/* =================================================================== */
/* THEME SYSTEM & GLOBAL STYLES                                        */
/* =================================================================== */
:root {
    --bg-color: #f5f5f5;
    --text-color: #212121;
    --primary-color: #0288d1;
    --primary-color-rgb: 2, 136, 209;
    --secondary-color: #fbc02d;
    --surface-color: #ffffff;
    --border-color: #e0e0e0;
    --error-bg: #ffebee;
    --error-text: #c62828;
    --shadow-color: rgba(0,0,0,0.05);
    --grid-color: rgba(0, 0, 0, 0.1);
    --zeroline-color: rgba(0, 0, 0, 0.25);
    /* Light mode diff colors */
    --diff-ins-bg: #e6ffed;
    --diff-ins-text: #22863a;
    --diff-del-bg: #ffeef0;
    --diff-del-text: #b31d28;
    --diff-info-bg: #f6f8fa;
    --diff-info-text: #586069;
    /* Button colors */
    --clear-button-bg: #6c757d;
}

.dark-mode {
    --bg-color: #1e1e1e;
    --text-color: #f5f5f5;
    --primary-color: #4fc3f7;
    --primary-color-rgb: 79, 195, 247;
    --secondary-color: #d29922;
    --surface-color: #2a2a2a;
    --border-color: #444;
    --error-bg: #3e2723;
    --error-text: #ef5350;
    --shadow-color: rgba(0,0,0,0.2);
    --grid-color: rgba(255, 255, 255, 0.3);
    --zeroline-color: rgba(255, 255, 255, 0.45);
    /* Dark mode diff colors */
    --diff-ins-bg: rgba(46, 160, 67, 0.15);
    --diff-ins-text: #7ee787;
    --diff-del-bg: rgba(248, 81, 73, 0.15);
    --diff-del-text: #ffa198;
    --diff-info-bg: var(--border-color);
    --diff-info-text: #a0a0a0;
    /* Button colors */
    --clear-button-bg: #555;
}

/* --- Foundational full-height layout --- */
html, body, #root {
    height: 100%;
    margin: 0;
    padding: 0;
    overflow: hidden;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen,
        Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    transition: background-color 0.3s, color 0.3s;
}

/* =================================================================== */
/* LAYOUT & HEADER                                                     */
/* =================================================================== */
.app-container {
    height: 100%;
    display: flex;
    flex-direction: column;
}

.app-header {
    flex-shrink: 0;
    position: relative; /* Context for the absolutely positioned controls */
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 15px 1rem;
    border-bottom: 1px solid var(--border-color);
    text-align: center;
}

.header-content {
    display: flex;
    align-items: center;
    gap: 1rem;
}

/* Prevent global styles from breaking the SVG's internal styling */
.header-icon {
    width: 48px;
    height: 48px;
    flex-shrink: 0;
    fill: none; /* Prevents a global fill from overriding internal fills */
}


.header-title h1 {
    color: var(--primary-color);
    margin: 0 0 4px 0;
    font-size: 2em;
    text-align: left;
}

.header-title p {
    margin: 0;
    font-size: 1em;
    opacity: 0.9;
    text-align: left;
}

.header-controls {
    position: absolute;
    top: 15px;
    right: 15px;
    display: flex;
    align-items: center;
    gap: 16px;
}

.github-link svg {
    display: block;
    fill: var(--text-color);
    transition: fill 0.2s ease-in-out;
}

.github-link:hover svg {
    fill: var(--primary-color);
}


main {
    flex: 1 1 0;
    display: flex;
    flex-direction: column;
    min-height: 0;
    padding: 1rem;
    gap: 1rem;
}

/* =================================================================== */
/* COMPONENTS                                                          */
/* =================================================================== */

.file-uploader {
    flex-shrink: 0;
    padding: 30px;
    border: 3px dashed var(--border-color);
    border-radius: 10px;
    background-color: var(--surface-color);
    text-align: center;
    width: 100%;
    max-width: 800px;
    margin: 15px auto;
    cursor: pointer;
    transition: all 0.3s ease;
    box-sizing: border-box;
}

.file-uploader:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.file-uploader.drag-over {
    border-color: var(--primary-color);
    background-color: rgba(var(--primary-color-rgb), 0.1);
}

.hidden,
.file-uploader input[type="file"] {
    display: none;
}

.status-message, .error-message {
    margin: 15px auto;
    padding: 12px;
    border-radius: 8px;
    width: 100%;
    max-width: 800px;
    text-align: center;
    box-sizing: border-box;
}

.status-message {
    font-size: 1.1em;
    color: var(--secondary-color);
}

.error-message {
    color: var(--error-text);
    background-color: var(--error-bg);
}

/* Theme Switcher */
.theme-switcher {
    display: flex;
    align-items: center;
    gap: 8px;
}

.theme-switcher .switch {
    position: relative;
    display: inline-block;
    width: 48px;
    height: 24px;
}

.theme-switcher .switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.theme-switcher .slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #555;
    transition: .4s;
    border-radius: 24px;
}

.theme-switcher .slider:before {
    position: absolute;
    content: "";
    height: 18px;
    width: 18px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

.theme-switcher input:checked + .slider {
    background-color: var(--primary-color);
}

.theme-switcher input:checked + .slider:before {
    transform: translateX(24px);
}

/* =================================================================== */
/* TABS & CONTENT AREA                                                 */
/* =================================================================== */

.tab-container {
    flex: 1 1 0;
    display: flex;
    flex-direction: column;
    min-height: 0;
    border-radius: 8px;
    background-color: var(--surface-color);
    overflow-y: auto;
    box-shadow: 0 1px 3px var(--shadow-color), 0 2px 8px var(--shadow-color);
}

.tab-navigation {
    flex-shrink: 0;
    display: flex;
    border-bottom: 1px solid var(--border-color);
    padding: 0 1rem;
    position: sticky;
    top: 0;
    background-color: var(--surface-color);
    z-index: 10;
}

.tab-navigation button {
    padding: 12px 18px;
    cursor: pointer;
    border: none;
    background-color: transparent;
    color: var(--text-color);
    opacity: 0.7;
    border-bottom: 3px solid transparent;
    font-size: 1em;
    transition: all 0.2s;
}

.tab-navigation button:hover { opacity: 1; }
.tab-navigation button.active {
    opacity: 1;
    border-bottom-color: var(--primary-color);
    font-weight: 600;
}


.controls-row {
    flex-shrink: 0;
    display: flex;
    flex-wrap: wrap;
    align-items: flex-end;
    gap: 1.5rem;
    padding: 1rem 1rem 0 1rem;
}

.file-content, .diff-content {
    border: 1px solid var(--border-color);
    border-radius: 5px;
    font-family: 'Courier New', Courier, monospace;
    margin: 1rem;
}

.file-selector-group { display: flex; align-items: center; gap: 0.5rem; }
.file-selector-label { flex-shrink: 0; font-weight: 500; font-size: 0.9em; }
select {
    width: 350px;
    cursor: pointer;
    border-radius: 5px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-color);
    padding: 8px 12px;
    font-size: 1em;
    color: var(--text-color);
}

.compare-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.compare-controls { display: flex; gap: 10px; }
.compare-button, .clear-button, .download-button { display: flex; align-items: center; justify-content: center; height: 37px; padding: 8px 12px; font-size: 0.9em; font-weight: 500; border: none; border-radius: 5px; cursor: pointer; transition: opacity 0.2s; }
.download-button { background-color: var(--primary-color); color: white; width: 37px; }
.download-button svg { width: 20px; height: 20px; }
.compare-button { background-color: var(--secondary-color); color: #212121; }
.clear-button {
    background-color: var(--clear-button-bg);
    color: white;
}
.download-button:disabled, .compare-button:disabled { background-color: #9e9e9e; cursor: not-allowed; opacity: 0.7; }
.viewer-placeholder { padding: 2rem; opacity: 0.6; text-align: center; flex-grow: 1; display: flex; align-items: center; justify-content: center; }
.file-content table { width: 100%; border-collapse: collapse; }

.file-content .line-number {
    position: sticky;
    left: 0;
    background-color: var(--surface-color);
    border-right: 1px solid var(--border-color);
    padding: 0 1em;
    text-align: right;
    color: var(--text-color);
    opacity: 0.5;
    user-select: none;
    width: 50px;
    box-sizing: border-box;
}

.file-content .line-text { padding-left: 1rem; white-space: pre; }
.diff-content .d2h-file-header { display: none; }

/* =================================================================== */
/* DARK MODE & DIFF FIXES                                              */
/* =================================================================== */

.dark-mode .file-content .line-number,
.dark-mode .diff-content .d2h-code-side-linenumber {
    color: #a0a0a0;
    opacity: 0.9;
}

.diff-content .d2h-code-side-linenumber {
    position: sticky;
    background-color: var(--surface-color);
    border-color: var(--border-color);
    z-index: 1;
}
.diff-content .d2h-code-side-linenumber:first-of-type { left: 0; }
.diff-content .d2h-code-side-linenumber:last-of-type { right: 0; }

.d2h-ins {
    background-color: var(--diff-ins-bg);
}
.d2h-del {
    background-color: var(--diff-del-bg);
}
.d2h-info {
    background-color: var(--diff-info-bg);
    color: var(--diff-info-text);
}

.dark-mode .d2h-diff-table {
    background-color: var(--surface-color);
}
.dark-mode .d2h-code-side-line,
.dark-mode .d2h-emptyplaceholder {
    background-image: none !important;
    background-color: var(--surface-color);
}
.dark-mode tr.d2h-info {
    background-color: var(--diff-info-bg);
    color: var(--diff-info-text);
}

/* FIX: Ensure text within diffs is readable in dark mode */
.dark-mode .d2h-ins,
.dark-mode .d2h-ins .d2h-code-line-ctn,
.dark-mode .d2h-ins .d2h-code-line-prefix {
    color: var(--diff-ins-text);
}

.dark-mode .d2h-del,
.dark-mode .d2h-del .d2h-code-line-ctn,
.dark-mode .d2h-del .d2h-code-line-prefix {
    color: var(--diff-del-text);
}

/* FIX: Style the word-level diff highlights for readability */
.dark-mode .d2h-ins ins {
    background-color: rgba(46, 160, 67, 0.4);
    color: #e6ffed;
    text-decoration: none;
}

.dark-mode .d2h-del del {
    background-color: rgba(248, 81, 73, 0.4);
    color: #ffeef0;
    text-decoration: none;
}