:root{--surface:#fff;--page:#f6faf8;--text:#18332e;--muted:#60746e;--line:#d9e7e2;--brand:#0c8b6b;--soft:#e9f8f2;--card:#fff;--bg:#f6faf8;--ink:#18332e;--accent:#0c8b6b;--hover:#e9f8f2;color-scheme:light}
*{box-sizing:border-box}
html,body{margin:0;padding:0;background:var(--page);color:var(--text);font:16px/1.55 system-ui,-apple-system,"Microsoft YaHei",sans-serif}
body{min-height:100vh;transition:background-color .35s ease,color .35s ease}
a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}

/* ===== Header / language picker ===== */
.site-header{height:72px;display:flex;align-items:center;gap:28px;padding:0 clamp(20px,6vw,88px);border-bottom:1px solid var(--line);background:color-mix(in srgb,var(--surface) 90%,transparent);position:sticky;top:0;z-index:20;backdrop-filter:blur(14px);transition:background-color .35s ease,border-color .35s ease}
.site-brand{font-size:24px;font-weight:800;letter-spacing:-1px;color:var(--brand)}
.site-link{color:var(--muted);font-size:14px}.site-link:hover{color:var(--brand)}
.header-spacer{margin-left:auto}
.language-picker{position:relative}
.language-trigger{display:flex;align-items:center;gap:7px;height:38px;padding:0 11px;border:1px solid var(--line);border-radius:10px;background:var(--surface);color:var(--text);cursor:pointer;font:14px inherit;transition:background-color .35s ease,border-color .35s ease}
.language-trigger:hover{border-color:var(--brand)}
.language-menu{position:absolute;right:0;top:46px;width:160px;max-height:280px;overflow:auto;margin:0;padding:6px;list-style:none;border:1px solid var(--line);border-radius:12px;background:var(--surface);box-shadow:0 14px 30px rgba(18,60,49,.16);opacity:0;visibility:hidden;transform:translateY(-5px);transition:opacity .18s ease,transform .18s ease,visibility .18s}
.language-picker.open .language-menu{opacity:1;visibility:visible;transform:translateY(0)}
.language-menu button{width:100%;padding:8px 10px;border:0;border-radius:7px;background:transparent;color:var(--text);text-align:left;cursor:pointer;font:14px inherit}
.language-menu button:hover,.language-menu button[aria-selected="true"]{background:var(--soft);color:var(--brand)}
.theme-toggle{width:38px;height:38px;border:1px solid var(--line);border-radius:10px;background:var(--surface);color:var(--text);cursor:pointer;font-size:18px;display:grid;place-items:center;transition:background-color .35s ease,border-color .35s ease}
.theme-toggle:hover{border-color:var(--brand)}
.theme-toggle .sun{display:none}
:root.dark-mode .theme-toggle .moon{display:none}
:root.dark-mode .theme-toggle .sun{display:inline}

/* ===== Home ===== */
.home-main{min-height:calc(100vh - 72px - 64px);display:grid;place-items:center;padding:48px 20px;background:radial-gradient(circle at 15% 10%,#d7f5e9 0,transparent 32%),radial-gradient(circle at 85% 85%,#caeee0 0,transparent 30%)}
.home-hero{width:min(820px,100%);text-align:center}
.home-hero h1{margin:0;font-size:clamp(44px,8vw,88px);line-height:1.05;letter-spacing:-.055em}
.home-lead{width:min(560px,100%);margin:26px auto 34px;color:var(--muted);font-size:18px}
.home-cta{display:inline-flex;gap:13px;align-items:center;padding:13px 19px;border-radius:12px;background:var(--brand);color:#fff;font-weight:750;text-decoration:none;box-shadow:0 12px 28px rgba(12,139,107,.25);transition:transform .2s ease,box-shadow .2s ease}
.home-cta:hover{transform:translateY(-2px);box-shadow:0 16px 34px rgba(12,139,107,.32)}

/* ===== Directory (list) ===== */
.tool-directory,.tool-page{width:min(1120px,calc(100% - 40px));margin:0 auto;padding:64px 0 80px}
.directory-hero{max-width:700px;margin-bottom:36px}
.eyebrow{margin:0 0 8px;color:var(--brand);font-size:12px;font-weight:800;letter-spacing:.14em}
.directory-hero h1,.tool-page h1{font-size:clamp(34px,5vw,56px);line-height:1.08;letter-spacing:-.04em;margin:0 0 12px}
.directory-hero>p:not(.eyebrow),.tool-page .lead{color:var(--muted);margin:0}
.search-box{display:flex;align-items:center;gap:10px;padding:0 16px;height:52px;margin-top:28px;border:1px solid var(--line);border-radius:14px;background:var(--card);box-shadow:0 6px 20px rgba(19,70,57,.05)}
.search-box:focus-within{border-color:var(--brand);box-shadow:0 0 0 3px rgba(12,139,107,.14)}
.search-box span{color:var(--brand);font-size:28px}
.search-box input{flex:1;min-width:0;border:0;outline:0;font:inherit;background:transparent;color:inherit}
.directory-meta{display:flex;justify-content:space-between;margin:0 0 16px;color:var(--muted);font-size:14px}
/* Every page shows a whole number of categories, so the sections double as page breaks. */
.tool-categories{display:block}
.tool-category{margin:0 0 36px}
.tool-category:last-child{margin-bottom:0}
.category-title{display:flex;align-items:center;gap:10px;margin:0 0 14px;font-size:16px;line-height:1.2}
.category-title::after{content:'';flex:1;height:1px;background:var(--line)}
.category-count{color:var(--muted);font-size:12px;font-weight:600}
.tool-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
.tool-card{min-height:170px;padding:20px;display:flex;flex-direction:column;border:1px solid var(--line);border-radius:16px;background:var(--card);transition:transform .18s,box-shadow .18s,border-color .18s}
.tool-card:hover{transform:translateY(-3px);border-color:#a8d8c9;box-shadow:0 12px 28px rgba(18,77,61,.1)}
/* The badge is a fixed square, so the label is sized to stay inside it. */
.tool-icon{width:40px;height:40px;flex:none;display:grid;place-items:center;overflow:hidden;border-radius:10px;background:var(--soft);color:var(--brand);font-size:11px;font-weight:800;line-height:1;letter-spacing:-.4px}
.tool-card h2{font-size:17px;margin:16px 0 6px}
.tool-card p{margin:0;color:var(--muted);font-size:13px}
.tool-card .open{margin-top:auto;padding-top:14px;color:var(--brand);font-size:13px;font-weight:700}
.pagination{display:flex;justify-content:center;gap:8px;margin:34px 0 0}
.pagination button{min-width:38px;height:38px;border:1px solid var(--line);border-radius:9px;color:var(--text);background:var(--card);cursor:pointer;font:inherit}
.pagination button:hover,.pagination button[aria-current="page"]{border-color:var(--brand);background:var(--brand);color:#fff}
.pagination button:disabled{opacity:.4;cursor:not-allowed}
.empty-state{padding:44px;text-align:center;border:1px dashed var(--line);border-radius:16px;color:var(--muted)}

/* ===== Tool page ===== */
.crumb{display:inline-flex;margin-bottom:34px;color:var(--brand);font-weight:700}
.crumb:hover{text-decoration:underline}
.tool-shell{display:grid;grid-template-columns:1fr 1fr;gap:22px;margin-top:38px}
.panel{padding:22px;border:1px solid var(--line);border-radius:16px;background:var(--card)}
.panel label{display:block;margin-bottom:9px;font-size:14px;font-weight:700}
.panel textarea,.panel input,.panel select{width:100%;border:1px solid var(--line);border-radius:10px;padding:12px;color:var(--text);background:transparent;font:14px/1.5 ui-monospace,SFMono-Regular,Consolas,monospace;outline:0}
.panel textarea{min-height:280px;resize:vertical}
.panel textarea:focus,.panel input:focus,.panel select:focus{border-color:var(--brand);box-shadow:0 0 0 3px rgba(12,139,107,.12)}
.control-row{display:flex;flex-wrap:wrap;gap:10px;margin-top:14px}
.action{padding:10px 14px;border:0;border-radius:9px;background:var(--brand);color:#fff;cursor:pointer;font:inherit;font-weight:700}
.action.secondary{border:1px solid var(--line);color:var(--text);background:transparent}
/* The iplark report link is an anchor styled like the action buttons. */
.control-row a.action{display:inline-flex;align-items:center;text-decoration:none}
.action:hover{filter:brightness(.94)}
.message{min-height:22px;margin:12px 0 0;color:var(--muted);font-size:13px}

/* ===== Per-tool interface (tools/ui.js) ===== */
[hidden]{display:none !important}
body[data-layout="form"] .tool-shell{grid-template-columns:minmax(0,5fr) minmax(0,6fr)}
.controls{display:grid;grid-template-columns:repeat(auto-fit,minmax(190px,1fr));gap:14px;margin-bottom:14px}
.controls .field{display:flex;flex-direction:column;gap:6px;min-width:0}
.controls .field:has(textarea),.controls .field:has(.segmented){grid-column:1/-1}
.controls label,.controls .field-label{font-size:13px;font-weight:600;color:var(--muted);display:flex;align-items:center;justify-content:space-between;gap:8px}
.controls input[type="text"],.controls input[type="number"],.controls input[type="date"],.controls input[type="time"],.controls select,.controls textarea{width:100%;border:1px solid var(--line);border-radius:10px;padding:10px 12px;color:var(--text);background:transparent;font:14px/1.5 ui-monospace,SFMono-Regular,Consolas,monospace;outline:0}
.controls input:focus,.controls select:focus,.controls textarea:focus{border-color:var(--brand);box-shadow:0 0 0 3px rgba(12,139,107,.12)}
.controls input[type="color"]{width:100%;height:42px;padding:4px;border:1px solid var(--line);border-radius:10px;background:transparent;cursor:pointer}
.controls input[type="range"]{width:100%;accent-color:var(--brand)}
.controls output{font-variant-numeric:tabular-nums;color:var(--brand);font-weight:700}
/* An editable board (the sudoku grid): nine cells per row, thin lines inside, bold box borders. */
.field-grid{grid-column:1/-1}
.cell-grid{display:grid;grid-template-columns:repeat(var(--grid-size,9),1fr);grid-template-rows:repeat(var(--grid-size,9),1fr);width:min(100%,420px);aspect-ratio:1;border:2px solid var(--brand);border-radius:10px;overflow:hidden;background:var(--card)}
.cell-grid .cell{width:100%;height:100%;min-width:0;padding:0;border:0;border-right:1px solid var(--line);border-bottom:1px solid var(--line);border-radius:0;background:transparent;color:var(--muted);font:16px/1 ui-monospace,SFMono-Regular,Consolas,monospace;text-align:center;outline:0}
/* The box lines of a 9x9 board: after columns 3 and 6, and under rows 3 and 6. The rules for the
   right and bottom edge come last, so they win over the heavier box line and never double the frame. */
.cell-grid[data-grid="9"] .cell:nth-child(3n){border-right:2px solid var(--brand)}
.cell-grid[data-grid="9"] .cell:nth-child(n+19):nth-child(-n+27),.cell-grid[data-grid="9"] .cell:nth-child(n+46):nth-child(-n+54){border-bottom:2px solid var(--brand)}
.cell-grid[data-grid="9"] .cell:nth-child(9n){border-right:0}
.cell-grid[data-grid="9"] .cell:nth-child(n+73){border-bottom:0}
.cell-grid .cell.filled{color:var(--text);font-weight:700}
.cell-grid .cell.solved{color:var(--brand);font-weight:700}
.cell-grid .cell.hint{background:rgba(161,89,10,.16);color:#a1590a}
.cell-grid .cell.bad{background:rgba(185,28,28,.16);color:#b91c1c}
.cell-grid .cell.active,.cell-grid .cell:focus{background:var(--soft);box-shadow:inset 0 0 0 2px var(--brand);color:var(--brand)}
.controls .field-note{grid-column:1/-1;margin:0;color:var(--muted);font-size:12px;line-height:1.5}
.segmented{display:flex;flex-wrap:wrap;gap:6px}
.segmented label{display:inline-flex;align-items:center;font-weight:600;color:var(--text)}
.segmented input{position:absolute;opacity:0;width:1px;height:1px}
.segmented span{padding:8px 12px;border:1px solid var(--line);border-radius:9px;font-size:13px;cursor:pointer}
.segmented input:checked+span{border-color:var(--brand);background:var(--brand);color:#fff}
.segmented input:focus-visible+span{box-shadow:0 0 0 3px rgba(12,139,107,.18)}
.field-checkbox label{display:flex;align-items:center;gap:8px;color:var(--text);font-weight:600}
/* Result area */
.result{margin-top:14px}
.result:empty{display:none}
.kv{margin:0;display:flex;flex-direction:column;gap:2px}
.result>.kv+.kv{margin-top:12px;padding-top:12px;border-top:1px dashed var(--line)}
.kv-row{display:grid;grid-template-columns:minmax(96px,38%) 1fr;gap:10px;padding:7px 10px;border-radius:8px;align-items:baseline}
.kv-row:nth-child(odd){background:var(--soft)}
.kv-row dt{color:var(--muted);font-size:13px;font-weight:600;word-break:break-word}
.kv-row dd{margin:0;font:14px/1.5 ui-monospace,SFMono-Regular,Consolas,monospace;word-break:break-word;white-space:pre-wrap}
.kv-plain{grid-template-columns:1fr}
.kv-plain pre{margin:0;font:13px/1.45 ui-monospace,SFMono-Regular,Consolas,monospace;white-space:pre;overflow:auto}
.code{margin:0;padding:14px;border:1px solid var(--line);border-radius:12px;background:var(--soft);font:13px/1.5 ui-monospace,SFMono-Regular,Consolas,monospace;white-space:pre-wrap;word-break:break-word;max-height:420px;overflow:auto}
.json-key{color:#0c8b6b;font-weight:700}
.json-string{color:#a1590a}
.json-number{color:#1d4ed8}
.json-atom{color:#9333ea}
.table-wrap{overflow:auto;border:1px solid var(--line);border-radius:12px;max-height:420px}
.data-table{border-collapse:collapse;width:100%;font-size:13px}
.data-table th,.data-table td{padding:8px 10px;border-bottom:1px solid var(--line);text-align:left;white-space:nowrap}
.data-table th{position:sticky;top:0;background:var(--soft);font-weight:700}
.data-table tr:last-child td{border-bottom:0}
.items{margin:0;padding:0;list-style:none;display:flex;flex-direction:column;gap:6px}
.items li{padding:8px 12px;border:1px solid var(--line);border-radius:9px;background:var(--soft);font:13px/1.4 ui-monospace,SFMono-Regular,Consolas,monospace;word-break:break-all}
.sudoku-grid{display:grid;grid-template-columns:repeat(9,1fr);grid-template-rows:repeat(9,1fr);width:min(100%,380px);aspect-ratio:1;border:2px solid var(--brand);border-radius:10px;overflow:hidden}
.sudoku-grid .cell{display:grid;place-items:center;border-right:1px solid var(--line);border-bottom:1px solid var(--line);font:15px/1 ui-monospace,Consolas,monospace;color:var(--brand)}
/* Same box lines as the editable board, so a printed solution reads like a sudoku. */
.sudoku-grid .cell:nth-child(3n){border-right:2px solid var(--brand)}
.sudoku-grid .cell:nth-child(n+19):nth-child(-n+27),.sudoku-grid .cell:nth-child(n+46):nth-child(-n+54){border-bottom:2px solid var(--brand)}
.sudoku-grid .cell:nth-child(9n){border-right:0}
.sudoku-grid .cell:nth-child(n+73){border-bottom:0}
.maze-grid{display:grid;gap:0;font:12px/1 ui-monospace,Consolas,monospace;width:max-content}
.maze-cell{width:12px;height:12px;display:grid;place-items:center;color:var(--brand)}
.maze-cell.wall{background:var(--ink)}
.maze-cell.path{color:#a1590a}
.maze-cell.mark{font-weight:800;color:#b91c1c}
.plot{width:100%;height:auto}
.plot-bg{fill:var(--soft)}
.plot .axis{stroke:var(--line);stroke-width:1}
.plot .curve{fill:none;stroke:var(--brand);stroke-width:2.2;stroke-linejoin:round}
.plot .tick{fill:var(--muted);font-size:11px}
.plot .tick.end{text-anchor:end}
.color-result{display:flex;gap:14px;align-items:flex-start}
.swatch{width:64px;height:64px;flex:none;border-radius:12px;border:1px solid var(--line)}
.color-result .kv{flex:1}
/* Sandboxed iframe used to preview rendered Markdown without touching the page itself. */
.output-preview{display:block;width:100%;height:280px;min-height:280px;border:1px solid var(--line);border-radius:10px;background:#fff}
.output-preview[hidden]{display:none}
/* Sudoku photo panel: take a picture or pick one; it is read locally and never uploaded. */
.photo-panel{margin-top:16px;padding:12px;border:1px solid var(--line);border-radius:12px;background:var(--soft)}
.photo-panel.over{border-color:var(--brand);box-shadow:inset 0 0 0 2px var(--brand)}
.photo-choices{display:flex;flex-wrap:wrap;gap:8px}
.photo-choices .photo-drop{flex:1 1 130px}
.photo-drop{position:relative;display:flex;align-items:center;justify-content:center;padding:12px;border:1px dashed var(--line);border-radius:10px;background:var(--card);color:var(--text);font-size:13px;font-weight:600;cursor:pointer;text-align:center}
.photo-drop:hover{border-color:var(--brand);color:var(--brand)}
.photo-drop.primary{border-style:solid;border-color:var(--brand);background:var(--brand);color:#fff}
.photo-drop.primary:hover{filter:brightness(1.06);color:#fff}
.photo-drop input{position:absolute;width:1px;height:1px;opacity:0;pointer-events:none}
.photo-panel .field-note{margin:8px 0 0}
.photo-stage{position:relative;margin-top:12px;border:1px solid var(--line);border-radius:10px;overflow:hidden;background:var(--card)}
.photo-stage[hidden]{display:none}
.photo-stage img{display:block;width:100%;height:auto}
.photo-stage img[hidden]{display:none}
.photo-stage video{display:block;width:100%;height:auto;background:#000}
.photo-stage video[hidden]{display:none}

/* ===== Footer ===== */
footer{padding:24px;border-top:1px solid var(--line);color:var(--muted);text-align:center;font-size:13px}

/* ===== Dark mode (class lives on <html> so it can be applied before first paint) ===== */
:root.dark-mode{--ink:#e6f4ef;--muted:#aac1ba;--line:#29443d;--card:#172520;--soft:#1c3930;--bg:#101a17;--surface:#101a17;--page:#0d1614;--text:#e6f4ef;color-scheme:dark}
:root.dark-mode .site-header{background:rgba(16,26,23,.88)}
:root.dark-mode .home-main{background:radial-gradient(circle at 15% 10%,#173e34 0,transparent 32%),radial-gradient(circle at 85% 85%,#1b332c 0,transparent 30%)}

/* ===== Theme transition (applies to every themed surface) ===== */
.tool-card,.panel,.search-box,.tool-page textarea,.tool-page input,.tool-page select,.language-trigger,.language-menu,.theme-toggle,footer{transition:background-color .35s ease,color .35s ease,border-color .35s ease,box-shadow .35s ease}
@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{transition-duration:.01ms !important;animation-duration:.01ms !important;scroll-behavior:auto !important}
}

/* ===== Responsive ===== */
@media (max-width:850px){
  .tool-grid{grid-template-columns:repeat(2,1fr)}
  .tool-shell{grid-template-columns:1fr}
  .panel textarea,.output-preview{min-height:220px;height:220px}
}
@media (max-width:600px){
  .home-main{min-height:calc(100vh - 64px - 96px);padding:40px 18px}
  .home-lead{font-size:16px}
}
@media (max-width:500px){
  .site-header{gap:16px;padding:0 18px}
  .site-link{display:none}
  .tool-directory,.tool-page{width:min(100% - 28px,1120px);padding-top:38px}
  .tool-grid{grid-template-columns:1fr}
  .directory-meta{font-size:12px}
  .tool-card{min-height:145px}
  .panel{padding:16px}
}