:root {
  --bg-deep: #1C1512;
  --bg-panel: #271D18;
  --bg-section: #33261F;
  --border-color: #4A382F;
  --accent-cyan: #FB923C;
  --accent-blue: #EA580C;
  --accent-red: #EF4444;
  --accent-orange: #F59E0B;
  --text-main: #FFF7ED;
  --text-muted: #FDBA74;
  --font-sans: 'Inter', sans-serif;
  --tool-bg: rgba(251, 146, 60, 0.05);
  --tool-bg-hover: rgba(251, 146, 60, 0.1);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font-sans);
  background: var(--bg-deep);
  color: var(--text-main);
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

header {
  height: 56px;
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  flex-shrink: 0;
}

.logo { display: flex; align-items: center; gap: 8px; }
.logo h1 { font-size: 16px; font-weight: 500; }
.logo span { color: var(--accent-cyan); font-weight: 300; }

.header-actions { display: flex; gap: 16px; align-items: center; }
.toolbar-group { display: flex; gap: 8px; border-right: 1px solid var(--border-color); padding-right: 16px; }

.btn {
  padding: 6px 12px;
  border-radius: 4px;
  border: none;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: 0.15s ease;
  font-family: inherit;
}

.btn-primary { background: var(--accent-blue); color: #fff; }
.btn-primary:hover { background: #2563EB; }

.btn-outline { background: transparent; color: var(--text-muted); border: 1px solid var(--border-color); }
.btn-outline:hover { color: var(--text-main); border-color: var(--text-muted); }

.app-grid {
  display: flex;
  flex: 1;
  height: calc(100vh - 56px);
}

.panel {
  width: 320px;
  background: var(--bg-panel);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
}

.left-panel { border-right: 1px solid var(--border-color); width: 320px; }

/* Numeric Inputs */
.input-group { margin-bottom: 16px; }
.input-group label { display: block; font-size: 13px; color: var(--text-muted); margin-bottom: 6px; font-weight: 500; }
.input-group input { width: 100%; background: var(--bg-deep); border: 1px solid var(--border-color); color: var(--text-main); padding: 10px 12px; border-radius: 4px; font-family: var(--font-sans); font-size: 14px; transition: border-color 0.15s ease; outline: none; }
.input-group input:focus { border-color: var(--accent-cyan); }

/* Center Panel Results */
.center-panel { flex: 1; display: flex; flex-direction: column; background: var(--bg-deep); overflow-y: auto; }
.results-header { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; padding: 24px; background: var(--bg-panel); border-bottom: 1px solid var(--border-color); }
.result-card { background: var(--bg-section); padding: 16px; border-radius: 6px; border: 1px solid var(--border-color); display: flex; flex-direction: column; gap: 8px; }
.res-label { font-size: 12px; text-transform: uppercase; color: var(--text-muted); font-weight: 600; letter-spacing: 0.5px; }
.res-val { font-size: 20px; font-weight: 600; color: var(--text-main); }
.res-val.highlight { color: var(--accent-red); }

.canvas-toolbar { height: 48px; background: var(--bg-panel); border-bottom: 1px solid var(--border-color); display: flex; align-items: center; justify-content: space-between; padding: 0 24px; }
.tool-group { display: flex; gap: 4px; align-items: center; }
.tool-label { font-size: 12px; color: var(--text-muted); margin-right: 8px; }

.btn-tool { background: var(--tool-bg); border: none; color: var(--text-muted); padding: 6px 12px; border-radius: 4px; font-size: 12px; cursor: pointer; transition: 0.1s; font-weight: 500; }
.btn-tool:hover { background: var(--tool-bg-hover); color: var(--text-main); }
.btn-tool.active { background: rgba(251, 146, 60, 0.2); color: var(--accent-cyan); border-color: var(--accent-cyan); }

.canvas-container { flex: 1; position: relative; overflow: hidden; background-image: radial-gradient(var(--border-color) 1px, transparent 0); background-size: 40px 40px; background-position: -19px -19px; }
#flow-canvas { width: 100%; height: 100%; display: block; }

/* Custom Scrollbar */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }