/* =========================
   Back to Top Button - Circular
========================= */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 15px;
    width: 55px;
    height: 55px;
    
     background: #00629B !important;  /* IEEE Blue */
    color: white !important;
    
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: 11px;
    font-weight: 700;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2px;
    
    box-shadow: 0 4px 15px rgba(0, 98, 155, 0.3);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 1000;
}

.back-to-top.show {
    opacity: 1 !important;
    visibility: visible !important;
}

.back-to-top:hover {
    background: #004d7a !important;  /* IEEE Blue Dark */
    transform: translateY(-5px) scale(1.05);
    box-shadow: 0 8px 25px rgba(0, 98, 155, 0.4);
}

.back-to-top:active {
    transform: translateY(-2px) scale(1.02);
}

/* Dark Mode */
html[data-theme="dark"] .back-to-top {
    background: rgba(0, 153, 204, 0.25) !important;
    border: 2px solid rgba(0, 153, 204, 0.5);
    color: #ffffff !important;
    box-shadow: 0 4px 15px rgba(0, 153, 204, 0.3);
}

html[data-theme="dark"] .back-to-top:hover {
    background: rgba(0, 153, 204, 0.35) !important;
    border-color: rgba(0, 153, 204, 0.7);
    box-shadow: 0 8px 25px rgba(0, 153, 204, 0.4);
}

 .back-to-top svg {
    stroke: currentColor;
}