html { font-family: sans-serif;  background: rgb(255 255 255); background-color: #f7f9fc;}
nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--bg-light);
    height: var(--nav-height);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
    padding: 0 0.5rem;
}
nav h1 { flex: auto; margin: 0; }
nav h1 a { text-decoration: none; padding: 0.25rem 0.5rem; }
nav ul  { display: flex; list-style: none; margin: 0; padding: 0; }
nav ul li a, nav ul li span, header .action { display: block; padding: 0.5rem; }


:root {
    --bg-light: #ffffff;
    --bg-hover: #f5f7fa;
    --text-primary: #2c3e50;
    --text-secondary: #6a7480;
    --border-color: #e0e4e8;
    --primary-color: #3498db;
    --nav-height: 4rem;
    --shadow-subtle: 0 4px 6px rgba(0, 0, 0, 0.05);
    --shadow-hover: 0 6px 12px rgba(0, 0, 0, 0.08);
}

.content { padding: 0 0.8rem; }
.content h1 {
    color: var(--primary-color);
}
.content h2 {
    color: var(--primary-color);
}

.navbar-brand {
    display: flex;
    align-items: center;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    text-decoration: none;
}

.navbar-brand img {
    height: 2rem;
    margin-right: 0.5rem;
}

.navbar-menu {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.navbar-menu a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    transition: background-color 0.2s ease, color 0.2s ease;
}

.navbar-menu a:hover {
    background-color: var(--bg-hover);
    color: var(--text-primary);
}

.navbar-menu a.active {
    color: var(--primary-color);
    font-weight: 600;
}

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

body {
    background-color: #f7f9fc;
}

.header {
    color: var(--primary-color);
    padding: 1rem 0.5rem;
}

.pt {
    font-family: Arial, sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    margin: 0;
    padding: 20px;
}

#pt-table, #pt-table-fblock {
    display: grid;
    grid-template-columns: repeat(18, 1fr);
    gap: 5px;
    max-width: 1200px;
    margin-bottom: 20px;
}

#pt-table-fblock {
    grid-template-columns: repeat(14, 1fr);
}

.pt-element {
    background-color: #e0e0e0;
    border: 1px solid #999;
    border-radius: 5px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.pt-element:hover {
    background-color: #c0c0c0;
}

.pt-element.selected {
    background-color: #4CAF50;
    color: white;
}

.pt-element-symbol {
    font-weight: bold;
    font-size: 1.2em;
}

.pt-element-number {
    font-size: 0.8em;
    /* align-self: flex-start; */
}

.pt-element-name {
    font-size: 0.6em;
}

.pt-search-container {
    display: flex;
    align-items: center;
    margin-bottom: 20px;
}

#pt-search-bar {
    padding: 10px;
    font-size: 16px;
    width: 300px;
    margin-right: 10px;
}

#pt-clear-btn {
    padding: 10px;
    background-color: #f44336;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}

.system-groups-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 1rem;
    max-width: 1400px;
    margin: 0 auto;

    --bg-light: #ffffff;
    --bg-hover: #f5f7fa;
    --text-primary: #2c3e50;
    --text-secondary: #6a7480;
    --border-color: #e0e4e8;
    --shadow-subtle: 0 4px 6px rgba(0, 0, 0, 0.05);
    --shadow-hover: 0 6px 12px rgba(0, 0, 0, 0.08);

    line-height: 1.6;
    color: var(--text-primary);
    margin: 0;
    padding: 1rem;

}

.system-group-card {
    background-color: var(--bg-light);
    border-radius: 12px;
    box-shadow: var(--shadow-subtle);
    overflow: hidden;
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
    max-height: 4rem; /* Collapsed height */
    overflow: hidden;
}

.system-group-card.expanded {
    max-height: 100vh; /* Allow full expansion */
}

.system-group-card:hover {
    box-shadow: var(--shadow-hover);
    transform: translateY(-5px);
}

.system-group-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background-color: var(--bg-hover);
    cursor: pointer;
}

.system-group-header h3 {
    margin: 0;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.system-group-header .group-count {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-left: 0.5rem;
}

.system-group-content {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height 0.3s ease, opacity 0.3s ease;
}

.system-group-card.expanded .system-group-content {
    max-height: 500px; /* Adjust as needed */
    opacity: 1;
}

.system-group-content ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
}

.system-group-content li {
    padding: 0.5rem 1rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background-color 0.2s ease;
}

.system-group-content li:hover {
    background-color: var(--bg-hover);
}

.toggle-icon {
    transition: transform 0.2s ease;
    color: var(--text-secondary);
}

.system-group-card.expanded .toggle-icon {
    transform: rotate(90deg);
}

/* Responsive adjustments */
@media (max-width: 600px) {
    .system-groups-container {
        grid-template-columns: 1fr;
    }
}