:root{--bg:#f5f6f3;--surface:#fff;--ink:#24372f;--muted:#526456;--line:#e2e7e1;--green:#166d63;--green-soft:#e7f2ed;--amber:#8a5a0a;--amber-soft:#fbf2de;--red:#b3323e;--red-soft:#fcebea;--purple:#8268aa;--shadow:0 5px 24px #263d2f05;font-family:var(--font-family);color:var(--ink);font-synthesis:none}
*{box-sizing:border-box}body{margin:0;background:var(--bg);font-size:var(--font-body,1rem);line-height:1.55}button,input,select,textarea{font:inherit}button,select{cursor:pointer}button{color:inherit}button:disabled{cursor:not-allowed;opacity:.4}button:focus-visible,select:focus-visible,input:focus-visible,textarea:focus-visible,[tabindex]:focus-visible{outline:3px solid #72b9ab;outline-offset:3px}a{color:var(--green);text-decoration:none}button{border:0;background:none}h1,h2,h3,p{margin:0}h1{font-size:var(--font-page,1.625rem);letter-spacing:normal;font-weight:600}h2{font-size:var(--font-section,1.375rem);font-weight:600}h3{font-size:var(--font-lead,1.125rem);font-weight:600}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}[hidden]{display:none!important}
.topbar{height:81px;padding:0 3.3%;display:flex;align-items:center;justify-content:space-between;background:#fff;border-bottom:1px solid var(--line)}.brand{display:flex;gap:12px;align-items:center;color:var(--ink);font-size:20px;font-weight:600;letter-spacing:normal}.brand small{display:block;color:var(--muted);font-size:var(--font-small,.9375rem);font-weight:400;letter-spacing:normal;margin-top:2px}.top-actions{display:flex;align-items:center;gap:12px}.local-badge{font-size:var(--font-small,.9375rem);color:var(--green);padding:5px 11px;background:#edf5ef;border-radius:30px;margin-right:8px;white-space:nowrap}.local-badge i{display:inline-block;width:6px;height:6px;background:#5a9e72;border-radius:50%;margin-right:6px;vertical-align:middle}.button{display:inline-flex;align-items:center;justify-content:center;gap:7px;min-height:38px;padding:8px 14px;border-radius:7px;font-size:var(--font-body,1rem);font-weight:600;transition:background .15s,color .15s,box-shadow .15s}.button span[aria-hidden]{font-size:17px;line-height:1}.button.primary{background:var(--green);color:#fff}.button.primary:hover{background:#105b53;box-shadow:0 2px 8px #166d6320}.button.outline{border:1px solid #cfdbd1;background:#fff}.button.outline:hover{background:#f1f6f2}.button.quiet:hover,.icon-button:hover{background:#eef3ee}.icon-button{display:inline-flex;align-items:center;justify-content:center;width:34px;height:34px;border:1px solid var(--line);border-radius:7px;color:#526456;font-size:21px}.top-actions>.icon-button{font-size:var(--font-body,1rem);width:30px;height:30px;border-radius:50%}.app-shell{max-width:1550px;margin:0 auto;padding:30px 3.3% 0}.page-heading{display:flex;align-items:center;justify-content:space-between;margin-bottom:25px}.eyebrow{font-size:var(--font-small,.9375rem);color:var(--muted);letter-spacing:normal;margin-bottom:5px}.learn-entry{gap:8px;align-self:flex-end}.workspace{display:grid;grid-template-columns:210px minmax(420px,1fr) 292px;gap:23px;align-items:start}.settings-panel,.board-panel,.assistant-panel{background:#fff;border:1px solid var(--line);border-radius:12px;box-shadow:var(--shadow)}.settings-panel{overflow:hidden}.settings-section{padding:18px 17px;border-bottom:1px solid #edf0eb}.settings-section:last-child{border:0}.settings-section h2{font-size:var(--font-section,1.375rem);letter-spacing:normal;margin-bottom:11px;color:#475d4e;font-weight:600}.settings-section select{width:100%;font-size:var(--font-body,1rem)}.puzzle-meta{display:flex;gap:6px;font-size:var(--font-small,.9375rem);color:var(--muted);padding-top:9px}.puzzle-meta span{background:#f3f5f0;border-radius:4px;padding:2px 6px}.mini-actions{display:flex;justify-content:space-between;gap:4px;margin-top:10px}.mini-actions button{padding:3px 0;color:#526456;font-size:var(--font-body,1rem)}.mini-actions button:hover,.text-button:hover{text-decoration:underline}.mode-list{display:flex;flex-direction:column;gap:4px}.mode-list button{display:flex;align-items:center;gap:9px;text-align:left;padding:8px 9px;font-size:var(--font-body,1rem);border-radius:6px;color:#526456}.mode-list button>span{width:19px;font-size:17px;line-height:1;color:#526456}.mode-list button.active{background:var(--green-soft);color:#1a6756;font-weight:600}.mode-list button.active>span{color:var(--green)}kbd{font-family:var(--font-family);font-size:var(--font-small,.9375rem);color:#526456;margin-left:auto;border:1px solid #dfe6dd;border-radius:3px;min-width:18px;text-align:center}.small-help{font-size:var(--font-small,.9375rem);color:#526456;margin-top:9px;line-height:1.7}.tool-grid{display:grid;grid-template-columns:1fr 1fr;gap:6px}.tool-grid button{border:1px solid var(--line);border-radius:5px;padding:6px 2px;color:#526456;font-size:var(--font-body,1rem)}.tool-grid button.active{border-color:#79ab98;background:#eef5f0;color:var(--green)}.text-button{display:block;font-size:var(--font-body,1rem);color:#526456;padding:8px 0 0;text-align:left}.check-row{display:flex;gap:7px;align-items:center;font-size:var(--font-small,.9375rem);color:#526456;margin-bottom:9px}input[type=checkbox]{accent-color:var(--green);width:13px;height:13px;margin:0;flex-shrink:0}.setting-divider{height:1px;background:#edf0eb;margin:14px 0}.small-label{display:block;font-size:var(--font-body,1rem);color:var(--muted);margin-bottom:7px}.inline-checks{display:flex;justify-content:space-between;font-size:var(--font-small,.9375rem);color:#526456}.inline-checks label{display:flex;align-items:center;gap:6px}.digit-filters{display:grid;grid-template-columns:repeat(5,1fr);gap:6px}.digit-filters button{height:27px;border:1px solid var(--line);border-radius:4px;font-size:var(--font-body,1rem);color:#526456}.digit-filters button.active{background:var(--green);color:white;border-color:var(--green)}.color-tools{display:flex;gap:10px;margin:12px 0 5px}.color-dot{width:21px;height:21px;border-radius:50%;border:2px solid white;outline:1px solid transparent}.color-dot.active{outline-color:#6b7f70}.teal{background:#64ad9c}.amber{background:#e1b15e}.purple{background:#a18ac9}.rose{background:#d88d96}#link-tools{margin-top:10px}.more-tools{padding:10px 17px}.more-tools button{display:flex;width:100%;align-items:center;justify-content:space-between;font-size:var(--font-body,1rem);color:#526456;padding:8px 0}.more-tools span{color:#526456}
select{padding:8px 25px 8px 9px;border:1px solid #dfe5dc;border-radius:5px;background:#fff;color:#506453;min-width:0}input[type=text],textarea{width:100%;border:1px solid #d7e1d6;border-radius:7px;padding:12px;color:var(--ink);background:#fff}textarea{min-height:160px;resize:vertical;line-height:1.7}label{user-select:none}
.board-panel{padding:24px 24px 20px;min-width:0}.board-heading{display:flex;align-items:center;justify-content:space-between;gap:8px;margin-bottom:21px}.board-heading h2{font-size:var(--font-section,1.375rem);letter-spacing:normal;font-weight:600}.board-heading p{font-size:var(--font-body,1rem);color:#526456;margin-top:3px}.board-quick-actions{display:flex;gap:7px}.board-quick-actions .icon-button{border:0;width:29px;height:29px;color:#526456}.board-frame{position:relative;padding-top:19px;padding-left:20px;max-width:660px;margin:auto}.column-labels{position:absolute;left:20px;right:0;top:0;display:grid;grid-template-columns:repeat(9,1fr);font-size:var(--font-body,1rem);color:#526456;text-align:center}.row-labels{position:absolute;left:0;top:19px;bottom:0;width:16px;display:grid;grid-template-rows:repeat(9,1fr);font-size:var(--font-body,1rem);color:#526456;text-align:center;align-items:center}.grid-wrap{position:relative;aspect-ratio:1;width:100%}.sudoku-grid{width:100%;height:100%;display:grid;grid-template-columns:repeat(9,1fr);grid-template-rows:repeat(9,1fr);border:2.1px solid #4b6456;border-radius:2px;overflow:hidden}.cell{position:relative;display:flex;align-items:center;justify-content:center;border-right:1px solid #d4dfd2;border-bottom:1px solid #d4dfd2;cursor:pointer;background:#fff;min-width:0;min-height:0;transition:background .1s;font-variant-numeric:tabular-nums}.cell:nth-child(9n){border-right:0}.cell:nth-child(n+73){border-bottom:0}.cell.box-right{border-right:2px solid #6c806f}.cell.box-bottom{border-bottom:2px solid #6c806f}.cell.peer{background:#f3f6f1}.cell.same-value{background:#e1eee7}.cell.selected{background:#d4e9df;box-shadow:inset 0 0 0 2px #397f68;z-index:1}.cell.conflict{background:#f9e8e4}.cell.conflict .value{color:#bb5149}.cell.bivalue{background:#f9f4e4}.cell.pattern{background:#fcf0d2}.cell.placement{background:#d3efdf}.cell.color-teal{background:#d6eee5}.cell.color-amber{background:#f7eac9}.cell.color-purple{background:#e9e1f3}.cell.color-rose{background:#f6dee5}.value{font-size:clamp(24px,2.4vw,39px);color:#4e7cbe;line-height:1}.cell.given .value{color:#344d3d;font-weight:550}.cell.same-value:not(.conflict) .value{color:#216b50;font-weight:700}.candidate-grid{display:grid;grid-template-columns:repeat(3,1fr);grid-template-rows:repeat(3,1fr);width:100%;height:100%;padding:3px;gap:0}.candidate{display:flex;align-items:center;justify-content:center;font-size:clamp(8px,.86vw,13px);line-height:1;border-radius:3px;padding:0;color:#8b9a8b;min-width:0;min-height:0}.candidate.absent{visibility:hidden;pointer-events:none}.candidate.highlight{background:#f7da8b;color:#8b5f08;font-weight:700}.candidate.focus-candidate{background:#d7e9dc;color:#246443;font-weight:700;box-shadow:inset 0 0 0 1px #a4cbb4}.candidate.remove{background:#f9dcd7;color:#b14640;position:relative;font-weight:650}.candidate.remove:after{content:'';position:absolute;height:1px;background:#b14640;width:75%;transform:rotate(-40deg)}.candidate.link-anchor{outline:2px solid #9d79bf;background:#f2eafb}.candidate.color-teal{background:#c8e8db;color:#0e6d51}.candidate.color-amber{background:#f5dc9d;color:#8b5c16}.candidate.color-purple{background:#e0d2f1;color:#7349a2}.candidate.color-rose{background:#f0cbd6;color:#9d4062}.link-overlay{position:absolute;inset:2px;width:calc(100% - 4px);height:calc(100% - 4px);pointer-events:none;z-index:3;overflow:visible}.selection-line{display:flex;justify-content:space-between;gap:8px;font-size:var(--font-body,1rem);color:#526456;margin:13px 0 16px;padding-left:20px}.save-state{color:#526456;font-size:var(--font-small,.9375rem);white-space:nowrap}.number-pad{display:grid;grid-template-columns:repeat(9,1fr);gap:6px;padding-left:20px}.number-pad button{height:45px;border:1px solid #dee5da;border-radius:6px;font-size:21px;color:#526f58;background:#fbfcf8;position:relative}.number-pad button:hover{background:#e9f1e5;border-color:#8fab91}.number-pad button small{position:absolute;right:4px;bottom:1px;color:#526456;font-size:var(--font-body,1rem)}.board-bottom-actions{display:flex;justify-content:center;gap:12px;margin-top:16px}.board-bottom-actions .button{font-size:var(--font-body,1rem);color:#526456;padding:6px 9px;min-height:32px}.board-bottom-actions #notes-shortcut{font-size:var(--font-small,.9375rem);color:#526456;background:#f0f3ec;padding:1px 5px;border-radius:3px}.keyboard-hint{font-size:var(--font-small,.9375rem);color:#526456;text-align:center;margin-top:14px}.progress-area{display:flex;align-items:center;gap:12px;margin-top:23px;padding-left:20px}.progress-track{height:4px;background:#edf1e9;flex:1;border-radius:5px;overflow:hidden}.progress-track i{height:100%;display:block;background:#8eae93;transition:width .2s}.progress-area>span{font-size:var(--font-small,.9375rem);color:#526456;white-space:nowrap}.board-status{margin-top:12px;font-size:var(--font-body,1rem);color:#526456;text-align:center;min-height:18px}.board-status.error{color:#ba605a}
.assistant-panel{overflow:hidden;min-height:640px}.panel-tabs{display:flex;border-bottom:1px solid var(--line);padding:0 15px}.panel-tabs button{flex:1;padding:18px 0 14px;font-size:var(--font-body,1rem);color:#526456;border-bottom:2px solid transparent;margin-bottom:-1px}.panel-tabs button[aria-selected=true]{color:var(--green);border-bottom-color:var(--green);font-weight:600}.panel-tabs button span{font-size:var(--font-body,1rem);background:#f0f3ed;color:#526456;border-radius:9px;padding:1px 5px;margin-left:6px}#assistant-content{padding:19px}.hint-options{margin-bottom:15px}.hint-options label{display:block;font-size:var(--font-body,1rem);color:#526456;margin-bottom:6px}.hint-options select{font-size:var(--font-body,1rem);width:100%;background:#fbfcf9}.step-content{min-height:245px}.empty-assistant{text-align:center;padding:30px 7px 22px;color:#526456}.empty-assistant .empty-symbol{display:flex;align-items:center;justify-content:center;margin:0 auto 17px;width:51px;height:51px;background:#f0f5ec;color:#526456;border-radius:50%;font-size:27px}.empty-assistant h3{font-size:var(--font-lead,1.125rem);font-weight:600;color:#526456;margin-bottom:9px}.empty-assistant p{font-size:var(--font-body,1rem);line-height:1.85;color:#526456}.step-badge{display:inline-block;color:#9b762c;background:#fbf1d7;border-radius:4px;font-size:var(--font-small,.9375rem);padding:2px 7px;margin-bottom:12px}.step-content h3{font-size:var(--font-lead,1.125rem);font-weight:600;margin-bottom:10px;color:#355d45}.step-description{font-size:var(--font-body,1rem);color:#526456;line-height:1.9;white-space:pre-line}.step-result{border-top:1px solid #edf0e8;margin-top:15px;padding-top:12px;font-size:var(--font-small,.9375rem);color:var(--green)}.step-result .remove-text{color:#b9584e}.step-cells{font-size:var(--font-small,.9375rem);color:#526456;margin-top:10px}.solver-actions{display:flex;flex-direction:column;gap:8px}.solver-actions .button{width:100%;min-height:39px;font-size:var(--font-body,1rem)}.analysis-secondary{display:flex;justify-content:space-between;margin:14px 0 22px}.analysis-secondary button{font-size:var(--font-body,1rem);color:#526456;padding:3px 0}.analysis-secondary button:hover{color:var(--green)}.strategy-summary{border-top:1px solid #edf0e8;padding-top:19px}.strategy-summary>div:first-child{display:flex;justify-content:space-between;align-items:center;font-size:var(--font-body,1rem);color:#526456}.strategy-summary button{font-size:var(--font-body,1rem);color:var(--green)}.strategy-summary>p{font-size:var(--font-body,1rem);color:#526456;margin:7px 0 12px}.strategy-chips{display:flex;flex-wrap:wrap;gap:6px}.strategy-chips span{font-size:var(--font-small,.9375rem);border:1px solid #e6ebdf;border-radius:4px;padding:3px 6px;color:#526456}.legend{display:flex;flex-wrap:wrap;gap:9px;margin-top:27px;border-top:1px solid #edf0e8;padding-top:16px;font-size:var(--font-small,.9375rem);color:#526456}.legend span{display:flex;align-items:center;gap:4px}.legend i{display:block;width:7px;height:7px;border-radius:2px}.legend-pattern{background:#f1d58b}.legend-remove{background:#e4a49b}.legend-place{background:#83bc9d}.small-source{display:block;color:#526456;font-size:var(--font-small,.9375rem);margin-top:17px}.history-empty{text-align:center;color:#526456;font-size:var(--font-small,.9375rem);padding:60px 20px}.history-list{list-style:none;margin:0;padding:16px}.history-list li{padding:10px 0;border-bottom:1px solid #edf0e7}.history-list strong{display:block;font-size:var(--font-small,.9375rem);color:#526456;font-weight:400}.history-list small{font-size:var(--font-small,.9375rem);color:#526456}.history-list .history-index{display:inline-block;width:22px;color:#526456;font-size:var(--font-small,.9375rem)}.site-footer{display:flex;justify-content:space-between;gap:20px;font-size:var(--font-small,.9375rem);color:#526456;padding:25px 0 20px}.site-footer button{font-size:var(--font-body,1rem);color:#526456}.toast{position:fixed;bottom:28px;left:50%;transform:translateX(-50%);background:#284d3d;color:#fff;box-shadow:0 6px 30px #162b3125;border-radius:8px;padding:11px 20px;max-width:min(90vw,620px);z-index:50;font-size:var(--font-small,.9375rem)}
dialog{border:1px solid #dae3d5;border-radius:14px;box-shadow:0 15px 90px #142c2940;width:min(850px,calc(100vw - 30px));max-height:90vh;padding:24px;color:var(--ink);background:#fff}dialog::backdrop{background:#1c332d55;backdrop-filter:blur(3px)}.dialog-heading{display:flex;justify-content:space-between;align-items:center;gap:20px;margin-bottom:19px}.dialog-heading h2{font-size:var(--font-section,1.375rem);font-weight:600}.dialog-heading .icon-button{border:0;font-size:25px}#dialog-body{max-height:calc(90vh - 110px);overflow:auto;padding:2px 3px 4px}.dialog-intro{color:#526456;font-size:var(--font-body,1rem);line-height:1.8;margin-bottom:15px}.dialog-actions{display:flex;gap:10px;justify-content:flex-end;margin-top:18px;flex-wrap:wrap}.inline-form{display:flex;align-items:center;gap:10px;margin-bottom:12px}.inline-form label{font-size:var(--font-body,1rem);white-space:nowrap}.form-label{display:block;font-size:var(--font-body,1rem);color:#526456;margin:12px 0 6px}.feedback{font-size:var(--font-body,1rem);margin-top:10px;color:#b8594d}.success-text{color:var(--green)}.modal-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.strategy-option{display:flex;align-items:flex-start;gap:8px;border-bottom:1px solid #edf1e8;padding:11px 0}.strategy-option input{margin-top:5px}.strategy-option strong{font-size:var(--font-small,.9375rem);font-weight:600}.strategy-option p{font-size:var(--font-body,1rem);color:#526456;margin-top:4px}.strategy-group-title{margin:18px 0 5px;font-size:var(--font-small,.9375rem)}.pill{display:inline-block;border-radius:4px;padding:2px 6px;font-size:var(--font-small,.9375rem);background:#edf3e9;color:#526456;margin-left:7px}.pill.reference{background:#f4f4ee;color:#526456}.reference-table{border-collapse:collapse;width:100%;font-size:var(--font-small,.9375rem)}.reference-table th,.reference-table td{padding:10px 8px;border-bottom:1px solid #e7ecdf;text-align:left;vertical-align:top}.reference-table th{background:#f1f5ec;color:#526456;font-weight:600}.reference-table td a{color:#5a8366}.help-section{margin:20px 0}.help-section h3{margin-bottom:8px}.help-section p,.help-section li{font-size:var(--font-body,1rem);color:#526456;line-height:1.9}.learning-layout{display:grid;grid-template-columns:150px minmax(0,1fr);gap:22px}.learning-nav{display:flex;flex-direction:column;gap:5px}.learning-nav button{text-align:left;font-size:var(--font-body,1rem);color:#526456;padding:9px 11px;border-radius:6px}.learning-nav button.active{background:#e8f2e7;color:var(--green)}.learning-card h3{font-size:var(--font-lead,1.125rem);margin-bottom:8px;font-weight:600}.learning-card .rule{font-size:var(--font-small,.9375rem);line-height:1.85;color:#526456}.learning-card ol{padding-left:21px;font-size:var(--font-small,.9375rem);color:#526456;line-height:1.9}.learning-diagram{max-width:340px;width:100%;display:block;margin:17px auto}.learning-note{font-size:var(--font-small,.9375rem);color:#526456;margin-top:15px}.solution-grid{max-width:340px;display:grid;grid-template-columns:repeat(9,1fr);border:2px solid #708363;margin:18px auto}.solution-grid span{text-align:center;padding:6px 0;border:1px solid #e1e7d8;font-size:17px;color:#718864}.solution-grid span:nth-child(3n){border-right:2px solid #8a9d7b}.solution-grid span:nth-child(n+19):nth-child(-n+27),.solution-grid span:nth-child(n+46):nth-child(-n+54){border-bottom:2px solid #8a9d7b}.solution-grid span.given{color:#344d36;font-weight:650}.path-list{max-height:380px;overflow:auto;padding-left:23px;font-size:var(--font-small,.9375rem);color:#526456;line-height:1.9}.path-list strong{color:#4e7952}.busy-spinner{width:24px;height:24px;border:2px solid #dcead6;border-top-color:var(--green);border-radius:50%;animation:spin 1s linear infinite;margin:22px auto}@keyframes spin{to{transform:rotate(360deg)}}
@media(min-width:1450px){.workspace{grid-template-columns:225px minmax(470px,1fr) 310px;gap:28px}.settings-section{padding:20px}.board-panel{padding:26px 30px}.candidate{font-size:13px}.value{font-size:37px}}
@media(max-width:1170px){.app-shell{padding:25px 20px 0}.topbar{padding:0 22px}.workspace{grid-template-columns:180px minmax(380px,1fr) 255px;gap:15px}.settings-section{padding:15px 13px}.board-panel{padding:20px 16px}.assistant-panel #assistant-content{padding:15px}.value{font-size:30px}.candidate{font-size:10px}.number-pad button{font-size:18px;height:39px}.board-bottom-actions{gap:3px}}
@media(max-width:1000px){.workspace{grid-template-columns:180px minmax(350px,1fr)}.assistant-panel{grid-column:2;min-height:0}.settings-panel{grid-row:1 / 3}.step-content{min-height:150px}.solver-actions{flex-direction:row;flex-wrap:wrap}.solver-actions .button{width:auto;flex:1}.strategy-summary{margin-top:5px}.legend{margin-top:15px}.value{font-size:36px}.candidate{font-size:12px}.site-footer{flex-wrap:wrap}.site-footer>span:last-child{display:none}}
@media(max-width:680px){.topbar{height:68px;padding:0 15px}.brand{font-size:17px;gap:8px}.brand img{width:32px;height:32px}.brand small{font-size:var(--font-small,.9375rem);letter-spacing:normal}.top-actions{gap:5px}.local-badge{font-size:var(--font-small,.9375rem);margin:0;padding:4px 7px}.top-actions .button{font-size:0;min-width:30px;padding:4px}.top-actions .button span{font-size:18px}.top-actions>.icon-button{width:26px;height:26px;font-size:var(--font-body,1rem)}.app-shell{padding:20px 12px 0}.page-heading{margin-bottom:15px}.eyebrow{font-size:var(--font-small,.9375rem)}h1{font-size:var(--font-page,1.625rem);font-weight:600}.learn-entry{font-size:var(--font-small,.9375rem);padding:7px 10px;min-height:33px}.workspace{display:flex;flex-direction:column;gap:15px}.board-panel{order:0;width:100%;padding:19px 14px 15px}.assistant-panel{order:1;width:100%}.settings-panel{order:2;width:100%;display:grid;grid-template-columns:repeat(2,minmax(0,1fr))}.settings-section{padding:15px}.settings-section:nth-child(odd){border-right:1px solid var(--line)}.settings-section:last-child{border-bottom:0}.settings-section.more-tools{grid-column:1 / -1;display:flex;gap:20px}.settings-section.more-tools button{font-size:var(--font-body,1rem);gap:5px}.board-heading{margin-bottom:16px}.board-heading h2{font-size:var(--font-section,1.375rem);font-weight:600}.board-heading p{font-size:var(--font-body,1rem)}.board-frame{padding-left:17px}.column-labels{left:17px;font-size:var(--font-body,1rem)}.row-labels{width:13px;font-size:var(--font-body,1rem)}.value{font-size:clamp(23px,6.9vw,39px)}.candidate{font-size:clamp(8px,2.4vw,13px)}.candidate-grid{padding:2px}.number-pad{padding-left:17px;gap:4px}.number-pad button{height:38px;font-size:19px}.selection-line{padding-left:17px;font-size:var(--font-body,1rem);margin-top:10px;margin-bottom:12px}.save-state{font-size:var(--font-small,.9375rem)}.board-bottom-actions{justify-content:space-around;margin-top:12px}.progress-area{margin-top:17px}.keyboard-hint{font-size:var(--font-small,.9375rem)}.site-footer{font-size:var(--font-small,.9375rem);gap:10px;padding-top:18px}.site-footer button{font-size:var(--font-body,1rem)}.step-content{min-height:135px}.empty-assistant{padding:19px 10px}.hint-options{display:flex;gap:20px;align-items:center}.hint-options label{white-space:nowrap;margin:0}.hint-options select{width:auto;flex:1}.analysis-secondary{margin-bottom:17px}.legend{margin-top:17px}dialog{padding:19px}.modal-grid{grid-template-columns:1fr}.learning-layout{grid-template-columns:1fr;gap:15px}.learning-nav{flex-direction:row;flex-wrap:wrap}.learning-nav button{padding:6px 8px;font-size:var(--font-body,1rem)}}
@media print{body{background:white}.topbar,.page-heading,.settings-panel,.assistant-panel,.site-footer,.board-quick-actions,.number-pad,.board-bottom-actions,.keyboard-hint,.progress-area,.save-state,.toast,dialog{display:none!important}.app-shell{padding:0;max-width:none}.workspace{display:block}.board-panel{border:0;box-shadow:none;width:170mm;margin:10mm auto;padding:0}.board-frame{max-width:none}.board-heading{margin-bottom:8mm}.cell,.cell.peer,.cell.selected{background:white!important;box-shadow:none}.value{font-size:25pt}.candidate{font-size:8pt}.selection-line{display:none}.board-status{display:none}.board-heading h2{font-size:16pt}.board-heading p{font-size:10pt}.link-overlay{display:block}.sudoku-grid{-webkit-print-color-adjust:exact;print-color-adjust:exact}}
.path-step{padding:6px 0;text-align:left;font-size:var(--font-small,.9375rem);line-height:1.9;width:100%;border-bottom:1px solid #edf1e6}.path-step:hover{background:#f5f8f0}.checkpoint-list{margin-top:20px}.checkpoint-item{display:flex;align-items:center;gap:9px;padding:12px 0;border-bottom:1px solid #e6eddf}.checkpoint-item>div{flex:1;min-width:0}.checkpoint-item strong{font-size:var(--font-small,.9375rem);font-weight:600;overflow-wrap:anywhere}.checkpoint-item small{display:block;font-size:var(--font-small,.9375rem);color:#526456;margin-top:3px}.checkpoint-item .button{font-size:var(--font-body,1rem);min-height:30px}.more-tools select{font-size:var(--font-body,1rem);width:100%;margin:8px 0 4px}@media(max-width:680px){.settings-section.more-tools{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:2px 15px}.more-tools select{grid-column:1 / -1}}
.mini-grid{display:grid;grid-template-columns:repeat(9,minmax(0,1fr));border:1.5px solid #6c806f;margin-top:12px}.mini-grid input{padding:0;width:100%;min-width:0;aspect-ratio:1;border:0;border-right:1px solid #e0e6dd;border-bottom:1px solid #e0e6dd;border-radius:0;text-align:center;font-size:12px;color:#4e7cbe}.mini-grid input.mini-given{color:#344d3d;font-weight:650;background:#f5f8f1}.mini-grid input.mini-right{border-right:1.5px solid #6c806f}.mini-grid input.mini-bottom{border-bottom:1.5px solid #6c806f}#quick-entry summary{font-size:var(--font-body,1rem);cursor:pointer;color:#475d4e}#chain-tools{margin-top:13px}#chain-tools select{width:100%;font-size:var(--font-body,1rem);margin-bottom:12px}#chain-depth{width:100%;margin:0 0 10px}.chain-summary{font-size:var(--font-body,1rem);line-height:1.8;color:#526456;margin:9px 0}.chain-summary strong{font-weight:600;color:#3d7258}.chain-summary p{margin-top:6px}.candidate.chain-on{background:#c4e7d9;color:#156147;font-weight:750;box-shadow:inset 0 0 0 1px #70b39c}.candidate.chain-off{background:#f4d3d3;color:#aa4245;text-decoration:line-through}.cell.chain-conflict{outline:3px solid #e5bd41;outline-offset:-4px;background:#fff4bc}.color-tools{flex-wrap:wrap}.sky{background:#67b1d0}.lime{background:#a2c46c}.orange{background:#e3a167}.indigo{background:#8a8dc7}.slate{background:#a0b0b8}.pink{background:#dba4ca}.cell.color-sky,.candidate.color-sky{background:#d7ecf6}.cell.color-lime,.candidate.color-lime{background:#e6f0d3}.cell.color-orange,.candidate.color-orange{background:#f6e2ce}.cell.color-indigo,.candidate.color-indigo{background:#e3e3f5}.cell.color-slate,.candidate.color-slate{background:#e3eaee}.cell.color-pink,.candidate.color-pink{background:#f5e2ee}.link-digit-filters{display:grid;grid-template-columns:repeat(5,1fr);gap:7px;margin-top:10px;font-size:var(--font-small,.9375rem);color:#526456}.link-digit-filters label{display:flex;gap:4px;align-items:center}.inline-checks+.small-label{margin-top:13px}.analysis-secondary{flex-wrap:wrap;gap:6px 12px}.strategy-panel{margin-top:18px;border-top:1px solid #e4ebdf;padding-top:13px}.strategy-panel>summary{cursor:pointer;font-size:var(--font-body,1rem);color:#4d7151}.strategy-panel>summary span{font-size:var(--font-body,1rem);color:#526456;margin-left:6px}.catalog-toolbar{display:flex;gap:12px;margin:11px 0;font-size:var(--font-small,.9375rem);color:#4e8061}.catalog-group{font-size:var(--font-small,.9375rem);font-weight:600;color:#526456;background:#f1f5ec;margin-top:7px;padding:6px}.catalog-row{display:grid;grid-template-columns:13px minmax(0,1fr) auto;gap:5px;align-items:center;min-height:32px;border-bottom:1px solid #f0f3ed;padding:4px 0}.catalog-name{text-align:left;padding:0;font-size:var(--font-small,.9375rem);color:#526456;line-height:1.65}.catalog-name span{color:#526456;font-size:var(--font-small,.9375rem)}.catalog-name:hover{text-decoration:underline}.scan-status{font-size:var(--font-body,1rem);color:#526456;white-space:nowrap}.scan-status.found{color:#176f4b;font-weight:600}.catalog-hit{background:#edf6e9}.scan-stage{display:flex;justify-content:space-between;gap:5px;font-size:var(--font-small,.9375rem);color:#526456;padding:6px 0}.scan-stage small{font-size:var(--font-small,.9375rem);color:#526456}.player-bar{display:flex;gap:12px;align-items:center;flex-wrap:wrap;background:#edf5e9;border-radius:6px;padding:10px 13px;margin-bottom:18px;color:#56815d;font-size:var(--font-small,.9375rem)}.player-bar span{flex:1}.player-bar .button{font-size:var(--font-body,1rem);min-height:28px}.player-mode .settings-panel,.player-mode .assistant-panel{display:none}.player-mode .workspace{display:block;max-width:760px;margin:auto}.player-mode .board-bottom-actions [data-action=count]{display:none}.guide-card{text-align:center;padding:20px 25px}.guide-number{width:60px;height:60px;display:grid;place-items:center;background:#e5f1e8;border:1px solid #cde1d0;border-radius:15px;font-size:27px;color:#40815d;margin:0 auto 18px}.guide-card h3{font-size:var(--font-lead,1.125rem);color:#47734f;font-weight:600}.guide-card p{font-size:var(--font-reading,1.125rem);line-height:var(--line-reading,1.666667);color:#526456;max-width:500px;margin:13px auto}.guide-dots{display:flex;justify-content:center;gap:9px;margin-top:25px}.guide-dots button{width:8px;height:8px;padding:0;border-radius:50%;background:#e0e9da}.guide-dots button.active{background:#6d9e79}#print-sheet{display:none}@media(max-width:680px){.top-actions #player-toggle,.top-actions [data-tutorial-nav=guide]{font-size:var(--font-small,.9375rem);min-width:0;padding:5px}.top-actions .local-badge{display:none}.mini-grid{max-width:250px}.strategy-panel{margin-top:14px}.catalog-row{min-height:35px}.catalog-name{font-size:var(--font-small,.9375rem)}.scan-status{font-size:var(--font-body,1rem)}.player-bar span{flex-basis:100%}.guide-card{padding:8px}.guide-card p{font-size:var(--font-reading,1.125rem)}.settings-section:has(#chain-tools){grid-column:1 / -1}}
@media print{body.print-sheet-mode .app-shell,body.print-sheet-mode .topbar{display:none!important}body.print-sheet-mode #print-sheet{display:block!important;max-width:170mm;margin:8mm auto;color:#172a20}#print-sheet h1{font-size:17pt;margin-bottom:3mm}#print-sheet p{font-size:9pt;margin-bottom:8mm}.paper-grid{display:grid;grid-template-columns:repeat(9,1fr);grid-template-rows:repeat(9,1fr);width:170mm;height:170mm;border:2px solid #20382c}.paper-cell{display:grid;place-items:center;border-right:1px solid #9da99c;border-bottom:1px solid #9da99c;min-width:0;min-height:0}.paper-cell:nth-child(9n){border-right:0}.paper-cell:nth-child(n+73){border-bottom:0}.paper-cell.paper-right{border-right:2px solid #20382c}.paper-cell.paper-bottom{border-bottom:2px solid #20382c}.paper-cell strong{font-size:25pt;font-weight:400;color:#536b5b}.paper-cell.paper-given strong{font-weight:650;color:#172a20}.paper-notes{width:100%;height:100%;padding:2mm;display:grid;grid-template-columns:repeat(3,1fr);grid-template-rows:repeat(3,1fr);text-align:center;align-items:center;font-size:8pt}.paper-cell small{font-size:8pt;line-height:1.8;padding:1.5mm;text-align:center;word-spacing:1mm}}

.candidate.chain-mixed{background:linear-gradient(135deg,#c4e7d9 0%,#c4e7d9 49%,#f4d3d3 50%,#f4d3d3 100%);color:#454f46;font-weight:750;outline:1px dashed #8d9c6b}.proof-details{font-size:var(--font-small,.9375rem);color:#526456;margin:12px 0}.proof-details summary{cursor:pointer;color:#4b8057}.proof-details>div{max-height:300px;overflow:auto;padding:10px 4px;line-height:1.9}.proof-details ol{padding-left:22px}.proof-details h4{margin:10px 0 4px;font-size:var(--font-lead,1.125rem);font-weight:600}.solution-gallery{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:20px}.solution-gallery h3{font-size:var(--font-lead,1.125rem);color:#526456;font-weight:600}.solution-gallery .solution-grid{margin-top:8px}.solution-gallery .solution-grid span{font-size:13px;padding:3px 0}

.board-panel,.settings-panel,.assistant-panel{align-self:start}@media(max-width:480px){.top-actions [data-tutorial-nav=guide]{display:none}}

.example-library{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:10px}.example-item{text-align:left;border:1px solid #e1ead9;border-radius:7px;padding:12px 14px;background:#fbfcf8}.example-item:hover{background:#eef5e8;border-color:#b3c8a4}.example-item strong{display:block;font-size:var(--font-small,.9375rem);color:#54784c;font-weight:600}.example-item small{display:block;margin-top:6px;font-size:var(--font-small,.9375rem);line-height:1.8;color:#526456}

/* Standalone tutorial navigation and the isolated teaching workspace. */
a.button,a.icon-button{text-decoration:none}.icon-button{display:inline-flex;align-items:center;justify-content:center}.practice-banner{display:flex;gap:16px;align-items:center;flex-wrap:wrap;background:#eff6e9;border:1px solid #d5e4c9;border-radius:9px;padding:14px 18px;margin-bottom:20px;color:#426b45}.practice-banner>div{flex:1;min-width:220px}.practice-banner p{font-size:var(--font-body,1rem);margin-top:5px;color:#526456}.practice-banner .button{font-size:var(--font-body,1rem)}.step-tutorial{display:block;font-size:var(--font-small,.9375rem);color:var(--green);margin:0 0 12px}.example-card{display:flex;flex-direction:column;gap:7px}.example-card .example-item{flex:1;width:100%}.example-tutorial{font-size:var(--font-small,.9375rem);color:var(--green);padding:0 4px 5px}.catalog-name{display:block;text-decoration:none}@media(max-width:680px){.practice-banner{gap:10px}.practice-banner>div{flex-basis:100%}}

.practice-task-panel{border:1px solid #d8e5cd;background:#fbfdf8;padding:18px 20px;border-radius:8px;margin-bottom:20px;font-size:var(--font-small,.9375rem);color:#526456}.practice-task-heading{display:flex;justify-content:space-between;gap:15px;align-items:center;flex-wrap:wrap}.practice-task-heading h2{font-size:var(--font-section,1.375rem);color:#4d7648;font-weight:600}.practice-task-heading .text-button{font-size:var(--font-body,1rem)}.practice-task-panel>p{margin-top:9px;line-height:1.9}.practice-task-hint{margin-top:12px;font-size:var(--font-small,.9375rem)}.practice-task-hint summary{cursor:pointer;color:#526456}.practice-task-hint p{margin-top:9px;line-height:1.8}.practice-operation-checklist{display:grid;gap:9px;margin-top:15px;font-size:var(--font-small,.9375rem)}.practice-operation-checklist label{display:flex;gap:8px;align-items:flex-start;line-height:1.8}.practice-operation-checklist input{margin-top:5px;flex:none}.practice-check-row{display:flex;gap:15px;align-items:center;margin-top:15px}.practice-check-row .button{white-space:nowrap;font-size:var(--font-body,1rem)}.practice-check-row p{font-size:var(--font-body,1rem);line-height:1.9;color:#526456}@media(max-width:680px){.practice-task-panel{padding:14px}.practice-check-row{align-items:flex-start;flex-direction:column;gap:8px}}

.course-practice-entry{display:block;margin-top:8px;font-size:var(--font-small,.9375rem);line-height:1.8}

/* Complete puzzle library: keep the next useful action close to the board. */
.level-entry-banner,.level-play-panel{border:1px solid #c6dfd9;border-radius:16px;background:#f0f8f5;padding:18px 22px;margin-bottom:18px}
.level-entry-banner{display:flex;align-items:center;justify-content:space-between;gap:16px}.level-entry-banner strong{font-size:18px;color:#154e46}.level-entry-banner p,.level-play-heading p{font-size:var(--font-body,1rem);color:#536a64;margin:7px 0 0;line-height:1.6}.level-entry-banner>div:last-child,.level-play-actions{display:flex;flex-wrap:wrap;gap:10px}.level-play-heading{display:flex;justify-content:space-between;gap:16px;align-items:center}.level-play-heading h2{font-size:var(--font-section,1.375rem);margin:5px 0;font-weight:600}.level-play-heading .eyebrow{font-size:var(--font-small,.9375rem)}.level-play-heading>strong{font-size:24px;font-variant-numeric:tabular-nums;color:#166d63}.level-play-panel #level-feedback{font-size:var(--font-body,1rem);line-height:1.7;margin:14px 0}.level-complete{background:#e9f7ed;border-color:#87bf98}.level-play-panel:not([hidden])~.workspace .board-heading{margin-top:0}body:has(.level-play-panel:not([hidden])) .level-entry-banner{display:none}
@media(max-width:700px){.level-entry-banner{align-items:stretch;flex-direction:column;padding:16px}.level-entry-banner>div:last-child{display:grid;grid-template-columns:1fr 1fr}.level-entry-banner .button{font-size:var(--font-body,1rem);padding:10px}.level-play-panel{padding:16px}.level-play-heading h2{font-size:var(--font-section,1.375rem);font-weight:600}.level-play-heading>strong{font-size:20px}.level-play-actions .button{padding:10px;font-size:var(--font-body,1rem)}.top-actions{flex-wrap:wrap}}
@media print{.level-entry-banner,.level-play-panel{display:none!important}}
/* Keep the remaining-digit count separate from the tap target's main digit. */
.number-pad button{min-width:0;height:54px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:4px;line-height:1.1}
.number-pad button small{position:static;font-size:.65rem;line-height:1;opacity:.8}
@media(max-width:650px){.number-pad button{height:50px}}

/* Keep the original vertical play flow; fit just the square to the viewport. */
@media screen and (min-width:861px) and (min-height:560px){
  .topbar{height:54px;padding:0 24px;gap:16px}
  .brand{font-size:18px;gap:9px;white-space:nowrap}
  .brand img{width:30px;height:30px}
  .brand small{display:none}
  .top-actions{gap:6px}
  .top-actions .button{padding:6px 9px;min-height:36px}
  .top-actions .local-badge{display:none}
  .app-shell{padding:12px 24px 0;max-width:1550px}
  .page-heading{margin-bottom:8px}
  .page-heading .eyebrow{display:none}
  .page-heading h1{font-size:var(--font-page,1.625rem);font-weight:600}
  .learn-entry{min-height:34px;padding:5px 10px}
  .level-entry-banner{padding:8px 14px;margin-bottom:10px;border-radius:10px;gap:12px}
  .level-entry-banner strong{font-size:16px}
  .level-entry-banner p{display:none}
  .level-entry-banner>div:last-child{gap:8px;flex:none}
  body:has(.level-play-panel:not([hidden])) .page-heading{display:none}
  body:has(#practice-banner:not([hidden])) .page-heading,body:has(#practice-banner:not([hidden])) .level-entry-banner{display:none}
  .practice-banner{padding:8px 14px;margin-bottom:10px;border-radius:10px;gap:10px}
  .practice-banner p{display:none}
  .practice-banner .button{min-height:34px;padding:5px 9px}
  .practice-banner .text-button{padding:0}
  .level-play-panel{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:4px 20px;padding:8px 14px;margin-bottom:8px;border-radius:10px}
  .level-play-heading{gap:12px;grid-column:1}
  .level-play-heading>div{display:flex;flex-wrap:wrap;align-items:baseline;gap:2px 12px}
  .level-play-heading .eyebrow{margin:0;letter-spacing:normal}
  .level-play-heading h2{font-size:var(--font-section,1.375rem);margin:0;font-weight:600}
  .level-play-heading p{width:100%;margin:0;line-height:1.45}
  .level-play-heading>strong{font-size:22px}
  .level-play-panel #level-feedback{grid-column:1;font-size:var(--font-body,1rem);line-height:1.45;margin:0}
  .level-play-actions{grid-column:2;grid-row:1 / 3;align-items:center;gap:6px}
  .level-play-actions .button{padding:6px 9px;min-height:36px}
  .board-panel{padding:10px 14px 12px}
  .board-heading{min-height:30px;margin-bottom:6px}
  .board-heading>div{display:flex;flex-wrap:wrap;align-items:baseline;gap:2px 10px}
  .board-heading h2{font-size:var(--font-section,1.375rem);line-height:1.35;font-weight:600}
  .board-heading p{margin:0;line-height:1.4}
  .board-frame{width:min(100%,calc(var(--board-max-size,calc(100dvh - 480px)) + 20px));max-width:620px;margin:0 auto;padding-top:15px}
  .row-labels{top:15px}
  .grid-wrap{container-type:inline-size}
  .value{font-size:clamp(18px,7cqw,37px)}
  .candidate{font-size:clamp(7px,2.6cqw,13px)}
  .player-bar{padding:4px 8px;margin-bottom:5px;gap:8px;justify-content:center}
  .player-bar strong,.player-bar span{display:none}
  .player-bar .button{min-height:30px;padding:3px 8px;font-size:.875rem}
  .selection-line,.number-pad,.board-bottom-actions,.keyboard-hint,.progress-area,.board-status{width:min(100%,max(400px,var(--board-max-size,540px)));margin-left:auto;margin-right:auto;padding-left:0}
  .selection-line{margin-top:5px;margin-bottom:6px;line-height:1.4;gap:6px}
  .number-pad{grid-template-columns:repeat(9,minmax(0,1fr));gap:4px}
  .number-pad button{height:44px;font-size:21px;gap:2px}
  .number-pad button small{font-size:.65rem}
  .board-bottom-actions{display:flex;justify-content:center;gap:8px;margin-top:7px}
  .board-bottom-actions .button{min-height:34px;padding:4px 9px;font-size:.875rem;gap:4px;color:#526d59;white-space:nowrap}
  .board-bottom-actions #notes-shortcut{font-size:.75rem;padding:1px 3px}
  .keyboard-hint{margin-top:7px;line-height:1.5}
  .progress-area{margin-top:8px}
  .board-status{margin-top:6px;min-height:0;line-height:1.5}
  .assistant-panel{min-height:0}
  .panel-tabs{padding:0 10px}
  .panel-tabs button{padding:12px 0 10px}
  .assistant-panel #assistant-content{padding:12px}
  .hint-options{display:flex;gap:8px;align-items:center;margin-bottom:10px}
  .hint-options label{flex:none;margin:0}
  .hint-options select{width:auto;min-width:0;flex:1;padding:6px}
  .step-content{min-height:96px}
  .empty-assistant{padding:7px 0 12px}
  .empty-assistant .empty-symbol{display:none}
  .empty-assistant h3{margin-bottom:6px}
  .empty-assistant p{line-height:1.6}
  .solver-actions{gap:6px}
  .solver-actions .button{min-height:38px}
  .analysis-secondary{margin:10px 0 14px;gap:6px 10px}
  .strategy-summary{padding-top:12px}
  .site-footer{padding:12px 0 16px}
}
@media screen and (min-width:861px) and (max-width:1100px) and (min-height:560px){
  .app-shell{padding-right:18px;padding-left:18px}
  .topbar{padding:0 18px;gap:12px}
  .top-actions{gap:3px}
  .top-actions .button{padding:6px 7px}
  .top-actions [data-tutorial-nav=help]{display:none}
  .level-play-panel{gap:4px 12px}
  .level-play-actions{max-width:230px;justify-content:flex-end}
  .level-play-actions .button{min-height:34px;padding:5px 7px}
}
@media screen and (min-width:861px) and (min-height:560px) and (max-height:800px){
  .level-play-heading p{display:none}
}