:root {
    --bg-top: #040812;
    --bg-bottom: #0d1b35;
    --panel-bg: rgba(10, 16, 32, 0.82);
    --panel-border: rgba(255, 255, 255, 0.08);
    --text-main: #f0f4ff;
    --text-muted: rgba(240,244,255,0.7);
    --accent: #58c2ff;
    --accent-warm: #f8c27a;
    --accent-cool: #5af5c0;
    --font-sans: "Source Han Sans", "Noto Sans SC", "Helvetica Neue", Arial, sans-serif;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: var(--font-sans);
    color: var(--text-main);
    background: radial-gradient(circle at top, rgba(12,20,40,0.8), rgba(4,8,18,1));
    overflow: hidden;
}

#scene-canvas {
    position: fixed;
    inset: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(var(--bg-top), var(--bg-bottom));
    z-index: 0;
}

.sidebar {
    position: absolute;
    top: 40px;
    left: 40px;
    width: min(420px, 90vw);
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    border-radius: 20px;
    padding: 24px;
    backdrop-filter: blur(18px);
    box-shadow: 0 25px 60px rgba(0,0,0,0.4);
    display: flex;
    flex-direction: column;
    gap: 24px;
    z-index: 10;
    max-height: calc(100vh - 80px);
    overflow-y: auto;
    transition: opacity 0.3s ease, transform 0.3s ease;
}

/* Floating Toggle Button */
.mobile-toggle {
    display: none; /* Hidden on desktop */
    position: fixed;
    top: 20px;
    right: 20px; /* Right side */
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: rgba(88, 194, 255, 0.2);
    border: 1px solid rgba(88, 194, 255, 0.5);
    color: #fff;
    font-family: serif;
    font-style: italic;
    font-weight: bold;
    font-size: 1.2rem;
    cursor: pointer;
    z-index: 100;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(10px);
    transition: all 0.2s;
}

.mobile-toggle:hover {
    background: rgba(88, 194, 255, 0.4);
    transform: scale(1.05);
}

.lang-switcher {
    display: flex;
    gap: 8px;
    margin-bottom: 8px;
}

.lang-btn {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    padding: 4px 10px;
    font-size: 0.8rem;
    color: var(--text-muted);
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s;
}

.lang-btn:hover {
    background: rgba(255, 255, 255, 0.1);
}

.lang-btn.active {
    background: var(--accent);
    color: #041423;
    border-color: var(--accent);
    font-weight: 600;
}

.eyebrow {
    font-size: 0.8rem;
    letter-spacing: 0.3em;
    text-transform: uppercase;
    color: var(--text-muted);
}

h1 {
    margin: 6px 0 10px;
    font-size: 1.8rem;
}

.intro {
    color: var(--text-muted);
    line-height: 1.7;
}

.controls {
    display: grid;
    gap: 14px;
}

.control-group {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.95rem;
    color: var(--text-muted);
}

.legend h4 {
    margin: 0 0 10px;
    color: var(--text-main);
    font-size: 0.9rem;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 8px;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.color-box {
    display: inline-block;
    width: 14px;
    height: 14px;
    border-radius: 4px;
}

button#btn-reset {
    background: rgba(255, 255, 255, 0.1);
    color: var(--text-main);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 8px;
    padding: 10px 18px;
    font-weight: 600;
    cursor: pointer;
    margin-top: 10px;
    width: 100%;
}

button#btn-reset:hover {
    background: rgba(255, 255, 255, 0.2);
}

@media (max-width: 768px) {
    .mobile-toggle {
        display: flex;
    }

    .sidebar {
        position: fixed;
        top: auto;
        bottom: 80px; /* Above controls/bottom area */
        left: 50%;
        transform: translateX(-50%) translateY(20px);
        width: 90%;
        max-height: 60vh;
        
        /* Hidden by default */
        opacity: 0;
        pointer-events: none; 
        visibility: hidden;
    }

    .sidebar.open {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
        pointer-events: auto;
        visibility: visible;
    }

    .lang-switcher {
        justify-content: center;
    }

    h1 {
        text-align: center;
        font-size: 1.4rem;
    }

    .eyebrow {
        text-align: center;
    }
}

/* Enhanced Back Button */
.back-to-home {
    position: fixed;
    top: 20px;
    left: 20px; /* Move to left to avoid conflict with toggle */
    padding: 8px 16px;
    background: rgba(20, 30, 50, 0.6);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: 999px;
    color: #ffffff;
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    transition: all 0.2s ease;
    z-index: 9999; /* Ensure it's on top */
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.back-to-home:hover {
    background: rgba(255, 255, 255, 0.15);
    border-color: rgba(255, 255, 255, 0.6);
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(0,0,0,0.3);
}