/* Reset cơ bản */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Poppins', Arial, sans-serif;
  background-color: #f0f2f5;
  color: #333;
  line-height: 1.6;
  scroll-behavior: smooth;
}

/* Thanh điều hướng */
nav {
  position: fixed;
  top: 0;
  width: 100%;
  background-color: rgba(51, 51, 51, 0.9);
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 10px 20px;
  z-index: 999;
  transition: background-color 0.3s;
}
nav .menu-items {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
}
nav a {
  color: #fff;
  margin: 0 15px;
  text-decoration: none;
  font-weight: 600;
  font-size: 1.1em;
  transition: color 0.3s, transform 0.2s;
}
nav a:hover {
  color: #17a2b8;
  transform: scale(1.05);
}
/* Nút menu mobile */
.menu-toggle {
  display: none;
  font-size: 1.5em;
  color: #fff;
  cursor: pointer;
  margin-left: auto;
}
/* Header */
header {
  background: linear-gradient(135deg, #17a2b8, #00c6ff);
  color: #fff;
  padding: 130px 20px 70px 20px;
  text-align: center;
  margin-top: 50px;
  border-radius: 10px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.2);
}
header h1 {
  font-size: 3em;
  margin-bottom: 15px;
  animation: slideInDown 1s ease-out;
}
header p {
  font-size: 1.3em;
  margin-top: 10px;
  max-width: 800px;
  margin-left: auto;
  margin-right: auto;
  animation: fadeIn 1.5s ease-in;
}
.cta {
  margin-top: 20px;
  animation: fadeIn 2s ease-in;
}
.btn {
  background: linear-gradient(135deg, #00c6ff, #0072ff);
  color: #fff;
  padding: 15px 30px;
  font-size: 1.2em;
  font-weight: 600;
  border-radius: 8px;
  text-decoration: none;
  box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}
.btn:hover {
  transform: scale(1.05);
  box-shadow: 0 8px 20px rgba(0,0,0,0.3);
  background: linear-gradient(135deg, #0072ff, #00c6ff);
}

/* Các section */
section {
  padding: 50px 20px;
  max-width: 1200px;
  margin: 20px auto;
  background: #fff;
  border-radius: 15px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  transition: transform 0.3s, box-shadow 0.3s;
}
section:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 30px rgba(0,0,0,0.2);
}
section h2 {
  text-align: center;
  margin-bottom: 20px;
  color: #00796b;
  font-weight: 600;
  font-size: 2.2em;
  position: relative;
}
.section-title {
  font-size: 2.5em;
  margin-bottom: 40px;
  color: #00796b;
  font-weight: 600;
  position: relative;
  text-align: center;
}
.section-title::after {
  content: "";
  display: block;
  width: 80px;
  height: 3px;
  margin: 10px auto 0;
  background-color: #00796b;
  border-radius: 2px;
}
/* Grid các tính năng */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 30px;
}
.feature-card {
  background-color: #fff;
  padding: 30px 20px;
  border-radius: 15px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  transition: 0.3s transform, box-shadow 0.3s;
  text-align: center;
}
.feature-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 8px 30px rgba(0,0,0,0.2);
}
.icon {
  font-size: 3em;
  color: #00796b;
  margin-bottom: 15px;
  transition: color 0.3s;
}
.feature-card:hover .icon {
  color: #004d40;
}
h3 {
  margin-bottom: 15px;
  color: #004d40;
  font-size: 1.4em;
}
p {
  font-size: 1.1em;
  color: #555;
  line-height: 1.6;
  margin-top: 10px;
}
/* Mẫu Giao Diện */
#mau-giao-dien {
  text-align: center;
}
#mau-giao-dien p {
  max-width: 700px;
  margin: 20px auto;
}
#mau-giao-dien div {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 15px;
  margin-top: 20px;
}
#mau-giao-dien img {
  width: 100%;
  max-width: 350px;
  border-radius: 8px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.1);
  transition: transform 0.3s, box-shadow 0.3s;
}
#mau-giao-dien img:hover {
  transform: scale(1.02);
  box-shadow: 0 8px 20px rgba(0,0,0,0.2);
}

/* Modal đăng ký */
.modal {
  display: none;
  position: fixed;
  z-index: 9999;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  overflow: auto;
  background-color: rgba(0,0,0,0.5);
  padding-top: 60px;
  justify-content: center;
  align-items: center;
}
.modal.show {
  display: flex;
}
.modal-content {
  background-color: #fff;
  margin: auto;
  padding: 30px;
  border-radius: 10px;
  max-width: 600px;
  width: 90%;
  box-shadow: 0 5px 15px rgba(0,0,0,0.3);
}
.modal h2 {
  text-align: center;
  margin-bottom: 20px;
  color: #17a2b8;
}
.close {
  position: absolute;
  top: 15px;
  right: 20px;
  font-size: 1.5em;
  cursor: pointer;
  color: #999;
}
.close:hover {
  color: #000;
}
/* Multi-step form */
#multiStepForm {
  display: flex;
  flex-direction: column;
}
#multiStepForm fieldset {
  border: none;
  display: none;
  flex-direction: column;
}
#multiStepForm fieldset.active {
  display: flex;
}
#multiStepForm label {
  margin-top: 15px;
  font-weight: 600;
  color: #333;
}
#multiStepForm input[type="text"],
#multiStepForm select {
  padding: 10px;
  margin-top: 8px;
  border: 1px solid #ccc;
  border-radius: 5px;
  font-family: 'Poppins', sans-serif;
  font-size: 1em;
  transition: border-color 0.3s;
}
#multiStepForm input[type="text"]:focus,
#multiStepForm select:focus {
  border-color: #17a2b8;
  outline: none;
}
.buttons {
  margin-top: 20px;
  display: flex;
  justify-content: space-between;
}
button[type="button"], button[type="submit"], .lnkSubmitForm {
    padding: 12px 25px;
    border: none;
    border-radius: 5px;
    background-color: #17a2b8;
    color: #fff;
    font-family: 'Poppins', sans-serif;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.2s;
}
    button[type="button"]:hover,
    button[type="submit"]:hover, .lnkSubmitForm:hover{
        background-color: #138496;
        transform: scale(1.05);
    }
button:active {
  transform: scale(0.98);
}

/* Footer */
footer {
  background-color: #222;
  color: #fff;
  text-align: center;
  padding: 20px 10px;
  margin-top: 40px;
  border-top: 2px solid #17a2b8;
}
footer div {
  margin-bottom: 10px;
}
footer a {
  margin: 0 10px;
  color: #fff;
  font-size: 1.5em;
  transition: color 0.3s;
}
footer a:hover {
  color: #17a2b8;
}
footer p {
  margin: 5px 0;
  font-size: 0.9em;
}

/* Responsive */
@media(max-width: 768px) {
  nav {
    flex-direction: column;
    align-items: flex-start;
  }
  nav .menu-items {
    width: 100%;
    flex-direction: column;
    display: none;
  }
  nav .menu-items.show {
    display: flex;
  }
  .menu-toggle {
    display: block;
    margin-right: 20px;
  }

}
  .feature{
    margin-bottom:25px;
  }
/* Hiệu ứng rung shake */
@keyframes shake {
  0% { transform: translate(1px, 1px) rotate(0deg); }
  10% { transform: translate(-1px, -2px) rotate(-1deg); }
  20% { transform: translate(-3px, 0px) rotate(1deg); }
  30% { transform: translate(3px, 2px) rotate(0deg); }
  40% { transform: translate(1px, -1px) rotate(1deg); }
  50% { transform: translate(-1px, 2px) rotate(-1deg); }
  60% { transform: translate(-3px, 1px) rotate(0deg); }
  70% { transform: translate(3px, 1px) rotate(-1deg); }
  80% { transform: translate(-1px, -1px) rotate(1deg); }
  90% { transform: translate(1px, 2px); }
  100% { transform: translate(1px, -2px) rotate(-1deg); }
}
.hover-shake:hover {
  animation: shake 0.5s;
  animation-iteration-count: 1;
}
@keyframes shake {
    0% {
        transform: translate(1px, 1px) rotate(0deg);
    }

    10% {
        transform: translate(-1px, -2px) rotate(-1deg);
    }

    20% {
        transform: translate(-3px, 0px) rotate(1deg);
    }

    30% {
        transform: translate(3px, 2px) rotate(0deg);
    }

    40% {
        transform: translate(1px, -1px) rotate(1deg);
    }

    50% {
        transform: translate(-1px, 2px) rotate(-1deg);
    }

    60% {
        transform: translate(-3px, 1px) rotate(0deg);
    }

    70% {
        transform: translate(3px, 1px) rotate(-1deg);
    }

    80% {
        transform: translate(-1px, -1px) rotate(1deg);
    }

    90% {
        transform: translate(1px, 2px);
    }

    100% {
        transform: translate(1px, -2px) rotate(-1deg);
    }
}

.hover-shake:hover {
    animation: shake 0.5s;
    animation-iteration-count: 1;
}
.required{
    color:red;
}
.invalid-feedback {
    color: red;
    font-size: 12px;
    font-style: italic;
}
.text-success{
    color:green;
}