body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background: #343541; /* ChatGPT dark background */
    color: #ececf1;      /* ChatGPT text color */
}

table {
    width: 100%;
    height: 100vh;
}

td {
    text-align: center;
}

a {
    display: block;
    width: 100%;
    height: 100%;
    font-size: 8vw;
    line-height: 45vh;
    text-decoration: none;
    color: #ececf1;
    background: #40414f; /* Button surface */
    
}

/* Primary / large action */
.null_button {
    background: #2a2b32;
    color: #ffffff; 
    font-size: 16vw;
}

/* ON / OFF buttons */
.on_button {
    background: #9999FF; 
    color: #ffffff;
    width: 100%;
}

.off_button {
    background: #9999FF; 
    color: #ffffff;
    width: 100%;
}

a:hover {
    background: #4b4c5a; 
}

.disclaimer {
    text-align: center;
    font-size: 2vw;
}

table.layout {
    width: 100%;
    height: 100vh;
    border-collapse: collapse;
}

table.layout td {
    width: 50%;
}

.center {
    text-align: center;
    vertical-align: middle;
}

h1 {
    margin: 0;
}

.disclaimer {
    font-size: 1.2vw;
    padding: 1rem;
    opacity: 0.7;
}