.page-shell {
    margin: 0 auto;
    max-width: 96rem;
    min-height: 100vh;
}

.masthead {
    backdrop-filter: blur(16px);
    background: rgba(8, 22, 29, 0.92);
    padding: 2.5rem clamp(1.2rem, 3vw, 3rem) 1.2rem;
    position: sticky;
    top: 0;
    z-index: 30;
}

.content-shell {
    padding: 0 clamp(1.2rem, 3vw, 3rem) 3rem;
}

@media (max-width: 900px) {
    .masthead {
        padding-top: 1.5rem;
        padding-bottom: 1rem;
    }

    .content-shell {
        padding-bottom: 2rem;
    }
}

@media (max-width: 640px) {
    .masthead {
        padding: 1rem 1rem 0.85rem;
    }

    .content-shell {
        padding: 0 1rem 1.5rem;
    }
}

.nav-shell {
    align-items: flex-start;
    display: flex;
    gap: 1rem;
    justify-content: space-between;
    width: 100%;
}

.nav-primary {
    flex: 1 1 auto;
    min-width: 0;
}

.nav-kicker {
    margin: 0 0 0.35rem;
    color: rgba(243, 247, 240, 0.72);
    font-size: 0.78rem;
    letter-spacing: 0.18em;
    text-transform: uppercase;
}

.nav-home {
    color: #f3f7f0;
    font-family: "Avenir Next", "Segoe UI", sans-serif;
    font-size: 1.55rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    text-decoration: none;
}

.nav-home.active {
    color: #f3f7f0;
}

.nav-copy {
    margin: 0.75rem 0 0;
    max-width: 34rem;
    color: rgba(243, 247, 240, 0.84);
}

.nav-preferences {
    display: flex;
    flex: 0 0 auto;
    gap: 0.9rem;
    justify-content: flex-end;
    margin-left: auto;
}

.culture-picker,
.currency-picker {
    align-items: flex-start;
    display: grid;
    gap: 0.45rem;
    min-width: min(14rem, 100%);
}

.culture-label {
    color: rgba(243, 247, 240, 0.72);
    font-size: 0.76rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.culture-select {
    background: rgba(243, 247, 240, 0.93);
    border: 0;
    border-radius: 14px;
    color: #102028;
    font: inherit;
    min-height: 2.8rem;
    padding: 0.7rem 0.85rem;
}

.theme-toggle {
    align-self: end;
    background: rgba(243, 247, 240, 0.1);
    border: 1px solid rgba(173, 219, 208, 0.28);
    border-radius: 14px;
    color: #f3f7f0;
    cursor: pointer;
    font: inherit;
    font-size: 1.2rem;
    height: 2.8rem;
    line-height: 1;
    min-width: 2.8rem;
}

.theme-toggle:hover,
.theme-toggle:focus-visible {
    background: rgba(141, 225, 206, 0.2);
    outline: 2px solid #8de1ce;
    outline-offset: 2px;
}

@media (max-width: 640px) {
    .nav-shell {
        align-items: flex-start;
        flex-direction: column;
        gap: 0.6rem;
    }

    .nav-kicker {
        font-size: 0.72rem;
    }

    .nav-home {
        font-size: 1.2rem;
        line-height: 1.15;
    }

    .nav-copy {
        font-size: 0.95rem;
        margin-top: 0.55rem;
    }

    .nav-preferences {
        width: 100%;
        flex-direction: column;
    }

    .culture-picker,
    .currency-picker {
        width: 100%;
    }

    .culture-select {
        width: 100%;
    }
}