.app,
footer,
main {
    margin: auto;
    max-width: 640px;
}

header {
    align-items: center;
    display: flex;
    gap: 8px;
    justify-content: space-between;
    margin-bottom: 12px;
}

.app {
    display: flex;
    gap: 12px;

    .app__content {
        flex: 1;
    }
}

.navbar {
    background-color: var(--colour-surface-container);
    bottom: 0;
    box-shadow:
        0 1px 2px 0 rgb(0 0 0 / 30%),
        0 1px 3px 1px rgb(0 0 0 / 15%);
    left: 0;
    position: fixed;
    right: 0;
    z-index: 1;
}

.nav {
    display: flex;
    flex-direction: row;
    gap: 8px;
    list-style-type: none;
    margin: 0;
    padding: 0;
}

.nav__item {
    --pill-colour: var(--colour-on-secondary-container);
    color: var(--colour-on-surface-variant);
    flex: 1;

    &.nav__item--current {
        --icon-colour: var(--colour-on-secondary-container);
        --pill-colour: var(--colour-secondary-container);
        color: var(--colour-secondary);
    }
}

.nav__link {
    --icon-size: 24px;
    align-items: center;
    box-sizing: border-box;
    color: inherit;
    display: flex;
    flex-direction: column;
    font: var(--label-medium);
    gap: 4px;
    height: var(--nav-height);
    padding: 12px 0 16px;
    position: relative;
    text-decoration: none;

    &::before {
        background-color: var(--pill-colour);
        border-radius: 16px;
        content: "";
        height: 32px;
        opacity: 0;
        position: absolute;
        top: 12px;
        transition: opacity var(--small-transition-effect);
        width: 56px;
    }

    &:hover::before {
        opacity: 0.08;
    }

    &:focus::before,
    &:active::before {
        opacity: 0.1;
    }

    .icon {
        margin: 4px 0;
        z-index: 1;
    }

    .nav__item--current &::before {
        opacity: 1;
    }
}

@media (min-width: 640px) {
    .app {
        margin: 16px auto 0;
    }

    .app__content {
        background-color: var(--colour-surface);
        border-radius: var(--medium-radius);
        padding: 16px;
    }

    header {
        margin: -4px -4px 12px -4px;
    }

    .navbar {
        --nav-height: auto;
        background-color: transparent;
        bottom: unset;
        box-shadow: none;
        position: relative;
        right: unset;
        top: -6px;

        .nav {
            align-items: center;
            flex-direction: column;
        }

        .nav__link {
            padding: 6px 0;
            width: 80px;

            &::before {
                top: 6px;
            }
        }
    }
}

.app__title {
    font: var(--headline-medium);
    margin: 0 0 12px;
}

.app__actions {
    display: flex;
    margin: -6px 0;
}

.app__subtitle {
    font: var(--title-large);
    margin: 0 0 8px;
}

.app__illustration {
    margin: auto;
    max-width: 256px;

    > * {
        height: 100%;
        width: 100%;
    }
}

footer {
    font: var(--body-medium);
    margin-top: 32px;
    text-align: right;

    .footer__link {
        color: var(--colour-on-surface-variant);
    }
}