:root {
    /* Monochromatic Dark Theme Palette */
    --background-color: #0d0d0d;
    --primary-text-color: #e0e0e0;
    --secondary-text-color: #888888;
    --panel-background: #1a1a1a;
    --item-background: #252525;
    --border-color: #333333;
    
    /* Button Colors (Grayscale) */
    --btn-secondary-bg: #2a2a2a;
    --btn-secondary-hover-bg: #3d3d3d;
    
    /* Status Colors */
    --success-color: #61fa7a; /* A subtle but clear green for success */
    --focus-color: #e0e0e0;

    /* Fonts */
    --font-sans-serif: 'Inter', sans-serif;
    --font-monospace: 'JetBrains Mono', monospace;
}

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

body {
    font-family: var(--font-sans-serif);
    background-color: var(--background-color);
    color: var(--primary-text-color);
    line-height: 1.6;
    font-weight: 400;
    display: flex;
    flex-direction: column;
    height: 100vh;
    overflow: hidden;
}

/* --- Footer --- */
.site-footer {
    border-top: 1px solid var(--border-color);
    padding: 0.9rem 2rem;
    color: var(--secondary-text-color);
    text-align: center;
    flex-shrink: 0;
}

.site-footer strong {
    color: var(--primary-text-color);
}

/* --- Site Header --- */
.site-header {
    padding: 1.5rem 2rem;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
}

.site-header h1 {
    font-size: 1.75rem;
    font-weight: 600;
    margin: 0;
}

.site-header p {
    color: var(--secondary-text-color);
    font-size: 1rem;
    font-weight: 300;
}

h2 {
    font-weight: 500;
    margin-bottom: 1rem;
    color: var(--primary-text-color);
}

.container {
    display: flex;
    padding: 2rem;
    gap: 2rem;
    flex-grow: 1;
    overflow: hidden;
}

.left-panel, .right-panel {
    background-color: var(--panel-background);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    border: 1px solid var(--border-color);
    overflow: hidden;
}

.left-panel {
    width: 40%;
    padding: 1.5rem;
}

.right-panel {
    width: 60%;
    position: relative; /* ADD THIS: Required for the overlay to position correctly */
}

/* --- Drop Zone --- */
.drop-zone {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    text-align: center;
    cursor: pointer;
    transition: background-color 0.2s ease, border-color 0.2s ease;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    flex-grow: 1;
    margin-bottom: 1.5rem;
}

.drop-zone:hover, .drop-zone.dragover {
    background-color: var(--item-background);
    border-color: var(--focus-color);
}

.drop-zone:focus-visible {
    outline: 2px solid var(--focus-color);
    outline-offset: 2px;
}

/* UPDATED DROP ZONE TEXT STYLES */
.drop-zone-text {
    color: var(--primary-text-color); /* Was secondary, primary is better */
    font-weight: 500;
    margin: 0;
}

.drop-zone-subtext {
    color: var(--secondary-text-color);
    margin-top: 0.25rem;
}

/* --- Buttons --- */
.btn.btn-secondary {
    font-family: var(--font-sans-serif);
    background-color: var(--btn-secondary-bg);
    color: var(--primary-text-color);
    border: none;
    padding: 0.6rem 1.25rem;
    border-radius: 5px;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    transition: background-color 0.2s ease;
}

.btn.btn-secondary:hover {
    background-color: var(--btn-secondary-hover-bg);
}

.controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    flex-shrink: 0;
}

/* --- Toggle --- */
.toggle {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    color: var(--primary-text-color);
    user-select: none;
}

.toggle-input {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
}

.toggle-track {
    width: 44px;
    height: 24px;
    background: var(--btn-secondary-bg);
    border: 1px solid var(--border-color);
    border-radius: 999px;
    position: relative;
    transition: background-color 0.2s ease, border-color 0.2s ease;
}

.toggle-thumb {
    position: absolute;
    top: 1px;
    left: 1px;
    width: 20px;
    height: 20px;
    background: var(--primary-text-color);
    border-radius: 50%;
    transition: transform 0.2s ease, background-color 0.2s ease;
}

.toggle-input:checked + .toggle-track {
    background: var(--focus-color);
    border-color: var(--focus-color);
}

.toggle-input:checked + .toggle-track .toggle-thumb {
    transform: translateX(20px);
    background: var(--background-color);
}

.toggle-label {
    color: var(--secondary-text-color);
    font-size: 0.95rem;
}

/* --- File List --- */
.file-list {
    overflow-y: auto;
    flex-grow: 1;
}

.file-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background-color: var(--item-background);
    padding: 0.75rem 1rem;
    border-radius: 5px;
    margin-bottom: 0.5rem;
}

.file-name-input {
    background-color: transparent;
    border: none;
    border-bottom: 1px solid transparent;
    color: var(--primary-text-color);
    font-family: var(--font-sans-serif);
    font-size: 1rem;
    width: 80%;
    padding: 0.25rem;
    transition: border-color 0.2s ease;
}

.file-name-input:focus {
    outline: none;
    border-bottom-color: var(--focus-color);
}

/* Lighter divider for lists */
.file-item + .file-item {
    border-top: 1px dashed rgba(255, 255, 255, 0.04);
}

/* Icon-only button for remove */
.icon-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    border-radius: 6px;
    border: 1px solid transparent;
    background: transparent;
    color: var(--secondary-text-color);
    cursor: pointer;
    transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.icon-btn:hover {
    background-color: rgba(255, 255, 255, 0.04);
    color: var(--primary-text-color);
    border-color: var(--border-color);
}

.icon-btn:focus-visible {
    outline: 2px solid var(--focus-color);
    outline-offset: 2px;
}

.remove-btn svg {
    pointer-events: none;
}

/* --- Right Panel - Code Output --- */
.code-header {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    padding: 0.75rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
}

.compression-stats {
    margin-left: auto;
    color: var(--secondary-text-color);
    font-size: 0.9rem;
    opacity: 0.9;
}

#copy-message {
    font-size: 0.9rem;
    color: var(--secondary-text-color);
    transition: color 0.3s ease;
}

#copy-message.success {
    color: var(--success-color);
}

/* --- CodeMirror --- */
.CodeMirror {
    height: 100%; 
    flex-grow: 1;
    font-size: 0.9rem; /* Adjusted from 0.8rem for readability */
    font-family: var(--font-monospace);
}

.cm-s-material-darker.CodeMirror {
    background-color: #212121;
}

.cm-base64-placeholder {
    background-color: var(--border-color);
    color: var(--secondary-text-color);
    padding: 2px 6px;
    border-radius: 4px;
    font-style: italic;
    cursor: default;
    user-select: none;
}

/* --- ADDED: Overlay & Spinner Styles --- */
.overlay-container {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.7);
    z-index: 10;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    transition: opacity 0.2s ease-in-out;
}

.overlay-container.hidden {
    opacity: 0;
    pointer-events: none;
}

.spinner {
    width: 48px;
    height: 48px;
    border: 5px solid var(--border-color);
    border-bottom-color: var(--primary-text-color);
    border-radius: 50%;
    display: inline-block;
    animation: rotation 1s linear infinite;
    margin-bottom: 1rem;
}

@keyframes rotation {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}