:root{
  --bg:#0f1220;
  --panel:#171a2b;
  --panel-2:#1d2140;
  --text:#e7e9f3;
  --muted:#9aa0b4;
  --accent:#23c9ff;
  --good:#3bd671;
}

*{ box-sizing: border-box; }
html,body{ height:100%; }
body{
  margin:0;
  background: radial-gradient(1200px 600px at 20% -10%, #1b1f38 0%, #0f1220 50%, #0b0d18 100%);
  color:var(--text);
  font: 16px/1.4 system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
}

.app{ max-width: 980px; margin: 0 auto; padding: 24px; }

.header{
  display:flex; align-items:center; justify-content:space-between; gap:16px;
}
.header h1{ margin:0; font-size:28px; letter-spacing:1px; }

.stats{ display:flex; gap:12px; flex-wrap:wrap; }
.stat{ background:var(--panel); padding:8px 12px; border-radius:8px; display:flex; gap:8px; align-items:baseline; }
.stat .label{ color:var(--muted); font-size:12px; text-transform:uppercase; letter-spacing:.08em; }

.main{ margin-top:16px; display:grid; grid-template-columns: 1fr 240px; gap:16px; align-items:start; }

.board-wrap{ position:relative; background:var(--panel); padding:12px; border-radius:12px; box-shadow: inset 0 0 0 1px rgba(255,255,255,.04); }
#board{ display:block; width:100%; height:auto; background:linear-gradient(180deg, #0a0d1a, #0e1122); border-radius:8px; box-shadow: 0 8px 24px rgba(0,0,0,.35); }

.board-wrap.shake{ animation: shake .18s linear 1; }
@keyframes shake{
  0%{ transform: translate3d(0,0,0); }
  20%{ transform: translate3d(2px,0,0); }
  40%{ transform: translate3d(-2px,0,0); }
  60%{ transform: translate3d(2px,0,0); }
  80%{ transform: translate3d(-2px,0,0); }
  100%{ transform: translate3d(0,0,0); }
}

.overlay{
  position:absolute; inset:12px; display:flex; align-items:center; justify-content:center; text-align:center;
  background: linear-gradient(to bottom right, rgba(24,28,56,.86), rgba(16,18,36,.86));
  border-radius:8px; padding:20px; font-size:18px; color:var(--text);
}
.overlay.hidden{ display:none; }

.sidebar{ display:flex; flex-direction:column; gap:16px; }
.next{ background:var(--panel); padding:12px; border-radius:12px; }
.next .label, .help .label{ color:var(--muted); font-size:12px; text-transform:uppercase; letter-spacing:.08em; margin-bottom:6px; }
#next{ width:100%; height:auto; display:block; background:linear-gradient(180deg, #10132a, #121537); border-radius:8px; }

.controls{ display:flex; gap:8px; flex-wrap:wrap; }
.btn{
  appearance:none; border:1px solid rgba(255,255,255,.08); background:var(--panel-2); color:var(--text);
  padding:8px 12px; border-radius:8px; cursor:pointer; font-weight:600; transition: .15s ease transform, .15s ease background;
}
.btn:hover{ transform: translateY(-1px); background:#23284e; }
.btn:active{ transform: translateY(0); }
.btn-secondary{ opacity:.9; }

.btn[aria-pressed="true"]{
  background:#2a2f5e;
  border-color:rgba(35,201,255,.4);
  box-shadow:0 0 0 2px rgba(35,201,255,.15) inset;
}

.help{ background:var(--panel); padding:12px; border-radius:12px; color:var(--muted); }
.help ul{ margin:8px 0 0; padding-left:18px; }
.help li{ margin:2px 0; }

.footer{ margin-top:20px; color:var(--muted); text-align:center; font-size:13px; }

/* Responsive */
@media (max-width: 860px){
  .main{ grid-template-columns: 1fr; }
  .sidebar{ order:-1; }
}