* { box-sizing: border-box; margin: 0; padding: 0; font-family: 'Segoe UI', sans-serif; }
body {
  background: #0d1117;
  color: #e6edf3;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
}
.login-box {
  background: #161b22;
  border: 1px solid #30363d;
  border-radius: 10px;
  padding: 40px;
  width: 320px;
  text-align: center;
}
h1 { color: #58a6ff; margin-bottom: 4px; }
.subtitle { color: #8b949e; margin-bottom: 24px; font-size: 14px; }
input {
  width: 100%;
  padding: 10px;
  margin-bottom: 12px;
  border-radius: 6px;
  border: 1px solid #30363d;
  background: #0d1117;
  color: #e6edf3;
}
button {
  width: 100%;
  padding: 10px;
  background: #238636;
  border: none;
  border-radius: 6px;
  color: white;
  cursor: pointer;
}
button:hover { background: #2ea043; }
.error { color: #f85149; margin-top: 12px; font-size: 13px; }