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

body{
  background:#f3f6fb;
  padding:30px 15px;
}

.container{
  max-width:1200px;
  margin:auto;
}

.top-header{
  text-align:center;
  margin-bottom:30px;
}

.top-header h1{
  font-size:40px;
  color:#111827;
  margin-bottom:10px;
}

.top-header p{
  color:#6b7280;
  font-size:18px;
}

.tabs{
  display:flex;
  flex-wrap:wrap;
  gap:10px;
  margin-bottom:25px;
  justify-content:center;
}

.tab-btn{
  border:none;
  padding:14px 22px;
  border-radius:10px;
  background:black;
  cursor:pointer;
  font-weight:600;
  transition:0.3s;
  box-shadow:0 2px 10px rgba(0,0,0,0.08);
}

.tab-btn.active,
.tab-btn:hover{
  background:#2563eb;
  color:white;
}

.tab-content{
  display:none;
}

.tab-content.active{
  display:block;
}

.calculator-card{
  background:white;
  padding:35px;
  border-radius:20px;
  box-shadow:0 8px 25px rgba(0,0,0,0.08);
}

.calculator-card h2{
  margin-bottom:30px;
  color:#111827;
}

.fraction-wrapper,
.mixed-wrapper{
  display:flex;
  align-items:center;
  justify-content:center;
  gap:25px;
  flex-wrap:wrap;
  margin-bottom:25px;
}

.fraction-box{
  width:150px;
}

.fraction-box input{
  width:100%;
  padding:14px;
  text-align:center;
  border:2px solid #dbe1ea;
  font-size:18px;
  outline:none;
  border-radius:10px;
}

.line{
  height:3px;
  background:#111827;
  margin:10px 0;
  border-radius:10px;
}

select{
  padding:12px 18px;
  border-radius:10px;
  border:2px solid #dbe1ea;
  font-size:18px;
  outline:none;
}

button{
  background:#2563eb;
  color:white;
  border:none;
  padding:14px 25px;
  border-radius:12px;
  cursor:pointer;
  font-size:17px;
  font-weight:600;
  transition:0.3s;
}

button:hover{
  background:#1d4ed8;
}

.result-box{
  margin-top:30px;
  background:#f8fafc;
  padding:20px;
  border-radius:15px;
  border-left:5px solid #2563eb;
  font-size:18px;
  line-height:1.8;
}

input[type="number"],
input[type="text"]{
  width:100%;
}

.calculator-card > input{
  width:100%;
  padding:16px;
  border-radius:12px;
  border:2px solid #dbe1ea;
  margin-bottom:20px;
  font-size:18px;
}

.mixed-group{
  display:flex;
  align-items:center;
  gap:15px;
}

.mixed-group > input{
  width:90px;
  padding:14px;
  border-radius:10px;
  border:2px solid #dbe1ea;
  text-align:center;
}

.error{
  color:red;
  font-weight:700;
}

.success{
  color:green;
  font-weight:700;
}

/* TABLET */
@media(max-width:991px){

  .top-header h1{
    font-size:32px;
  }

  .calculator-card{
    padding:25px;
  }

}

/* MOBILE */
@media(max-width:600px){

  .top-header h1{
    font-size:28px;
  }

  .tabs{
    flex-direction:column;
  }

  .tab-btn{
    width:100%;
  }

  .fraction-wrapper,
  .mixed-wrapper{
    flex-direction:column;
  }

  .mixed-group{
    flex-direction:column;
  }

  .fraction-box{
    width:100%;
    max-width:220px;
  }

  select{
    width:100%;
  }

  button{
    width:100%;
  }

  .calculator-card{
    padding:20px;
  }

}