/* ===================================
   CSS Custom Properties (Design Tokens)
   =================================== */
:root {
  /* Colors */
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #3b82f6;
  --color-secondary: #8b5cf6;
  --color-success: #10b981;
  --color-error: #ef4444;
  --color-warning: #f59e0b;

  /* Neutrals */
  --color-white: #ffffff;
  --color-gray-50: #f9fafb;
  --color-gray-100: #f3f4f6;
  --color-gray-200: #e5e7eb;
  --color-gray-300: #d1d5db;
  --color-gray-400: #9ca3af;
  --color-gray-500: #6b7280;
  --color-gray-600: #4b5563;
  --color-gray-700: #374151;
  --color-gray-800: #1f2937;
  --color-gray-900: #111827;

  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  --gradient-blue: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);

  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 0.75rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;

  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);

  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;
}

/* ===================================
   Reset & Base Styles
   =================================== */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-gray-900);
  background: var(--gradient-primary);
  min-height: 100vh;
  overflow-x: hidden;
  opacity: 0;
  transition: opacity var(--transition-slow);
}

body.loaded {
  opacity: 1;
}

/* ===================================
   Background Gradient Animation
   =================================== */
.background-gradient {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
  background-size: 200% 200%;
  animation: gradientShift 15s ease infinite;
  z-index: -1;
}

@keyframes gradientShift {
  0% {
    background-position: 0% 50%;
  }

  50% {
    background-position: 100% 50%;
  }

  100% {
    background-position: 0% 50%;
  }
}

/* ===================================
   Login Container
   =================================== */
.login-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: var(--spacing-lg);
  animation: fadeIn 0.6s ease-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===================================
   Login Card (Glassmorphism)
   =================================== */
.login-card {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  border-radius: var(--radius-2xl);
  box-shadow: var(--shadow-2xl);
  padding: var(--spacing-2xl);
  width: 100%;
  max-width: 440px;
  border: 1px solid rgba(255, 255, 255, 0.3);
  animation: slideUp 0.6s ease-out;
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(30px) scale(0.95);
  }

  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

/* ===================================
   Login Header
   =================================== */
.login-header {
  text-align: center;
  margin-bottom: var(--spacing-xl);
}

.logo {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--spacing-xs);
  letter-spacing: -0.02em;
}

.subtitle {
  font-size: var(--font-size-base);
  color: var(--color-gray-600);
  font-weight: 500;
}

/* ===================================
   Message Box (Error/Success)
   =================================== */
.message-box {
  padding: var(--spacing-md);
  border-radius: var(--radius-lg);
  margin-bottom: var(--spacing-lg);
  font-size: var(--font-size-sm);
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  opacity: 0;
  transform: translateY(-10px);
  transition: all var(--transition-base);
}

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

.message-box.error {
  background-color: #fee2e2;
  color: var(--color-error);
  border: 1px solid #fecaca;
}

.message-box.success {
  background-color: #d1fae5;
  color: var(--color-success);
  border: 1px solid #a7f3d0;
}

.message-box.hidden {
  display: none;
}

/* ===================================
   Loading Spinner
   =================================== */
.loading-spinner {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-xl);
  gap: var(--spacing-md);
}

.loading-spinner.hidden {
  display: none;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--color-gray-200);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

.loading-spinner p {
  color: var(--color-gray-600);
  font-size: var(--font-size-sm);
  font-weight: 500;
}

/* ===================================
   Login Form
   =================================== */
.login-form {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

/* ===================================
   Input Group
   =================================== */
.input-group {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.input-label {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-gray-700);
  margin-bottom: 0.25rem;
}

.input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.input-icon {
  position: absolute;
  left: var(--spacing-md);
  width: 20px;
  height: 20px;
  color: var(--color-gray-400);
  pointer-events: none;
  transition: color var(--transition-fast);
}

.input-field {
  width: 100%;
  padding: 0.875rem 1rem 0.875rem 3rem;
  font-size: var(--font-size-base);
  font-family: var(--font-family);
  color: var(--color-gray-900);
  background-color: var(--color-white);
  border: 2px solid var(--color-gray-200);
  border-radius: var(--radius-lg);
  outline: none;
  transition: all var(--transition-base);
}

.input-field::placeholder {
  color: var(--color-gray-400);
}

.input-field:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.input-field:focus+.input-icon,
.input-wrapper:focus-within .input-icon {
  color: var(--color-primary);
}

.input-field.error {
  border-color: var(--color-error);
}

.input-field.error:focus {
  box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.1);
}

.input-error {
  font-size: var(--font-size-xs);
  color: var(--color-error);
  margin-top: 0.25rem;
  display: block;
}

.input-error.hidden {
  display: none;
}

/* ===================================
   Form Options
   =================================== */
.form-options {
  display: flex;
  justify-content: flex-end;
  margin-top: -0.5rem;
}

.forgot-password {
  font-size: var(--font-size-sm);
  color: var(--color-primary);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--transition-fast);
}

.forgot-password:hover {
  color: var(--color-primary-dark);
  text-decoration: underline;
}

/* ===================================
   Buttons
   =================================== */
.btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: 0.875rem 1.5rem;
  font-size: var(--font-size-base);
  font-weight: 600;
  font-family: var(--font-family);
  border: none;
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-base);
  outline: none;
  position: relative;
  overflow: hidden;
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.btn-icon {
  width: 20px;
  height: 20px;
  transition: transform var(--transition-fast);
}

.btn:hover:not(:disabled) .btn-icon {
  transform: translateX(4px);
}

/* Primary Button */
.btn-primary {
  background: var(--gradient-primary);
  color: var(--color-white);
  box-shadow: var(--shadow-md);
}

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

.btn-primary:active:not(:disabled) {
  transform: translateY(0);
}

.btn-primary.loading {
  background: var(--color-gray-400);
}

/* Google Button */
.btn-google {
  background-color: var(--color-white);
  color: var(--color-gray-700);
  border: 2px solid var(--color-gray-200);
  box-shadow: var(--shadow-sm);
}

.btn-google:hover:not(:disabled) {
  background-color: var(--color-gray-50);
  border-color: var(--color-gray-300);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn-google:active:not(:disabled) {
  transform: translateY(0);
}

.google-icon {
  width: 20px;
  height: 20px;
}

/* ===================================
   Divider
   =================================== */
.divider {
  display: flex;
  align-items: center;
  margin: var(--spacing-xl) 0;
  position: relative;
}

.divider::before,
.divider::after {
  content: '';
  flex: 1;
  height: 1px;
  background-color: var(--color-gray-200);
}

.divider-text {
  padding: 0 var(--spacing-md);
  font-size: var(--font-size-sm);
  color: var(--color-gray-500);
  font-weight: 500;
}

/* ===================================
   Info Text
   =================================== */
.info-text {
  text-align: center;
  margin-top: var(--spacing-xl);
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--color-gray-200);
}

.info-text p {
  font-size: var(--font-size-xs);
  color: var(--color-gray-600);
  line-height: 1.5;
}

.info-text a {
  color: var(--color-primary);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--transition-fast);
}

.info-text a:hover {
  color: var(--color-primary-dark);
  text-decoration: underline;
}

/* ===================================
   ORCID Button
   =================================== */
.btn-orcid {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  width: 100%;
  max-width: 396px;
  padding: var(--spacing-md);
  background-color: #A6CE39;
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: var(--font-size-base);
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition-base);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.btn-orcid:hover {
  background-color: #8FB82E;
  box-shadow: 0 4px 12px rgba(166, 206, 57, 0.3);
  transform: translateY(-1px);
}

.btn-orcid:active {
  transform: translateY(0);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.orcid-icon {
  width: 24px;
  height: 24px;
  flex-shrink: 0;
}

/* ===================================
   Divider
   =================================== */
.divider {
  display: flex;
  align-items: center;
  margin: var(--spacing-xl) 0;
  text-align: center;
}

.divider::before,
.divider::after {
  content: '';
  flex: 1;
  border-bottom: 1px solid var(--color-gray-200);
}

.divider-text {
  padding: 0 var(--spacing-md);
  color: var(--color-gray-500);
  font-size: var(--font-size-sm);
  font-weight: 500;
  text-transform: lowercase;
}


/* ===================================
   Footer
   =================================== */
.login-footer {
  margin-top: var(--spacing-xl);
  text-align: center;
}

.login-footer p {
  font-size: var(--font-size-xs);
  color: rgba(255, 255, 255, 0.8);
  font-weight: 500;
}

/* ===================================
   Responsive Design
   =================================== */

/* Mobile Small (320px - 374px) */
@media (max-width: 374px) {
  .login-card {
    padding: var(--spacing-lg);
  }

  .logo {
    font-size: var(--font-size-2xl);
  }

  .btn {
    padding: 0.75rem 1.25rem;
    font-size: var(--font-size-sm);
  }
}

/* Mobile (375px - 767px) */
@media (min-width: 375px) and (max-width: 767px) {
  .login-container {
    padding: var(--spacing-md);
  }

  .login-card {
    padding: var(--spacing-xl);
  }
}

/* Tablet (768px - 1023px) */
@media (min-width: 768px) {
  .login-container {
    padding: var(--spacing-xl);
  }

  .login-card {
    padding: var(--spacing-2xl) 2.5rem;
  }

  .logo {
    font-size: 2.5rem;
  }
}

/* Desktop (1024px+) */
@media (min-width: 1024px) {
  .login-card {
    max-width: 480px;
  }

  .input-field:hover {
    border-color: var(--color-gray-300);
  }
}

/* Large Desktop (1440px+) */
@media (min-width: 1440px) {
  .login-card {
    max-width: 500px;
  }
}

/* ===================================
   Accessibility
   =================================== */
@media (prefers-reduced-motion: reduce) {

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Focus visible for keyboard navigation */
.btn:focus-visible,
.input-field:focus-visible,
a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  .login-card {
    border: 2px solid var(--color-gray-900);
  }

  .input-field {
    border-width: 2px;
  }
}

/* ===================================
   Print Styles
   =================================== */
@media print {
  body {
    background: white;
  }

  .background-gradient,
  .login-footer {
    display: none;
  }

  .login-card {
    box-shadow: none;
    border: 1px solid var(--color-gray-300);
  }
}