:root {
  font-family: Arial, sans-serif;
  --bg-dark: #0b1020;
  --bg-box: #111936;
  --border: #1f2a4a;
  --accent: #2a5bd7;
  --accent-hover: #1e40af;
  --error: #ff6b6b;
  --success: #50fa7b;
  --text-light: #eef2ff;
}

body {
  margin: 0;
  background: var(--bg-dark);
  color: var(--text-light);
}

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 24px;
  background: var(--bg-box);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
}

header nav a {
  color: var(--text-light);
  margin-left: 16px;
  text-decoration: none;
  font-weight: 600;
  transition: color 0.3s ease;
}

header nav a:hover {
  color: var(--accent);
}

.container {
  max-width: 800px;
  margin: 2rem auto;
  padding: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.box {
  width: 400px;
  background: var(--bg-box);
  padding: 2rem;
  border-radius: 12px;
  border: 1px solid var(--border);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
}

h2 {
  text-align: center;
  margin-bottom: 1.5rem;
  color: var(--accent);
}

form {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

input {
  padding: 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #1b2035;
  color: var(--text-light);
  font-size: 16px;
}

button {
  border: 0;
  padding: 10px 14px;
  border-radius: 12px;
  background: var(--accent);
  color: white;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.3s ease;
}

button:hover {
  background: var(--accent-hover);
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  filter: grayscale(15%);
}

.error {
  color: var(--error);
  font-weight: 600;
  text-align: center;
  margin-top: 10px;
}

.success {
  color: var(--success);
  font-weight: 600;
  text-align: center;
  margin-top: 10px;
}

.post {
  background: var(--bg-box);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  margin: 2em;
}