:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --border: #e2e5ea;
  --text: #1a1d23;
  --text-muted: #6b7280;
  --brand: #2563eb;
  --brand-hover: #1d4ed8;
  --success: #16a34a;
  --success-bg: #ecfdf3;
  --warning: #d97706;
  --warning-bg: #fffaeb;
  --danger: #dc2626;
  --danger-bg: #fef2f2;
  --neutral-bg: #f1f2f4;
  --radius: 10px;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  min-height: 100vh;
}

a {
  color: var(--brand);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

button, .button {
  font-family: inherit;
  font-size: 0.95rem;
  cursor: pointer;
}

.button {
  display: inline-block;
  padding: 0.6rem 1.1rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
}

.button:hover {
  background: var(--neutral-bg);
  text-decoration: none;
}

.button-primary {
  background: var(--brand);
  border-color: var(--brand);
  color: #fff;
}

.button-primary:hover {
  background: var(--brand-hover);
}

.button-danger {
  background: var(--danger-bg);
  border-color: var(--danger);
  color: var(--danger);
}

.button-danger:hover {
  background: var(--danger);
  color: #fff;
}

.notice {
  background: var(--warning-bg);
  border: 1px solid var(--warning);
  color: var(--text);
}

.link-button {
  background: none;
  border: none;
  color: var(--text-muted);
  padding: 0;
  font-size: inherit;
}

.link-button:hover {
  color: var(--danger);
  text-decoration: underline;
}

*:focus-visible {
  outline: 2px solid var(--brand);
  outline-offset: 2px;
}

/* --- Layout ---------------------------------------------------------- */

.layout {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  width: 240px;
  flex-shrink: 0;
  background: var(--surface);
  border-right: 1px solid var(--border);
  padding: 1.5rem 1rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.brand {
  font-weight: 700;
  font-size: 1.1rem;
  padding: 0 0.5rem;
}

.nav-links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

.nav-links a, .nav-links .link-button {
  display: block;
  width: 100%;
  text-align: left;
  padding: 0.55rem 0.75rem;
  border-radius: var(--radius);
  color: var(--text);
}

.nav-links a:hover, .nav-links .link-button:hover {
  background: var(--neutral-bg);
  text-decoration: none;
}

.nav-links a.active {
  background: var(--brand);
  color: #fff;
  font-weight: 600;
}

.nav-secondary {
  margin-top: auto;
  border-top: 1px solid var(--border);
  padding-top: 1rem;
}

.content {
  flex: 1;
  padding: 2rem;
  max-width: 900px;
}

.content-standalone {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 1.5rem;
}

@media (max-width: 768px) {
  .layout {
    flex-direction: column;
  }
  .sidebar {
    width: 100%;
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.5rem;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 0.75rem 1rem;
  }
  .nav-links {
    flex-direction: row;
    flex-wrap: wrap;
  }
  .nav-secondary {
    margin-top: 0;
    border-top: none;
    padding-top: 0;
  }
  .content {
    padding: 1.25rem;
    max-width: 100%;
  }
}

/* --- Components -------------------------------------------------------- */

h1 {
  font-size: 1.5rem;
  margin: 0 0 1.25rem;
}

h2 {
  font-size: 1.1rem;
  margin: 0 0 0.75rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  margin-bottom: 1rem;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
}

.field {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border);
}

.field:last-child {
  border-bottom: none;
}

.field-label {
  color: var(--text-muted);
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
}

.badge-success { background: var(--success-bg); color: var(--success); }
.badge-warning { background: var(--warning-bg); color: var(--warning); }
.badge-danger { background: var(--danger-bg); color: var(--danger); }
.badge-neutral { background: var(--neutral-bg); color: var(--text-muted); }

.empty-state {
  text-align: center;
  padding: 2.5rem 1rem;
  color: var(--text-muted);
}

.empty-state p {
  margin: 0.25rem 0 1rem;
}

.table {
  width: 100%;
  border-collapse: collapse;
}

.table th, .table td {
  text-align: left;
  padding: 0.6rem 0.5rem;
  border-bottom: 1px solid var(--border);
  font-size: 0.9rem;
}

.table th {
  color: var(--text-muted);
  font-weight: 600;
}

.table-wrap {
  overflow-x: auto;
}

.device-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.device-list li a {
  display: block;
  padding: 0.9rem 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
}

.device-list li a:hover {
  border-color: var(--brand);
  text-decoration: none;
}

.device-list li .inline-form {
  margin-top: 0.4rem;
}

.skeleton {
  background: linear-gradient(90deg, var(--neutral-bg) 25%, #e5e7eb 37%, var(--neutral-bg) 63%);
  background-size: 400% 100%;
  animation: skeleton-loading 1.4s ease infinite;
  border-radius: var(--radius);
  height: 1rem;
}

@keyframes skeleton-loading {
  0% { background-position: 100% 50%; }
  100% { background-position: 0 50%; }
}

.error-page {
  max-width: 420px;
  text-align: center;
}

.error-page .code {
  font-size: 3rem;
  font-weight: 700;
  color: var(--text-muted);
}

.login-card {
  max-width: 420px;
  width: 100%;
  text-align: center;
}

.login-card .brand {
  font-size: 1.4rem;
  margin-bottom: 0.5rem;
}

.muted {
  color: var(--text-muted);
  font-size: 0.9rem;
}