 16px)}.practice-app{padding:8px}.engine-footer{gap:8px}.engine-depth form{max-width:calc(100vw - 44px)}}
@media(prefers-reduced-motion:reduce){.evaluation-white{transition:none}}
.board-evaluation{padding:0}.evaluation-track{position:absolute;top:5.22388%;bottom:5.22388%;height:auto;left:50%;transform:translateX(-50%)}

.practice-board-top{padding-left:44px}.evaluation-score{top:-7px}