header {
    position: fixed;
    top: 0;
    width: 100%;
    background: linear-gradient(350deg, var(--header-gradient-1), var(--header-gradient-2));
    backdrop-filter: blur(10px);
    padding: var(--spacing-lg) var(--spacing-md);
    z-index: 1000;
    border-bottom: 1px solid var(--border-color);
    left: 0;
    right: 0;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
    transition: background-color 0.7s ease, transform 0.7s ease, box-shadow 0.7s ease;
    max-height: var(--header-height);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.logo-container {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.logo-text {
    font-size: 2.2rem;
    font-weight: bold;
    text-align: center;
    line-height: 1;
}

.logo-text span:nth-child(1) { color: var(--primary-gradient-1); }
.logo-text span:nth-child(2) { color: var(--primary-gradient-2); }
.logo-text span:nth-child(3) { color: var(--primary-gradient-3); }
.logo-text span:nth-child(4) { color: var(--primary-gradient-4); }

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

.nav-menu a {
    color: var(--text);
    text-decoration: none;
    font-size: 1rem;
    transition: color var(--transition-speed) ease;
}

.nav-menu a:hover {
    color: var(--primary);
}

.theme-toggle {
    background: none;
    border: none;
    color: var(--text);
    cursor: pointer;
    padding: var(--spacing-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color var(--transition-speed) ease;
}

.theme-toggle:hover {
    color: var(--primary);
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text);
    cursor: pointer;
    padding: var(--spacing-sm);
}