:root {
    --bg-color: #020617;
    --card-bg: rgba(15, 23, 42, 0.7);
    --accent-primary: #a855f7;
    --accent-secondary: #3b82f6;
    --accent-tertiary: #ec4899;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.8);
    --font-main: 'Outfit', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
}

@keyframes glow {
    0% { filter: drop-shadow(0 0 5px var(--accent-primary)); }
    50% { filter: drop-shadow(0 0 15px var(--accent-primary)); }
    100% { filter: drop-shadow(0 0 5px var(--accent-primary)); }
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-main);
    overflow: hidden;
    height: 100vh;
    width: 100vw;
}

#app {
    position: relative;
    height: 100%;
    width: 100%;
    display: flex;
}

canvas {
    position: absolute;
    top: 0;
    left: 0;
    z-index: 1;
    cursor: crosshair;
}

/* Sidebar / Overlay Controls */
.controls-container {
    position: absolute;
    top: 20px;
    left: 20px;
    width: 340px;
    height: calc(100vh - 40px);
    background: var(--card-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 32px;
    z-index: 10;
    display: flex;
    flex-direction: column;
    gap: 24px;
    box-shadow: var(--glass-shadow);
    overflow-y: auto;
    scrollbar-width: none;
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.controls-container::-webkit-scrollbar {
    display: none;
}

.header-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
}

.icon-btn {
    background: rgba(255, 255, 255, 0.1);
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 800;
    color: var(--accent-primary);
    border: 1px solid var(--glass-border);
}

header h1 {
    font-size: 2rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary), var(--accent-tertiary));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.02em;
    margin-bottom: 4px;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 600;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.control-group label {
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--text-secondary);
    display: flex;
    justify-content: space-between;
}

.control-group label span {
    font-family: var(--font-mono);
    color: var(--accent-primary);
}

/* Custom Range Input Styling */
input[type=range] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    background: transparent;
}

input[type=range]:focus {
    outline: none;
}

input[type=range]::-webkit-slider-runnable-track {
    width: 100%;
    height: 6px;
    cursor: pointer;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 3px;
}

input[type=range]::-webkit-slider-thumb {
    height: 20px;
    width: 20px;
    border-radius: 50%;
    background: var(--accent-primary);
    cursor: pointer;
    -webkit-appearance: none;
    margin-top: -7px;
    box-shadow: 0 0 15px var(--accent-primary);
    border: 2px solid white;
    transition: transform 0.1s ease;
}

input[type=range]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.vertex-actions {
    display: grid;
    grid-template-columns: 1fr 1fr 2fr;
    gap: 8px;
}

button {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
    padding: 10px;
    border-radius: 12px;
    cursor: pointer;
    font-family: var(--font-main);
    font-weight: 600;
    transition: all 0.2s ease;
}

button:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-2px);
    border-color: var(--accent-secondary);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.2);
}

button:active {
    transform: translateY(0px);
}

.color-presets, .preset-btns {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
}

.color-btn.active, .preset-btn:active {
    background: var(--accent-primary);
    border-color: transparent;
}

.stats {
    background: rgba(0, 0, 0, 0.2);
    padding: 16px;
    border-radius: 16px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.stats p {
    font-family: var(--font-mono);
    font-size: 0.85rem;
}

#clearCanvas {
    background: rgba(239, 68, 68, 0.2);
    color: #ef4444;
    border-color: rgba(239, 68, 68, 0.2);
}

#clearCanvas:hover {
    background: #ef4444;
    color: white;
}

.special-btn {
    background: linear-gradient(45deg, var(--accent-primary), var(--accent-tertiary));
    border: none;
    color: white;
    font-weight: 800;
}

.special-btn.active {
    animation: glow-pulse 2s infinite;
}

@keyframes glow-pulse {
    0% { box-shadow: 0 0 5px var(--accent-tertiary); }
    50% { box-shadow: 0 0 20px var(--accent-tertiary); }
    100% { box-shadow: 0 0 5px var(--accent-tertiary); }
}

/* Modal & Tabs */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(8px);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: opacity 0.3s ease;
}

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

.modal-content {
    background: var(--card-bg);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    width: 90%;
    max-width: 600px;
    max-height: 85vh;
    position: relative;
    padding: 40px;
    overflow-y: auto;
    box-shadow: var(--glass-shadow);
}

.close-btn {
    position: absolute;
    top: 20px;
    right: 20px;
    background: transparent;
    border: none;
    font-size: 24px;
    color: var(--text-secondary);
    cursor: pointer;
}

.modal-tabs {
    display: flex;
    gap: 20px;
    margin-bottom: 32px;
    border-bottom: 1px solid var(--glass-border);
}

.tab-btn {
    background: transparent;
    border: none;
    border-bottom: 2px solid transparent;
    padding: 10px 0;
    color: var(--text-secondary);
    border-radius: 0;
}

.tab-btn.active {
    color: var(--accent-primary);
    border-bottom-color: var(--accent-primary);
    background: transparent;
}

.tab-panel {
    display: none;
}

.tab-panel.active {
    display: block;
    animation: fadeIn 0.3s ease;
}

.theory-box {
    background: rgba(0, 0, 0, 0.3);
    padding: 24px;
    border-radius: 16px;
    margin: 20px 0;
    border-left: 4px solid var(--accent-primary);
}

.theory-box h3 {
    margin-bottom: 12px;
    color: var(--accent-primary);
}

.theory-box ol {
    padding-left: 20px;
}

.theory-box li {
    margin-bottom: 8px;
    color: var(--text-primary);
}

h2 {
    margin-bottom: 20px;
    color: var(--text-primary);
}

p {
    margin-bottom: 15px;
    line-height: 1.6;
    color: var(--text-secondary);
}

ul {
    padding-left: 20px;
}

ul li {
    margin-bottom: 12px;
    color: var(--text-secondary);
}

li strong {
    color: var(--text-primary);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 768px) {
    .modal-content {
        padding: 24px;
    }
}

/* Tooltip Hint Overlay */
.hint {
    position: absolute;
    bottom: 40px;
    right: 40px;
    background: var(--card-bg);
    backdrop-filter: blur(8px);
    padding: 12px 24px;
    border-radius: 50px;
    border: 1px solid var(--glass-border);
    z-index: 5;
    animation: float 4s ease-in-out infinite;
    pointer-events: none;
    color: var(--text-secondary);
    font-weight: 600;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

/* Responsive sidebar */
@media (max-width: 768px) {
    .controls-container {
        top: auto;
        bottom: 0;
        left: 0;
        width: 100%;
        height: 60vh;
        border-radius: 32px 32px 0 0;
        border-bottom: none;
    }
    
    .hint {
        top: 20px;
        bottom: auto;
        right: 20px;
    }
}