* {
  box-sizing: border-box;
  font-family: Arial, sans-serif;
}

body {
  background: #f4f6f8;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 16px;
}

.container {
  background: #fff;
  max-width: 420px;
  width: 100%;
  padding: 20px;
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0,0,0,.1);
}

h1 {
  font-size: 20px;
  text-align: center;
  margin-bottom: 14px;
}

.info {
  font-size: 13px;
  background: #eef3f7;
  padding: 10px;
  border-radius: 10px;
  margin-bottom: 14px;
}

form {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

label {
  font-size: 13px;
  font-weight: bold;
}

input {
  padding: 10px;
  border-radius: 10px;
  border: 1px solid #ccc;
}

button {
  padding: 12px;
  border-radius: 12px;
  border: none;
  background: #3498db;
  color: white;
  font-weight: bold;
  cursor: pointer;
}

.result {
  margin-top: 16px;
  background: #f8f9fb;
  padding: 14px;
  border-radius: 12px;
  font-size: 14px;
  line-height: 1.6;
}

.result.success {
  border-left: 5px solid #2ecc71;
}

.result.fail {
  border-left: 5px solid #e74c3c;
}

.reset {
  margin-top: 12px;
  background: #e67e22;
}

.about {
  margin-top: 15px;
 _toggle-border: none;
  padding: 10px 14px;
  background: #2c3e50;
  color: #fff;
  border-radius: 8px;
  cursor: pointer;
}

.about:hover {
  background: #34495e;
}

/* Modal */
.modal {
  display: none;
  position: fixed;
  z-index: 999;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.6);
}

.modal-content {
  background: #fff;
  max-width: 420px;
  margin: 10% auto;
  padding: 20px;
  border-radius: 12px;
  text-align: left;
  animation: fadeIn 0.3s ease;
}

.modal-content h2 {
  margin-top: 0;
  text-align: center;
}

.modal-content p {
  font-size: 14px;
  line-height: 1.6;
}

.modal-content .note {
  background: #f4f6f8;
  padding: 10px;
  border-radius: 8px;
  font-size: 13px;
}

.close {
  float: right;
  font-size: 22px;
  cursor: pointer;
}

.btn-close {
  margin-top: 15px;
  width: 100%;
  padding: 10px;
  border: none;
  background: #27ae60;
  color: #fff;
  border-radius: 8px;
  cursor: pointer;
}

.btn-close:hover {
  background: #219150;
}

@keyframes fadeIn {
  from {opacity: 0; transform: scale(0.95);}
  to {opacity: 1; transform: scale(1);}
}