:root{--bg:#f4f5f7;--panel:#fff;--line:#e2e4e9;--ink:#1d2330;--sub:#6b7280;--accent:#2563eb}
*{box-sizing:border-box}
html,body{height:100%;margin:0}
body{font-family:system-ui,-apple-system,"Segoe UI",sans-serif;color:var(--ink);background:var(--bg);display:grid;grid-template-columns:1fr 1fr}
@media (max-width:800px){body{grid-template-columns:1fr;height:auto}}

aside{background:var(--panel);border-right:1px solid var(--line);padding:24px;overflow:auto;height:100vh}
@media (max-width:800px){aside{height:auto}}
h1{font-size:20px;margin:0 0 4px}
.sub{color:var(--sub);font-size:12px;margin-bottom:16px}
section{border-top:1px solid var(--line);padding:14px 0}
h2{font-size:12px;margin:0 0 10px;text-transform:uppercase;letter-spacing:.04em;color:var(--sub)}
.grid{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.row{display:flex;gap:8px;flex-wrap:wrap}
label.f{display:flex;flex-direction:column;font-size:12px;color:var(--sub);gap:4px}
input[type=number],select{width:100%;padding:8px;border:1px solid var(--line);border-radius:6px;font-size:14px;background:#fff;color:var(--ink)}
input[type=range]{width:100%}
.chk{display:flex;align-items:center;gap:6px;font-size:13px;margin-top:10px}
button{padding:8px 12px;border:1px solid var(--line);border-radius:6px;background:#fff;cursor:pointer;font-size:13px}
button:hover:not(:disabled){border-color:var(--accent)}
button.primary{background:var(--accent);border-color:var(--accent);color:#fff;width:100%;padding:12px;font-weight:600;font-size:14px}
button:disabled{opacity:.5;cursor:not-allowed}
#fileBtn{width:100%;border-style:dashed;padding:10px}
#info{font-size:12px;color:var(--sub);margin-top:8px;min-height:1em}
#result,#dlResult{font-size:12px;color:var(--sub);margin-top:8px;min-height:1.2em;word-break:break-all}
.hint{font-size:11px;color:var(--sub);margin-top:6px;line-height:1.4}

main{display:flex;align-items:center;justify-content:center;padding:24px;height:100vh;overflow:hidden}
@media (max-width:800px){main{height:60vh}}
#empty{color:var(--sub);border:2px dashed var(--line);border-radius:12px;padding:60px 40px;text-align:center}
#empty.drag{border-color:var(--accent);color:var(--accent)}
#wrap{position:relative;display:none;line-height:0;overflow:hidden;box-shadow:0 2px 16px rgba(0,0,0,.15);
  background:repeating-conic-gradient(#ddd 0 25%,#fff 0 50%) 0 0/16px 16px;touch-action:none;user-select:none}
#src{display:block;max-width:calc(50vw - 48px);max-height:calc(100vh - 48px)}
@media (max-width:800px){#src{max-width:calc(100vw - 48px);max-height:calc(60vh - 48px)}}
#wrap.brush #src{cursor:crosshair}
#box{position:absolute;border:2px solid #fff;box-shadow:0 0 0 9999px rgba(0,0,0,.55);cursor:move;outline:1px solid var(--accent)}
#box::before,#box::after{content:"";position:absolute;pointer-events:none;border:0 solid rgba(255,255,255,.5)}
#box::before{left:33.3%;right:33.3%;top:0;bottom:0;border-left-width:1px;border-right-width:1px}
#box::after{top:33.3%;bottom:33.3%;left:0;right:0;border-top-width:1px;border-bottom-width:1px}
.h{position:absolute;width:14px;height:14px;background:#fff;border:2px solid var(--accent);border-radius:3px;margin:-7px 0 0 -7px;z-index:1}
.h[data-m=nw]{left:0;top:0;cursor:nwse-resize}.h[data-m=n]{left:50%;top:0;cursor:ns-resize}
.h[data-m=ne]{left:100%;top:0;cursor:nesw-resize}.h[data-m=e]{left:100%;top:50%;cursor:ew-resize}
.h[data-m=se]{left:100%;top:100%;cursor:nwse-resize}.h[data-m=s]{left:50%;top:100%;cursor:ns-resize}
.h[data-m=sw]{left:0;top:100%;cursor:nesw-resize}.h[data-m=w]{left:0;top:50%;cursor:ew-resize}

#bar{width:100%;height:10px;margin-top:10px;accent-color:var(--accent)}