:root {
  --brand1: #1e3c72;
  --brand2: #2a5298;
  --text: #333;
  --accent1: #ff6f61;
  --accent2: #ff9966;
  --success: #4caf50;
  --error: #e53935;
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: "Segoe UI", Arial, sans-serif;
  background: linear-gradient(135deg, var(--brand1), var(--brand2));
  color: var(--text);
  display: flex;
  flex-direction: column;
}

header {
  background: linear-gradient(to right, rgb(0, 0, 0), rgb(26, 26, 75));
  color: #fff;
  padding: 15px 30px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
  position: sticky;
  top: 0;
  z-index: 100;
}

.logo {
  font-size: 20px;
  font-weight: 700;
}

nav a {
  color: #fff;
  text-decoration: none;
  margin-left: 20px;
  padding: 8px 10px;
  border-radius: 6px;
  transition: background 0.25s ease;
}

nav a.active,
nav a:hover {
  background: #1f1f1f;
}

.container {
  max-width: 600px;
  margin: 40px auto;
  background: #fff;
  padding: 32px;
  border-radius: 14px;
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.25);
  animation: slideInUp 0.5s ease;
}

@keyframes slideInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

h2 {
  margin: 0 0 10px;
  color: #1e3c72;
  font-size: 28px;
}

p {
  margin: 0 0 20px;
  color: #555;
  font-size: 15px;
}

label {
  display: block;
  margin-bottom: 6px;
  font-weight: 600;
  color: #444;
  font-size: 14px;
}

input {
  width: 100%;
  padding: 12px 14px;
  margin-bottom: 4px;
  border: 2px solid #ddd;
  border-radius: 10px;
  transition: all 0.25s ease;
  font-size: 15px;
  background: #fafafa;
}

input:focus {
  outline: none;
  border-color: #2a5298;
  background: #fff;
  box-shadow: 0 0 0 3px rgba(42, 82, 152, 0.1);
}

input.invalid {
  border-color: var(--error);
  background: #fff5f5;
}

input.invalid:focus {
  box-shadow: 0 0 0 3px rgba(229, 57, 53, 0.1);
}

.error-message {
  color: var(--error);
  font-size: 13px;
  margin-bottom: 12px;
  display: none;
  padding: 6px 10px;
  background: #ffebee;
  border-radius: 6px;
  border-left: 3px solid var(--error);
  animation: shake 0.3s ease;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-5px); }
  75% { transform: translateX(5px); }
}

button {
  width: 100%;
  padding: 14px;
  border: none;
  border-radius: 30px;
  background: linear-gradient(135deg, var(--accent1), var(--accent2));
  color: #fff;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.25);
  transition: all 0.3s ease;
  margin-top: 10px;
}

button:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.35);
}

button:active {
  transform: translateY(0);
}

button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

/* Password strength indicator */
.password-strength {
  height: 4px;
  background: #e0e0e0;
  border-radius: 2px;
  margin: 8px 0 12px;
  overflow: hidden;
  display: none;
}

.password-strength-bar {
  height: 100%;
  width: 0%;
  transition: all 0.3s ease;
  background: linear-gradient(90deg, #e53935, #ffa726, #4caf50);
}

footer {
  background: linear-gradient(to right, rgb(0, 0, 0), rgb(26, 26, 75));
  color: #aaa;
  text-align: center;
  padding: 14px;
  margin-top: auto;
}

.startButton{
  background-color: #29325a;
}

/* Responsive design */
@media (max-width: 768px) {
  .container {
    margin: 20px;
    padding: 24px;
  }
  
  h2 {
    font-size: 24px;
  }
  
  nav a {
    margin-left: 10px;
    font-size: 14px;
  }
}