:root{
  --bg:#FDFAF6; --surface:#FFFFFF; --ink:#1E1A14; --muted:#6E5F49;
  --line:#E8DFD0; --primary:#D95F00; --primary-dark:#B34D00;
  --ok:#1E6B3A; --warn:#B34D00; --bad:#C03920; --cat:#1A4D8C;
  --shadow:0 1px 3px rgba(60,40,10,.08),0 1px 2px rgba(60,40,10,.04);
  --radius:14px; --fs-base:16px;
}
*{box-sizing:border-box}
html{font-size:var(--fs-base)}
body{
  margin:0; background:var(--bg); color:var(--ink);
  font-family:'Pretendard','Noto Sans KR',system-ui,-apple-system,sans-serif;
  line-height:1.65; -webkit-font-smoothing:antialiased;
}

/* ---------- top bar ---------- */
.topbar{
  display:flex; align-items:center; gap:24px; padding:14px 28px;
  background:var(--surface); border-bottom:1px solid var(--line);
  position:sticky; top:0; z-index:20; box-shadow:var(--shadow);
}
.brand{font-size:1.25rem; font-weight:800; letter-spacing:-.01em; display:flex; gap:8px; align-items:center}
.logo{font-size:1.4rem}
.topnav{display:flex; gap:4px; flex:1}
.navlink{
  border:0; background:transparent; color:var(--muted); font-size:1rem;
  font-weight:600; padding:10px 16px; border-radius:10px; cursor:pointer;
  transition:.15s;
}
.navlink:hover{background:var(--bg); color:var(--ink)}
.navlink.active{background:#FFF0E0; color:var(--primary)}
.userbox{display:flex; align-items:center; gap:10px}
.user-label{font-weight:700; color:var(--ink)}

/* ---------- buttons ---------- */
.btn{
  border:0; border-radius:10px; padding:10px 18px; font-size:.98rem;
  font-weight:700; cursor:pointer; transition:.15s; font-family:inherit;
  text-decoration:none; display:inline-flex; align-items:center; gap:6px;
}
.btn-primary{background:var(--primary); color:#fff}
.btn-primary:hover{background:var(--primary-dark)}
.btn-ghost{background:transparent; color:var(--muted); border:1px solid var(--line)}
.btn-ghost:hover{background:var(--bg); color:var(--ink)}

/* ---------- layout ---------- */
.container{max-width:1140px; margin:0 auto; padding:28px}
.view{display:none; animation:fade .2s ease}
.view.active{display:block}
@keyframes fade{from{opacity:0;transform:translateY(4px)}to{opacity:1;transform:none}}
.section-head{display:flex; align-items:center; justify-content:space-between; margin-bottom:20px; flex-wrap:wrap; gap:12px}
.section-head h2{font-size:1.5rem; font-weight:800; margin:0}
.filters{display:flex; gap:10px}
.filters select{
  padding:8px 12px; border:1px solid var(--line); border-radius:10px;
  background:var(--surface); font-size:.95rem; font-family:inherit; color:var(--ink);
}
.card{background:var(--surface); border:1px solid var(--line); border-radius:var(--radius); box-shadow:var(--shadow)}

/* ---------- problem list ---------- */
.card-list{display:flex; flex-direction:column; gap:12px}
.prob-row{
  display:flex; align-items:center; gap:16px; padding:18px 22px;
  background:var(--surface); border:1px solid var(--line);
  border-radius:var(--radius); cursor:pointer; transition:.15s; box-shadow:var(--shadow);
}
.prob-row:hover{border-color:var(--primary); transform:translateY(-1px)}
.prob-check{font-size:1.3rem; width:28px; text-align:center}
.prob-title{font-size:1.1rem; font-weight:700; flex:1}
.chip{
  font-size:.82rem; font-weight:700; padding:4px 11px; border-radius:999px;
  background:#FFF0E0; color:var(--primary); white-space:nowrap;
}
.chip-cat{background:#e0f2fe; color:var(--cat)}
.chip-dim{background:var(--bg); color:var(--muted)}
.diff-입문{background:#dcfce7;color:#15803d}
.diff-기초{background:#dbeafe;color:#1d4ed8}
.diff-중급{background:#fef3c7;color:#b45309}
.diff-심화{background:#fee2e2;color:#b91c1c}

/* ---------- solve view ---------- */
.back-btn{margin-bottom:16px}
.solve-grid{display:grid; grid-template-columns:1fr 1fr; gap:20px; align-items:start}
.statement{padding:26px}
.prob-head h2{font-size:1.4rem; margin:0 0 10px}
.prob-meta{display:flex; gap:8px; flex-wrap:wrap; margin-bottom:18px}
.markdown{font-size:1.02rem; color:var(--ink)}
.markdown h1,.markdown h2,.markdown h3{margin:18px 0 8px}
.markdown pre{background:#0f172a; color:#e2e8f0; padding:14px; border-radius:10px; overflow:auto}
.markdown code{background:var(--bg); padding:2px 6px; border-radius:6px; font-size:.92em}
.markdown pre code{background:none; padding:0}
.io-block{margin-top:18px}
.io-block h4{margin:0 0 6px; font-size:1rem; color:var(--muted)}
.sample{margin-top:16px}
.sample-grid{display:grid; grid-template-columns:1fr 1fr; gap:10px}
.sample pre{background:#f8fafc; border:1px solid var(--line); padding:12px; border-radius:10px; margin:0; font-size:.92rem; white-space:pre-wrap}
.sample .lbl{font-size:.85rem; font-weight:700; color:var(--muted); margin-bottom:4px}

.editor-col{padding:0; overflow:hidden; display:flex; flex-direction:column}
.editor-toolbar{display:flex; align-items:center; justify-content:space-between; padding:12px 18px; border-bottom:1px solid var(--line); background:var(--bg)}
.muted{color:var(--muted); font-size:.9rem}
.CodeMirror{height:380px; font-size:14px; font-family:'JetBrains Mono','Fira Code',monospace}
.verdict-box{padding:0 18px; max-height:0; overflow:hidden; transition:.2s}
.verdict-box.show{padding:18px; max-height:600px; border-top:1px solid var(--line)}
.verdict{font-size:1.2rem; font-weight:800; display:flex; align-items:center; gap:8px; margin-bottom:10px}
.v-AC{color:var(--ok)} .v-WA,.v-RE,.v-CE{color:var(--bad)} .v-TLE,.v-MLE{color:var(--warn)}
.feedback{background:var(--bg); border-radius:10px; padding:14px; white-space:pre-wrap; font-size:.96rem; margin-top:8px}

/* ---------- tables ---------- */
.rank-table{width:100%; border-collapse:collapse; background:var(--surface); border-radius:var(--radius); overflow:hidden; box-shadow:var(--shadow)}
.rank-table th{background:var(--bg); text-align:left; padding:14px 18px; font-size:.9rem; color:var(--muted); font-weight:700}
.rank-table td{padding:14px 18px; border-top:1px solid var(--line); font-size:1rem}
.rank-table tr:hover td{background:#fafbff}
.rank-1{font-weight:800;color:#b45309}

/* ---------- modal ---------- */
.modal-overlay{position:fixed; inset:0; background:rgba(15,23,42,.5); display:none; align-items:center; justify-content:center; z-index:50; padding:20px}
.modal-overlay.show{display:flex}
.modal{background:var(--surface); border-radius:18px; padding:30px; width:100%; max-width:420px; box-shadow:0 20px 60px rgba(0,0,0,.25)}
.modal h3{margin:0 0 6px; font-size:1.3rem}
.modal input{width:100%; padding:12px 14px; margin-top:14px; border:1px solid var(--line); border-radius:10px; font-size:1rem; font-family:inherit}
.modal-actions{display:flex; justify-content:flex-end; gap:10px; margin-top:20px}
.error-text{color:var(--bad); font-size:.9rem; margin-top:8px; min-height:1.2em}

/* ---------- toast ---------- */
.toast{position:fixed; bottom:24px; left:50%; transform:translateX(-50%); background:var(--ink); color:#fff; padding:12px 22px; border-radius:12px; font-weight:600; z-index:100; opacity:0; transition:.25s; box-shadow:0 8px 24px rgba(0,0,0,.2)}
.toast.show{opacity:1; bottom:34px}

@media(max-width:860px){
  .solve-grid{grid-template-columns:1fr}
  .sample-grid{grid-template-columns:1fr}
  .topbar{flex-wrap:wrap; gap:12px}
  .container{padding:18px}
}

/* ---------- AI 피드백 박스 ---------- */
.ai-box{display:none;margin-top:14px;border:1px solid #F2C79A;border-radius:12px;
  background:linear-gradient(180deg,#f5f3ff,#FFF0E0);overflow:hidden}
.ai-box.show{display:block}
.ai-box .ai-head{padding:8px 14px;font-weight:700;color:#B34D00;
  background:#FFE4CC;border-bottom:1px solid #F2C79A}
.ai-box .ai-body{padding:12px 14px;color:#1e2338;font-size:.95rem}
.ai-box .ai-body pre{background:#1e293b;color:#e2e8f0;padding:10px 12px;
  border-radius:8px;overflow:auto}
.ai-box .ai-body code{background:#FFE4CC;padding:1px 5px;border-radius:4px}
.editor-tools-hint{margin-left:auto;font-size:.8rem}

/* ---------- 문제 설명 속 SVG 그림 ---------- */
.markdown svg{display:block;margin:12px 0;max-width:100%;height:auto}
.markdown pre{background:#1e293b;color:#e2e8f0;padding:10px 12px;border-radius:8px;
  overflow:auto}
.markdown code{background:#FFF0E0;padding:1px 5px;border-radius:4px;font-size:.92em}
.markdown pre code{background:transparent;padding:0}

/* ---------- CodeMirror IDE 보조 ---------- */
.CodeMirror{height:auto;min-height:280px;border-radius:10px;font-size:14px}
.CodeMirror-hints{z-index:9999}

/* v2 (2026-10-21) */
[hidden]{display:none !important}
.chip-kind{background:#fef3c7;color:#92400e}
.func-note{background:#eef6ff;border:1px solid #bfdbfe;color:#1e3a8a;border-radius:10px;padding:10px 12px;margin:0 0 10px;font-size:14px;line-height:1.6}
.choice-box{border:1px solid var(--line,#e2e8f0);border-radius:12px;padding:12px 14px;margin:0 0 10px}
.choice-opt{display:flex;gap:10px;align-items:flex-start;padding:10px;border-radius:10px;cursor:pointer;border:1px solid transparent}
.choice-opt:hover{background:#f8fafc;border-color:#e2e8f0}.choice-opt input{margin-top:5px;width:18px;height:18px}
.choice-opt .md p{margin:0}.choice-box #short-answer{width:100%;padding:10px;font-size:16px}
.expl{margin-top:16px;background:#f0fdf4;border:1px solid #bbf7d0;border-radius:12px;padding:12px 16px}
.sb-ok{background:#dcfce7;font-weight:700}.sb-no{background:#fee2e2;color:#991b1b}
.table-wrap{overflow-x:auto}.small{font-size:13px}
.assign-card{margin-bottom:14px}.assign-card.closed{opacity:.75}
.markdown img{max-width:100%;height:auto;border-radius:8px}
.markdown table{border-collapse:collapse}.markdown td,.markdown th{border:1px solid #e2e8f0;padding:4px 8px}
#filter-q{padding:7px 10px;border-radius:8px;border:1px solid #cbd5e1}

/* 2026-10-29 다른 도구로 가는 링크 */
.tools-link{font-size:.88rem; font-weight:600; color:var(--muted); text-decoration:none; white-space:nowrap; padding:6px 4px}
.tools-link:hover{color:var(--ink); text-decoration:underline}
.chip-link{background:#dcfce7; color:#166534; text-decoration:none}
.chip-link:hover{text-decoration:underline}