*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  font-family: system-ui, -apple-system, sans-serif;
  font-size: 1rem;
  line-height: 1.5;
  color: #1a1a1a;
  background: #f9f9f9;
}

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.5rem;
  background: #fff;
  border-bottom: 1px solid #e0e0e0;
}

header a {
  font-weight: 600;
  text-decoration: none;
  color: #2563eb;
}

nav {
  display: flex;
  align-items: center;
  gap: 1rem;
}

nav a {
  text-decoration: none;
  color: #4b5563;
  font-size: 0.9rem;
}

nav a:hover { color: #2563eb; }

nav button {
  background: none;
  border: 1px solid #d1d5db;
  border-radius: 4px;
  padding: 0.25rem 0.75rem;
  cursor: pointer;
  font-size: 0.875rem;
  color: #4b5563;
}

nav button:hover { background: #f3f4f6; }

main {
  max-width: 480px;
  margin: 2rem auto;
  padding: 0 1rem;
}

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

form {
  display: flex;
  flex-direction: column;
  gap: 0.875rem;
}

label {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-size: 0.9rem;
  color: #374151;
}

input[type="email"],
input[type="password"],
input[type="text"] {
  padding: 0.5rem 0.75rem;
  border: 1px solid #d1d5db;
  border-radius: 6px;
  font-size: 1rem;
  outline: none;
}

input:focus { border-color: #2563eb; box-shadow: 0 0 0 2px #bfdbfe; }

button[type="submit"] {
  padding: 0.625rem 1.25rem;
  background: #2563eb;
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  cursor: pointer;
  align-self: flex-start;
}

button[type="submit"]:hover { background: #1d4ed8; }

ul.flash {
  list-style: none;
  padding: 0;
  margin: 1rem 0;
}

ul.flash li {
  background: #fef2f2;
  border: 1px solid #fecaca;
  color: #b91c1c;
  padding: 0.625rem 1rem;
  border-radius: 6px;
  font-size: 0.9rem;
}