nav {
    width: 220px;
    height: 100vh;
    background-color: #2c3e50;
    color: white;
    overflow-y: auto;
    padding: 20px;
    position: fixed;
    top: 0;
    right: 0;
    transition: transform 0.3s ease-in-out;
    scrollbar-color: #888 #e1d7d7;
    scrollbar-width: thin;
    direction: ltr;
    z-index: 999;
}

nav ul {
    list-style: none;
    padding: 0;
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 30px;
}

nav li {
    margin: 4px 0;
    width: 100%;
    display: flex;
    justify-content: center;
}


.exercise-menu-btn {
    width: 90%;
    padding: 12px 18px;
    background: #0a84ff;
    color: #fff;
    border: none;
    border-radius: 10px;
    font-size: 1em;
    cursor: pointer;
    margin-bottom: 10px;
    margin-top: 2px;
    transition: background 0.2s, color 0.2s;
}

.exercise-menu-btn.completed {
    background: #10b981;
    color: #fff;
    position: relative;
}

.exercise-menu-btn.completed::after {
    content: '✔';
    position: absolute;
    left: 12px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 1.1em;
    color: #fff;
}

.exercise-menu-btn.active,
.exercise-menu-btn:hover {
     background: #005bb5;
    color: #fff;
}

.exercise-menu-btn.selected {
    background: #e4c239;
    color: #222;
    font-weight: bold;
    box-shadow: 0 0 6px rgba(234, 179, 8, 0.4);
    border: none;
}

.menu-cover-img {
    display: block;
    margin: 0 auto 12px auto;
    width: 100px;
    height: 100px;
    object-fit: contain;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.10);
}


.content {
    margin-right: 220px;
    padding: 0 20px;
    flex-grow: 1;
}

.nav-close-btn {
    display: none;
    align-items: center;
    justify-content: center;
    padding: 0;
}

@media (max-width:900px) {
    nav {
        transform: translateX(100%);
    }

    nav.open {
        transform: translateX(0);
    }

    .nav-close-btn {
        display: block !important;
        position: absolute;
        top: 16px;
        left: 16px;
        background: #e74c3c;
        color: #fff;
        border: none;
        border-radius: 50%;
        width: 32px;
        height: 32px;
        font-size: 1.3em;
        cursor: pointer;
        z-index: 1001;
        display: flex !important;
        align-items: center;
        justify-content: center;
        padding: 0;
    }

    .content {
        margin-right: 0;
    }

}