:root {
    /* Color Palette - Premium Dark Mode */
    --bg-color: #0b0c10;
    --panel-bg: rgba(22, 24, 31, 0.7);
    --panel-border: rgba(255, 255, 255, 0.08);
    --text-primary: #f8f9fa;
    --text-secondary: #a0a5ba;
    --accent-glow: rgba(100, 200, 255, 0.2);
    --close-btn-hover: #ff4757;

    /* Typography */
    --font-primary: 'Inter', sans-serif;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-primary);
    overflow: hidden;
    /* Prevent scrolling, 3D graph takes full viewport */
    user-select: none;
    /* Make UI feel more like an app */
}

#graph-container {
    width: 100vw;
    height: 100vh;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 1;
    /* Lowest layer */
}

/* --- UI Overlay (Title) --- */
#ui-overlay {
    position: absolute;
    top: 2rem;
    left: 2rem;
    z-index: 10;
    pointer-events: none;
    /* Let clicks pass through to the canvas */
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.8);
}

#ui-overlay h1 {
    font-size: 2.5rem;
    font-weight: 600;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, #fff, #888);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
}

#ui-overlay p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-weight: 300;
    letter-spacing: 0.05em;
    text-transform: uppercase;
}

/* --- Details Panel --- */
#details-panel {
    position: absolute;
    top: 0;
    right: 0;
    width: 400px;
    height: 100vh;
    background: var(--panel-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    /* Safari support */
    border-left: 1px solid var(--panel-border);
    z-index: 20;
    padding: 2.5rem;
    box-shadow: -10px 0 30px rgba(0, 0, 0, 0.5);

    /* Animation */
    transform: translateX(100%);
    transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.4s ease;
    opacity: 0;

    display: flex;
    flex-direction: column;
}

#details-panel:not(.hidden) {
    transform: translateX(0);
    opacity: 1;
}

/* Close Button */
#close-panel {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 1.8rem;
    cursor: pointer;
    transition: color 0.2s;
    line-height: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border-radius: 50%;
}

#close-panel:hover {
    color: var(--close-btn-hover);
    background: rgba(255, 255, 255, 0.05);
}

/* Panel Content Styling */
.panel-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 0.5rem;
    padding-right: 2rem;
    /* Save space for close btn */
}

.node-color-indicator {
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background-color: #fff;
    box-shadow: 0 0 10px currentColor;
    /* Glow effect matching color */
    flex-shrink: 0;
}

#node-title {
    font-size: 1.4rem;
    font-weight: 500;
    word-break: break-word;
}

.node-meta {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--panel-border);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.panel-content {
    flex-grow: 1;
    overflow-y: auto;
    padding-right: 0.5rem;

    /* Custom Scrollbar for details */
    scrollbar-width: thin;
    scrollbar-color: rgba(255, 255, 255, 0.2) transparent;
}

.panel-content::-webkit-scrollbar {
    width: 6px;
}

.panel-content::-webkit-scrollbar-track {
    background: transparent;
}

.panel-content::-webkit-scrollbar-thumb {
    background-color: rgba(255, 255, 255, 0.2);
    border-radius: 10px;
}

#node-description {
    font-size: 0.95rem;
    line-height: 1.7;
    color: rgba(255, 255, 255, 0.85);
    /* Essential setting so text can be selected and read naturally */
    user-select: text;
}

/* --- Loading Overlay --- */
#loading-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: var(--bg-color);
    z-index: 100;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    transition: opacity 0.5s ease;
}

#loading-overlay.hidden {
    opacity: 0;
    pointer-events: none;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 3px solid rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s ease-in-out infinite;
    margin-bottom: 1.5rem;
    box-shadow: 0 0 20px rgba(255, 255, 255, 0.1);
}

#loading-overlay p {
    font-size: 1.1rem;
    letter-spacing: 0.1em;
    color: var(--text-secondary);
    animation: pulse 2s infinite alternate;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

@keyframes pulse {
    from {
        opacity: 0.5;
    }

    to {
        opacity: 1;
    }
}

/* Responsive Panel */
@media (max-width: 768px) {
    #details-panel {
        width: 100%;
        max-width: 100vw;
        border-left: none;
        box-shadow: none;
        transform: translateY(100%);
    }

    #details-panel:not(.hidden) {
        transform: translateY(0);
    }

    #ui-overlay {
        top: 1rem;
        left: 1rem;
    }

    #ui-overlay h1 {
        font-size: 1.8rem;
    }
}