:root {
    --primary-bg: #fff;
    --primary-text: #333;
    --secondary-bg: #f4f4f4;
    --accent-color: #3498db;
    --border-color: #ddd;
    --button-bg: #f0f0f0;
    --button-hover-bg: #e0e0e0;
    --tooltip-bg: #333;
    --tooltip-text: #fff;
    --shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    --font-stack: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif;
    --transition: all 0.3s ease;
}

body.dark-theme {
    --primary-bg: #1e1e1e;
    --primary-text: #e6e6e6;
    --secondary-bg: #2a2a2a;
    --accent-color: #66b0ff;
    --border-color: #555;
    --button-bg: #3a3a3a;
    --button-hover-bg: #4a4a4a;
    --tooltip-bg: #555;
    --tooltip-text: #e6e6e6;
    --shadow: 0 2px 5px rgba(0, 0, 0, 0.5);
    --button-text: #ffffff; /* New variable for better contrast in dark theme */
}

body {
    font-family: var(--font-stack);
    margin: 1.5rem;
    line-height: 1.6;
    background-color: var(--primary-bg);
    color: var(--primary-text);
    transition: var(--transition);
}

h1, h2 {
    color: var(--primary-text);
    transition: var(--transition);
}

#chartContainer, #resistanceChartContainer {
    width: 90%;
    max-width: 1200px;
    margin: 1.5rem auto;
    position: relative;
    min-height: 400px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: var(--shadow);
    overflow-y: auto;
    padding: 1rem;
}

canvas {
	
  width: 100% !important;
  height: auto !important; /* let the container height control this */
  display: block;	
	
}

canvas.chart-inactive { outline: 2px dashed transparent; box-shadow: none; cursor: default; }
canvas.chart-active   { outline: 2px solid rgba(66,133,244,0.6); box-shadow: 0 0 0 3px rgba(66,133,244,0.25); cursor: grab; }
canvas.chart-active:active { cursor: grabbing; }


#chartError, #resistanceChartError {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 1em;
    color: #d32f2f;
    background-color: rgba(255, 255, 255, 0.9);
    padding: 0.5rem 1rem;
    border-radius: 4px;
    display: none;
    transition: var(--transition);
}

body.dark-theme #chartError, body.dark-theme #resistanceChartError {
    background-color: rgba(30, 30, 30, 0.9);
    color: #ef5350;
}

.zoom-slider-container {
    width: 90%;
    max-width: 1200px;
    margin: 1.5rem auto;
}

.zoom-slider {
    width: 100%;
    accent-color: var(--accent-color);
}

button {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    cursor: pointer;
    background-color: var(--button-bg);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    box-shadow: var(--shadow);
    color: var(--primary-text); /* Ensure text color matches body */
    font-family: var(--font-stack); /* Match font */
    transition: var(--transition);
}

button:hover, button:focus {
    background-color: var(--button-hover-bg);
    border-color: var(--accent-color);
    outline: none;
}

button:focus {
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.3);
}

body.dark-theme button {
    color: var(--button-text); /* Use lighter text in dark theme for contrast */
}

input[type="file"] {
    display: none; /* Hide the native file input */
}

.file-input-label {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    cursor: pointer;
    background-color: var(--button-bg);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    box-shadow: var(--shadow);
    color: var(--primary-text); /* Match button text color */
    font-family: var(--font-stack); /* Match button font */
    transition: var(--transition);
    display: inline-block;
}

.file-input-label:hover, .file-input-label:focus {
    background-color: var(--button-hover-bg);
    border-color: var(--accent-color);
    outline: none;
}

body.dark-theme .file-input-label {
    color: var(--button-text); /* Use lighter text in dark theme for contrast */
}

.file-input-label:focus {
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.3);
}

.file-name-display {
    font-size: 0.875rem;
    color: var(--primary-text);
    margin-left: 0.5rem;
    max-width: 15rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    display: inline-block;
    vertical-align: middle;
}

body.dark-theme .file-name-display {
    color: var(--button-text); /* Ensure file name matches button text contrast */
}

input[type="checkbox"]:focus, input[type="range"]:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

/* Tooltip styles */
.control-group [data-tooltip] {
    position: relative;
}

body.tooltips-enabled .control-group [data-tooltip]:hover:after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background-color: var(--tooltip-bg);
    color: var(--tooltip-text);
    padding: 0.75rem 1rem;
    border-radius: 6px;
    white-space: normal;
    max-width: 300px;
    font-size: 0.875rem;
    line-height: 1.4;
    z-index: 1000;
    transition: var(--transition);
    transition-delay: 0.2s;
}

body.tooltips-enabled .control-group [data-tooltip]:hover:before {
    content: '';
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    border: 8px solid transparent;
    border-top-color: var(--tooltip-bg);
    margin-bottom: -16px;
    transition: var(--transition);
}

/* Loading message styles */
#loadingMessage, #resistanceLoadingMessage {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 1.1em;
    color: var(--primary-text);
    display: none;
    animation: pulse 1.5s infinite;
}

@keyframes pulse {
    0% { opacity: 0.6; }
    50% { opacity: 1; }
    100% { opacity: 0.6; }
}

#statistics {
    margin: 2rem auto;
    max-width: 1200px;
}

#statistics h2 {
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

#statistics table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
}

#statistics thead th {
    position: sticky;
    top: 0;
    background-color: var(--button-bg);
    border: 1px solid var(--border-color);
    padding: 0.75rem;
    text-align: left;
    cursor: pointer;
    font-weight: 600;
    color: var(--primary-text); /* Match table header text */
    transition: var(--transition);
}

body.dark-theme #statistics thead th {
    color: var(--button-text); /* Ensure contrast in dark theme */
}

#statistics th[aria-sort="ascending"]::after {
    content: " ↑";
    font-size: 0.875rem;
}

#statistics th[aria-sort="descending"]::after {
    content: " ↓";
    font-size: 0.875rem;
}

#statistics td {
    border: 1px solid var(--border-color);
    padding: 0.75rem;
    text-align: left;
    color: var(--primary-text); /* Match table cell text */
    transition: var(--transition);
}

body.dark-theme #statistics td {
    color: var(--button-text); /* Ensure contrast in dark theme */
}

#checkboxContainer {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

#checkboxContainer label {
    display: inline-flex;
    align-items: center;
    padding: 0.5rem;
    font-size: 0.875rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--button-bg);
    color: var(--primary-text); /* Match checkbox label text */
    transition: var(--transition);
}

body.dark-theme #checkboxContainer label {
    color: var(--button-text); /* Ensure contrast in dark theme */
}

#checkboxContainer label:hover {
    background-color: var(--button-hover-bg);
    cursor: pointer;
}

footer {
    background-color: var(--secondary-bg);
    color: var(--primary-text);
    padding: 1.5rem;
    text-align: center;
    margin-top: 2rem;
    transition: var(--transition);
}

footer a {
    color: var(--primary-text);
    text-decoration: none;
    margin: 0 0.5rem;
    transition: var(--transition);
}

footer a:hover, footer a:focus {
    color: var(--accent-color);
}

.footer-content {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
    flex-wrap: wrap;
}

.social-icons a {
    font-size: 1.5rem;
    margin: 0 0.75rem;
    color: var(--primary-text);
    transition: var(--transition);
}

.social-icons a:hover, .social-icons a:focus {
    color: var(--accent-color);
}

.copyright {
    font-size: 0.875rem;
    opacity: 0.9;
    margin-top: 0.5rem;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    #chartContainer, #resistanceChartContainer {
        width: 100%;
        min-height: 300px;
    }

    .control-row {
        grid-template-columns: 1fr;
    }

    .footer-content {
        flex-direction: column;
        gap: 1rem;
    }
}

@media (max-width: 600px) {
    h1 { font-size: 1.25rem; }
    h2 { font-size: 1.1rem; }
    button, .file-input-label { font-size: 0.75rem; }
}

/* Control bar styling */
.control-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 1rem;
    justify-content: space-between;
}

.control-group {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    align-items: center;
    font-size: 0.875rem;
    border-left: 1px solid var(--border-color);
    padding-left: 1rem;
    transition: var(--transition);
    justify-content: flex-start; /* Left-justify buttons */
}

.control-group:first-child {
    border-left: none;
    padding-left: 0;
}

.status-text {
    margin: 0.5rem 0;
    font-size: 0.875rem;
    color: var(--primary-text);
    transition: var(--transition);
    background: transparent;
    border: none;
    box-shadow: none;
}

.block-label {
    font-weight: 600;
    font-size: 0.875rem;
    background-color: var(--button-bg);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    color: var(--primary-text); /* Match block label text */
    transition: var(--transition);
}

body.dark-theme .block-label {
    color: var(--button-text); /* Ensure contrast in dark theme */
}

.checkbox-wrap {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 0.5rem;
}

.sticky-controls {
    position: sticky;
    top: 0;
    background: var(--primary-bg);
    padding: 1rem;
    z-index: 100;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.layout {
    display: flex;
    min-height: calc(100vh - 200px);
}

.sidebar {
    width: 250px;
    padding: 1rem;
    background-color: var(--secondary-bg);
    overflow-y: auto;
    transition: width 0.3s ease, background-color 0.3s;
    z-index: 50; /* Lower than header */
}

.sidebar.collapsed {
    width: 60px;
    padding: 1rem 0.5rem;
}

.hide-when-collapsed {
    transition: opacity 0.3s ease;
}

.sidebar.collapsed .hide-when-collapsed {
    display: none;
    opacity: 0;
}

.main {
    flex: 1;
    padding: 1rem;
    overflow-y: auto;
}

#toggleSidebar {
    background: var(--button-bg);
    border: none;
    padding: 0.5rem;
    font-size: 0.875rem;
    cursor: pointer;
    width: 100%;
    text-align: center;
    color: var(--primary-text); /* Match toggle button text */
    transition: var(--transition);
}

body.dark-theme #toggleSidebar {
    color: var(--button-text); /* Ensure contrast in dark theme */
}

#toggleSidebar:hover, #toggleSidebar:focus {
    background: var(--button-hover-bg);
}

#toggleSidebar::after {
    content: 'Menu';
}

#toggleSidebar.collapsed::after {
    content: '';
}

#toggleSidebar[title]:hover:after, #toggleSidebar[title]:focus:after {
    content: attr(title);
    position: absolute;
    background: var(--tooltip-bg);
    color: var(--tooltip-text);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    z-index: 1;
    top: -2rem;
    left: 50%;
    transform: translateX(-50%);
    transition: var(--transition);
}

header {
    position: sticky;
    top: 0;
    z-index: 200; /* Higher than sticky-controls */
    background-color: var(--secondary-bg);
    padding: 1rem;
    box-shadow: var(--shadow);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

header h1 {
    margin: 0;
    font-size: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

header h1 i {
    color: var(--accent-color);
    transition: var(--transition);
}

.time-slider {
    width: 120px;
    accent-color: var(--accent-color);
    transition: var(--transition);
}

.time-value {
    font-size: 0.875rem;
    margin-left: 0.5rem;
    color: var(--primary-text);
    transition: var(--transition);
}

.time-filter-group {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

/* ARIA live region for status */
.status-text {
    font-size: 0.875rem;
}

#myChart, #resistanceChart { touch-action: none; }

/* Stack menu above charts on narrow screens */

/* Stack menu above charts on narrow screens */
@media (max-width: 900px) {
  .layout {
    flex-direction: column;   /* sidebar above, charts below */
  }

  .sidebar {
    width: 100%;
    position: static;         /* let it scroll with the page */
  }

  .sidebar.collapsed {        /* keep full width even when "collapsed" */
    width: 100%;
  }

  .main {
    width: 100%;
    overflow: visible;        /* allow charts to size naturally */
    padding-top: 0.5rem;
  }

  /* Ensure full-width chart containers with a floor height */
  #chartContainer,
  #resistanceChartContainer {
    width: 100%;
    min-height: 320px;
  }
}

/* --- Touch comfort for charts --- */
#myChart,
#resistanceChart,
canvas.chartjs-render-monitor {
  touch-action: none;           /* let Chart.js handle pan/zoom gestures */
  user-select: none;
  -webkit-user-select: none;
  -webkit-tap-highlight-color: transparent;
  cursor: grab;                 /* hint that you can drag */
}

#myChart:active,
#resistanceChart:active {
  cursor: grabbing;
}

/* Prevent browser nav/refresh gestures from stealing drags that start on the charts */
.main {
  overscroll-behavior: contain;
}

/* Smooth scrolling within sticky/scrollable areas on iOS */
.sticky-controls {
  -webkit-overflow-scrolling: touch;
}

/* 10% smaller than surrounding text */
.text-sm { font-size: 0.9em; line-height: 1.5; }

/* Optional variants */
.text-xs { font-size: 0.85em; line-height: 1.5; }
.muted   { color: var(--muted-text, #94a3b8); } /* if you use color vars */