:root{--bg:#f2f6f9;--grid:#d9e5ee;--ink:#17283d;--mut:#55667a;--card:#fff;--line:#c6d4e1;--hi:#ffe066;--hiink:#3a2f00;--ac:#2f6fed;--acink:#fff;--warn:#b3261e;
box-sizing:border-box;padding-top:env(safe-area-inset-top,0px);padding-bottom:env(safe-area-inset-bottom,0px)}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){--bg:#14202e;--grid:#1d2e42;--ink:#e8eef5;--mut:#9fb0c3;--card:#1b2b3d;--line:#2d4259;--hi:#8a7416;--hiink:#fff6cf;--ac:#6ea0ff;--acink:#0d1a2b;--warn:#ff8a80}}
:root[data-theme="dark"]{--bg:#14202e;--grid:#1d2e42;--ink:#e8eef5;--mut:#9fb0c3;--card:#1b2b3d;--line:#2d4259;--hi:#8a7416;--hiink:#fff6cf;--ac:#6ea0ff;--acink:#0d1a2b;--warn:#ff8a80}
*{box-sizing:border-box}
[hidden]{display:none!important}
html{height:100%;scroll-padding-top:env(safe-area-inset-top,0px)}
body{margin:0;min-height:100%;background-color:var(--bg);background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);background-size:24px 24px;color:var(--ink);font:17px/1.65 'Gowun Dodum','Apple SD Gothic Neo','Malgun Gothic',sans-serif}
main{max-width:720px;margin:0 auto;padding:28px 16px 56px}
h1{font:400 40px/1.15 'Jua','Gowun Dodum',sans-serif;margin:0 0 8px}
h2{font:400 22px/1.3 'Jua','Gowun Dodum',sans-serif;margin:28px 0 10px}
p{margin:0 0 10px}
.sub,.hint,.mut{color:var(--mut)}
.warn{color:var(--warn)}
.paper{background:var(--card);border:2px solid var(--ink);border-radius:6px;padding:20px;margin-top:22px;box-shadow:5px 5px 0 var(--line)}
.btn,.ghost,.card{font:inherit;cursor:pointer;border-radius:6px}
.btn{display:inline-block;background:var(--ac);color:var(--acink);border:2px solid var(--ink);padding:10px 18px;box-shadow:3px 3px 0 var(--ink)}
.btn:active{transform:translate(2px,2px);box-shadow:1px 1px 0 var(--ink)}
.ghost{background:transparent;color:var(--ink);border:2px solid var(--line);padding:8px 14px}
.ghost:disabled{opacity:.4;cursor:default}
.btn:focus-visible,.ghost:focus-visible,.card:focus-visible,label.btn:focus-within,.vz button:focus-visible{outline:3px solid var(--ac);outline-offset:3px}
.vh{position:absolute;width:1px;height:1px;opacity:0;overflow:hidden}
.row{display:flex;flex-wrap:wrap;gap:10px;align-items:center}
.card{display:flex;flex-direction:column;gap:2px;width:100%;text-align:left;background:var(--card);color:var(--ink);border:2px solid var(--line);padding:12px 14px;margin-bottom:10px}
.card span{color:var(--mut);font-size:15px}
.card:hover{border-color:var(--ink)}
.shot{max-width:100%;max-height:220px;border:2px solid var(--line);border-radius:6px;background:#fff}
.prob{padding:12px 14px;border-left:5px solid var(--ac);background:var(--card);white-space:pre-wrap}
ol{padding-left:1.4em;margin:0}li{margin:8px 0}
.note{margin-top:16px;padding:18px 20px;background:var(--hi);color:var(--hiink);font:400 24px/1.4 'Jua','Gowun Dodum',sans-serif;border-radius:2px;box-shadow:4px 5px 0 var(--line);transform:rotate(-1deg);white-space:pre-wrap}
.sp{display:inline-block;width:14px;height:14px;border:3px solid var(--line);border-top-color:var(--ac);border-radius:50%;animation:r 1s linear infinite;vertical-align:-2px}
@keyframes r{to{transform:rotate(360deg)}}
@media (prefers-reduced-motion:reduce){.sp{animation:none}}
#viewer{position:fixed;inset:0;z-index:9;display:flex;flex-direction:column;background:var(--bg);padding-top:env(safe-area-inset-top,0px);padding-bottom:env(safe-area-inset-bottom,0px)}
.vbar{display:flex;align-items:center;justify-content:space-between;gap:8px;padding:8px 12px;background:var(--card);border-bottom:2px solid var(--line)}
.vz{display:flex;gap:6px}
.vz button{font:inherit;min-width:40px;padding:4px 10px;border:2px solid var(--line);background:transparent;color:var(--ink);border-radius:6px;cursor:pointer}
#stage{flex:1;min-height:0;overflow:hidden;touch-action:none;display:flex;align-items:center;justify-content:center;background:#8a96a3}
#pg{max-width:100%;max-height:100%;user-select:none;-webkit-user-drag:none;transform-origin:center;background:#fff}
h3{font:400 18px/1.3 'Jua','Gowun Dodum',sans-serif;margin:0 0 8px}
.prob ol{white-space:normal}
#sol{margin-top:16px}
.stg{background:var(--card);border:2px solid var(--line);border-radius:6px;padding:14px 16px;margin-bottom:12px}
.stg.ok{border-color:var(--ac)}
.stg.lock{opacity:.55}
.pr{display:flex;flex-direction:column;gap:6px;padding:10px 0;border-top:1px dashed var(--line)}
.chk{display:inline-flex;align-items:center;gap:8px;cursor:pointer}
.chk input{width:20px;height:20px;accent-color:var(--ac)}
.sel{position:relative;display:inline-block;max-width:100%;touch-action:none;cursor:crosshair;line-height:0;border:2px solid var(--line);border-radius:6px;overflow:hidden}
.sel img{max-width:100%;max-height:380px;display:block;user-select:none;-webkit-user-drag:none}
.selbox{position:absolute;border:3px solid var(--ac);background:rgba(47,111,237,.2);pointer-events:none}
.pr>.btn,.pr>.ghost{align-self:flex-start}
#askT:focus{outline:none}
.vbar{flex-wrap:wrap;gap:6px 8px}
.vbar button{white-space:nowrap}
#vt{flex:1 1 90px;min-width:0}
.vz{margin-left:auto}
.vz button{padding:4px 9px;font-size:15px}
.gate-row{display:flex;gap:10px;flex-wrap:wrap}
.gate-row input{font:inherit;padding:10px 12px;border:2px solid var(--ink);border-radius:6px;background:var(--card);color:var(--ink);min-width:0;flex:1 1 180px}
#notice{margin:0;border-radius:0;border-width:0 0 2px 0;box-shadow:none;display:flex;gap:12px;align-items:flex-start;justify-content:space-between}
#notice p{margin:0}