:root {
    --background: 222 47% 11%;
    --card: 222 47% 14%;
    --primary: 199 89% 48%;
    --cat-alkali: 340 82% 52%;
    --cat-alkaline: 25 95% 53%;
    --cat-transition: 45 93% 47%;
    --cat-post-transition: 170 60% 40%;
    --cat-metalloid: 190 80% 40%;
    --cat-nonmetal: 200 80% 50%;
    --cat-halogen: 280 60% 50%;
    --cat-noble: 320 60% 50%;
    --cat-lanthanide: 30 60% 60%;
    --cat-actinide: 340 60% 60%;
}

body {
    background-color: hsl(222, 47%, 11%);
    color: white;
    font-family: 'Plus Jakarta Sans', sans-serif;
    margin: 0;
    height: 100vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.periodic-grid {
    display: grid;
    grid-template-columns: repeat(18, minmax(0, 1fr));
    gap: 4px;
    width: 100%;
    max-width: 1400px;
    padding-bottom: 2rem;
}

.element-cell {
    aspect-ratio: 1 / 1;
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 4px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s;
    position: relative;
    background: rgba(255, 255, 255, 0.02);
}

.element-cell:hover {
    transform: scale(1.1);
    z-index: 10;
    background-color: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.3);
}

.ion-charge-badge {
    position: absolute;
    top: 2px;
    right: 3px;
    font-size: 7px;
    font-weight: 900;
    color: #a855f7;
    background: rgba(168, 85, 247, 0.15);
    padding: 1px 3px;
    border-radius: 3px;
    line-height: 1;
}

.ion-charge-badge:empty {
    display: none;
}

.trend-toggle {
    cursor: pointer;
}

.trend-toggle input {
    display: none;
}

.trend-btn {
    display: inline-block;
    padding: 3px 8px;
    font-size: 9px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-radius: 4px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.5);
    transition: all 0.2s;
}

.trend-btn:hover {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.7);
}

.trend-toggle input:checked + .trend-en {
    background: rgba(59, 130, 246, 0.2);
    border-color: rgba(59, 130, 246, 0.5);
    color: #3b82f6;
}

.trend-toggle input:checked + .trend-radius {
    background: rgba(34, 197, 94, 0.2);
    border-color: rgba(34, 197, 94, 0.5);
    color: #22c55e;
}

.trend-toggle input:checked + .trend-ionization {
    background: rgba(249, 115, 22, 0.2);
    border-color: rgba(249, 115, 22, 0.5);
    color: #f97316;
}

.trend-toggle input:checked + .trend-ions {
    background: rgba(168, 85, 247, 0.2);
    border-color: rgba(168, 85, 247, 0.5);
    color: #a855f7;
}

.nav-tab {
    color: rgba(255, 255, 255, 0.5);
    background: transparent;
}

.nav-tab:hover {
    color: rgba(255, 255, 255, 0.8);
    background: rgba(255, 255, 255, 0.05);
}

.nav-tab.active {
    background: #3b82f6;
    color: white;
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.3);
}

#simulator-canvas {
    flex: 1;
    width: 100%;
    background: rgba(0, 0, 0, 0.4);
    border-radius: 12px;
    position: relative;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.particle {
    position: absolute;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    border: 2px solid rgba(255, 255, 255, 0.2);
    background: rgba(0, 0, 0, 0.6);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    cursor: grab;
    user-select: none;
    backdrop-filter: blur(4px);
    box-shadow: 0 0 20px rgba(0,0,0,0.5);
    transition: transform 0.1s, border-color 0.3s, box-shadow 0.3s, opacity 0.3s;
}

.fused-atoms-visual {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 1;
}

.fused-atom-circle {
    position: absolute;
    border-radius: 50%;
    transform: translate(-50%, -50%);
    box-shadow: inset -5px -5px 10px rgba(0,0,0,0.3), inset 5px 5px 10px rgba(255,255,255,0.2);
    border: 1px solid rgba(0,0,0,0.1);
}

/* Unique Molecule Animations */
@keyframes wave {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}
.animate-wave {
    background: linear-gradient(90deg, transparent, rgba(59, 130, 246, 0.4), transparent);
    width: 200%;
    height: 100%;
    animation: wave 3s infinite linear;
}
.animate-wave-slow {
    background: linear-gradient(90deg, transparent, rgba(147, 197, 253, 0.2), transparent);
    width: 200%;
    height: 100%;
    animation: wave 5s infinite linear;
}

@keyframes explosion-pulse {
    0% { transform: scale(1); opacity: 1; }
    50% { transform: scale(1.2); opacity: 0.8; filter: brightness(1.5); }
    100% { transform: scale(1); opacity: 1; }
}
.behavior-explosive {
    animation: explosion-pulse 2s infinite ease-in-out;
}

.fused-compound .flex-col {
    z-index: 10;
    pointer-events: none;
}

@keyframes pulse-glow {
    0%, 100% { box-shadow: 0 0 20px rgba(16, 185, 129, 0.4); }
    50% { box-shadow: 0 0 40px rgba(16, 185, 129, 0.7); }
}

.fused-compound {
    animation: pulse-glow 2s infinite ease-in-out;
}

.particle:hover {
    filter: brightness(1.2);
    box-shadow: 0 0 25px rgba(255, 255, 255, 0.2);
}

.particle:active {
    cursor: grabbing;
    transform: scale(1.05);
}

.electron-shell {
    position: absolute;
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    pointer-events: none;
}

.electron {
    position: absolute;
    width: 1.5px;
    height: 1.5px;
    background: #3b82f6;
    border-radius: 50%;
}

@keyframes rotate {
    from { transform: translate(-50%, -50%) rotate(0deg); }
    to { transform: translate(-50%, -50%) rotate(360deg); }
}

.orbit {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    animation: rotate linear infinite;
}