:root {
  --bg-color: #0d1117;
  --card-bg: #161b22;
  --border-color: #30363d;
  --accent-color: #58a6ff;
  --text-main: #c9d1d9;
  --text-bright: #f0f6fc;
  --pass-color: #238636;
  --warn-color: #d29922;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, monospace;
  background-color: var(--bg-color);
  color: var(--text-main);
}

.top-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 24px;
  background-color: #010409;
  border-bottom: 1px solid var(--border-color);
}

.top-bar h1 { margin: 0; font-size: 1.2rem; color: var(--text-bright); }
.system-status { display: flex; gap: 15px; font-weight: bold; }

.main-nav {
  display: flex;
  background-color: var(--card-bg);
  border-bottom: 1px solid var(--border-color);
}

.main-nav a {
  padding: 12px 20px;
  color: var(--text-main);
  text-decoration: none;
  border-right: 1px solid var(--border-color);
}

.main-nav a.active, .main-nav a:hover {
  background-color: #21262d;
  color: var(--accent-color);
}

.grid-container {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
  padding: 20px;
}

.card {
  background-color: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 16px;
}

.freq-display {
  font-family: "Courier New", Courier, monospace;
  font-size: 2.2rem;
  color: #3fb950;
  background: #000;
  padding: 10px;
  border-radius: 4px;
  text-align: center;
  letter-spacing: 2px;
  margin: 10px 0;
}

.control-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
}

input, select, button {
  background: #21262d;
  border: 1px solid var(--border-color);
  color: #fff;
  padding: 6px 10px;
  border-radius: 4px;
}

button {
  background: #238636;
  cursor: pointer;
}

button:hover { background: #2ea043; }

.badge {
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 0.8rem;
}

.badge.pass { background-color: var(--pass-color); color: #fff; }
.isb-table, .data-table { width: 100%; border-collapse: collapse; margin-top: 10px; }
.isb-table th, .isb-table td, .data-table th, .data-table td {
  border: 1px solid var(--border-color);
  padding: 8px;
  text-align: left;