/* Header Styles - Clinical/Research Professional */
.header {
    position: fixed;
    top: 0;
    width: 100%;
    height: 70px;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: var(--glass-blur);
    transition: var(--transition-normal);
    display: flex;
    align-items: center;
    border-bottom: 1px solid var(--color-border);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

.logo {
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--color-primary);
    display: flex;
    align-items: center;
    gap: 12px;
    letter-spacing: 0.5px;
    text-decoration: none;
}

.logo-img {
    height: 40px;
    width: auto;
    object-fit: contain;
    display: block;
}

.logo-dot {
    color: var(--color-accent);
    font-size: 1.8rem;
    line-height: 0;
    margin-left: 2px;
}

.nav-list {
    display: flex;
    gap: var(--space-lg);
}

.nav-link {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--color-text-muted);
    position: relative;
    padding: var(--space-xs) 0;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-accent);
}

.nav-link::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    bottom: 0;
    left: 0;
    background-color: var(--color-accent);
    transition: var(--transition-fast);
}

.nav-link:hover::after {
    width: 100%;
}

/* Mobile Menu Button */
.hamburger {
    display: none;
    cursor: pointer;
    z-index: 1001;
}

@media (max-width: 768px) {
    .header {
        background: rgba(255, 255, 255, 1); /* Solid on mobile for clarity */
        border-bottom: 1px solid var(--color-border);
    }

    .nav-list {
        display: none;
        position: fixed;
        top: 70px;
        left: 0;
        width: 100%;
        height: calc(100vh - 70px);
        background: #ffffff; /* Use solid white for maximum clarity on mobile */
        flex-direction: column;
        align-items: center;
        justify-content: center;
        gap: var(--space-lg);
        padding: var(--space-xl);
        z-index: 1000;
        border-top: 1px solid var(--color-border);
        box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    }

    .nav-list.active {
        display: flex;
    }

    .nav-link {
        font-size: 1.2rem; /* Larger font size for mobile touch targets */
        font-weight: 600;
        color: var(--color-primary);
    }

    .hamburger {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        width: 24px;
        height: 18px;
    }

    .hamburger span {
        display: block;
        width: 100%;
        height: 2px;
        background-color: var(--color-primary);
        transition: var(--transition-normal);
        border-radius: var(--radius-sm);
    }

    /* Hamburger Animation */
    .hamburger.active span:nth-child(1) {
        transform: translateY(8px) rotate(45deg);
    }

    .hamburger.active span:nth-child(2) {
        opacity: 0;
        transform: translateX(10px);
    }

    .hamburger.active span:nth-child(3) {
        transform: translateY(-8px) rotate(-45deg);
    }
}