:root {
  --bg: #0f1720;
  --panel: #17212b;
  --border: #24303d;
  --text: #e6edf3;
  --muted: #8b98a5;
  --accent: #3fb950;
}

* { box-sizing: border-box; }

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

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  background: var(--panel);
}

.topbar h1 {
  font-size: 1.15rem;
  margin: 0;
  letter-spacing: 0.02em;
}

.controls {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.controls label {
  display: flex;
  flex-direction: column;
  font-size: 0.7rem;
  color: var(--muted);
  gap: 0.2rem;
}

.controls input,
.controls select {
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.35rem 0.5rem;
  border-radius: 6px;
  font-size: 0.85rem;
}

.controls button {
  align-self: flex-end;
  background: var(--accent);
  color: #05230d;
  border: 0;
  padding: 0.45rem 0.9rem;
  border-radius: 6px;
  font-weight: 600;
  cursor: pointer;
}

.status { font-size: 0.75rem; color: var(--muted); }

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 1rem;
  padding: 1.5rem;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.1rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.card .label { font-size: 0.75rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.05em; }
.card .value { font-size: 2rem; font-weight: 700; }
.card .unit { font-size: 0.8rem; color: var(--muted); }

.charts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1rem;
  padding: 0 1.5rem 1.5rem;
}

.chart-wrap {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1rem;
  height: 260px;
}

.footer {
  padding: 1rem 1.5rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.75rem;
}

/* Navigation between pages */
.nav {
  display: flex;
  gap: 1rem;
}

.nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.85rem;
  padding: 0.3rem 0.1rem;
  border-bottom: 2px solid transparent;
}

.nav a:hover {
  color: var(--text);
}

.nav a.active {
  color: var(--text);
  border-bottom-color: var(--accent);
}

/* Readings table */
.table-wrap {
  margin: 1.5rem;
  max-height: calc(100vh - 220px);
  overflow: auto;
  border: 1px solid var(--border);
  border-radius: 10px;
}

.readings-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}

.readings-table thead th {
  position: sticky;
  top: 0;
  background: var(--panel);
  color: var(--muted);
  text-align: left;
  font-weight: 600;
  text-transform: uppercase;
  font-size: 0.7rem;
  letter-spacing: 0.05em;
  padding: 0.6rem 0.9rem;
  border-bottom: 1px solid var(--border);
}

.readings-table tbody td {
  padding: 0.5rem 0.9rem;
  border-bottom: 1px solid var(--border);
}

.readings-table tbody tr:hover {
  background: rgba(255, 255, 255, 0.03);
}

.readings-table .empty {
  text-align: center;
  color: var(--muted);
  padding: 1.5rem;
}

.pager {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.pager button {
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.4rem 0.8rem;
  border-radius: 6px;
  cursor: pointer;
}

.pager button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* Usage page */
.usage-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(360px, 1fr));
  gap: 1rem;
  padding: 1.5rem;
  align-items: start;
}

.usage-card h2 {
  margin: 0 0 0.5rem;
  font-size: 1rem;
}

.usage-card .hint {
  color: var(--muted);
  font-size: 0.8rem;
  margin: 0 0 1rem;
  line-height: 1.5;
}

.field-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
}

.field-grid label {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-size: 0.7rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.field-grid input {
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 0.45rem 0.55rem;
  border-radius: 6px;
  font-size: 0.9rem;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}

.field-grid input[readonly] {
  cursor: default;
  opacity: 0.9;
}

.usage-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-top: 1.1rem;
  flex-wrap: wrap;
}

.usage-actions button {
  background: var(--accent);
  color: #05230d;
  border: 0;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  font-weight: 600;
  cursor: pointer;
}

.usage-actions button.secondary {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  font-weight: 500;
}

.usage-actions button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.tabs {
  display: flex;
  gap: 0.4rem;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}

.tabs button {
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 0.35rem 0.7rem;
  border-radius: 6px;
  font-size: 0.8rem;
  cursor: pointer;
}

.tabs button.active {
  color: var(--text);
  border-color: var(--accent);
}

.sample {
  background: #0b1017;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.9rem;
  overflow-x: auto;
  font-size: 0.78rem;
  line-height: 1.5;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  color: #cdd9e5;
  white-space: pre;
  margin: 0;
}