:root {
  --bg: #0f172a;
  --panel: #1e293b;
  --border: #334155;
  --text: #f1f5f9;
  --muted: #94a3b8;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --error: #ef4444;
  --success: #22c55e;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 24px 16px;
}

.center-screen {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 28px;
  width: 100%;
  max-width: 420px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}

.card h1, .card h2 {
  margin: 0 0 16px;
  font-size: 1.4rem;
}

label {
  display: block;
  font-size: 0.85rem;
  color: var(--muted);
  margin-bottom: 6px;
}

input, select, textarea {
  width: 100%;
  padding: 10px 12px;
  background: #0f172a;
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 1rem;
  margin-bottom: 14px;
}

input:focus, select:focus, textarea:focus {
  outline: none;
  border-color: var(--accent);
}

button, .btn {
  display: inline-block;
  padding: 10px 16px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
}

button:hover, .btn:hover { background: var(--accent-hover); }
button:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-secondary {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
}

.btn-danger { background: var(--error); }

.error {
  color: var(--error);
  margin: 8px 0;
  font-size: 0.9rem;
}

.success {
  color: var(--success);
  margin: 8px 0;
  font-size: 0.9rem;
}

.muted { color: var(--muted); font-size: 0.85rem; }

table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 16px;
}

th, td {
  padding: 8px 10px;
  text-align: left;
  border-bottom: 1px solid var(--border);
  font-size: 0.9rem;
}

th {
  color: var(--muted);
  font-weight: 600;
  text-transform: uppercase;
  font-size: 0.75rem;
  letter-spacing: 0.05em;
}

nav {
  display: flex;
  gap: 16px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  background: var(--panel);
}

nav a {
  color: var(--text);
  text-decoration: none;
  font-size: 0.95rem;
  padding: 6px 12px;
  border-radius: 6px;
}

nav a:hover { background: rgba(255,255,255,0.05); }
nav a.active { background: var(--accent); color: #fff; }