:root {
  /* Color System */
  --primary: #4361ee;
  --primary-hover: #3a56d4;
  --primary-focus: rgba(67, 97, 238, 0.15);
  --error: #ef233c;
  --error-bg: rgba(239, 35, 60, 0.03);
  --success: #2ecc71;
  --text-dark: #2b2d42;
  --text-medium: #4a4e69;
  --text-light: #6c757d;
  --border: #ced4da;
  --border-light: #e9ecef;
  --disabled: #adb5bd;
  --white: #ffffff;
  
  /* Elevation */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 10px 30px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 15px 50px rgba(0, 0, 0, 0.15);
  
  /* Shape */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  
  /* Motion */
  --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-fast: all 0.15s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Base Styles */
.login-container {
  background: var(--white);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  width: min(100% - 2rem, 440px);
  padding: clamp(2rem, 5vw, 3rem);
  transition: var(--transition);
  border: 1px solid var(--border-light);
  margin-inline: auto;
  margin-block: 2rem;
}

.login-container:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

/* Typography */
.login-header {
  text-align: center;
  margin-bottom: 2.5rem;
}

.login-header h2 {
  color: var(--text-dark);
  font-size: clamp(1.5rem, 4vw, 1.75rem);
  font-weight: 700;
  margin-bottom: 0.5rem;
  letter-spacing: -0.5px;
  line-height: 1.3;
}

.login-header p {
  color: var(--text-light);
  font-size: 0.875rem;
  font-weight: 400;
  line-height: 1.5;
}

/* Form Elements */
.input-group {
  margin-bottom: 1.5rem;
  position: relative;
}

.input-group label {
  display: block;
  margin-bottom: 0.5rem;
  color: var(--text-medium);
  font-size: 0.875rem;
  font-weight: 500;
  line-height: 1.5;
}

.input-group input {
  width: 100%;
  padding: 0.875rem 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.9375rem;
  transition: var(--transition-fast);
  background-color: var(--white);
  color: var(--text-dark);
  line-height: 1.5;
}

.input-group input::placeholder {
  color: var(--text-light);
  opacity: 0.6;
}

.input-group input:focus {
  border-color: var(--primary);
  outline: none;
  box-shadow: 0 0 0 3px var(--primary-focus);
}

.input-group input.error {
  border-color: var(--error);
  background-color: var(--error-bg);
}

/* Feedback States */
.error-message {
  color: var(--error);
  font-size: 0.8125rem;
  margin-top: 0.5rem;
  display: block;
  min-height: 1.125rem;
  line-height: 1.4;
  opacity: 0;
  transform: translateY(-5px);
  transition: var(--transition);
}

.error-message.show {
  opacity: 1;
  transform: translateY(0);
}

/* Button Styles */
.login-btn {
  width: 100%;
  padding: 1rem;
  background: var(--primary);
  color: var(--white);
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  margin-top: 0.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  letter-spacing: 0.5px;
}

.login-btn:hover:not(:disabled) {
  background: var(--primary-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.login-btn:active:not(:disabled) {
  transform: translateY(0);
  box-shadow: none;
}

.login-btn:disabled {
  background: var(--disabled);
  cursor: not-allowed;
}

.login-btn.success {
  background: var(--success);
}

/* Animations */
.shake-animation {
  animation: shake 0.4s ease-in-out;
}

.loading-spinner {
  display: inline-block;
  width: 1.125rem;
  height: 1.125rem;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: var(--white);
  animation: spin 0.8s linear infinite;
}

.success-checkmark {
  width: 1.125rem;
  height: 1.125rem;
  opacity: 0;
  transform: scale(0.8);
  transition: var(--transition);
}

.login-btn.success .success-checkmark {
  opacity: 1;
  transform: scale(1);
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  15%, 45%, 75% { transform: translateX(-5px); }
  30%, 60%, 90% { transform: translateX(5px); }
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Responsive Adjustments */
@media (max-width: 480px) {
  .login-container {
    padding: 2rem 1.5rem;
    margin: 1rem;
    border: none;
    box-shadow: var(--shadow-sm);
  }
  
  .login-header {
    margin-bottom: 2rem;
  }
}

/* Accessibility Enhancements */
.input-group input:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* Reduced Motion Preferences */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  
  .login-container,
  .login-btn,
  .input-group input {
    transition: none !important;
  }
}

/* Print Styles */
@media print {
  .login-container {
    box-shadow: none;
    border: 1px solid var(--border);
    page-break-inside: avoid;
  }
  
  .login-btn {
    background: var(--text-dark) !important;
    color: var(--white) !important;
  }
}