/* Custom Scrollbar */
.custom-scrollbar::-webkit-scrollbar {
    width: 8px;
}
.custom-scrollbar::-webkit-scrollbar-track {
    background: transparent;
}
.custom-scrollbar::-webkit-scrollbar-thumb {
    background: #334155;
    border-radius: 4px;
}
.custom-scrollbar::-webkit-scrollbar-thumb:hover {
    background: #475569;
}

/* Chapter Transition */
.chapter {
    display: none;
    animation: fadeIn 0.5s ease-out forwards;
}
.chapter.active {
    display: block;
}

/* Visual Container Transition */
.vis-container {
    display: none;
    animation: fadeInScale 0.6s ease-out forwards;
}
.vis-container.active {
    display: flex;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInScale {
    from { opacity: 0; transform: scale(0.95); }
    to { opacity: 1; transform: scale(1); }
}

/* Tags */
.tag {
    display: inline-block;
    padding: 0.25rem 1rem;
    background: rgba(99, 102, 241, 0.2);
    color: #818cf8;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 800;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 1.5rem;
}

/* Step Buttons in Header */
.step-btn {
    padding: 0.5rem 1.25rem;
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 600;
    color: #94a3b8;
    transition: all 0.3s;
    border: 1px solid transparent;
}
.step-btn:hover {
    color: #e2e8f0;
    background: rgba(255, 255, 255, 0.05);
}
.step-btn.active {
    color: white;
    background: rgba(99, 102, 241, 0.2);
    border-color: rgba(99, 102, 241, 0.5);
    box-shadow: 0 0 15px rgba(99, 102, 241, 0.2);
}

/* Custom Range Sliders */
input[type=range] {
    -webkit-appearance: none;
    height: 6px;
    background: #334155;
    border-radius: 5px;
    outline: none;
}
input[type=range]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    cursor: pointer;
    transition: transform 0.1s;
}
input[type=range]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}
.slider-indigo::-webkit-slider-thumb {
    background: #818cf8;
    box-shadow: 0 0 10px #818cf8;
}
.slider-pink::-webkit-slider-thumb {
    background: #f472b6;
    box-shadow: 0 0 10px #f472b6;
}

/* Neural Network Neurons */
.neuron {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background: #1e293b;
    border: 3px solid #334155;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    color: #cbd5e1;
    position: relative;
    z-index: 10;
    transition: all 0.3s ease;
    box-shadow: 0 0 15px rgba(0,0,0,0.5);
}

.input-neuron {
    cursor: pointer;
    border-color: #64748b;
}
.input-neuron:hover {
    border-color: #f8fafc;
    transform: scale(1.1);
}

.neuron.active-purple {
    background: rgba(168, 85, 247, 0.2);
    border-color: #a855f7;
    box-shadow: 0 0 20px rgba(168, 85, 247, 0.6);
    color: #fff;
}

.neuron.active-pink {
    background: rgba(236, 72, 153, 0.2);
    border-color: #ec4899;
    box-shadow: 0 0 20px rgba(236, 72, 153, 0.6);
    color: #fff;
}

/* NN Canvas Line animation */
canvas#nnCanvas {
    pointer-events: none;
}