:root {
  color-scheme: light dark;
  --accent: #2563eb;
  --bg: #f3f5f8;
  --surface: #ffffff;
  --text: #111827;
  --muted: #667085;
  --border: #d9dee8;
  --danger: #b42318;
  --shadow: 0 8px 24px rgba(16, 24, 40, .08);
}

:root[data-theme="dark"] {
  --bg: #0e1117;
  --surface: #171b23;
  --text: #f5f7fa;
  --muted: #a5adba;
  --border: #303744;
  --shadow: 0 8px 24px rgba(0, 0, 0, .28);
}

* { box-sizing: border-box; }
html { background: var(--bg); }
body {
  margin: 0;
  min-height: 100vh;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  padding-bottom: calc(78px + env(safe-area-inset-bottom));
}
button, input, select { font: inherit; }
button, input, select, summary { min-height: 46px; }
button {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  font-weight: 700;
  padding: .75rem 1rem;
}
button:active { transform: translateY(1px); }
button.primary { background: var(--accent); border-color: var(--accent); color: white; }
button.full { width: 100%; margin-top: 1rem; }
input, select {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface);
  color: var(--text);
  padding: .7rem .8rem;
}
label span, .label { display: block; color: var(--muted); font-size: .82rem; margin-bottom: .35rem; }
.topbar {
  position: sticky;
  top: 0;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: calc(.8rem + env(safe-area-inset-top)) 1rem .8rem;
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
}
.topbar h1 { margin: 0; font-size: 1.25rem; }
.eyebrow { color: var(--accent); font-weight: 800; font-size: .72rem; letter-spacing: .14em; }
.status-dot { width: 12px; height: 12px; border-radius: 50%; background: #98a2b3; box-shadow: 0 0 0 5px color-mix(in srgb, #98a2b3 20%, transparent); }
.status-dot.online { background: #12b76a; box-shadow: 0 0 0 5px color-mix(in srgb, #12b76a 20%, transparent); }
main { width: min(100%, 720px); margin: 0 auto; padding: 1rem; }
.view { display: none; }
.view.active { display: block; }
h2 { font-size: 1.15rem; margin: .2rem 0 .9rem; }
h3 { margin-top: 0; }
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 1rem;
  margin-bottom: .9rem;
}
.status-card { display: grid; grid-template-columns: repeat(3, 1fr); gap: .8rem; }
.status-card div { display: flex; flex-direction: column; gap: .25rem; }
.status-card span { color: var(--muted); font-size: .8rem; }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: .8rem; }
.form-grid .wide, details.wide { grid-column: 1 / -1; }
details { border-top: 1px solid var(--border); padding-top: .5rem; }
details label { margin-top: .8rem; display: block; }
.button-grid { display: grid; grid-template-columns: 1fr 1fr; gap: .7rem; }
.button-grid .wide { grid-column: 1 / -1; }
.frequency-card { text-align: center; padding: 1.2rem 1rem; }
.frequency { font-variant-numeric: tabular-nums; font-size: clamp(2.2rem, 12vw, 4.2rem); font-weight: 850; line-height: 1; letter-spacing: -.045em; }
.unit { display: block; color: var(--muted); margin-top: .3rem; }
.meter-row { display: grid; grid-template-columns: 1fr 1fr; gap: .7rem; margin-top: 1.2rem; }
.meter-row div { background: var(--bg); border-radius: 12px; padding: .75rem; }
.meter-row span, .meter-row small { display: block; color: var(--muted); }
.meter-row strong { display: block; font-size: 1.35rem; margin: .15rem 0; }
.switch { display: flex; align-items: center; gap: .7rem; min-height: 46px; }
.switch input { width: 22px; height: 22px; }
.progress { height: 8px; background: var(--bg); border-radius: 999px; overflow: hidden; margin-top: 1rem; }
.progress span { display: block; height: 100%; width: 0; background: var(--accent); transition: width .2s ease; }
.bottom-nav {
  position: fixed;
  z-index: 10;
  left: 0;
  right: 0;
  bottom: 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: .25rem;
  padding: .5rem .55rem calc(.5rem + env(safe-area-inset-bottom));
  background: color-mix(in srgb, var(--surface) 94%, transparent);
  backdrop-filter: blur(16px);
  border-top: 1px solid var(--border);
}
.bottom-nav button { border: 0; background: transparent; padding: .35rem .15rem; min-height: 54px; color: var(--muted); }
.bottom-nav button span, .bottom-nav button small { display: block; }
.bottom-nav button span { font-size: 1.25rem; }
.bottom-nav button small { margin-top: .1rem; font-size: .68rem; }
.bottom-nav button.active { color: var(--accent); }
.toast-region { position: fixed; z-index: 30; left: .8rem; right: .8rem; bottom: calc(82px + env(safe-area-inset-bottom)); display: grid; gap: .5rem; pointer-events: none; }
.toast { width: min(100%, 520px); margin: 0 auto; background: #101828; color: #fff; border-radius: 12px; box-shadow: 0 14px 30px rgba(0,0,0,.25); padding: .85rem 1rem; animation: toast-in .18s ease-out; }
.toast.error { background: var(--danger); }
.toast.success { background: #067647; }
@keyframes toast-in { from { opacity: 0; transform: translateY(10px); } }
@media (max-width: 430px) {
  .form-grid { grid-template-columns: 1fr; }
  .form-grid .wide, details.wide { grid-column: auto; }
  .status-card { grid-template-columns: 1fr; }
}
.safety-note {
  margin: 0;
  padding: .75rem;
  border: 1px solid var(--border);
  border-radius: .65rem;
  color: var(--muted);
  font-size: .82rem;
  line-height: 1.4;
}