:root {
  --bg: #0f172a;
  --surface: #1e293b;
  --surface2: #334155;
  --border: #475569;
  --text: #f1f5f9;
  --text-muted: #94a3b8;
  --accent: #3b82f6;
  --green: #22c55e;
  --red: #ef4444;
  --yellow: #eab308;
  --radius: 10px;
  --gap: 1rem;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

/* ── Navbar ──────────────────────────────────────── */
.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.5rem;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 100;
}

.brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--accent);
  text-decoration: none;
}

.sse-status { font-size: 1.2rem; color: var(--red); transition: color .3s; }
.sse-status.connected { color: var(--green); }

/* ── Layout ──────────────────────────────────────── */
.container { max-width: 1200px; margin: 0 auto; padding: 1.5rem var(--gap); }

.page-header { margin-bottom: 1.5rem; }
.page-header h1 { font-size: 1.6rem; margin-bottom: .25rem; }
.subtitle { color: var(--text-muted); font-size: .9rem; }

.header-row { display: flex; align-items: center; gap: .75rem; flex-wrap: wrap; margin-bottom: .25rem; }

.back-link { color: var(--accent); text-decoration: none; font-size: .9rem; display: inline-block; margin-bottom: .5rem; }
.back-link:hover { text-decoration: underline; }

/* ── Badges ──────────────────────────────────────── */
.badge {
  display: inline-block;
  padding: .2rem .6rem;
  border-radius: 99px;
  font-size: .75rem;
  font-weight: 600;
  letter-spacing: .03em;
}
.badge-online { background: rgba(34,197,94,.15); color: var(--green); }
.badge-offline { background: rgba(239,68,68,.12); color: var(--red); }

/* ── Device grid (dashboard) ─────────────────────── */
.device-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--gap);
}

.device-card {
  display: block;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  text-decoration: none;
  color: var(--text);
  transition: border-color .2s, transform .15s;
}
.device-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.device-card.online { border-left: 3px solid var(--green); }
.device-card.offline { border-left: 3px solid var(--red); opacity: .75; }

.card-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: .4rem; }
.device-name { font-weight: 600; }
.card-location { color: var(--text-muted); font-size: .85rem; margin-bottom: .6rem; }
.card-meta { display: flex; flex-direction: column; gap: .15rem; font-size: .75rem; color: var(--text-muted); }

/* ── Sensor grid ─────────────────────────────────── */
.sensor-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  gap: var(--gap);
  margin-bottom: 1.5rem;
}

.sensor-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  text-align: center;
}
.sensor-label { font-size: .75rem; color: var(--text-muted); margin-bottom: .3rem; text-transform: uppercase; letter-spacing: .04em; }
.sensor-value { font-size: 1.8rem; font-weight: 700; line-height: 1.1; }
.sensor-unit { font-size: .8rem; color: var(--text-muted); margin-top: .15rem; }

/* ── Light panel ─────────────────────────────────── */
.light-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  margin-bottom: 2rem;
}
.light-panel h2 { font-size: 1rem; margin-bottom: 1rem; }

.light-controls { display: flex; align-items: flex-start; gap: 2rem; flex-wrap: wrap; }

.mode-toggle { display: flex; align-items: center; }
.toggle-label { display: flex; align-items: center; gap: .6rem; cursor: pointer; user-select: none; }
.toggle-label input { display: none; }

.toggle-track {
  width: 44px; height: 24px;
  background: var(--surface2);
  border-radius: 99px;
  position: relative;
  transition: background .2s;
}
.toggle-label input:checked ~ .toggle-track { background: var(--accent); }
.toggle-thumb {
  position: absolute;
  top: 3px; left: 3px;
  width: 18px; height: 18px;
  background: #fff;
  border-radius: 50%;
  transition: left .2s;
}
.toggle-label input:checked ~ .toggle-track .toggle-thumb { left: 23px; }

.brightness-control { display: flex; flex-direction: column; gap: .5rem; }
.brightness-control label { font-size: .9rem; color: var(--text-muted); }
.brightness-control input[type=range] { width: 220px; accent-color: var(--accent); }

/* ── Charts ──────────────────────────────────────── */
.charts-section h2 { font-size: 1rem; margin-bottom: 1rem; }
.chart-row { display: grid; grid-template-columns: 1fr 1fr; gap: var(--gap); margin-bottom: var(--gap); }
.chart-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
}
@media (max-width: 700px) { .chart-row { grid-template-columns: 1fr; } }

/* ── Edit form / settings panel ──────────────────── */
.settings-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: .75rem 1rem;
  margin-bottom: 1.5rem;
}
.settings-panel summary { cursor: pointer; font-size: .9rem; color: var(--text-muted); }
.edit-form { display: flex; flex-wrap: wrap; gap: .75rem; margin-top: 1rem; align-items: flex-end; }
.edit-form label { display: flex; flex-direction: column; gap: .3rem; font-size: .85rem; color: var(--text-muted); }
.edit-form input {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: .4rem .6rem;
  color: var(--text);
  font-size: .9rem;
  width: 200px;
}
.edit-form input:focus { outline: none; border-color: var(--accent); }

/* ── Buttons ─────────────────────────────────────── */
.btn {
  padding: .45rem 1rem;
  border-radius: 6px;
  border: none;
  cursor: pointer;
  font-size: .9rem;
  font-weight: 600;
  transition: opacity .15s;
}
.btn:hover { opacity: .85; }
.btn-primary { background: var(--accent); color: #fff; }

/* ── Empty state ─────────────────────────────────── */
.empty-state {
  background: var(--surface);
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  padding: 3rem;
  text-align: center;
  color: var(--text-muted);
}
.empty-state .hint { font-size: .85rem; margin-top: .5rem; }