/* Minimal, no frameworks */
:root{
  --bg:#0b1220;
  --panel:#0f172a;
  --text:#e5e7eb;
  --muted:#9ca3af;
  --border:#253047;
  --btn:#1f2937;
  --btn2:#2563eb;
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: system-ui, -apple-system, "Segoe UI", "Noto Sans JP", "Hiragino Kaku Gothic ProN", "Yu Gothic", sans-serif;
  background: linear-gradient(180deg, #0b1220 0%, #0a0f1a 100%);
  color:var(--text);
}
.app-header{
  padding:16px 18px;
  border-bottom:1px solid var(--border);
}
.app-title{font-weight:800;font-size:18px;letter-spacing:.2px}
.app-subtitle{color:var(--muted);margin-top:4px;font-size:12px}

.app-main{
  display:grid;
  grid-template-columns: 1fr;
  gap:14px;
  padding:14px;
}
@media (min-width: 1100px){
  .app-main{grid-template-columns: 1.05fr .95fr; align-items:start;}
}

.panel{
  background: rgba(15,23,42,.75);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow:hidden;
}
.panel-head{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:10px;
  padding:10px 12px;
  border-bottom:1px solid var(--border);
}
.panel-title{font-weight:700;font-size:13px;color:#f3f4f6}
.panel-actions{display:flex;gap:8px;align-items:center;flex-wrap:wrap}

.btn{
  appearance:none;
  border:1px solid var(--border);
  background: var(--btn);
  color:var(--text);
  padding:8px 10px;
  border-radius:10px;
  font-weight:700;
  font-size:12px;
  cursor:pointer;
}
.btn:hover{filter:brightness(1.08)}
.btn.primary{
  background: var(--btn2);
  border-color: rgba(255,255,255,.12);
}

textarea{
  width:100%;
  min-height: 320px;
  padding:12px;
  background: rgba(2,6,23,.6);
  color: var(--text);
  border:0;
  outline:none;
  resize: vertical;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  font-size:12px;
  line-height: 1.45;
}

.format{
  border-top:1px solid var(--border);
  padding:10px 12px;
}
.format summary{
  cursor:pointer;
  color:var(--muted);
  font-size:12px;
  user-select:none;
}
.format pre{
  margin:10px 0 0;
  white-space: pre-wrap;
  word-break: break-word;
  color:#cbd5e1;
  background: rgba(2,6,23,.55);
  border:1px solid var(--border);
  padding:10px;
  border-radius:10px;
  font-size:12px;
}

.status{
  padding:10px 12px;
  border-top:1px solid var(--border);
  color: var(--muted);
  font-size:12px;
  min-height: 20px;
}
.status.ok{color:#a7f3d0}
.status.err{color:#fecaca}

.preview-wrap{
  padding:12px;
  display:flex;
  justify-content:center;
}
canvas{
  width:min(540px, 100%);
  height:auto;
  border-radius:12px;
  background:#f5f2e8;
  border:1px solid rgba(255,255,255,.06);
}
.hint{
  padding:0 12px 12px;
  color:var(--muted);
  font-size:12px;
}

.toggle{
  display:flex;
  align-items:center;
  gap:8px;
  font-size:12px;
  color:var(--muted);
  user-select:none;
}
.toggle input{transform: translateY(1px);}