.app-header {
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(12px);
    background: color-mix(in srgb, var(--surface, #17191b) 88%, transparent);
    border-bottom: 1px solid var(--line, #1f2123);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 1.3rem;
    height: 56px;
    gap: 1rem;
}

.app-header-left {
    display: flex;
    align-items: center;
    gap: 0.7rem;
    flex-shrink: 0;
}

.app-header-left a {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    text-decoration: none;
    color: inherit;
}

.app-header-mark {
    width: 28px;
    height: 28px;
    border-radius: 8px;
    object-fit: contain;
}

.app-header-mark-fallback {
    width: 28px;
    height: 28px;
    border-radius: 8px;
    background: linear-gradient(135deg, var(--brand, #1b3569), var(--accent, #36599f));
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    flex-shrink: 0;
}

.app-header-label {
    font-family: 'Sora', sans-serif;
    font-size: 1.05rem;
    font-weight: 600;
    letter-spacing: 0.01em;
    color: var(--ink, #ecedee);
}

.app-header-nav {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    margin-left: 1.2rem;
}

.app-header-nav a {
    text-decoration: none;
    color: var(--muted, #909397);
    font-size: 0.88rem;
    font-weight: 500;
    padding: 0.4rem 0.7rem;
    border-radius: 6px;
    transition: color 0.15s, background 0.15s;
}

.app-header-nav a:hover {
    color: var(--ink, #ecedee);
    background: rgba(255, 255, 255, 0.06);
}

.app-header-right {
    display: flex;
    align-items: center;
    gap: 0.7rem;
    min-height: 2rem;
}

.app-header-right .auth-email {
    font-size: 0.84rem;
    color: var(--muted, #909397);
    max-width: 180px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

@media (max-width: 860px) {
    .app-header {
        padding: 0 0.9rem;
        height: 50px;
    }

    .app-header-label {
        font-size: 0.95rem;
    }

    .app-header-nav {
        margin-left: 0.6rem;
        gap: 0.1rem;
    }

    .app-header-nav a {
        font-size: 0.82rem;
        padding: 0.35rem 0.5rem;
    }
}