:root {
    --bg-color: #f0f2f5;
    --panel-bg: #ffffff;
    --text-color: #1e293b;
    --accent-color: #0284c7;
    --accent-hover: #0369a1;
    --border-color: #cbd5e1;
    --input-bg: #f8fafc;
    --controls-bg: rgba(241, 245, 249, 0.92);
    --nucleus-color: #1e293b;
    --bohr-btn-bg: #f1f5f9;
    --bohr-btn-stroke: #0284c7;
    --bohr-label-fill: #0284c7;
    --active-btn-stroke: #1e293b;
    --instruction-color: #64748b;
    --scene-bg: #f0f2f5;

    --phase-pos: #ef4444;
    --phase-neg: #3b82f6;
}

:root[data-theme="dark"] {
    --bg-color: #0f172a;
    --panel-bg: #1e293b;
    --text-color: #e2e8f0;
    --accent-color: #38bdf8;
    --accent-hover: #0ea5e9;
    --border-color: #334155;
    --input-bg: #1e293b;
    --controls-bg: rgba(30, 41, 59, 0.9);
    --nucleus-color: #ffffff;
    --bohr-btn-bg: #1e293b;
    --bohr-btn-stroke: #38bdf8;
    --bohr-label-fill: #38bdf8;
    --active-btn-stroke: #ffffff;
    --instruction-color: #94a3b8;
    --scene-bg: #000000;
}

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

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    height: 100vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: background-color 0.2s ease, color 0.2s ease;
}

#app {
    display: flex;
    flex: 1;
    height: 100%;
}

.panel {
    padding: 1rem;
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--border-color);
    transition: background-color 0.2s ease, border-color 0.2s ease;
}

h2 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: var(--accent-color);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
}

/* --- Vue 1: Bohr Selector --- */
#bohr-container {
    width: 350px;
    background-color: var(--panel-bg);
    overflow-y: auto;
    transition: background-color 0.2s ease;
}

#bohr-diagram {
    flex: 1;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
}

.instruction {
    font-size: 0.9rem;
    color: var(--instruction-color);
    text-align: center;
    margin-top: 1rem;
}

svg text {
    fill: var(--text-color);
    font-size: 12px;
    font-family: monospace;
    pointer-events: none;
    text-anchor: middle;
    dominant-baseline: middle;
}

.orbital-btn {
    fill: var(--bg-color);
    stroke: var(--accent-color);
    stroke-width: 2;
    cursor: pointer;
    transition: all 0.2s;
}

.orbital-btn:hover {
    fill: var(--accent-color);
    fill-opacity: 0.2;
}

.orbital-btn.active {
    fill: var(--accent-color);
    stroke: var(--active-btn-stroke);
}

.shell-ring {
    fill: none;
    stroke: var(--border-color);
    stroke-dasharray: 4;
}

/* --- Vue 2: Visualizer --- */
#visualizer-container {
    flex: 1;
    position: relative;
    padding: 0;
    background-color: var(--scene-bg);
    transition: background-color 0.2s ease;
}

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

#controls-overlay {
    position: absolute;
    bottom: 20px;
    right: 20px;
    width: 300px;
    background: var(--controls-bg);
    padding: 1rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    z-index: 10;
    backdrop-filter: blur(4px);
    transition: background-color 0.2s ease, border-color 0.2s ease;
}

.control-group {
    margin-bottom: 1rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    font-weight: 600;
}

select,
input[type="range"] {
    width: 100%;
    background: var(--input-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    padding: 0.5rem;
    border-radius: 4px;
    transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

input[type="range"] {
    cursor: pointer;
}

#orbital-info {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

#orbital-info h3 {
    font-size: 1rem;
    margin-bottom: 0.5rem;
}

.legend {
    display: flex;
    gap: 1rem;
    font-size: 0.85rem;
}

.dot {
    display: inline-block;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    margin-right: 4px;
}

.dot.positive {
    background-color: var(--phase-pos);
}

.dot.negative {
    background-color: var(--phase-neg);
}

.app-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 1rem;
    background: var(--panel-bg);
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
    transition: background-color 0.2s ease, border-color 0.2s ease;
}

.app-header h1 {
    font-size: 1rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--accent-color);
    border: none;
    padding: 0;
    margin: 0;
}

.app-header .header-right {
    display: flex;
    align-items: center;
    gap: 12px;
}

.header-credit {
    font-size: 0.7em;
    font-weight: 300;
    color: var(--text-muted, var(--text-color));
    opacity: 0.7;
}

.theme-toggle {
    font-family: 'Inter', system-ui, sans-serif;
    font-size: 0.85rem;
    font-weight: 500;
    background: var(--input-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 6px 10px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 4px;
    transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.theme-toggle:hover {
    background: var(--accent-color);
    color: #fff;
    border-color: var(--accent-color);
}