:root {
  --bg: #0b0b0f;
  --card: #171720;
  --accent: #3ba7ff;
  --text-main: #f5f5f5;
  --text-sub: #a0a0b0;
  --danger: #ff4d6a;
  --success: #3bd17f;
}

body {
  margin: 0;
  padding: 16px;
  font-family: system-ui, sans-serif;
  background: radial-gradient(circle at top, #1b1b2a 0, #050509 55%, #000 100%);
  color: var(--text-main);
}

h1 {
  margin: 0 0 4px;
  font-size: 1.4rem;
}

.subtitle {
  font-size: 0.85rem;
  color: var(--text-sub);
  margin-bottom: 16px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 12px;
}

.card {
  background: var(--card);
  border-radius: 10px;
  padding: 12px 14px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.4);
}

.label {
  font-size: 0.75rem;
  color: var(--text-sub);
  text-transform: uppercase;
}

.value {
  font-size: 1.3rem;
  margin-top: 4px;
}

.small {
  font-size: 0.85rem;
  color: var(--text-sub);
  margin-top: 4px;
}

.row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}

.badge {
  padding: 2px 6px;
  border-radius: 999px;
  font-size: 0.7rem;
  border: 1px solid rgba(255, 255, 255, 0.15);
}

.badge.up {
  color: var(--success);
  border-color: var(--success);
}

.badge.down {
  color: var(--danger);
  border-color: var(--danger);
}

.alert-log {
  max-height: 120px;
  overflow-y: auto;
  font-size: 0.8rem;
  margin-top: 6px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.alert-item {
  color: var(--danger);
}

iframe {
  width: 100%;
  height: 320px;
  border: none;
  border-radius: 10px;
}

.chart-wide {
  grid-column: span 3;
}

#btcChart {
  width: 85% !important;
  margin: 0 auto;
  display: block;
}

.chart-range-buttons {
  margin-bottom: 8px;
}

.chart-range-buttons button {
  margin-right: 6px;
  padding: 4px 8px;
  background: #2a2a35;
  color: #fff;
  border: 1px solid #444;
  border-radius: 4px;
  cursor: pointer;
}

.chart-range-buttons button:hover {
  background: #3ba7ff;
  border-color: #3ba7ff;
}

.chart-range-buttons button.active {
  background: #3ba7ff;
  border-color: #3ba7ff;
  color: #000;
}

/* 注意書き（相場判断ガイド） */
.guide-card {
  margin-top: 20px;
  padding: 16px;
  background: #1e1e28;
  border-radius: 8px;
  line-height: 1.6;
  font-size: 14px;
  color: #ddd;
}

.guide-card b {
  color: #fff;
}

.guide-card u {
  color: #3ba7ff;
  text-decoration: none;
  font-weight: bold;
}

@media (max-width: 600px) {
  body {
    padding: 10px;
  }

  h1 {
    font-size: 1.2rem;
  }

  .value {
    font-size: 1.1rem;
  }

  iframe {
    height: 260px;
  }
}