:root{
  --bg: #f4fafb; --panel: #ffffff; --panel-2: #e6f2f4; --line: #cae3e7;
  --accent: #258d9d; --accent-soft: #c9e5e9; --accent-dim: #f0f6f8;
  --text: #142629; --muted: #4d7980; --muted-2: #94b3b8;
}

.toolbar{ display: flex; gap: 8px; margin-bottom: 14px; flex-wrap: wrap; align-items: center; justify-content: space-between; }
.device-btns{ display: flex; gap: 6px; }
.device-btn{ padding: 7px 14px; border-radius: 6px; border: 1px solid var(--line); background: var(--panel-2); color: var(--muted); font-size: 12px; font-weight: 600; cursor: pointer; }
.device-btn.active{ background: var(--accent); color: #fff; border-color: var(--accent); }

.grid{ display: grid; grid-template-columns: 1fr 1fr; gap: 16px; align-items: stretch; }
@media (max-width: 900px){ .grid{ grid-template-columns: 1fr; } }

.pane{ border-radius: 10px; overflow: hidden; display: flex; flex-direction: column; border: 1px solid var(--line); }
.pane-head{ padding: 12px 16px; display: flex; justify-content: space-between; align-items: center; border-bottom: 1px solid var(--line); background: var(--panel-2); }
.pane-head .title{ font-size: 11px; font-weight: 700; letter-spacing: 1.2px; text-transform: uppercase; }

textarea{ flex: 1; width: 100%; min-height: 460px; max-height: 600px; padding: 16px; border: none; resize: vertical; font-family: 'JetBrains Mono', monospace; font-size: 13px; line-height: 1.7; background: transparent; color: var(--text); overflow: auto; }
textarea:focus{ outline: none; }

.preview-wrap{ flex: 1; background: #fff; display: flex; align-items: flex-start; justify-content: center; overflow: auto; padding: 12px; }
iframe{ border: none; background: #fff; width: 100%; height: 460px; transition: width .2s ease; box-shadow: 0 0 0 1px var(--line); }
iframe.tablet{ width: 768px; }
iframe.mobile{ width: 375px; }

.btns{ display: flex; justify-content: flex-end; gap: 10px; margin-top: 16px; flex-wrap: wrap; }
.app{ padding: 11px 20px; border: none; border-radius: 6px; cursor: pointer; font-weight: 600; font-size: 13.5px; font-family: 'Inter', sans-serif; color: #fff; background: var(--accent); transition: filter .15s ease; }
.app:hover{ filter: brightness(1.08); }
.gray{ background: var(--line); color: var(--text); }

.note{ margin-top: 14px; font-size: 12px; color: var(--muted); line-height: 1.6; background: var(--panel-2); border: 1px solid var(--line); border-radius: 8px; padding: 10px 14px; }