:root {
  --bg: #0c0f14;
  --panel: #12161c;
  --text: #e5e7eb;
  --muted: #b8c1cc;
  --accent: #3b82f6;
  --accent-2: #10b981;
  --btn-bg: #1a2230;
  --btn-bg-hover: #233043;
  --outline: #2a3342;
  --radius: 14px;
}

html, body { height: 100%; }
* { box-sizing: border-box; }
body {
  margin: 0;
  background: radial-gradient(1200px 800px at 10% 0%, #0e131a, #0c0f14);
  color: var(--text);
  font: 16px/1.5 system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji", "Segoe UI Emoji";
}

/* Header */
.site-header { padding: 28px 24px 10px; text-align: center; }
.site-header h1 { margin: 0; letter-spacing: 0.4px; font-weight: 650; font-size: 28px;}

/* Main container */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px 32px; }

/* Columns */
.columns { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; align-items: start; }
.column {
  background: linear-gradient(180deg, var(--panel), #0f141a 80%);
  border: 1px solid var(--outline);
  border-radius: var(--radius);
  padding: 18px 18px 16px;
  box-shadow: 0 10px 30px rgba(0,255,0,0.25);
}
.column h2 { margin: 0 0 12px 0; font-size: 18px; font-weight: 600; color: var(--muted); text-transform: uppercase; letter-spacing: 1px; text-align: center; }

/* Buttons list */
.link-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 42px; padding: 10px 14px;
  border-radius: 10px; background: var(--btn-bg); border: 1px solid var(--outline);
  color: var(--text); text-decoration: none; font-weight: 600; letter-spacing: 0.2px;
  transition: transform .08s ease, background .12s ease, border-color .12s ease, box-shadow .12s ease;
  background: rgba(0,255,180,0.25)
}
.btn:hover { background: var(--btn-bg-hover); border-color: #344156; box-shadow: 0 4px 14px rgba(0,255,0,0.50); transform: translateY(-1px); }
.btn:active { transform: translateY(0); }

/* Viewer */
.viewer { margin-top: 24px; background: var(--panel); border: 1px solid var(--outline); border-radius: var(--radius); padding: 12px; }
.viewer iframe#frame {
  display: block; width: 100%; height: 800px; min-height: 600px; border: 0; background: #0a0f14; border-radius: 10px;
}

/* Footer */
.site-footer { padding: 18px 24px 30px; color: var(--muted); text-align: center; }