* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary-color: #2563eb;
  --primary-hover: #1d4ed8;
  --text-primary: #0f172a;
  --text-secondary: #64748b;
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --border-color: #e2e8f0;
  --error-color: #ef4444;
  --focus-ring: rgba(37, 99, 235, 0.2);
}

[data-theme="dark"] {
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --bg-main: #0f172a;
  --bg-card: #1e293b;
  --border-color: #334155;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
  background: var(--bg-main);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.login-container {
  width: 100%;
  max-width: 420px;
  animation: fadeIn 0.5s ease-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.login-card {
  background: var(--bg-card);
  border-radius: 16px;
  padding: 48px 40px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -1px rgba(0, 0, 0, 0.03);
  border: 1px solid var(--border-color);
  transition: background-color 0.3s ease, border-color 0.3s ease;
}

.login-header {
  text-align: center;
  margin-bottom: 32px;
}

.login-header h2 {
  font-size: 28px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.login-header p {
  font-size: 14px;
  color: var(--text-secondary);
}

.login-form {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.form-group label {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
}

.form-group input {
  width: 100%;
  padding: 12px 16px;
  font-size: 15px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  transition: all 0.2s ease;
  background: var(--bg-card);
  color: var(--text-primary);
}

[data-theme="dark"] .form-group input {
  background: #0f172a;
}

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

.form-group input::placeholder {
  color: #94a3b8;
}

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

.error-message {
  font-size: 13px;
  color: var(--error-color);
  min-height: 18px;
  display: none;
}

.error-message.visible {
  display: block;
}

.form-options {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 14px;
  margin-top: 4px;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  user-select: none;
}

.checkbox-label input[type="checkbox"] {
  width: 16px;
  height: 16px;
  cursor: pointer;
  accent-color: var(--primary-color);
}

.checkbox-label span {
  color: var(--text-secondary);
}

.forgot-link {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.2s ease;
}

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

.submit-btn {
  width: 100%;
  padding: 14px 24px;
  font-size: 15px;
  font-weight: 600;
  color: white;
  background: var(--primary-color);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s ease;
  margin-top: 8px;
  position: relative;
  overflow: hidden;
}

.submit-btn:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.submit-btn:active {
  transform: translateY(0);
}

.submit-btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
}

.btn-loader {
  display: none;
  width: 18px;
  height: 18px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-top-color: white;
  border-radius: 50%;
  animation: spin 0.6s linear infinite;
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

@keyframes spin {
  to {
    transform: translate(-50%, -50%) rotate(360deg);
  }
}

.submit-btn.loading .btn-text {
  opacity: 0;
}

.submit-btn.loading .btn-loader {
  display: block;
}

.theme-toggle {
  position: fixed;
  top: 24px;
  right: 24px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
  z-index: 1000;
}

.theme-toggle:hover {
  transform: scale(1.1);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.theme-toggle svg {
  position: absolute;
  transition: all 0.3s ease;
  color: var(--text-primary);
}

.theme-toggle .sun-icon {
  opacity: 1;
  transform: rotate(0deg) scale(1);
}

.theme-toggle .moon-icon {
  opacity: 0;
  transform: rotate(180deg) scale(0);
}

[data-theme="dark"] .theme-toggle .sun-icon {
  opacity: 0;
  transform: rotate(-180deg) scale(0);
}

[data-theme="dark"] .theme-toggle .moon-icon {
  opacity: 1;
  transform: rotate(0deg) scale(1);
}

@media (max-width: 480px) {
  .login-card {
    padding: 32px 24px;
  }

  .login-header h2 {
    font-size: 24px;
  }

  .form-options {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }
}

@media (max-width: 480px) {
  .theme-toggle {
    top: 16px;
    right: 16px;
    width: 40px;
    height: 40px;
  }
}