:root {
    /* Palette: Cyber Teal (Between Green and Blue) */
    --teal-primary: #2dd4bf;
    /* Teal 400 - Vibrant */
    --teal-light: #5eead4;
    /* Teal 300 - Glow */
    --teal-dim: #115e59;
    /* Teal 800 - Deep */

    --accent-blue: #3b82f6;
    /* Royal Blue for contrast */
    --accent-cyan: #06b6d4;
    /* Cyan 500 */

    --bg-dark: #050505;
    /* Ultra Dark */
    --bg-card: #0F0F0F;
    /* Card Surface */

    --glass-border: rgba(45, 212, 191, 0.15);
}

/* Base optimizations */
body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-dark);
    color: #f5f5f5;
    background-image:
        radial-gradient(circle at 10% 20%, rgba(45, 212, 191, 0.05), transparent 40%),
        radial-gradient(circle at 90% 80%, rgba(59, 130, 246, 0.05), transparent 40%);
    /* Prevent horizontal scroll on mobile */
    overflow-x: hidden;
    -webkit-tap-highlight-color: transparent;
}

h1,
h2,
h3,
.serif-font {
    font-family: 'Cinzel', serif;
}

.gradient-text {
    background: linear-gradient(135deg, var(--teal-light), var(--accent-cyan));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    background-attachment: fixed;
    /* Parallax-like feel */
}

/* Glassmorphism - Optimized */
.card-glass {
    background: rgba(15, 15, 15, 0.85);
    /* Slightly more opaque to reduce reliance on blur */
    backdrop-filter: blur(8px);
    /* Reduced from potentially higher values in original concepts */
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid var(--glass-border);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
    /* GPU Acceleration */
    transform: translateZ(0);
    will-change: transform;
    /* Hint to browser */
}

.card-hover {
    transition: transform 0.2s cubic-bezier(0.2, 0, 0, 1),
        /* Faster easing */
        box-shadow 0.2s cubic-bezier(0.2, 0, 0, 1),
        border-color 0.2s ease;
    will-change: transform;
}

@media (hover: hover) {
    .card-hover:hover {
        transform: translateY(-4px) scale(1.005);
        background: rgba(20, 25, 30, 0.95);
        /* Nearly opaque on hover for crispness */
        border-color: rgba(45, 212, 191, 0.4);
        box-shadow:
            0 10px 20px -5px rgba(0, 0, 0, 0.5),
            /* Reduced shadow spread for perf */
            0 0 10px rgba(45, 212, 191, 0.1);
    }


    .card-hover:hover .step-id {
        color: var(--teal-light);
        opacity: 0.15;
        transform: scale(1.05);
    }

    .card-hover:hover .learn-icon {
        color: var(--teal-primary);
        transform: rotate(12deg);
    }
}

/* Mobile Active State for touch feedback */
.card-hover:active {
    transform: scale(0.98);
    border-color: var(--teal-primary);
}

/* Animation utilities */
.fade-in-up {
    opacity: 0;
    transform: translateY(20px);
    /* Faster transition for snappier feel */
    transition: opacity 0.5s ease-out, transform 0.5s ease-out;
    content-visibility: auto;
    /* Browser optimization for off-screen content */
}

.fade-in-up.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-dark);
}

::-webkit-scrollbar-thumb {
    background: #333;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--teal-dim);
}

/* Skeleton Loading Animation */
@keyframes pulse-fast {

    0%,
    100% {
        opacity: 1;
    }

    50% {
        opacity: .5;
    }
}

.skeleton {
    animation: pulse-fast 1.5s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}