* { margin: 0; padding: 0; box-sizing: border-box; }
html, body {
    width: 100%;
    height: 100%;
    font-family: Arial, Helvetica, sans-serif;
    background: #ffffff;
    color: #212529;
}
main { display: block; width: 100%; height: 100%; }
#wrap {
    width: 100%;
    min-height: 100%;
    padding: 10px 14px 14px;
    display: flex;
    flex-direction: column;
    align-items: center;
}
#title {
    font-size: 18px;
    color: #0d47a1;
    text-align: center;
    margin-bottom: 4px;
    font-weight: 600;
}
#diagram { width: 100%; display: flex; justify-content: center; }
#diagram svg { max-width: 100%; max-height: 430px; height: auto; }
.seg, .hub, .listitem { cursor: pointer; }
.seg path, .hub circle { transition: filter 0.15s; }
.seg:hover path, .hub:hover circle { filter: brightness(1.12); }
.seg.active path, .hub.active circle { stroke: #0d2b4a; stroke-width: 4px; }
#tip {
    margin: 10px auto 0;
    max-width: 640px;
    min-height: 64px;
    background: #f8fafc;
    color: #334155;
    border: 1px solid #e2e8f0;
    border-radius: 6px;
    padding: 12px 14px;
    font-size: 15px;
    line-height: 1.45;
    text-align: center;
}
#caption {
    margin-top: 10px;
    max-width: 660px;
    font-size: 13px;
    color: #455a64;
    font-style: italic;
    text-align: center;
}
/* vertical list (rendered below 600px) */
.list { width: 100%; max-width: 460px; }
.listitem {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    border: 1px solid #cbd5e1;
    border-radius: 6px;
    padding: 8px 10px;
    margin: 6px 0;
    background: #fff;
}
.listitem .num {
    flex: 0 0 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    color: #fff;
}
.listitem .body strong { display: block; font-size: 15px; }
.listitem .body span { font-size: 13px; color: #455a64; }
.listitem.active { outline: 3px solid #0d2b4a; }