.gc-builder {
    background: #0d1117;
    color: #fff;
    padding: 20px;
    border-radius: 12px;
    max-width: 650px;
    margin: 30px auto;
    box-shadow: 0 0 20px rgba(0,0,0,0.7);
}
.gc-builder h1 {
    text-align: center;
    color: #00ffcc;
}
.gc-step {
    margin-bottom: 15px;
}
select, button {
    width: 100%;
    padding: 10px;
    border-radius: 8px;
    border: none;
    margin-top: 5px;
}
button {
    background: #00ffcc;
    color: #000;
    font-weight: bold;
    cursor: pointer;
}
.gc-summary {
    margin-top: 20px;
    padding: 10px;
    background: #161b22;
    border-radius: 8px;
}
#gc-compatibility {
    margin-bottom: 10px;
}
#gc-compatibility.ok { color: #4ade80; }
#gc-compatibility.bad { color: #fb7185; }
#result { margin-top: 15px; }