:root {
  --bg: #0f172a;
  --panel: #1e293b;
  --panel-2: #243347;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --accent: #38bdf8;
  --accent-2: #a855f7;
  --ok: #22c55e;
  --bad: #ef4444;
  --border: #334155;
  --radius: 12px;
}

* { box-sizing: border-box; }
html, body { margin: 0; height: 100%; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: linear-gradient(160deg, #0f172a, #1e1b4b);
  color: var(--text);
  display: flex;
  flex-direction: column;
}

/* Top bar */
.topbar {
  background: rgba(15,23,42,.85);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 10;
}
.topbar-inner {
  max-width: 1400px; margin: 0 auto; padding: 12px 20px;
  display: flex; align-items: center; gap: 16px;
}
.topbar h1 { font-size: 20px; margin: 0; font-weight: 700; flex: 1; }
.topbar .sub { font-size: 13px; color: var(--muted); font-weight: 400; }
.lang-select {
  background: var(--panel); color: var(--text);
  border: 1px solid var(--border); border-radius: 8px;
  padding: 7px 10px; font-size: 13px; cursor: pointer;
}
.lang-select:focus { outline: none; border-color: var(--accent); }
.score-box {
  display: flex; align-items: center; gap: 8px;
  background: var(--panel); border: 1px solid var(--border);
  padding: 6px 12px; border-radius: 999px;
}
.score-label { font-size: 12px; color: var(--muted); }
.score-value { font-size: 18px; font-weight: 700; color: var(--accent); }

/* Buttons */
.btn {
  border: 1px solid var(--border); background: var(--panel-2);
  color: var(--text); padding: 8px 14px; border-radius: 8px;
  font-size: 14px; cursor: pointer; transition: .15s;
}
.btn:hover { filter: brightness(1.15); }
.btn-primary { background: linear-gradient(135deg, var(--accent), var(--accent-2)); border: none; color: #04101f; font-weight: 600; }
.btn-ghost { background: transparent; }
.btn-tool { padding: 6px 10px; font-size: 13px; }
.btn-success { background: var(--ok); border: none; color: #04150a; }
.btn-danger { background: var(--bad); border: none; color: #fff; }
.btn:disabled { opacity: .5; cursor: not-allowed; }

/* Layout */
.layout {
  flex: 1; max-width: 1400px; width: 100%; margin: 0 auto;
  padding: 20px; display: grid; grid-template-columns: 1.6fr 1fr; gap: 20px;
}
@media (max-width: 900px) { .layout { grid-template-columns: 1fr; } }

.board-panel, .result-panel {
  background: var(--panel); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 16px;
}

/* Toolbar */
.toolbar { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 12px; align-items: center; }
.tool-group { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.swatch {
  width: 26px; height: 26px; border-radius: 50%;
  border: 2px solid transparent; cursor: pointer;
}
.swatch.active { border-color: #fff; transform: scale(1.1); }
.slider-label { font-size: 13px; color: var(--muted); display: flex; align-items: center; gap: 6px; }
.slider-label span { color: var(--text); min-width: 20px; }

.canvas-wrap {
  background: #fff; border-radius: 8px; overflow: hidden;
  border: 1px solid var(--border); line-height: 0;
}
#board {
  width: 100%; display: block; touch-action: none; cursor: crosshair;
  background: #fff;
}

.board-actions { margin-top: 14px; display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.board-actions .btn-primary { font-size: 16px; padding: 10px 20px; }
.hint { color: var(--muted); font-size: 13px; }

/* Result panel */
.result-panel h2 { margin: 0 0 12px; font-size: 18px; }
.result-panel h3 { font-size: 14px; color: var(--muted); margin: 16px 0 8px; }
.result-body { min-height: 160px; }
.empty-state {
  text-align: center; color: var(--muted); padding: 30px 10px;
  border: 1px dashed var(--border); border-radius: var(--radius);
}
.empty-icon { font-size: 34px; margin-bottom: 10px; }
.result-reason { font-size: 15px; margin-top: 4px; }
.result-reason strong {
  color: var(--accent); font-size: 24px; font-weight: 700;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.result-text { font-size: 15px; line-height: 1.7; color: var(--text); }
.result-thumb { max-width: 140px; border-radius: 8px; border: 1px solid var(--border); margin-top: 12px; }
.result-loading { display: flex; align-items: center; gap: 10px; color: var(--muted); }
.spinner {
  width: 18px; height: 18px; border: 3px solid var(--border);
  border-top-color: var(--accent); border-radius: 50%;
  animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.error-box {
  background: rgba(239,68,68,.15); border: 1px solid var(--bad);
  color: #fecaca; padding: 12px; border-radius: 8px; font-size: 14px;
}

.feedback { margin-top: 14px; display: flex; gap: 10px; flex-wrap: wrap; }
.feedback.hidden { display: none; }
.history { margin-top: 8px; }
#historyList { list-style: none; padding: 0; margin: 0; max-height: 180px; overflow-y: auto; }
#historyList li {
  font-size: 13px; color: var(--muted); padding: 6px 0;
  border-bottom: 1px solid var(--border); display: flex; gap: 8px;
}
#historyList li .tag { color: var(--text); font-weight: 600; }
#historyList li .ok { color: var(--ok); }
#historyList li .bad { color: var(--bad); }

/* Drawer */
.drawer-mask {
  position: fixed; inset: 0; background: rgba(0,0,0,.5); z-index: 40;
}
.drawer-mask.hidden { display: none; }
.drawer {
  position: fixed; top: 0; right: 0; width: 380px; max-width: 92vw;
  height: 100%; background: var(--panel); z-index: 50;
  border-left: 1px solid var(--border); transform: translateX(100%);
  transition: transform .25s ease; display: flex; flex-direction: column;
}
.drawer.open { transform: translateX(0); }
.drawer-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 16px; border-bottom: 1px solid var(--border);
}
.drawer-head h2 { margin: 0; font-size: 17px; }
.drawer-close { padding: 4px 8px; }
.drawer-body { padding: 16px; display: flex; flex-direction: column; gap: 14px; overflow-y: auto; }
.drawer-body label { display: flex; flex-direction: column; gap: 6px; font-size: 13px; color: var(--muted); }
.drawer-body input, .drawer-body select {
  background: var(--panel-2); border: 1px solid var(--border);
  color: var(--text); padding: 9px 11px; border-radius: 8px; font-size: 14px;
}
.drawer-body input:focus, .drawer-body select:focus { outline: none; border-color: var(--accent); }
.field-hint { color: var(--muted); font-size: 12px; }
.field-note { font-size: 12px; color: var(--muted); line-height: 1.5; }
.field-note a { color: var(--accent); word-break: break-all; }
.check-line { flex-direction: row; align-items: center; gap: 8px; }
.check-line input { width: 16px; height: 16px; }
.drawer-actions { display: flex; gap: 10px; margin-top: 4px; }
.drawer-actions .btn { flex: 1; }
.conn-test-result { font-size: 13px; margin: 4px 0 0; min-height: 16px; }
.conn-test-result.ok { color: var(--ok); }
.conn-test-result.bad { color: var(--bad); }
.hidden { display: none; }