/* CSS Custom Properties for Design System */
:root {
  --primary-color: #4f46e5;       /* Indigo */
  --primary-hover: #4338ca;
  --primary-light: #e0e7ff;
  --background-gradient: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  --card-bg: rgba(255, 255, 255, 0.9);
  --text-main: #1f2937;
  --text-muted: #6b7280;
  --border-color: #e5e7eb;
  --focus-ring: rgba(79, 70, 229, 0.2);
  --error-color: #ef4444;
  --success-color: #10b981;
  --font-family: 'Outfit', 'Noto Sans JP', sans-serif;
  --border-radius: 16px;
  --transition-speed: 0.3s;
}

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

body {
  font-family: var(--font-family);
  background: var(--background-gradient);
  color: var(--text-main);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

/* Layout */
.app-container {
  display: flex;
  flex-direction: column;
  width: 100%;
  max-width: 440px;
  min-height: 600px;
  justify-content: space-between;
}

.app-header {
  text-align: center;
  margin-bottom: 24px;
}

.logo-area {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(255, 255, 255, 0.7);
  padding: 8px 16px;
  border-radius: 50px;
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.5);
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
}

.logo-icon {
  font-size: 1.5rem;
  animation: float 3s ease-in-out infinite;
}

.logo-text {
  font-size: 1.25rem;
  font-weight: 800;
  background: linear-gradient(135deg, #4f46e5 0%, #ec4899 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: 0.5px;
}

.app-main {
  flex-grow: 1;
  display: flex;
  align-items: center;
}

/* Card Style */
.card {
  background: var(--card-bg);
  border-radius: var(--border-radius);
  border: 1px solid rgba(255, 255, 255, 0.7);
  padding: 40px 32px;
  width: 100%;
  backdrop-filter: blur(20px);
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.05), 
              0 10px 10px -5px rgba(0, 0, 0, 0.04);
  transform: translateY(0);
  transition: transform var(--transition-speed) cubic-bezier(0.4, 0, 0.2, 1),
              box-shadow var(--transition-speed) ease;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 25px 30px -5px rgba(0, 0, 0, 0.08), 
              0 15px 15px -5px rgba(0, 0, 0, 0.06);
}

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

.card-header h2 {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 8px;
}

.subtitle {
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* Form Styles */
.login-form {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

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

.form-group label {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-main);
  padding-left: 4px;
}

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

.input-icon {
  position: absolute;
  left: 16px;
  font-size: 1.1rem;
  color: var(--text-muted);
  pointer-events: none;
}

.input-wrapper input {
  width: 100%;
  padding: 14px 16px 14px 44px;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  background: rgba(255, 255, 255, 0.6);
  font-size: 0.95rem;
  color: var(--text-main);
  outline: none;
  transition: all var(--transition-speed) ease;
}

.input-wrapper input:focus {
  border-color: var(--primary-color);
  background: #ffffff;
  box-shadow: 0 0 0 4px var(--focus-ring);
}

/* Form Options (Checkbox & Link) */
.form-options {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.8rem;
  margin-top: 4px;
}

.checkbox-container {
  display: flex;
  align-items: center;
  position: relative;
  padding-left: 24px;
  cursor: pointer;
  user-select: none;
  color: var(--text-muted);
}

.checkbox-container input {
  position: absolute;
  opacity: 0;
  cursor: pointer;
  height: 0;
  width: 0;
}

.checkmark {
  position: absolute;
  top: 0;
  left: 0;
  height: 16px;
  width: 16px;
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  transition: all 0.2s ease;
}

.checkbox-container:hover input ~ .checkmark {
  border-color: var(--primary-color);
}

.checkbox-container input:checked ~ .checkmark {
  background-color: var(--primary-color);
  border-color: var(--primary-color);
}

.checkmark:after {
  content: "";
  position: absolute;
  display: none;
}

.checkbox-container input:checked ~ .checkmark:after {
  display: block;
}

.checkbox-container .checkmark:after {
  left: 5px;
  top: 2px;
  width: 4px;
  height: 8px;
  border: solid white;
  border-width: 0 2px 2px 0;
  transform: rotate(45deg);
}

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

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

/* Button */
.btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 24px;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all var(--transition-speed) cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: var(--primary-color);
  color: #ffffff;
  box-shadow: 0 4px 10px rgba(79, 70, 229, 0.3);
}

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 14px rgba(79, 70, 229, 0.4);
}

.btn-primary:active {
  transform: translateY(1px);
}

.btn-arrow {
  transition: transform var(--transition-speed) ease;
}

.btn:hover .btn-arrow {
  transform: translateX(4px);
}

/* Footer & Extras */
.card-footer {
  margin-top: 24px;
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.app-footer {
  text-align: center;
  padding: 24px 0;
}

.app-footer p {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Animations */
@keyframes float {
  0%, 100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-4px);
  }
}

/* Error Banner for validation feedback */
.error-banner {
  background-color: #fef2f2;
  color: var(--error-color);
  border: 1px solid #fecaca;
  padding: 12px 16px;
  border-radius: 10px;
  font-size: 0.85rem;
  font-weight: 500;
  margin-bottom: 20px;
  text-align: center;
  line-height: 1.4;
  animation: shake 0.4s ease-in-out;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-4px); }
  75% { transform: translateX(4px); }
}