*{
  margin:0;
  padding:0;
  box-sizing:border-box;
  font-family:Arial, sans-serif;
}


header{
  background:#000;
  color:#fff;
  padding:15px 0;
  position:sticky;
  top:0;
  z-index:999;
}

.container{
  width:90%;
  margin:auto;
  display:flex;
  justify-content:space-between;
  align-items:center;
}

.logo{
  font-size:20px;
  font-weight:bold;
}

nav ul{
  list-style:none;
  display:flex;
}

nav ul li{
  margin-left:20px;
}

nav ul li a{
  color:#fff;
  text-decoration:none;
}

nav ul li a:hover{
  color:#f4b400;
}

.menu-toggle{
  display:none;
  font-size:26px;
  cursor:pointer;
}

.hero{
  background:url('images/solar1.jpg') center/cover;
  height:90vh;
  display:flex;
  flex-direction:column;
  justify-content:center;
  align-items:center;
  color:#fff;
  text-align:center;
}

.hero h1{
  font-size:40px;
}

.btn{
  background:#f4b400;
  color:#000;
  padding:10px 20px;
  text-decoration:none;
  margin-top:20px;
  border-radius:5px;
}

.section{
  padding:60px 10%;
  text-align:center;
}

.light{
  background:#f5f5f5;
}

.grid{
  display:grid;
  grid-template-columns:repeat(auto-fit,minmax(250px,1fr));
  gap:20px;
  margin-top:30px;
}

.card{
  background:#fff;
  padding:20px;
  border-radius:10px;
  box-shadow:0 5px 15px rgba(0,0,0,0.1);
}

.card img{
  width:100%;
  border-radius:10px;
}

footer{
  background:#000;
  color:#fff;
  text-align:center;
  padding:15px;
}

/* MOBILE */
@media(max-width:768px){

  nav{
    position:absolute;
    top:60px;
    left:0;
    width:100%;
    background:#000;
    display:none;
  }

  nav ul{
    flex-direction:column;
    text-align:center;
  }

  nav ul li{
    margin:15px 0;
  }

  .menu-toggle{
    display:block;
  }

  .hero h1{
    font-size:28px;
  }
}

.calculator-box {
  max-width: 500px;
  margin: 20px auto;
  background: #fff;
  padding: 25px;
  border-radius: 10px;
  box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.calculator-box input {
  width: 100%;
  padding: 12px;
  margin: 10px 0;
  border-radius: 5px;
  border: 1px solid #ccc;
}