/* ===================================================================
   SPA TRANSITION - Subtle & Clean
   =================================================================== */
#appContent {
    opacity: 1;
    transform: translateY(0);
    transition: opacity 0.25s cubic-bezier(0.4, 0, 0.2, 1),
                transform 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    will-change: opacity, transform;
}

#appContent.spa-exit {
    opacity: 0;
    transform: translateY(8px);
}

#appContent.spa-enter {
    opacity: 1;
    transform: translateY(0);
}

/* ===================================================================
   SKELETON LOADER
   =================================================================== */
.skeleton {
    background: linear-gradient(
        90deg,
        #f0f0f0 0%,
        #e0e0e0 20%,
        #f0f0f0 40%,
        #f0f0f0 100%
    );
    background-size: 200% 100%;
    animation: shimmer 1.5s ease-in-out infinite;
    border-radius: 8px;
    position: relative;
    overflow: hidden;
}

@keyframes shimmer {
    0% {
        background-position: -200% 0;
    }
    100% {
        background-position: 200% 0;
    }
}

/* ===================================================================
   CONTENT FADE IN
   =================================================================== */
.content-item {
    opacity: 0;
    transform: translateY(15px);
    animation: fadeInUp 0.5s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

.content-item:nth-child(1) { animation-delay: 0.05s; }
.content-item:nth-child(2) { animation-delay: 0.1s; }
.content-item:nth-child(3) { animation-delay: 0.15s; }
.content-item:nth-child(4) { animation-delay: 0.2s; }
.content-item:nth-child(5) { animation-delay: 0.25s; }
.content-item:nth-child(6) { animation-delay: 0.3s; }

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ===================================================================
   SMOOTH SCROLL
   =================================================================== */
html {
    scroll-behavior: smooth;
}

/* ===================================================================
   NAVBAR ACTIVE STATE ENHANCEMENT
   =================================================================== */
.nav-link.active {
    position: relative;
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 2px;
    background: rgb(13, 161, 99);
    animation: underlineExpand 0.3s ease forwards;
}

@keyframes underlineExpand {
    to {
        width: 70%;
    }
}

/* ===================================================================
   PERFORMANCE OPTIMIZATION
   =================================================================== */
.custom-card-glass,
.navbar-glass,
.skeleton,
.content-item {
    backface-visibility: hidden;
    perspective: 1000px;
}

/* ===================================================================
   DROPDOWN ANIMATION
   =================================================================== */
.dropdown-menu.glass-dropdown {
    animation-duration: 0.3s !important;
}