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

body{
display:flex;
justify-content:center;
align-items:center;
height:100vh;
background:#f4f4f4;
transition:0.3s;
}

.container{
background:white;
padding:20px;
border-radius:15px;
box-shadow:0 10px 25px rgba(0,0,0,0.2);
width:280px;
}

.top{
display:flex;
justify-content:space-between;
align-items:center;
margin-bottom:10px;
}

#themeToggle{
border:none;
padding:5px 10px;
cursor:pointer;
border-radius:5px;
}

#display{
width:100%;
height:50px;
margin-bottom:10px;
font-size:22px;
text-align:right;
padding:10px;
border-radius:8px;
border:1px solid #ccc;
}

.buttons{
display:grid;
grid-template-columns:repeat(4,1fr);
gap:8px;
}

button{
padding:15px;
font-size:18px;
border:none;
border-radius:8px;
cursor:pointer;
background:#e0e0e0;
transition:0.2s;
}

button:hover{
background:#d0d0d0;
}

.equal{
grid-row:span 2;
background:#4CAF50;
color:white;
}

.zero{
grid-column:span 2;
}

/* DARK MODE */

.dark{
background:#121212;
}

.dark .container{
background:#1e1e1e;
color:white;
}

.dark button{
background:#333;
color:white;
}

.dark #display{
background:#222;
color:white;
border:none;
}

.dark .equal{
background:#00c853;
}