:root {
    --bg-color: #ffffff;
    --border-color: #000000;
    --border-width: 2px;
    
    /* High Contrast Palette */
    --cat-alkali: #ff9999;       
    --cat-alkaline: #ffcc66;     
    --cat-transition: #ff99cc;   
    --cat-basic: #99ccff;        
    --cat-metalloid: #66ffff;    
    --cat-nonmetal: #66ff99;     
    --cat-halogen: #66ffcc;      
    --cat-noble: #cc99ff;        
    --cat-lanthanide: #ffcc99;   
    --cat-actinide: #ff6666;     
    --cat-unknown: #e0e0e0;      
}

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

body {
    background-color: #f4f4f0;
    background-image: radial-gradient(#d1d1d1 1px, transparent 1px);
    background-size: 20px 20px;
    color: #000;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    /* Reduced padding to fit better on standard laptop screens */
    padding: 1vw; 
    overflow-x: hidden; /* Prevent horizontal scroll */
}

header {
    text-align: center;
    margin-bottom: 1.5vw;
    background: #fff;
    padding: 0.8vw 2vw;
    border: var(--border-width) solid var(--border-color);
    box-shadow: 0.4vw 0.4vw 0px var(--border-color);
    width: fit-content;
}

h1 {
    font-weight: 900;
    text-transform: uppercase;
    font-size: clamp(1.2rem, 3vw, 2rem);
    letter-spacing: -1px;
    margin: 0;
}

/* --- Table Layout --- */
.table-wrapper {
    width: 100%;
    display: flex;
    justify-content: center;
    /* Ensure container doesn't overflow viewport */
    max-width: 100vw; 
}

.periodic-table {
    display: grid;
    /* minmax(0, 1fr) is critical: allows columns to shrink below content size if needed to fit screen */
    grid-template-columns: repeat(18, minmax(0, 1fr));
    grid-template-rows: repeat(10, auto);
    gap: 0.3vw;
    width: 100%;
    max-width: 1600px; /* Max width for huge screens */
    margin: 0 auto;
}

/* --- Element Card --- */
.element {
    position: relative;
    background-color: var(--element-color);
    border: clamp(1px, 0.15vw, 2px) solid var(--border-color);
    padding: 0.3vw 0.2vw;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    cursor: pointer;
    transition: transform 0.1s ease, background-color 0.1s;
    box-shadow: 0.3vw 0.3vw 0px var(--border-color);
    user-select: none;
    aspect-ratio: 0.82;
    overflow: hidden; /* Clip content that forces width */
}

.element:hover {
    transform: translate(-0.15vw, -0.15vw);
    box-shadow: 0.5vw 0.5vw 0px var(--border-color);
    z-index: 100;
    background-color: #fff !important;
}

.element:active {
    transform: translate(0.1vw, 0.1vw);
    box-shadow: 0.1vw 0.1vw 0px var(--border-color);
}

.element-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    padding: 0 0.2vw;
}

.element-number {
    font-size: clamp(7px, 0.8vw, 12px);
    font-weight: 700;
    line-height: 1;
}

.element-symbol {
    font-size: clamp(10px, 2vw, 28px);
    font-weight: 900;
    text-align: center;
    margin-top: -0.2vw;
    color: #000;
    line-height: 1.1;
}

.element-name {
    font-size: clamp(5px, 0.55vw, 10px);
    text-align: center;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-weight: 600;
    text-transform: uppercase;
    padding: 0 0.1vw;
}

/* Special Rows alignment */
.row-8 { grid-row: 9; margin-top: 1.5vw; } 
.row-9 { grid-row: 10; }

/* Labels */
.label-spacer {
    grid-column: 3;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: clamp(7px, 0.8vw, 12px);
    font-weight: 700;
    border: clamp(1px, 0.15vw, 2px) dashed #000;
    background: rgba(255,255,255,0.5);
    color: #000;
    aspect-ratio: 0.82;
}
.label-lanth { grid-row: 6; }
.label-actin { grid-row: 7; }

/* --- Legend --- */
.legend-container {
    width: 100%;
    max-width: 1000px;
    background: #fff;
    padding: 1vw 1.5vw;
    border: var(--border-width) solid var(--border-color);
    box-shadow: 0.4vw 0.4vw 0px var(--border-color);
    margin-top: 2vw;
}

.legend-title {
    font-size: clamp(0.9rem, 1.2vw, 1.2rem);
    font-weight: 900;
    text-transform: uppercase;
    margin-bottom: 1vw;
    border-bottom: 2px solid #000;
    padding-bottom: 0.5vw;
}

.legend-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.8vw;
    justify-content: center;
}

.legend-item {
    display: flex;
    align-items: center;
    padding: 0.4vw 0.8vw;
    border: 1px solid #000;
    background: #fff;
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: 0.2vw 0.2vw 0px #000;
}

.legend-item:hover {
    transform: translate(-1px, -1px);
    box-shadow: 0.3vw 0.3vw 0px #000;
}

.legend-item.active {
    background: #000;
    color: #fff;
}

.legend-box {
    width: clamp(10px, 1.2vw, 16px);
    height: clamp(10px, 1.2vw, 16px);
    border: 1px solid #000;
    margin-right: 0.5vw;
}

.legend-name {
    font-size: clamp(8px, 0.9vw, 12px);
    font-weight: 700;
    text-transform: uppercase;
}

/* --- Modal --- */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(5px);
    z-index: 2000;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease;
    padding: 20px;
}

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

.focus-card {
    width: 90%;
    max-width: 400px;
    background: #fff;
    border: 3px solid #000;
    box-shadow: 10px 10px 0px #000;
    position: relative;
    transform: scale(0.9);
    transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.overlay.active .focus-card { transform: scale(1); }

.card-header {
    background: var(--card-color);
    padding: 30px;
    border-bottom: 3px solid #000;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
}

.card-symbol-large {
    font-size: 4rem;
    font-weight: 900;
    line-height: 1;
}

.card-number-large {
    font-size: 2.5rem;
    font-weight: 900;
    opacity: 0.5;
}

.close-btn {
    position: absolute;
    top: -15px;
    right: -15px;
    background: #ff4d4d;
    border: 3px solid #000;
    color: #fff;
    width: 40px;
    height: 40px;
    font-size: 1.5rem;
    font-weight: 700;
    cursor: pointer;
    box-shadow: 4px 4px 0px #000;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.1s;
}
.close-btn:hover { transform: scale(1.1); }
.close-btn:active { transform: scale(0.95); }

.card-body { padding: 30px; }

.card-name-large {
    font-size: 2rem;
    font-weight: 900;
    text-transform: uppercase;
    margin-bottom: 5px;
    line-height: 1;
}

.card-category-badge {
    display: inline-block;
    background: #000;
    color: #fff;
    padding: 4px 8px;
    font-size: 0.8rem;
    font-weight: 700;
    text-transform: uppercase;
    margin-bottom: 25px;
}

.info-row {
    display: flex;
    justify-content: space-between;
    border-bottom: 2px solid #eee;
    padding: 8px 0;
    font-size: 0.95rem;
}
.info-row:last-child { border-bottom: none; }

.info-label { font-weight: 600; color: #555; }
.info-value { font-weight: 800; }

/* Mobile Adjustments */
@media (max-width: 600px) {
    .periodic-table { gap: 1px; }
    .element { border-width: 1px; box-shadow: 1px 1px 0px var(--border-color); }
    .element:hover { box-shadow: 2px 2px 0px var(--border-color); }
    body { padding: 5px; }
}