:root{
  --bg:#0f1216; --panel:#141a21; --muted:#99a2ad; --text:#e6edf3;
  --primary:#5aa6ff; --accent:#7ee787; --card:#1b222c; --border:#26303b;
  --danger:#ff6b6b; --high:#ffb86b; --low:#6be6ff;
}
*{box-sizing:border-box}
html,body{height:100%}
body{margin:0;background:var(--bg);color:var(--text);font:14px/1.4 system-ui,Segoe UI,Roboto,Helvetica,Arial}

.app-header{display:flex;justify-content:space-between;align-items:center;padding:12px 16px;border-bottom:1px solid var(--border);background:var(--panel);position:sticky;top:0;z-index:2}
.app-header h1{margin:0;font-size:18px}
.header-actions{display:flex;gap:8px}
.btn{background:transparent;color:var(--text);border:1px solid var(--border);padding:8px 10px;border-radius:8px;cursor:pointer}
.btn.primary{background:var(--primary);border-color:transparent;color:#051128;font-weight:600}
.btn:disabled{opacity:.6;cursor:not-allowed}

.board{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;padding:12px}
.column{background:var(--panel);border:1px solid var(--border);border-radius:10px;display:flex;flex-direction:column;max-height:calc(100vh - 70px)}
.column h2{margin:10px 10px 6px;font-size:14px;color:var(--muted);display:flex;justify-content:space-between;align-items:center}
.count{background:#1f2a35;color:var(--muted);border:1px solid var(--border);border-radius:999px;padding:0 8px;font-size:12px}
.column-drop{padding:8px;display:flex;flex-direction:column;gap:8px;overflow:auto}
.column-drop.dragover{outline:2px dashed var(--primary);outline-offset:-6px}

.card{background:var(--card);border:1px solid var(--border);border-radius:10px;padding:8px;display:flex;flex-direction:column;gap:8px}
.card-head{display:flex;justify-content:space-between;gap:8px}
.card-head .title{font-weight:600}
.icon-btn{border:none;background:transparent;color:var(--muted);cursor:pointer}
.card-body{color:var(--muted);font-size:13px}
.card-foot{display:flex;gap:6px;flex-wrap:wrap}
.tag{font-size:11px;border:1px solid var(--border);border-radius:999px;padding:2px 6px;color:var(--muted)}
.badge{font-size:11px;border-radius:6px;padding:2px 6px}
.badge.low{background:rgba(107,230,255,.12);color:var(--low)}
.badge.medium{background:rgba(90,166,255,.12);color:var(--primary)}
.badge.high{background:rgba(255,184,107,.12);color:var(--high)}
.badge.overdue{background:rgba(255,107,107,.12);color:var(--danger)}

/* dialog */
dialog{border:none;border-radius:12px;max-width:520px;width:92vw;background:var(--panel);color:var(--text)}
dialog::backdrop{background:#0009}
#taskForm{display:flex;flex-direction:column;gap:10px;padding:12px}
#taskForm label{display:flex;flex-direction:column;gap:6px;color:var(--muted)}
#taskForm input, #taskForm textarea, #taskForm select{background:var(--card);border:1px solid var(--border);border-radius:8px;color:var(--text);padding:8px}
.grid-2{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.dialog-actions{display:flex;justify-content:flex-end;gap:8px;margin-top:6px}

@media (max-width: 960px){.board{grid-template-columns:repeat(2,1fr)}}
@media (max-width: 600px){.board{grid-template-columns:1fr}}