/*
|--------------------------------------------------------------------------
| Site shell & shared UI
|--------------------------------------------------------------------------
|
| Global website frame, footer navigation, shared page appearance and cover
| content. Book geometry and animation states live in trifold.css.
|
*/

.site-shell {
    min-height: 100vh;
    min-height: 100svh;
    display: grid;
    grid-template-rows: 1fr auto;
    place-items: center;
    overflow: hidden;
    padding: clamp(1rem, 2.4vw, 2rem) clamp(1rem, 3vw, 2.5rem);
    background:
        radial-gradient(circle at 50% 42%, rgba(79, 140, 138, 0.08), transparent 34rem),
        var(--color-bg);
}

.site-footer {
    width: 100%;
    align-self: start;
    padding-top: clamp(0.35rem, 0.8vh, 0.6rem);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(0.45rem);
    transition:
        opacity 320ms ease,
        transform 320ms ease,
        visibility 0s linear 320ms;
}

.site-shell.is-book-open .site-footer {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(0);
    transition-delay: 80ms;
}

.secondary-nav {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.7rem;
    color: var(--color-text-muted);
    font-size: 0.78rem;
}

.secondary-nav__link {
    padding: 0.2rem;
    border: 0;
    background: none;
    color: inherit;
    font: inherit;
    cursor: pointer;
    transition: color var(--transition-fast);
}

.secondary-nav__link:hover,
.secondary-nav__link.is-active {
    color: var(--color-accent-hover);
}

.secondary-nav__link:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 0.3rem;
    border-radius: 0.2rem;
}

.secondary-nav__copyright {
    color: rgba(168, 163, 155, 0.72);
}

.site-stage {
    width: min(100%, var(--content-width));
}

.book-experience {
    display: grid;
    place-items: center;
    width: 100%;
}

/* Shared book-page appearance. */
.book__page {
    position: relative;
    min-width: 0;
    overflow: hidden;
    border: 1px solid var(--color-border);
    background:
        linear-gradient(90deg, rgba(255, 255, 255, 0.018), transparent 16%, transparent 84%, rgba(255, 255, 255, 0.012)),
        var(--color-page);
}

.book__page--left {
    border-radius: 1.1rem 0 0 1.1rem;
    box-shadow:
        inset -2rem 0 2.6rem rgba(0, 0, 0, 0.26),
        -1.8rem 1.8rem 4.5rem rgba(0, 0, 0, 0.34);
}

.book__page--right {
    border-radius: 0 1.1rem 1.1rem 0;
    box-shadow:
        inset 2rem 0 2.6rem rgba(0, 0, 0, 0.24),
        1.8rem 1.8rem 4.5rem rgba(0, 0, 0, 0.34);
}

.book__page--left::after,
.book__page--right::before {
    content: "";
    position: absolute;
    top: 0;
    bottom: 0;
    width: 1px;
    background: rgba(255, 255, 255, 0.045);
}

.book__page--left::after { right: 0; }
.book__page--right::before { left: 0; }

.book__page-inner {
    position: relative;
    height: 100%;
    padding: clamp(2.2rem, 4vw, 4.25rem);
}

.book__page-kicker {
    margin: 0 0 var(--space-3);
    color: var(--color-accent);
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.18em;
    text-transform: uppercase;
}

.book__page h2 {
    margin: 0;
    color: var(--color-text);
    font-family: var(--font-serif);
    font-size: clamp(2.4rem, 4vw, 3.7rem);
    font-weight: 500;
    line-height: 1.05;
}

/* Cover content. */
.book-cover__content {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    height: 100%;
    padding: clamp(3rem, 5vw, 5rem) clamp(2.4rem, 4vw, 4.5rem) clamp(2.5rem, 4vw, 4rem);
    text-align: center;
}

.book-cover__line {
    width: clamp(3.2rem, 7vw, 5.4rem);
    height: 1px;
    margin: 15% 0 clamp(2rem, 4vh, 3.2rem);
    background: var(--color-accent);
    box-shadow: 0 0 1.4rem rgba(79, 140, 138, 0.2);
}

.book-cover__name {
    color: var(--color-text);
    font-family: var(--font-serif);
    font-size: clamp(2.6rem, 5vw, 4.7rem);
    font-weight: 500;
    line-height: 1.02;
    letter-spacing: -0.025em;
}

.book-cover__subtitle {
    margin-top: var(--space-4);
    color: var(--color-text-muted);
    font-size: clamp(0.82rem, 1.25vw, 1rem);
    font-weight: 600;
    letter-spacing: 0.16em;
    text-transform: uppercase;
}

.book-cover__button {
    margin-top: auto;
    padding: 0.8rem 1.15rem;
    border: 1px solid rgba(79, 140, 138, 0.48);
    border-radius: 999px;
    background: rgba(79, 140, 138, 0.08);
    color: var(--color-accent);
    font: inherit;
    font-size: 0.8rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    cursor: pointer;
    transition:
        background var(--transition-fast),
        border-color var(--transition-fast),
        color var(--transition-fast),
        transform var(--transition-fast);
}

.book-cover__button:hover {
    border-color: var(--color-accent-hover);
    background: rgba(79, 140, 138, 0.14);
    color: var(--color-accent-hover);
    transform: translateY(-1px);
}

.book-cover__button:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 0.3rem;
}

.book-cover__button:disabled {
    cursor: default;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

@media (max-width: 900px) {
    .site-footer {
        padding-top: 0.65rem;
    }

    .secondary-nav {
        gap: 0.4rem 0.55rem;
        font-size: 0.72rem;
        line-height: 1.5;
    }
}

@media (max-width: 620px) {
    .secondary-nav {
        font-size: 0.68rem;
    }
}

@media (prefers-reduced-motion: reduce) {
    .site-footer {
        transition: none !important;
    }
}