* { box-sizing: border-box; }

html, body {
    margin: 0;
    padding: 0;
    min-height: 100%;
}

body {
    min-height: 100vh;
    background: #f4f2ed;
}
main {
    width: 100%;
    padding: 8px 8px 20px;
}

.layout {
    width: 100%;
    display: grid;
    grid-template-columns: 290px minmax(0, 1fr);
    gap: 10px;
    align-items: start;
}

#sidebar {
    width: 100%;
    min-width: 0;
}

.book {
    min-width: 0;
}

@media (max-width: 900px) {
    .layout {
        grid-template-columns: 230px minmax(0, 1fr);
        gap: 8px;
    }
}

@media (max-width: 700px) {
    .layout {
        grid-template-columns: 1fr;
    }

    #sidebar {
        width: 100%;
    }
}