:root {
  --bg: #0d1117;
  --card: #161b22;
  --text: #e6edf3;
  --muted: #9da7b3;
  --gold: #d4af37;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Segoe UI", Arial, sans-serif;
  background: radial-gradient(circle at top, #1f2937, #0d1117 50%);
  color: var(--text);
}

.container { width: min(1100px, 92%); margin: 0 auto; }
.site-header { border-bottom: 1px solid #2d333b; backdrop-filter: blur(4px); }
.nav { display: flex; align-items: center; justify-content: space-between; padding: 1rem 0; }
.logo { font-weight: 700; color: var(--gold); }
nav a { margin-left: 1rem; color: var(--text); text-decoration: none; }
nav a:hover { color: var(--gold); }

.hero { padding: 4rem 0 2rem; }
.eyebrow { color: var(--gold); letter-spacing: .08em; text-transform: uppercase; font-size: .85rem; }
h1 { font-size: clamp(1.8rem, 4vw, 3rem); margin: .4rem 0 1rem; }
.lead { color: var(--muted); max-width: 760px; line-height: 1.7; }

.actions { display: flex; gap: .8rem; flex-wrap: wrap; margin-top: 1rem; }
.btn {
  border: 1px solid transparent; padding: .7rem 1rem; border-radius: .6rem; text-decoration: none;
  color: white; cursor: pointer; font-weight: 600;
}
.btn-gold { background: var(--gold); color: #111; }
.btn-dark { background: #222b36; border-color: #3a4655; }

.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1rem; margin: 1.5rem 0 2rem; }
.card { background: rgba(22, 27, 34, .9); border: 1px solid #30363d; border-radius: .8rem; padding: 1rem; }
.card p { color: var(--muted); line-height: 1.5; }

.form-grid { display: grid; gap: .8rem; margin: 1rem 0 2rem; max-width: 780px; }
.form-grid.compact { max-width: 460px; }
label { display: grid; gap: .4rem; color: #dbe1e8; }
input, select {
  width: 100%; padding: .65rem .7rem; border-radius: .55rem;
  border: 1px solid #3d4653; background: #0f1620; color: var(--text);
}
h2, h3 { margin-top: 1.1rem; }
.hidden { display: none; }

.flash-wrap { margin-top: 1rem; }
.flash { padding: .7rem .9rem; border-radius: .5rem; margin-bottom: .5rem; }
.flash.error { background: #3b1416; border: 1px solid #7d2429; }
.flash.success { background: #15361d; border: 1px solid #2f8f49; }

.tree-canvas {
  width: 100%;
  min-height: 520px;
  margin: 1rem 0 1.25rem;
  border: 1px solid #2e3744;
  border-radius: .8rem;
  background: #0b121b;
}