.app-header {
    position: sticky;
    top: 0;
    z-index: 20;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1.5rem;
    padding: 0.85rem var(--space-extra-large);
    border-bottom: 1px solid var(--color-border-control-translucent);
    background: var(--color-canvas-translucent-strong);
    box-shadow: var(--shadow-header);
    backdrop-filter: blur(18px);
}

.app-brand-lockup {
    min-width: 0;
}

.app-brand {
    display: inline-flex;
    min-height: var(--control-height);
    align-items: center;
    gap: 0.7rem;
    color: var(--color-text);
    font-family: var(--font-family-heading);
    font-size: 1.08rem;
    font-weight: var(--font-weight-heading);
    letter-spacing: -0.015em;
    text-decoration: none;
}

.app-brand:hover {
    color: var(--color-text);
}

.app-brand-mark {
    width: 2rem;
    height: 2rem;
    flex: 0 0 auto;
    border-radius: 0.6rem;
    box-shadow: var(--shadow-brand);
}

.app-nav {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: flex-end;
    gap: 0.25rem;
}

.nav-form {
    margin: 0;
}

.app-nav a {
    display: inline-flex;
    min-height: var(--control-height);
    align-items: center;
    padding: 0.68rem 0.78rem;
    border: 1px solid transparent;
    border-radius: var(--radius-small);
    background: transparent;
    color: var(--color-text-muted);
    font: inherit;
    font-size: 0.9rem;
    font-weight: var(--font-weight-medium);
    line-height: 1;
    text-decoration: none;
    white-space: nowrap;
}

.app-nav a:hover {
    border-color: var(--color-border-subtle);
    background: var(--color-surface-hover);
    color: var(--color-text);
}

.app-nav .current-nav-item {
    border-color: var(--color-primary-border);
    background: var(--color-primary-soft);
    color: var(--color-primary-hover);
}

@media (width <= 52rem) {
    .app-header {
        position: static;
        align-items: stretch;
        flex-direction: column;
        gap: 0.9rem;
        padding: 1rem;
    }

    .app-nav {
        justify-content: flex-start;
    }

}

@media (width <= 32rem) {
    .app-nav a {
        padding-inline: 0.65rem;
        font-size: 0.86rem;
    }
}