:root {
    --light-bg: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    --dark-bg: linear-gradient(135deg, #232526 0%, #414345 100%);
    --light-panel-bg: rgba(255, 255, 255, 0.85);
    --dark-panel-bg: rgba(50, 50, 55, 0.85);
    --light-text: #333;
    --dark-text: #e0e0e0;
    --light-button-bg: rgba(255, 255, 255, 0.9);
    --dark-button-bg: rgba(70, 70, 80, 0.9);
    --light-button-hover-bg: white;
    --dark-button-hover-bg: rgba(90, 90, 100, 1);
    --light-border: rgba(0, 0, 0, 0.1);
    --dark-border: rgba(255, 255, 255, 0.15);
    --accent-color-light: #3498db;
    --accent-color-dark: #FF6A88;
    --shadow-light: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-dark: 0 4px 12px rgba(0, 0, 0, 0.3);
    --border-radius-sm: 4px;
    --border-radius-md: 8px;
    --border-radius-lg: 12px;
    --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-size-sm: 12px;
    --font-size-md: 14px;
    --font-size-lg: 16px;
}

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

body {
    margin: 0;
    padding: 0;
    overflow: hidden;
    background: var(--light-bg);
    height: 100vh;
    font-family: var(--font-family);
    color: var(--light-text);
    transition: background 0.4s ease, color 0.4s ease;
}

body.dark-theme {
    background: var(--dark-bg);
    color: var(--dark-text);
}

#canvas-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}

/* UI Overlay Container */
#ui-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none; /* Allow clicks to pass through */
    z-index: 100;
}

/* General UI Panel Style */
.ui-panel {
    position: fixed;
    background: var(--light-panel-bg);
    color: var(--light-text);
    padding: 12px 15px;
    border-radius: var(--border-radius-md);
    box-shadow: var(--shadow-light);
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
    border: 1px solid var(--light-border);
    font-size: var(--font-size-sm);
    transition: background 0.4s ease, color 0.4s ease, border-color 0.4s ease;
    pointer-events: auto; /* Panels are interactive */
}

body.dark-theme .ui-panel {
    background: var(--dark-panel-bg);
    color: var(--dark-text);
    box-shadow: var(--shadow-dark);
    border-color: var(--dark-border);
}

/* General Button Style */
.ui-button {
    border: none;
    border-radius: var(--border-radius-md);
    padding: 8px 12px;
    background: var(--light-button-bg);
    color: var(--light-text);
    box-shadow: var(--shadow-light);
    cursor: pointer;
    transition: transform 0.2s ease, background 0.2s ease, box-shadow 0.2s ease;
    font-family: var(--font-family);
    font-size: var(--font-size-md);
    pointer-events: auto; /* Buttons are interactive */
    backdrop-filter: blur(3px);
    -webkit-backdrop-filter: blur(3px);
    border: 1px solid var(--light-border);
}

.ui-button:hover {
    transform: translateY(-2px);
    background: var(--light-button-hover-bg);
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.15);
}

.ui-button:active {
    transform: translateY(0px);
    box-shadow: var(--shadow-light);
}

body.dark-theme .ui-button {
    background: var(--dark-button-bg);
    color: var(--dark-text);
    box-shadow: var(--shadow-dark);
    border-color: var(--dark-border);
}

body.dark-theme .ui-button:hover {
    background: var(--dark-button-hover-bg);
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.4);
}

body.dark-theme .ui-button:active {
    box-shadow: var(--shadow-dark);
}

/* Icon Button Style */
.icon-button {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    font-size: 20px;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
}

/* Control Buttons Container */
.control-buttons-container {
    position: fixed;
    top: 15px;
    right: 70px; /* Adjust based on theme toggle position */
    display: flex;
    gap: 10px;
    pointer-events: auto; /* Container itself doesn't block, but buttons do */
}

/* Theme Toggle Button */
#theme-toggle {
    position: fixed;
    top: 15px;
    right: 15px;
}

/* Simulation Status Panel */
.sim-status {
    bottom: 15px;
    left: 15px;
    font-size: var(--font-size-sm);
    white-space: nowrap;
}

.status-active {
    color: #2ecc71; /* Green */
    font-weight: bold;
}

.status-inactive {
    color: #e74c3c; /* Red */
    font-weight: bold;
}

body.dark-theme .status-active {
    color: #58d68d;
}

body.dark-theme .status-inactive {
    color: #f1948a;
}


/* Debug Info Panel */
.debug-info {
    top: 15px;
    left: 15px;
    font-family: monospace;
    font-size: var(--font-size-sm);
    line-height: 1.4;
}

/* Control Panel */
.control-panel {
    bottom: 15px;
    right: 15px;
    max-width: 220px;
}

.control-panel h4 {
    margin-top: 0;
    margin-bottom: 8px;
    font-weight: 600;
}

.control-panel ul {
    list-style: none;
    padding-left: 0;
    margin: 0;
}

.control-panel li {
    margin-bottom: 4px;
    font-size: var(--font-size-sm);
}

/* Instruction Popup */
.instruction-popup {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 90%;
    max-width: 400px;
    z-index: 1001; /* Above other UI */
    padding: 20px 25px;
    text-align: center;
    animation: fadeInScale 0.4s ease-out;
}

.instruction-popup h4 {
    margin-top: 0;
    margin-bottom: 10px;
    font-size: var(--font-size-lg);
}

.instruction-popup p {
    margin-bottom: 10px;
    font-size: var(--font-size-md);
    line-height: 1.5;
}

.instruction-popup .close-button {
    position: absolute;
    top: 8px;
    right: 8px;
    background: transparent;
    border: none;
    font-size: 24px;
    line-height: 1;
    padding: 5px;
    cursor: pointer;
    color: inherit;
    opacity: 0.7;
    transition: opacity 0.2s ease;
}

.instruction-popup .close-button:hover {
    opacity: 1;
}


/* Hide touch/keyboard specific controls */
body:not(.touch-device) .touch-only {
    display: none;
}

body.touch-device .keyboard-only {
    display: none;
}

/* Media query for smaller screens (adjust layout) */
@media (max-width: 600px) {
    .control-panel {
        bottom: 10px;
        right: 10px;
        max-width: 180px;
        padding: 10px;
    }
    .sim-status {
        bottom: 10px;
        left: 10px;
        padding: 8px 10px;
    }
    .debug-info {
        display: none; /* Hide debug info on small screens */
    }
    .control-buttons-container {
        top: auto;
        bottom: 10px;
        right: 50%;
        transform: translateX(50%);
        gap: 15px;
    }
    #theme-toggle {
        top: 10px;
        right: 10px;
        width: 40px;
        height: 40px;
        font-size: 18px;
    }
    .icon-button {
        width: 40px;
        height: 40px;
        font-size: 18px;
    }
}


/* Animations */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes fadeInScale {
    from { opacity: 0; transform: translate(-50%, -50%) scale(0.9); }
    to { opacity: 1; transform: translate(-50%, -50%) scale(1); }
}

@keyframes fadeOut {
    from { opacity: 1; }
    to { opacity: 0; }
}