/* Clinical & Professional Style System */
    :root {
        --hifu-navy: #102a43;    /* Professional Depth Blue */
        --hifu-teal: #243b53;    /* Technical Slate */
        --hifu-accent: #007ace;  /* Clinical Blue */
        --hifu-warn-bg: #fff5f5; /* Safety Warning Background */
        --hifu-warn-text: #c53030;
        --hifu-bg: #f8fafc;
        --hifu-border: #dae1e7;
    }

    .hifu-guide {
        font-family: Arial, sans-serif;
        line-height: 1.7;
        color: #333;
        max-width: 1920px;
        margin: 0 auto;
        padding: 0;
        background-color: #ffffff;
    }

    /* Typography */
    h1 { font-size: 2.2rem; color: var(--hifu-navy); text-align: center; line-height: 1.2; margin: 40px 0; padding: 0 20px; }
    h2 { font-size: 1.7rem; color: var(--hifu-teal); margin-top: 50px; border-left: 5px solid var(--hifu-accent); padding-left: 15px; background: var(--hifu-bg); padding-top: 10px; padding-bottom: 10px; }
    h3 { font-size: 1.3rem; color: var(--hifu-accent); margin-top: 30px; text-transform: uppercase; letter-spacing: 0.5px; }

    p { margin-bottom: 20px; text-align: justify; }

    /* Callout Boxes */
    .hifu-info-box {
        background: #f0f7ff;
        border: 1px solid #cce3ff;
        padding: 20px;
        margin: 25px 0;
        border-radius: 4px;
    }

    .hifu-warning {
        background: var(--hifu-warn-bg);
        border: 1px solid #feb2b2;
        color: var(--hifu-warn-text);
        padding: 20px;
        margin: 25px 0;
        border-radius: 4px;
        position: relative;
    }

    .hifu-warning strong { color: #9b2c2c; }

    /* Visual Elements */
    .hifu-img-wrapper {
        margin: 35px 0;
        text-align: center;
    }

    .hifu-img-wrapper img {
        max-width: 100%;
        height: auto;
        border: 1px solid var(--hifu-border);
        border-radius: 4px;
        box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    }

    .hifu-img-caption {
        font-size: 0.85rem;
        color: #718096;
        margin-top: 12px;
        font-style: italic;
    }

    /* Data List */
    .hifu-data-list {
        margin: 20px 0;
        padding: 0;
        list-style: none;
    }

    .hifu-data-list li {
        margin-bottom: 10px;
        padding-left: 20px;
        position: relative;
    }

    .hifu-data-list li::before {
        content: "•";
        color: var(--hifu-accent);
        font-weight: bold;
        position: absolute;
        left: 0;
    }

    /* Footer CTA */
    .hifu-footer {
        margin-top: 60px;
        padding: 40px 20px;
        background: var(--hifu-navy);
        color: #ffffff;
        text-align: center;
        border-radius: 4px;
    }

    /* Responsive */
    @media (max-width: 768px) {
        h1 { font-size: 1.8rem; }
        h2 { font-size: 1.4rem; }
    }