.shm-burger {
    width: 30px;
    cursor: pointer;
    position: relative;
    z-index: 2001;
}

.shm-burger span {
    display: block;
    height: 3px;
    margin: 6px 0;
    transition: 0.3s;
}

/* animation */
.shm-burger.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px,5px);
}
.shm-burger.active span:nth-child(2) {
    opacity: 0;
}
.shm-burger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(6px,-6px);
}

/* MENU GPU */
.shm-menu {
    position: fixed;
    top: 0;
    height: 100%;
    transform: translateX(-100%);
    transition: transform 0.4s ease, opacity 0.3s ease;
    will-change: transform;
    backface-visibility: hidden;
    visibility: hidden;
    pointer-events: none;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
}

.shm-menu.active {
    transform: translateX(0);
    visibility: visible;
    pointer-events: auto;
}

.shm-menu ul {
    list-style: none;
    text-align: center;
    padding: 0;
}

/* overlay */
.shm-overlay {
    position: fixed;
    inset: 0;
    display: none;
    z-index: 1999;
}

.shm-overlay.active {
    display: block;
}

/* animations */
.shm-menu.fade { opacity: 0; }
.shm-menu.fade.active { opacity: 1; }

.shm-menu.scale { transform: translateX(-100%) scale(0.95); }
.shm-menu.scale.active { transform: translateX(0) scale(1); }