:root {
    --primary: #a855f7;
    --primary-dark: #8b5cf6;
    --bg: #0b0f19;
    --card-bg: rgba(17, 24, 39, 0.8);
    --text: #f3f4f6;
    --text-muted: #9ca3af;
    --border: rgba(55, 65, 81, 0.5);
    --laser-red: #ef4444;
    --laser-green: #22c55e;
    --laser-blue: #3b82f6;
    --radius: 12px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    background-color: var(--bg);
    color: var(--text);
    overflow-x: hidden;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.container-flex {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Header */
.simulation-header {
    background: rgba(11, 15, 25, 0.8);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.sim-title {
    font-family: 'Outfit', sans-serif;
    font-size: 1.4rem;
    background: linear-gradient(135deg, var(--primary), #ec4899);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.back-link {
    text-decoration: none;
    color: var(--primary);
    font-weight: 600;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.badge {
    background: var(--primary);
    color: white;
    padding: 0.4rem 1rem;
    border-radius: 50px;
    font-weight: 700;
    font-size: 0.8rem;
    box-shadow: 0 0 15px rgba(168, 85, 247, 0.3);
}

/* Layout */
.sim-main { padding: 2rem 0; }

.sim-layout {
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 2rem;
}

@media (max-width: 1000px) {
    .sim-layout { grid-template-columns: 1fr; }
}

/* Controls */
.controls-panel {
    background: var(--card-bg);
    border: 1px solid var(--border);
    padding: 2rem;
    border-radius: var(--radius);
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    height: fit-content;
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
}

.control-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.75rem;
    font-size: 0.85rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.toggle-group {
    display: flex;
    background: #1f2937;
    padding: 3px;
    border-radius: 8px;
    gap: 2px;
}

.btn-toggle {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-muted);
    padding: 0.6rem;
    border-radius: 6px;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.4rem;
}

.btn-toggle.active {
    background: var(--primary);
    color: white;
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
}

input[type="range"] {
    width: 100%;
    accent-color: var(--primary);
    cursor: pointer;
}

.range-labels {
    display: flex;
    justify-content: space-between;
    font-size: 0.7rem;
    color: var(--text-muted);
    margin-top: 4px;
}

.btn-primary {
    background: var(--primary);
    color: white;
    padding: 1rem;
    border: none;
    border-radius: 8px;
    font-weight: 700;
    cursor: pointer;
    transition: 0.2s;
    box-shadow: 0 4px 14px rgba(168, 85, 247, 0.4);
}

.btn-primary:hover { transform: translateY(-2px); background: var(--primary-dark); }
.btn-secondary { background: #374151; color: white; border: none; padding: 0.8rem; border-radius: 8px; cursor: pointer; }

.theory-box {
    margin-top: 1rem;
    padding: 1rem;
    background: rgba(168, 85, 247, 0.05);
    border-left: 3px solid var(--primary);
    border-radius: 4px;
}

.theory-box h3 { font-size: 0.9rem; color: var(--primary); margin-bottom: 0.5rem; }
.theory-box p { font-size: 0.8rem; line-height: 1.5; color: var(--text-muted); }

/* Visualizer Area */
.experiment-area {
    display: flex;
    gap: 1.5rem;
    height: 500px;
}

.canvas-wrapper {
    flex-grow: 1;
    position: relative;
    background: #05070a;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    overflow: hidden;
}

#mainCanvas { width: 100%; height: 100%; }

.v-distribution {
    width: 150px;
    background: rgba(255,255,255,0.02);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    overflow: hidden;
}

#graphCanvas { width: 100%; height: 100%; }

.label-tag {
    position: absolute;
    bottom: 10px;
    font-size: 0.7rem;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--text-muted);
    letter-spacing: 0.1em;
}

. gun { left: 20px; }
.slits { left: 50%; transform: translateX(-50%); }
.screen { right: 20px; }

/* Data Summary */
.data-summary {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.data-item {
    background: var(--card-bg);
    padding: 1.25rem;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
}

.data-item span { font-size: 0.75rem; color: var(--text-muted); text-transform: uppercase; font-weight: 600; }
.data-item strong { font-size: 1.4rem; font-family: 'Outfit'; color: var(--primary); }
 .w-100 { width: 100%; }
 .button-group { display: flex; flex-direction: column; gap: 0.75rem; margin-top: 1rem; }