:root {
    --bg-color: #0a0a0f;
    --text-color: #ffffff;
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --primary-glow: rgba(0, 255, 255, 0.3);
    --font-main: 'Outfit', sans-serif;
    --font-mono: 'Space Mono', monospace;
    --transition-speed: 0.3s;
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: var(--font-main);
    overflow-x: hidden;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.video-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
}

.gradient-sphere {
    position: absolute;
    top: -20%;
    right: -10%;
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, rgba(76, 29, 149, 0.4) 0%, rgba(10, 10, 15, 0) 70%);
    filter: blur(80px);
    animation: float 20s infinite ease-in-out;
}

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

.container {
    width: 95%;
    max-width: 1600px;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
}

header {
    text-align: center;
    margin-bottom: 2rem;
}

h1 {
    font-size: 3rem;
    font-weight: 700;
    letter-spacing: -2px;
    margin-bottom: 0.5rem;
}

.highlight {
    color: cyan;
    text-shadow: 0 0 20px cyan;
}

.subtitle {
    font-family: var(--font-mono);
    color: rgba(255, 255, 255, 0.6);
    font-size: 1rem;
}

/* Legend */
.legend {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 2rem;
    justify-content: center;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.8);
}

.legend-color {
    width: 16px;
    height: 16px;
    border-radius: 4px;
}

/* Periodic Table Grid */
.periodic-table {
    display: grid;
    grid-template-columns: repeat(18, 1fr);
    grid-template-rows: repeat(10, 1fr); /* Estimated rows */
    gap: 8px;
    padding: 20px;
    /* Basic Layout for wide screens */
    width: 100%;
    overflow-x: auto;
}

/* Element Card */
.element {
    aspect-ratio: 1; /* Square */
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 8px;
    padding: 8px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    cursor: pointer;
    transition: all var(--transition-speed) ease;
    position: relative;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    min-width: 70px; /* Minimum size */
}

.element:hover {
    transform: scale(1.2) translateY(-10px);
    z-index: 10;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.5), 0 0 10px var(--element-color);
    border-color: var(--element-color);
}

.element-number {
    font-size: 0.7rem;
    color: rgba(255, 255, 255, 0.5);
    font-family: var(--font-mono);
}

.element-symbol {
    font-size: 1.5rem;
    font-weight: 700;
    text-align: center;
    /* Fallback color */
    color: #fff; 
}

.element-name {
    font-size: 0.65rem;
    text-align: center;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    color: rgba(255, 255, 255, 0.8);
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 100;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
    backdrop-filter: blur(5px);
}

.modal-overlay.active {
    opacity: 1;
    pointer-events: all;
}

.modal-content {
    background: #1a1a20;
    border: 1px solid rgba(255, 255, 255, 0.2);
    padding: 2rem;
    border-radius: 16px;
    width: 90%;
    max-width: 500px;
    position: relative;
    box-shadow: 0 0 50px rgba(0, 0, 0, 0.5);
    transform: scale(0.9);
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.modal-overlay.active .modal-content {
    transform: scale(1);
}

.close-btn {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
}

.modal-header {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.element-preview {
    width: 80px;
    height: 80px;
    border-radius: 12px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: bold;
    font-size: 2rem;
    box-shadow: 0 0 20px rgba(0,0,0,0.3);
}

.modal-title-group h2 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.badge {
    background: rgba(255, 255, 255, 0.1);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-family: var(--font-mono);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.modal-body p {
    line-height: 1.6;
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 2rem;
}

.action-btn {
    display: inline-block;
    padding: 12px 24px;
    background: white;
    color: black;
    text-decoration: none;
    font-weight: 600;
    border-radius: 8px;
    transition: transform 0.2s, background 0.2s;
}

.action-btn:hover {
    transform: translateY(-2px);
    background: cyan;
}

.hidden {
    display: none; /* Just helper, opacity handles transition */
}

/* Tooltip (Hover Card) - Optional if not using Modal on hover, but user asked for "show some info on hover" */
/* We can do a tooltip or use the modal on click. Let's do a quick tooltip on hover maybe? 
   Actually user said: "when mouse hangover element will show some information"
   Let's append a small tooltip to the element itself or a fixed info box.
   Due to grid constraints, a fixed info box/HUD might be better, OR simple tooltip.
   I'll stick to a nice tooltip for now.
*/

.tooltip {
    position: absolute;
    bottom: 140%;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0, 0, 0, 0.9);
    border: 1px solid rgba(255, 255, 255, 0.2);
    padding: 10px;
    width: 200px;
    border-radius: 8px;
    font-size: 0.8rem;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.2s;
    z-index: 20;
    text-align: left;
}

.element:hover .tooltip {
    opacity: 1;
}

/* Responsive */
@media (max-width: 1000px) {
    .periodic-table {
        /* On simplified mobile view, maybe just a flex list? Or scrollable grid. 
           Scrollable grid is more "scientific".
        */
        padding-bottom: 50px;
    }
}