:root {
    /* Colors */
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --text-dark: #333;
    --text-muted: #555;
    --error-color: #ff4444;
    --border-color: #ddd;
    --bg-color: #f4f4f9;
    --white: #fff;

    /* Spacing */
    --spacing-sm: 5px;
    --spacing-md: 10px;
    --spacing-lg: 15px;
    --spacing-xl: 20px;

    /* Shadows */
    --shadow-default: 0 0 15px rgba(0, 0, 0, 0.1);

    /* Transitions */
    --transition-default: 0.3s ease;
}

/* Base styles */
body {
    font-family: 'Segoe UI', Arial, sans-serif;
    background-color: var(--bg-color);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}

/* Container styles */
.login-container {
    max-width: 400px;
    width: 100%;
    padding: var(--spacing-xl);
    background-color: var(--white);
    box-shadow: var(--shadow-default);
    border-radius: 8px;
    text-align: center;
    animation: fadeIn var(--transition-default);
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

h2 {
  margin-bottom: var(--spacing-xl);
  color: var(--text-dark);
}

/* Form elements */
.form-group {
    margin-bottom: var(--spacing-lg);
    text-align: left;
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-sm);
    color: var(--text-muted);
    font-weight: 500;
}

.form-group input {
    width: 100%;
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    box-sizing: border-box;
    transition: border-color var(--transition-default);
}

.form-group input.invalid {
  border-color: var(--error-color);
  background-color: #fff8f8;
}

.form-group.remember-me {
  display: flex;
  align-items: center;
}

.form-group.remember-me input {
  width: auto;
  margin-right: var(--spacing-md);
}

.btn-login {
  width: 100%;
  padding: 12px;
  background-color: var(--primary-color);
  color: var(--white);
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: background-color var(--transition-default);
  font-size: 16px;
}

.btn-login:hover {
  background-color: var(--primary-hover);
}

.error-message {
  color: var(--error-color);
  margin-bottom: var(--spacing-md);
  min-height: 20px;
  transition: opacity var(--transition-default);
}

.forgot-password {
  margin-top: var(--spacing-md);
}

.forgot-password a {
  color: var(--primary-color);
  text-decoration: none;
}

.forgot-password a:hover {
  text-decoration: underline;
}

.signup-link {
  margin-top: var(--spacing-lg);
}

.signup-link a {
  color: var(--primary-color);
  text-decoration: none;
}

.signup-link a:hover {
  text-decoration: underline;
}