:root {
  --navy-900: #0b1b2a;
  --navy-800: #0f2538;
  --navy-700: #12304a;
  --navy-600: #173c5d;
  --accent-cyan: #39d1ff;
  --accent-blue: #5aa6ff;
  --text-100: #f4f7fb;
  --text-300: #c7d3e0;
  --panel-700: rgba(255,255,255,0.04);
  --panel-600: rgba(255,255,255,0.06);
  --border-500: rgba(255,255,255,0.1);
  --shadow-900: 0 10px 30px rgba(0,0,0,0.35);
}
* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0; color: var(--text-100);
  font-family: 'Inter', system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial;
  background: radial-gradient(1200px 700px at 80% -100px, var(--navy-600), transparent 60%),
              radial-gradient(900px 600px at 20% -100px, var(--navy-700), transparent 55%),
              linear-gradient(160deg, var(--navy-900), var(--navy-800));
  height: 100dvh; overflow: hidden;
}
.teachings-page { height: 100dvh; display: grid; grid-template-rows: auto 1fr; gap: 16px; padding: 18px; }
.teachings-header { display: flex; align-items: center; gap: 12px; }
.back-link { color: var(--text-300); text-decoration: none; background: var(--panel-600); border: 1px solid var(--border-500); padding: 6px 10px; border-radius: 8px; }
.back-link:hover { color: var(--text-100); }
.title { margin: 0; font-size: 20px; font-weight: 800; letter-spacing: 0.3px; }

.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 18px;
  min-height: 0;
  align-items: stretch;
}
.tool-card {
  position: relative;
  border-radius: 14px;
  border: 1px solid var(--border-500);
  background: linear-gradient(180deg, rgba(255,255,255,0.06), rgba(255,255,255,0.02));
  box-shadow: var(--shadow-900);
  color: var(--text-100);
  text-decoration: none;
  padding: 16px 18px;
  min-height: 180px;
  display: grid;
  grid-template-rows: auto auto 1fr;
  gap: 10px;
  isolation: isolate;
  overflow: hidden;
  transition: transform 140ms ease, box-shadow 200ms ease, border-color 200ms ease, background 200ms ease;
}
.tool-card::before {
  content:''; position: absolute; inset: -20%; z-index: -1;
  background: radial-gradient(500px 240px at 20% 10%, rgba(57,209,255,0.14), transparent 60%),
              radial-gradient(500px 240px at 80% 90%, rgba(90,166,255,0.12), transparent 60%);
}
.tool-card:hover { transform: translateY(-4px); border-color: rgba(255,255,255,0.22); box-shadow: 0 14px 30px rgba(0,0,0,0.38); background: linear-gradient(180deg, rgba(255,255,255,0.08), rgba(255,255,255,0.03)); }
.tool-card:focus-visible { outline: 2px solid var(--accent-blue); outline-offset: 2px; }
.tool-card__icon { width: 48px; height: 48px; border-radius: 12px; background: var(--panel-600); border: 1px solid var(--border-500); }
.tool-card__icon--wing { background: linear-gradient(180deg, rgba(57,209,255,0.2), rgba(255,255,255,0.02)); }
.tool-card__icon--boundary { background: linear-gradient(180deg, rgba(90,166,255,0.2), rgba(255,255,255,0.02)); }
.tool-card__icon--cfd { background: linear-gradient(180deg, rgba(57,209,255,0.2), rgba(90,166,255,0.2)); }
.tool-card__title { margin: 0; font-size: 17px; font-weight: 800; letter-spacing: .2px; }
.tool-card__desc { margin: 0; color: var(--text-300); line-height: 1.4; }

@media (max-width: 1024px) { .tools-grid { grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); } }

/* App layout for individual tools (Boundary Layer, etc.) */
.app { display: grid; grid-template-columns: 320px 1fr; gap: 16px; height: 100%; }
.controls { border: 1px solid var(--border-500); border-radius: 16px; background: var(--panel-700); box-shadow: var(--shadow-900); padding: 14px; display: grid; gap: 10px; align-content: start; }
.controls h2 { margin: 0 0 6px 0; font-size: 16px; font-weight: 800; letter-spacing: .2px; }
.control-row { display: grid; grid-template-columns: 1fr auto; align-items: center; gap: 10px; }
.control-row label { color: var(--text-300); font-size: 13px; }
.control-row input[type="range"] { width: 180px; }
.control-row input[type="number"] { width: 90px; background: var(--panel-600); border: 1px solid var(--border-500); border-radius: 8px; color: var(--text-100); padding: 6px 8px; }
.select { background: var(--panel-600); border: 1px solid var(--border-500); border-radius: 8px; color: var(--text-100); padding: 6px 8px; }
.viewport { border: 1px solid var(--border-500); border-radius: 16px; background: var(--panel-700); box-shadow: var(--shadow-900); padding: 10px; display: grid; grid-template-rows: 1fr auto; gap: 12px; }
.canvas-wrap { position: relative; border-radius: 12px; overflow: hidden; background: radial-gradient(600px 300px at 20% -20%, rgba(57,209,255,0.05), transparent 60%); }
.canvas-wrap canvas { display: block; width: 100%; height: auto; }
.charts { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.charts canvas { width: 100%; height: 180px; background: var(--panel-600); border: 1px solid var(--border-500); border-radius: 10px; display: block; }

@media (max-width: 1100px) {
  .app { grid-template-columns: 1fr; grid-template-rows: auto 1fr; }
}