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

body {
  font-family: Arial, sans-serif;
  line-height: 1.6;
  background: #f9f9f9;
  color: #333;
}

/* ===== Header ===== */
header {
  position: fixed;
  top: 0;
  width: 100%;
  min-height: 75px;
  padding: 0 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  background-color: #eee;
  z-index: 10;
}

#header-img {
  max-width: 150px;   /* giới hạn chiều rộng tối đa */
  height: auto;       /* tự co theo tỉ lệ */
  display: block;
}


nav > ul {
  width: 35vw;
  display: flex;
  flex-direction: row;
  justify-content: space-around;
  list-style: none;
}

nav a {
  text-decoration: none;
  color: #333;
  font-weight: bold;
}

/* ===== Hero Section ===== */
#hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  height: 80vh;
  margin-top: 75px;
  padding: 20px;
  background: #fff;
}

#hero h1 {
  font-size: 2rem;
  margin-bottom: 10px;
}

#hero p {
  font-size: 1.2rem;
  margin-bottom: 20px;
}

#hero input[type='email'] {
  padding: 10px;
  height: 40px;
  font-size: 1em;
  border: 2px solid black;
  border-radius: 4px;
  width: 250px;
}

#hero input[type='submit'] {
  max-width: 150px;
  width: 100%;
  height: 40px;
  margin: 15px 0;
  border: 0;
  background-color: #f1c40f;
  font-weight: bold;
  cursor: pointer;
}

#hero input[type='submit']:hover {
  background-color: #d4ac0d;
}

/* ===== Features Section ===== */
#features {
  display: flex;
  justify-content: space-around;
  align-items: flex-start;
  padding: 50px 20px;
  background: #f4f4f4;
  flex-wrap: wrap;
}

.feature {
  flex: 1 1 250px;
  margin: 10px;
  padding: 20px;
  background: white;
  border-radius: 8px;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  text-align: center;
}

/* ===== Video Section ===== */
#video {
  padding: 50px 20px;
  text-align: center;
  background: #fff;
}

#video iframe {
  max-width: 100%;
  border: none;
}

/* ===== Pricing Section ===== */
#pricing {
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: 50px 20px;
  background: #f4f4f4;
  flex-wrap: wrap;
}

.price-box {
  flex: 1 1 250px;
  margin: 10px;
  padding: 20px;
  background: white;
  border: 2px solid #333;
  border-radius: 8px;
  text-align: center;
}

.price-box h3 {
  margin-bottom: 10px;
}

.price-box p {
  font-size: 1.5rem;
  margin-bottom: 10px;
}

.price-box button {
  padding: 10px 20px;
  border: none;
  background: #f1c40f;
  cursor: pointer;
  font-weight: bold;
  border-radius: 4px;
}

.price-box button:hover {
  background: #d4ac0d;
}

/* ===== Footer ===== */
footer {
  background: #333;
  color: #fff;
  text-align: center;
  padding: 20px;
}

/* ===== Responsive cho tablet & mobile ===== */
@media (max-width: 768px) {
  header {
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 10px;
  }

  nav > ul {
    width: 100%;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 10px;
    margin-top: 10px;
  }

  #hero {
    height: auto;
    margin-top: 120px; /* tránh header đè */
  }

  #hero h1 {
    font-size: 1.5rem;
  }

  #hero p {
    font-size: 1rem;
  }

  #hero input[type='email'],
  #hero input[type='submit'] {
    width: 90%;
  }

  #features {
    flex-direction: column;
    align-items: center;
  }

  #pricing {
    flex-direction: column;
    align-items: center;
  }
}
nav a {
  text-decoration: none;
  color: #333;
  font-weight: bold;
  padding: 8px 12px;      /* thêm padding để hover dễ bấm hơn */
  border-radius: 4px;     /* bo nhẹ */
  transition: background 0.3s, color 0.3s;
}

nav a:hover {
  background: #f1c40f;    /* nền vàng khi hover */
  color: white;           /* chữ đổi màu trắng */
}