.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: var(--z-index-header);
    background: var(--color-bg-overlay);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all var(--transition-base);
    border-bottom: 1px solid var(--color-border);
}

[data-theme="light"] .header {
    background: rgba(255, 255, 255, 0.95);
}

.header.scrolled {
    box-shadow: var(--shadow-md);
    padding: var(--spacing-sm) var(--spacing-xl);
}

.header-logo {
    font-size: 1.5rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    transition: all 0.3s ease;
}

.header-logo-text {
    font-family: var(--font-display);
    font-weight: 700;
    letter-spacing: -0.02em;
}

.header-lang {
    display: inline-flex;
    align-items: center;
    gap: 0;
    border: var(--hairline);
    border-radius: var(--border-radius-sm);
    overflow: hidden;
}

.header-lang-btn {
    appearance: none;
    border: 0;
    background: transparent;
    color: var(--color-text-secondary);
    font-family: var(--font-mono-tech);
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.06em;
    padding: 0.35rem 0.55rem;
    cursor: pointer;
    transition: background var(--transition-fast), color var(--transition-fast);
}

.header-lang-btn.is-active {
    background: rgba(42, 157, 143, 0.18);
    color: var(--color-accent-tertiary);
}

.header-lang-btn:hover {
    color: var(--color-text-primary);
}


.header-left {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    min-width: 0;
}

.header-status {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: 0.2rem 0.6rem;
    border: var(--hairline);
    border-radius: var(--border-radius-sm);
    font-family: var(--font-mono-tech);
    font-size: 0.7rem;
    font-weight: 500;
    letter-spacing: 0.5px;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    background: rgba(34, 197, 94, 0.06);
}

.header-status-dot {
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: var(--color-online);
    box-shadow: 0 0 8px rgba(34, 197, 94, 0.8);
    animation: statusPulse 2.4s ease-in-out infinite;
}

@keyframes statusPulse {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.55; transform: scale(0.85); }
}

.header-version {
    font-family: var(--font-mono-tech);
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.5px;
    color: var(--color-accent-tertiary);
    padding: 0.15rem 0.45rem;
    border: var(--hairline);
    border-radius: var(--border-radius-sm);
    background: rgba(0, 212, 255, 0.06);
}

.header-logo-image {
    height: 40px;
    width: auto;
    transition: all 0.3s ease;
}

.header-logo-text {
    background: linear-gradient(135deg, var(--color-accent-primary) 0%, var(--color-accent-tertiary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header.scrolled .header-logo-image {
    height: 32px;
}

.header-nav {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.header-auth-info {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    transition: color 0.3s ease;
}

.header-link {
    text-decoration: none;
    cursor: pointer;
}

.header-link:hover {
    color: var(--color-accent-primary);
}

.header-button {
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--border-radius-md);
    font-weight: 500;
    transition: all var(--transition-base);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    text-decoration: none;
    cursor: pointer;
    border: none;
}

.header-button-primary {
    background: linear-gradient(135deg, var(--color-accent-primary) 0%, var(--color-accent-tertiary) 100%);
    color: white;
    transition: all var(--transition-base);
}

.header-button-primary:hover {
    box-shadow: 0 0 0 1px rgba(0, 212, 255, 0.4), var(--shadow-md);
    filter: brightness(1.08);
}

.header-button-secondary {
    background: var(--color-bg-card);
    color: var(--color-text-primary);
    border: 2px solid var(--color-border);
    transition: all var(--transition-base);
}

[data-theme="light"] .header-button-secondary {
    background: white;
}

.header-button-secondary:hover {
    border-color: var(--color-accent-primary);
    color: var(--color-accent-primary);
    background: var(--color-bg-card-hover);
}

.header-button-logout {
    background: var(--color-error);
    color: var(--color-white);
}

.header-button-logout:hover {
    background: #d32f2f;
    transform: translateY(-2px);
}

@media (max-width: 768px) {
    .header {
        padding: var(--spacing-sm) var(--spacing-md);
    }

    .header-logo {
        font-size: 1.2rem;
    }

    .header-logo-image {
        height: 32px;
    }

    .header-status,
    .header-version {
        display: none;
    }

    .header-auth-info {
        font-size: 0.8rem;
    }

    .header-button {
        padding: var(--spacing-xs) var(--spacing-md);
        font-size: 0.9rem;
    }
}

@media (max-width: 560px) {
    .header {
        padding: var(--spacing-xs) var(--spacing-sm);
        gap: var(--spacing-sm);
    }

    .header-logo-text {
        display: none;
    }

    .header-left {
        gap: var(--spacing-sm);
    }

    .header-nav {
        gap: var(--spacing-sm);
    }

    .header-button {
        padding: var(--spacing-xs) var(--spacing-sm);
        font-size: 0.78rem;
    }
}




.header-lang {
    display: inline-flex;
    align-items: center;
    gap: 0;
    border: var(--hairline);
    border-radius: var(--border-radius-sm);
    overflow: hidden;
    background: var(--color-bg-card);
}

.header-lang-btn {
    appearance: none;
    border: none;
    background: transparent;
    color: var(--color-text-secondary);
    font-family: var(--font-mono-tech);
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    padding: 0.35rem 0.55rem;
    cursor: pointer;
    transition: background var(--transition-fast), color var(--transition-fast);
}

.header-lang-btn.is-active,
.header-lang-btn:hover {
    background: var(--color-accent-primary);
    color: #fff;
}