:root {
    --main-color: #667eea;
    --nav-bg: #fff;
    --nav-shadow: 0 -2px 12px #0001;
    --nav-radius: 22px 22px 0 0;
    --nav-icon-active: var(--main-color);
    --nav-icon-inactive: #888888;
    --nav-text-active: var(--main-color);
    --nav-text-inactive: #888888;
}

.nav-bar {
    position: fixed;
    bottom: 18px;
    left: 50%;
    transform: translateX(-50%);
    width: calc(100% - 36px);
    max-width: 500px;
    background: #ffffff;
    border-radius: 22px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12);
    border: 1px solid rgba(255,255,255,0.2);
    display: flex;
    justify-content: space-around;
    padding: 12px 8px;
    z-index: 20;
    height: 68px;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    font-size: 13px;
    font-weight: 500;
    color: #666;
    text-decoration: none;
    flex: 1;
    gap: 4px;
    transition: all 0.2s;
}

.nav-item a {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    color: inherit;
    font-size: inherit;
    font-weight: inherit;
    gap: 2px;
}

.nav-item img {
    width: 26px;
    height: 26px;
    filter: grayscale(1) brightness(0.7) contrast(0.9);
    transition: all 0.2s;
}

.nav-item.active {
    color: var(--main-color);
    background: rgba(102, 126, 234, 0.15);
    border-radius: 16px;
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.2);
}

.nav-item.active a {
    color: var(--nav-text-active);
}

.nav-item.active img {
    filter: none;
    transform: scale(1.1);
}

.nav-item a:visited {
    color: inherit;
}

.nav-item a:active,
.nav-item a:focus {
    color: var(--nav-text-active);
    outline: none;
}


@media (max-width: 500px) {
    .nav-bar {
        max-width: 100vw;
        padding: 8px 4px;
        height: 60px;
    }

    .nav-item {
        font-size: 11px;
        gap: 2px;
    }

    .nav-item i {
        font-size: 16px;
    }
}

.menu {
    display: none;
    position: absolute;
    top: 70px;
    right: 30px;
    background: rgba(255,255,255,0.95);
    backdrop-filter: blur(15px);
    box-shadow: 0 4px 20px rgba(0,0,0,0.15);
    border-radius: 12px;
    padding: 15px 0;
    width: 250px;
    transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    z-index: 2000;
    border: 1px solid #f0f0f0;
}

.menu ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.menu li {
    padding: 12px 20px;
    transition: background 0.2s;
}

.menu li:hover {
    background: #f8f8f8;
}

.menu a {
    text-decoration: none;
    color: #333;
    font-size: 16px;
    display: block;
}

.menu.active {
    display: block;
    opacity: 1;
    transform: translateY(5px);
    animation: fadeIn 0.3s ease-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(5px); }
}

/* Slide-in Menu */
.slide-in-menu.open { left: 0; }

.slide-in-menu {
    position: fixed;
    top: 0;
    left: -300px; /* Start off-screen */
    width: 280px;
    height: 100%;
    background: #ffffff;
    box-shadow: 4px 0 15px rgba(0,0,0,0.1);
    z-index: 2000;
    transition: left 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    padding-top: 60px;
}



.slide-in-menu ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.slide-in-menu li a {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 15px 25px;
    color: #333;
    text-decoration: none;
    font-size: 16px;
    font-weight: 500;
    transition: background-color 0.2s, color 0.2s;
}

.slide-in-menu li a:hover {
    background-color: #f5f5f5;
    color: var(--main-color);
}

.slide-in-menu li a i {
    font-size: 20px;
    width: 24px;
    text-align: center;
    color: #888;
    transition: color 0.2s;
}

.slide-in-menu li a:hover i {
    color: var(--main-color);
}

.menu-overlay.open { display: block; }

.menu-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: none;
    z-index: 1000;
}

.menu-overlay.open {
    display: block;
    visibility: visible;
    opacity: 1;
}

/* Scroll behavior animations for navigation */
.nav-bar {
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.3s ease;
}

.nav-bar.nav-hidden {
    transform: translateX(-50%) translateY(120px);
    opacity: 0.7;
}