:root {
    --primary-color: #6200EE;
    --primary-variant-color: #3700B3;
    --secondary-color: #03DAC6;
    --background-color: #f5f5f5;
    --surface-color: #ffffff;
    --on-primary-color: #ffffff;
    --on-surface-color: #000000;
    --on-background-color: #000000;
    --text-muted-color: #666666;
    --border-color: #e0e0e0;
    --error-color: #B00020;
    --success-color: #4CAF50;
    --font-family: 'Roboto', sans-serif;
    --border-radius: 8px;
    --border-radius-small: 4px;
    --box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    --box-shadow-hover: 0 4px 8px rgba(0,0,0,0.15);
    --transition-speed: 0.3s ease;
    --highlight-bg-color: #fff3cd; /* Kept for light theme, might be adjusted if needed */
    --highlight-text-color: #856404; /* Kept for light theme */
}

body.dark-theme {
    /* New Dark Theme Accent Colors */
    --primary-color: #2979FF; /* A nice blue */
    --primary-variant-color: #004ECB; /* Darker blue for hover/variants */
    --secondary-color: #00BFA5; /* Teal for secondary accents */
    
    --background-color: #121212;
    --surface-color: #1e1e1e;
    --on-primary-color: #ffffff; /* Text on primary buttons */
    --on-surface-color: #e0e0e0;
    --on-background-color: #e0e0e0;
    --text-muted-color: #999999;
    --border-color: #333333;
    --highlight-bg-color: #3A3A3A; /* Darker highlight for dark theme */
    --highlight-text-color: #E0E0E0; /* Lighter text on dark highlight */
}

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

body {
    font-family: var(--font-family);
    background-color: var(--background-color);
    color: var(--on-background-color);
    line-height: 1.6;
    transition: background-color var(--transition-speed), color var(--transition-speed);
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
}

header h1 {
    color: var(--primary-color);
    font-weight: 500;
}

#theme-toggle {
    background: none;
    border: none;
    color: var(--on-surface-color);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 8px;
    border-radius: 50%;
    transition: background-color var(--transition-speed), color var(--transition-speed);
}
#theme-toggle:hover {
    background-color: rgba(0,0,0,0.08);
}
body.dark-theme #theme-toggle:hover {
    background-color: rgba(255,255,255,0.08);
}

.card {
    background-color: var(--surface-color);
    color: var(--on-surface-color);
    border-radius: var(--border-radius);
    padding: 25px;
    margin-bottom: 25px;
    box-shadow: var(--box-shadow);
    transition: background-color var(--transition-speed), color var(--transition-speed), box-shadow var(--transition-speed);
}
.card:hover {
    box-shadow: var(--box-shadow-hover);
}

.card h2 {
    margin-top: 0;
    color: var(--primary-variant-color); /* For light theme, usually darker */
    font-weight: 500;
}
body.dark-theme .card h2 {
    color: var(--primary-color); /* For dark theme, use the primary accent */
}

.input-section .input-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
}
.input-section .input-header h2 {
    margin-bottom: 0;
    border-bottom: none;
    padding-bottom: 0;
}

#text-input {
    width: 100%;
    min-height: 150px;
    padding: 15px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-family: var(--font-family);
    font-size: 1rem;
    background-color: var(--background-color);
    color: var(--on-background-color);
    resize: vertical;
    transition: border-color var(--transition-speed), background-color var(--transition-speed), color var(--transition-speed);
}
#text-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px var(--primary-color-alpha, rgba(98, 0, 238, 0.25)); /* Default alpha, might need adjustment for new blue */
}
body.dark-theme #text-input:focus {
     box-shadow: 0 0 0 2px rgba(41, 121, 255, 0.35); /* Alpha for the new blue */
}
body.dark-theme #text-input {
    background-color: #2c2c2c;
    color: var(--on-surface-color);
}

.controls-section h2 {
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
}

.control-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
    padding: 15px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-small);
    background-color: rgba(0,0,0,0.02);
}
body.dark-theme .control-group {
    background-color: rgba(255,255,255,0.03);
}

.control-group .format-group-label {
    display: block;
    font-weight: 500;
    margin-bottom: 5px;
    color: var(--on-surface-color);
}

.checkbox-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}
.checkbox-group div {
    display: flex;
    align-items: center;
    gap: 8px;
}
.checkbox-group label {
    cursor: pointer;
    user-select: none;
}
.checkbox-group input[type="checkbox"] {
    cursor: pointer;
    accent-color: var(--primary-color);
    width: 18px;
    height: 18px;
    flex-shrink: 0;
}
.checkbox-group code {
    background-color: var(--background-color);
    padding: 2px 5px;
    border-radius: 3px;
    font-size: 0.9em;
    border: 1px solid var(--border-color);
}
body.dark-theme .checkbox-group code {
    background-color: #2c2c2c;
}

.button-group {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}
.button-group .action-button.small-button {
    flex-grow: 1;
}

.prefix-suffix-group {
    display: flex;
    gap: 8px;
    align-items: center;
}
.prefix-suffix-group input[type="text"] {
    flex-grow: 1;
    padding: 8px 10px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-small);
    background-color: var(--surface-color);
    color: var(--on-surface-color);
    font-size: 0.9rem;
}
body.dark-theme .prefix-suffix-group input[type="text"] {
    background-color: #2c2c2c;
}

.structure-options {
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.structure-options > div {
    display: flex;
    align-items: center;
    gap: 8px;
}
.structure-options label {
     min-width: 80px;
}
.structure-options input[type="number"] {
    width: 60px;
    padding: 6px 8px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-small);
    text-align: center;
}
body.dark-theme .structure-options input[type="number"] {
    background-color: #2c2c2c;
    color: var(--on-surface-color);
}


#numbering-type, #bullet-type {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-small);
    background-color: var(--surface-color);
    color: var(--on-surface-color);
    font-family: var(--font-family);
    font-size: 0.9rem;
    flex-grow: 1;
    cursor: pointer;
}
#numbering-type:focus, #bullet-type:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px var(--primary-color-alpha, rgba(98, 0, 238, 0.25));
}
body.dark-theme #numbering-type:focus, body.dark-theme #bullet-type:focus {
     box-shadow: 0 0 0 2px rgba(41, 121, 255, 0.35);
}
body.dark-theme #numbering-type, body.dark-theme #bullet-type {
    background-color: #2c2c2c;
    color: var(--on-surface-color);
    border-color: var(--border-color);
}

.action-button {
    background-color: var(--primary-color);
    color: var(--on-primary-color);
    border: none;
    padding: 12px 20px;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    transition: background-color var(--transition-speed), box-shadow var(--transition-speed), transform var(--transition-speed);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}
.action-button:hover {
    background-color: var(--primary-variant-color);
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}
.action-button:active {
    transform: translateY(1px);
}
.action-button.small-button {
    padding: 8px 15px;
    font-size: 0.85rem;
    text-transform: none;
}
.action-button.danger-button {
    background-color: var(--error-color);
}
.action-button.danger-button:hover {
    background-color: #cf0000;
}

.preview-section .preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
    flex-wrap: wrap;
}
.preview-section .preview-header h2 {
    margin-bottom: 0;
    border-bottom: none;
    padding-bottom: 0;
}
.preview-controls {
    display: flex;
    gap: 10px;
    align-items: center;
    flex-grow: 1;
    margin-left: auto;
}
#filter-preview-input {
    padding: 8px 10px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-small);
    background-color: var(--surface-color);
    color: var(--on-surface-color);
    font-size: 0.9rem;
    min-width: 150px;
    flex-grow: 1;
    max-width: 300px;
}
body.dark-theme #filter-preview-input {
    background-color: #2c2c2c;
}

.preview-section .preview-content {
    min-height: 100px;
    border: 1px dashed var(--border-color);
    border-radius: var(--border-radius);
    padding: 15px;
    background-color: var(--background-color);
    transition: background-color var(--transition-speed), border-color var(--transition-speed);
}
body.dark-theme .preview-section .preview-content {
    background-color: #2c2c2c;
}

.preview-content p, .preview-content div {
    margin-bottom: 5px;
    word-break: break-word;
    color: var(--on-background-color);
    display: flex;
    gap: 0; 
    align-items: baseline;
}
.preview-content .prefix-container {
    display: inline-flex;
    align-items: baseline;
    flex-shrink: 0;
    margin-right: 0;
}
.preview-content .bullet-point {
    font-weight: bold;
    flex-shrink: 0;
    color: var(--primary-color);
}
.preview-content .item-number {
    font-weight: 500;
    flex-shrink: 0;
    color: var(--primary-color);
}
body.dark-theme .preview-content .item-number,
body.dark-theme .preview-content .bullet-point {
    color: var(--secondary-color); 
}
.preview-content .item-text {
    flex-grow: 1;
}
.preview-content .placeholder {
    color: var(--text-muted-color);
    font-style: italic;
    display: block;
}
.preview-content strong {
    font-weight: 700;
}
.preview-content em {
    font-style: italic;
}
.preview-content .highlight {
    background-color: var(--highlight-bg-color);
    color: var(--highlight-text-color);
    padding: 0.1em 0.2em;
    border-radius: 3px;
}
.preview-content s, .preview-content del {
    text-decoration: line-through;
    opacity: 0.7;
}
.preview-content sub {
    vertical-align: sub;
    font-size: smaller;
}
.preview-content sup {
    vertical-align: super;
    font-size: smaller;
}

.stats-section h2 {
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
}
.stats-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 10px;
    font-size: 0.95rem;
}
.stats-content p {
    margin: 0;
    background-color: var(--background-color);
    padding: 10px;
    border-radius: var(--border-radius-small);
    border: 1px solid var(--border-color);
}
body.dark-theme .stats-content p {
    background-color: #2c2c2c;
}
.stats-content p span {
    font-weight: bold;
    color: var(--primary-color);
}
body.dark-theme .stats-content p span {
    color: var(--secondary-color); 
}

footer {
    text-align: center;
    margin-top: 40px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
    font-size: 0.9rem;
    color: var(--text-muted-color);
}

#notification-area {
    position: fixed;
    bottom: 20px;
    right: 20px;
    z-index: 1000;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.notification {
    padding: 15px 20px;
    border-radius: var(--border-radius);
    color: #fff;
    font-weight: 500;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
    opacity: 0;
    transform: translateX(100%);
    animation: slideInNotification 0.5s forwards, fadeOutNotification 0.5s 2.5s forwards;
}
.notification.info { background-color: var(--primary-color); }
.notification.success { background-color: var(--success-color); }
.notification.error { background-color: var(--error-color); }

@keyframes slideInNotification {
    to {
        opacity: 1;
        transform: translateX(0);
    }
}
@keyframes fadeOutNotification {
    from {
        opacity: 1;
        transform: translateX(0);
    }
    to {
        opacity: 0;
        transform: translateX(100%);
    }
}

@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    header {
        flex-direction: column;
        gap: 10px;
        text-align: center;
    }
    .input-section .input-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    .input-section .input-header .action-button {
        align-self: stretch;
    }
    .control-grid {
        grid-template-columns: 1fr;
    }
    .structure-options > div {
        flex-direction: column;
        align-items: flex-start;
    }
    .structure-options label {
        min-width: auto;
        margin-bottom: 5px;
    }
    #numbering-type, #bullet-type, #bullet-spacing {
        width: 100%;
    }
    .preview-section .preview-header {
        flex-direction: column;
        align-items: flex-start;
    }
    .preview-controls {
        width: 100%;
        margin-left: 0;
        margin-top: 10px;
    }
    #filter-preview-input {
        max-width: none;
    }
}

@media (max-width: 480px) {
    body {
        padding: 10px 5px;
    }
    .card {
        padding: 15px;
    }
    header h1 {
        font-size: 1.8rem;
    }
    #text-input {
        min-height: 120px;
    }
    .action-button {
        padding: 10px 15px;
        font-size: 0.9rem;
    }
    .action-button.small-button {
        padding: 8px 12px;
        font-size: 0.8rem;
    }
    #notification-area {
        bottom: 10px;
        right: 10px;
        left: 10px;
        align-items: stretch;
    }
}