.cas-calculator-wrapper{
    max-width:900px;
    margin:auto;
    background:#ffffff;
    padding:25px;
    border-radius:12px;
    box-shadow:0 8px 20px rgba(0,0,0,0.08);
    font-family:Arial,sans-serif;
}
.cas-header{
    display:flex;
    justify-content:space-between;
    align-items:center;
    gap:12px;
    margin-bottom:15px;
}
.cas-header h2{
    margin:0;
}
.cas-display input{
    width:100%;
    height:60px;
    font-size:26px;
    text-align:right;
    padding:10px 14px;
    border-radius:8px;
    border:1px solid #ddd;
    margin-bottom:15px;
    box-sizing:border-box;
}
.cas-grid{
    display:grid;
    grid-template-columns:repeat(5,1fr);
    gap:10px;
}
.cas-grid button,
.cas-actions button,
.cas-toggle button{
    padding:14px;
    border:none;
    border-radius:8px;
    background:#eef2f7;
    font-size:16px;
    font-weight:600;
    cursor:pointer;
    transition:0.2s ease;
}
.cas-grid button:hover,
.cas-actions button:hover,
.cas-toggle button:hover{
    background:#dfe7f5;
}
#equals{
    background:#3558d6;
    color:#fff;
}
#equals:hover{
    background:#2746b8;
}
.cas-actions{
    margin-top:15px;
    display:flex;
    gap:10px;
}
.cas-actions button{
    flex:1;
}
.cas-history{
    margin-top:20px;
}
.cas-history h3{
    margin:0 0 10px;
}
.cas-history ul{
    list-style:none;
    padding:0;
    margin:0;
    max-height:180px;
    overflow:auto;
}
.cas-history li{
    padding:8px 0;
    border-bottom:1px solid #eee;
    font-size:14px;
    word-break:break-word;
}
.cas-toggle{
    display:flex;
    gap:8px;
}
.cas-toggle button{
    padding:8px 14px;
}
.cas-toggle .active{
    background:#3558d6;
    color:#fff;
}
@media (max-width: 640px){
    .cas-grid{
        grid-template-columns:repeat(4,1fr);
    }
    .cas-header{
        flex-direction:column;
        align-items:flex-start;
    }
    .cas-actions{
        flex-direction:column;
    }
}