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

body {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans KR', sans-serif;
  padding: 24px;
}

.container {
  width: 100%;
  max-width: 460px;
}

.card {
  background: #fff;
  border-radius: 20px;
  padding: 48px 40px 40px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.2);
}

.card-header {
  text-align: center;
  margin-bottom: 36px;
}

.card-header h1 {
  font-size: 28px;
  font-weight: 700;
  color: #1a1a2e;
  margin-bottom: 8px;
}

.card-header p {
  font-size: 15px;
  color: #6b7280;
}

.form-group {
  margin-bottom: 20px;
}

label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  color: #374151;
  margin-bottom: 8px;
}

input[type="text"],
input[type="email"],
input[type="password"] {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid #e5e7eb;
  border-radius: 10px;
  font-size: 15px;
  color: #1f2937;
  background: #f9fafb;
  transition: border-color 0.2s, background 0.2s, box-shadow 0.2s;
  outline: none;
}

input[type="text"]:focus,
input[type="email"]:focus,
input[type="password"]:focus {
  border-color: #667eea;
  background: #fff;
  box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.12);
}

input.valid {
  border-color: #10b981;
}

input.invalid {
  border-color: #ef4444;
}

.input-wrapper {
  position: relative;
}

.input-wrapper input {
  padding-right: 46px;
}

.toggle-pw {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  cursor: pointer;
  color: #9ca3af;
  display: flex;
  align-items: center;
  padding: 4px;
  border-radius: 4px;
  transition: color 0.2s;
}

.toggle-pw:hover {
  color: #667eea;
}

/* Password strength */
.strength-bar {
  height: 4px;
  background: #e5e7eb;
  border-radius: 2px;
  margin-top: 8px;
  overflow: hidden;
}

.strength-fill {
  height: 100%;
  width: 0%;
  border-radius: 2px;
  transition: width 0.3s, background-color 0.3s;
}

.strength-label {
  font-size: 12px;
  margin-top: 4px;
  display: block;
  font-weight: 500;
}

/* Error messages */
.error {
  display: block;
  font-size: 12px;
  color: #ef4444;
  margin-top: 6px;
  min-height: 16px;
}

/* Checkbox */
.checkbox-group {
  margin-bottom: 28px;
}

.checkbox-label {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  cursor: pointer;
  font-size: 14px;
  color: #4b5563;
  font-weight: 400;
}

.checkbox-label input[type="checkbox"] {
  display: none;
}

.checkmark {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  border: 2px solid #d1d5db;
  border-radius: 5px;
  background: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-top: 1px;
  transition: border-color 0.2s, background 0.2s;
}

.checkbox-label input:checked + .checkmark {
  background: #667eea;
  border-color: #667eea;
}

.checkbox-label input:checked + .checkmark::after {
  content: '';
  width: 5px;
  height: 9px;
  border: 2px solid #fff;
  border-top: none;
  border-left: none;
  transform: rotate(45deg) translateY(-1px);
}

.link {
  color: #667eea;
  text-decoration: none;
  font-weight: 600;
}

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

/* Submit button */
.btn-submit {
  width: 100%;
  padding: 14px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: #fff;
  border: none;
  border-radius: 10px;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  transition: opacity 0.2s, transform 0.1s, box-shadow 0.2s;
  box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
  margin-bottom: 20px;
}

.btn-submit:hover {
  opacity: 0.9;
  box-shadow: 0 6px 20px rgba(102, 126, 234, 0.5);
}

.btn-submit:active {
  transform: scale(0.98);
}

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

.login-link {
  text-align: center;
  font-size: 14px;
  color: #6b7280;
}

/* Toast notification */
.toast {
  position: fixed;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%) translateY(80px);
  background: #1f2937;
  color: #fff;
  padding: 14px 24px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 15px;
  font-weight: 500;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
  transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1), opacity 0.3s;
  opacity: 0;
  pointer-events: none;
  white-space: nowrap;
}

.toast.show {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}

.toast svg {
  color: #10b981;
}

@media (max-width: 480px) {
  .card {
    padding: 36px 24px 32px;
  }
}