* {
  box-sizing: border-box;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
}

body {
  margin: 0;
  background: radial-gradient(circle at top, #0f2027, #000);
  color: #fff;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.app {
  width: 90%;
  max-width: 900px;
  text-align: center;
}

h1 {
  margin-bottom: 0;
  font-size: 2.4rem;
}

.subtitle {
  opacity: 0.7;
  margin-bottom: 30px;
}

.stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin-bottom: 30px;
}

.card {
  background: rgba(255,255,255,0.05);
  border-radius: 14px;
  padding: 20px;
  backdrop-filter: blur(10px);
}

.card span {
  display: block;
  font-size: 0.85rem;
  opacity: 0.7;
}

.card strong {
  font-size: 1.6rem;
}

.graph-container {
  background: rgba(255,255,255,0.04);
  border-radius: 16px;
  padding: 20px;
  margin-bottom: 30px;
}

svg {
  width: 100%;
  height: 200px;
}

button {
  background: linear-gradient(135deg, #00c6ff, #0072ff);
  border: none;
  color: #fff;
  padding: 14px 30px;
  border-radius: 999px;
  font-size: 1rem;
  cursor: pointer;
  transition: transform 0.2s ease;
}

button:hover {
  transform: scale(1.05);
}

.gauge-wrapper {
  position: relative;
  margin-bottom: 30px;
}

.gauge {
  width: 220px;
  margin: auto;
}

.gauge path {
  fill: none;
  stroke-width: 14;
  stroke-linecap: round;
}

.gauge .bg {
  stroke: rgba(255,255,255,0.1);
}

.gauge .fg {
  stroke: #00c6ff;
  transition: stroke-dashoffset 0.5s ease, stroke 0.5s ease;
}

.gauge-text {
  position: absolute;
  top: 50%;               /* push text down */
  left: 50%;
  transform: translateX(-50%);
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  font-size: 1.6rem;
}


#gauge-text strong {
  font-size: 1.6rem;
}

.gauge-text span {
  display: block;
  opacity: 0.7;
  font-size: 0.9rem;
}

.countdown {
  margin-bottom: 20px;
  font-size: 1rem;
  opacity: 0.8;
  letter-spacing: 0.3px;
}

.grade {
  font-size: 1.2rem;
  font-weight: 600;
  margin-top: 4px;
}

#stabilityGrade {
  font-size: 4.5rem;      /* bigger but safe */
  line-height: 1;
  margin-bottom: 2px;
}

.session-list {
  margin-top: 12px;
  max-height: 300px;
  overflow-y: auto;
}

.session {
  padding: 10px 12px;
  border-radius: 10px;
  background: rgba(255,255,255,0.04);
  margin-bottom: 8px;
  cursor: pointer;
  transition: background 0.2s ease;
}

.session:hover {
  background: rgba(255,255,255,0.08);
}

.session.active {
  outline: 2px solid #00c6ff;
}

.session small {
  display: block;
  opacity: 0.7;
  font-size: 0.75rem;
}