:root{
  --bg: #0b0f17;
  --panel: #101826;
  --panel2: #0f1624;
  --text: #e6edf3;
  --muted: #9aa4b2;
  --line: rgba(255,255,255,.08);
  --accent: #39d98a;
  --danger: #ff5d5d;

  --easy: #2dd4bf;
  --medium: #fbbf24;
  --hard: #fb7185;
}

*{ box-sizing: border-box; }
html,body{ height:100%; }
body{
  margin:0;
  background: radial-gradient(1200px 600px at 20% -10%, rgba(57,217,138,.12), transparent 60%),
              radial-gradient(900px 500px at 90% 0%, rgba(99,102,241,.10), transparent 55%),
              var(--bg);
  color: var(--text);
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, "Noto Sans KR", Arial, "Apple SD Gothic Neo", sans-serif;
}

a{ color:inherit; text-decoration:none; }
a:hover{ text-decoration: underline; }

.topbar{
  position: sticky;
  top: 0;
  z-index: 10;
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:16px;
  padding:16px 18px;
  border-bottom: 1px solid var(--line);
  background: rgba(11,15,23,.72);
  backdrop-filter: blur(10px);
}

.brand{
  display:flex;
  align-items:center;
  gap:12px;
}
.logo{
  width:38px; height:38px;
  border-radius: 12px;
  display:grid; place-items:center;
  background: linear-gradient(135deg, rgba(57,217,138,.18), rgba(57,217,138,.06));
  border: 1px solid rgba(57,217,138,.22);
  color: var(--accent);
  font-weight: 800;
}
.title{ font-size: 16px; font-weight: 800; letter-spacing:.2px; }
.subtitle{ font-size: 12px; color: var(--muted); margin-top: 2px; }

.stats{
  display:flex;
  gap:10px;
  flex-wrap: wrap;
  justify-content:flex-end;
}
.pill{
  display:flex;
  align-items:center;
  gap:8px;
  padding:8px 10px;
  border-radius: 999px;
  background: rgba(255,255,255,.04);
  border: 1px solid var(--line);
  font-size: 12px;
  color: var(--muted);
}
.pill strong{ color: var(--text); font-weight: 800; }

.container{
  max-width: 1120px;
  margin: 0 auto;
  padding: 18px;
}

.controls{
  display:grid;
  grid-template-columns: 1.2fr .9fr .7fr 1.2fr;
  gap: 12px;
  padding: 14px;
  border-radius: 16px;
  background: rgba(16,24,38,.65);
  border: 1px solid var(--line);
}

.control label{
  display:block;
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 6px;
}
.control input, .control select{
  width:100%;
  padding: 10px 12px;
  border-radius: 12px;
  outline: none;
  border: 1px solid var(--line);
  background: rgba(15,22,36,.85);
  color: var(--text);
}

.actions{
  display:grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 10px;
  align-content:end;
}
button{
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: rgba(255,255,255,.04);
  color: var(--text);
  cursor:pointer;
  font-weight: 700;
}
button:hover{ border-color: rgba(57,217,138,.25); }
button.danger:hover{ border-color: rgba(255,93,93,.35); }
button.danger{ color: #ffd1d1; }

.board{
  margin-top: 14px;
  display:flex;
  flex-direction: column;
  gap: 10px;
}

.section{
  border: 1px solid var(--line);
  background: rgba(16,24,38,.55);
  border-radius: 16px;
  overflow: hidden;
}
.sectionHeader{
  display:flex;
  justify-content:space-between;
  align-items:center;
  padding: 12px 14px;
  cursor:pointer;
  user-select:none;
  background: rgba(15,22,36,.55);
  border-bottom: 1px solid var(--line);
}
.sectionTitle{
  display:flex;
  gap:10px;
  align-items:baseline;
  font-weight: 900;
}
.sectionTitle small{
  color: var(--muted);
  font-weight: 700;
}
.sectionBody{
  padding: 8px 10px 12px;
}
.sectionBody.hidden{ display:none; }

.table{
  width:100%;
  border-collapse: collapse;
}
.table th, .table td{
  padding: 10px 10px;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
}
.table th{
  font-size: 12px;
  color: var(--muted);
  text-align:left;
  font-weight: 800;
}
.row{
  transition: background .12s ease;
}
.row:hover{
  background: rgba(255,255,255,.03);
}

.doneBox{
  width: 18px;
  height: 18px;
  accent-color: var(--accent);
  cursor:pointer;
}

.problem{
  display:flex;
  align-items:center;
  gap:10px;
}
.problem .meta{
  display:flex;
  gap:8px;
  align-items:center;
  flex-wrap: wrap;
}
.badge{
  font-size: 12px;
  padding: 4px 8px;
  border-radius: 999px;
  border: 1px solid var(--line);
  color: var(--text);
  font-weight: 900;
}
.badge.easy{ background: rgba(45,212,191,.12); border-color: rgba(45,212,191,.25); }
.badge.medium{ background: rgba(251,191,36,.12); border-color: rgba(251,191,36,.25); }
.badge.hard{ background: rgba(251,113,133,.12); border-color: rgba(251,113,133,.25); }

.linkchip{
  font-size: 12px;
  padding: 4px 8px;
  border-radius: 999px;
  background: rgba(255,255,255,.04);
  border: 1px solid var(--line);
  color: var(--muted);
}
.linkchip:hover{ color: var(--text); border-color: rgba(57,217,138,.25); text-decoration:none; }

.footer{
  max-width:1120px;
  margin: 0 auto;
  padding: 18px;
  color: var(--muted);
  font-size: 12px;
  opacity: .9;
}

@media (max-width: 980px){
  .controls{ grid-template-columns: 1fr 1fr; }
  .actions{ grid-template-columns: 1fr 1fr; }
}
@media (max-width: 520px){
  .controls{ grid-template-columns: 1fr; }
  .actions{ grid-template-columns: 1fr; }
}