body{
font-family:Arial;
margin:0;
background:linear-gradient(120deg,#89f7fe,#66a6ff);
}

header{
background:#333;
color:white;
padding:20px;
text-align:center;
}

.container{
display:flex;
padding:20px;
}

#sidebar{
width:200px;
background:white;
padding:20px;
border-radius:10px;
box-shadow:0 4px 10px rgba(0,0,0,0.2);
}

#sidebar ul{
list-style:none;
padding:0;
}

#sidebar li{
margin:10px 0;
}

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

#sidebar a:hover{
color:#4CAF50;
}

#main{
flex:1;
margin-left:20px;
background:white;
padding:20px;
border-radius:10px;
box-shadow:0 4px 10px rgba(0,0,0,0.2);
}

.activity-card{
background:#f9f9f9;
padding:15px;
margin-bottom:15px;
border-radius:10px;
box-shadow:0 3px 8px rgba(0,0,0,0.1);
}

button{
padding:8px 15px;
border:none;
background:#4CAF50;
color:white;
border-radius:5px;
cursor:pointer;
}

button:hover{
background:#45a049;
}

input{
padding:5px;
margin:5px;
}

#box{
width:100px;
height:100px;
background:#4CAF50;
position:relative;
margin-top:10px;
border-radius:10px;
}

.dark{
background:#111;
color:white;
}

footer{
text-align:center;
padding:10px;
background:#333;
color:white;
margin-top:20px;
}