*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --bg:#f7f8fa;--surface:#fff;--text:#172b4d;--text-sub:#626f86;
  --primary:#0065ff;--primary-hover:#0747a6;--border:#dfe1e6;
  --danger:#de350b;--radius:8px;--shadow:0 1px 3px rgba(0,0,0,.08);
}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Oxygen,Ubuntu,sans-serif;background:var(--bg);color:var(--text);line-height:1.5;min-height:100vh}

header{text-align:center;padding:24px 16px 16px;background:var(--surface);border-bottom:1px solid var(--border)}
header h1{font-size:1.6rem;font-weight:700;color:var(--text)}
header p{color:var(--text-sub);font-size:.9rem;margin-top:4px}
.lang-switcher{display:flex;justify-content:center;gap:4px;margin-top:12px}
.lang-switcher button{padding:4px 10px;border:1px solid var(--border);border-radius:4px;background:var(--surface);cursor:pointer;font-size:.75rem;color:var(--text-sub);transition:all .15s}
.lang-switcher button.active{background:var(--primary);color:#fff;border-color:var(--primary)}
.lang-switcher button:hover:not(.active){background:#f0f0f0}

main{max-width:1200px;margin:0 auto;padding:24px 16px}
.workspace{display:grid;grid-template-columns:1fr 1fr;gap:24px}
@media(max-width:860px){.workspace{grid-template-columns:1fr}}

/* プレビュー */
.preview-section{background:var(--surface);border-radius:var(--radius);border:1px solid var(--border);padding:24px;box-shadow:var(--shadow)}
.preview-container{display:flex;align-items:center;justify-content:center;min-height:320px;border-radius:var(--radius);background:#f0f0f0;transition:background .2s}
#preview-box{width:200px;height:200px;background:#fff;border-radius:8px;transition:all .15s}
.preview-controls{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-top:16px;padding-top:16px;border-top:1px solid var(--border)}
.preview-controls label{font-size:.8rem;font-weight:600;color:var(--text-sub);min-width:70px}
.preview-controls input[type="color"]{width:36px;height:28px;border:1px solid var(--border);border-radius:4px;cursor:pointer;padding:0}
.preview-controls input[type="range"]{width:100px;accent-color:var(--primary)}

/* コントロール */
.controls-section{display:flex;flex-direction:column;gap:16px}
.layers-header{display:flex;justify-content:space-between;align-items:center}
.layers-header h2{font-size:1.1rem;font-weight:600}

.btn{padding:8px 16px;border:none;border-radius:var(--radius);font-size:.85rem;font-weight:600;cursor:pointer;transition:all .15s}
.btn-primary{background:var(--primary);color:#fff}
.btn-primary:hover{background:var(--primary-hover)}
.btn-secondary{background:var(--surface);border:1px solid var(--border);color:var(--text)}
.btn-secondary:hover{background:#f0f0f0}
.btn-danger{background:none;border:none;color:var(--danger);cursor:pointer;font-size:.8rem;padding:4px 8px}
.btn-danger:hover{text-decoration:underline}

/* レイヤーカード */
.layer-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px;box-shadow:var(--shadow)}
.layer-card.collapsed .layer-body{display:none}
.layer-header{display:flex;justify-content:space-between;align-items:center;cursor:pointer;user-select:none}
.layer-header-left{display:flex;align-items:center;gap:8px}
.layer-header-left span{font-weight:600;font-size:.9rem}
.layer-toggle{font-size:.7rem;color:var(--text-sub);transition:transform .2s}
.layer-card.collapsed .layer-toggle{transform:rotate(-90deg)}
.layer-actions{display:flex;gap:4px;align-items:center}
.layer-visible-btn{background:none;border:none;cursor:pointer;font-size:1rem;padding:2px 6px;border-radius:4px}
.layer-visible-btn:hover{background:#f0f0f0}
.layer-body{margin-top:12px;display:flex;flex-direction:column;gap:10px}
.control-row{display:flex;align-items:center;gap:8px}
.control-row label{font-size:.8rem;font-weight:500;color:var(--text-sub);min-width:70px;flex-shrink:0}
.control-row input[type="range"]{flex:1;accent-color:var(--primary)}
.control-row .value-display{font-size:.75rem;color:var(--text-sub);min-width:40px;text-align:right;font-variant-numeric:tabular-nums}
.control-row input[type="color"]{width:36px;height:28px;border:1px solid var(--border);border-radius:4px;cursor:pointer;padding:0}
.inset-toggle{display:flex;align-items:center;gap:8px}
.inset-toggle label{font-size:.8rem;font-weight:500;color:var(--text-sub)}
.inset-toggle input{accent-color:var(--primary)}

/* プリセット */
.presets-section{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px;box-shadow:var(--shadow)}
.presets-section h2{font-size:1.1rem;font-weight:600;margin-bottom:12px}
.presets-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(90px,1fr));gap:10px}
.preset-item{aspect-ratio:1;display:flex;align-items:center;justify-content:center;border-radius:var(--radius);border:1px solid var(--border);cursor:pointer;transition:all .15s;background:#f7f8fa}
.preset-item:hover{border-color:var(--primary);transform:translateY(-2px)}
.preset-item .preset-box{width:50px;height:50px;background:#fff;border-radius:6px}
.preset-item span{font-size:.65rem;color:var(--text-sub);margin-top:4px;text-align:center}

/* 出力 */
.output-section{margin-top:24px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:16px;box-shadow:var(--shadow)}
.output-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:12px}
.output-header h2{font-size:1.1rem;font-weight:600}
#css-output{background:#1e1e1e;color:#d4d4d4;padding:16px;border-radius:var(--radius);overflow-x:auto;font-size:.85rem;line-height:1.6}
#css-output code{font-family:"Fira Code","Cascadia Code",Consolas,monospace}

.copied-toast{position:fixed;top:20px;right:20px;background:#36b37e;color:#fff;padding:10px 20px;border-radius:var(--radius);font-size:.85rem;font-weight:600;opacity:0;transform:translateY(-10px);transition:all .3s;pointer-events:none;z-index:999}
.copied-toast.show{opacity:1;transform:translateY(0)}

footer{text-align:center;padding:24px;color:var(--text-sub);font-size:.8rem}

#layers-container{display:flex;flex-direction:column;gap:12px}