/* --- CSS Variables (Theme) --- */
:root {
    --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    --font-weight-light: 300;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;

    --primary-color: #4f46e5; /* Indigo */
    --primary-hover: #4338ca;
    --success-color: #10b981; /* Emerald */
    --success-hover: #059669;
    --warning-color: #f59e0b; /* Amber */
    --danger-color: #ef4444; /* Red */
    --info-color: #3b82f6; /* Blue */

    --text-primary: #111827; /* Very dark grey */
    --text-secondary: #4b5563; /* Medium grey */
    --text-muted: #6b7280; /* Lighter grey */
    --text-on-primary: #ffffff;
    --text-on-success: #ffffff;

    --bg-app: #f9fafb; /* Very light grey */
    --bg-content: #ffffff; /* White */
    --bg-subtle: #f3f4f6; /* Slightly darker grey */
    --bg-input: #ffffff;
    --bg-input-readonly: #f3f4f6;

    --border-color: #d1d5db; /* Light grey border */
    --border-color-light: #e5e7eb;
    --focus-ring-color: rgba(79, 70, 229, 0.3); /* Indigo focus ring */

    --border-radius-sm: 0.25rem;  /* 4px */
    --border-radius-md: 0.375rem; /* 6px */
    --border-radius-lg: 0.5rem;   /* 8px */
    --border-radius-xl: 0.75rem;  /* 12px */

    --shadow-xs: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);

    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
}

/* --- Base & Reset --- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px; /* Base font size */
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-app);
    color: var(--text-primary);
    line-height: 1.65;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* --- App Layout Container --- */
.app-container {
    max-width: 1400px;
    margin: var(--spacing-8) auto;
    padding: var(--spacing-8) var(--spacing-10);
    background-color: var(--bg-content);
    border-radius: var(--border-radius-xl);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color-light);
}

/* --- Header --- */
.app-header {
    text-align: center;
    margin-bottom: var(--spacing-10);
    padding-bottom: var(--spacing-6);
    border-bottom: 1px solid var(--border-color-light);
}

.app-header h1 {
    font-size: 2.25rem; /* ~36px */
    font-weight: var(--font-weight-bold);
    color: var(--text-primary);
    margin-bottom: var(--spacing-1);
}

.app-header h1 i {
    color: var(--primary-color);
    margin-right: var(--spacing-2);
    vertical-align: middle; /* Align icon better */
}

.app-header .subtitle {
    font-size: 1.125rem; /* ~18px */
    color: var(--text-secondary);
    margin-bottom: var(--spacing-4);
}

.warning-banner {
    display: inline-flex; /* Prevent full width */
    align-items: center;
    gap: var(--spacing-2);
    font-size: 0.9rem;
    color: #92400e; /* Darker Amber Text */
    background-color: #fef3c7; /* Amber 100 */
    padding: var(--spacing-2) var(--spacing-4);
    border-radius: var(--border-radius-md);
    border: 1px solid #fde68a; /* Amber 200 */
}
.warning-banner i {
    color: var(--warning-color); /* Amber 500 */
}
.warning-banner strong {
    font-weight: var(--font-weight-medium);
}

/* --- Main Content Area --- */
.content-area {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-8);
}

/* --- Text IO Grid --- */
.text-io-grid {
    display: grid;
    grid-template-columns: 1fr 1fr; /* Two equal columns */
    gap: var(--spacing-8);
}

.text-box {
    display: flex;
    flex-direction: column;
}

.text-box label {
    margin-bottom: var(--spacing-3);
    display: block; /* Ensure label takes space */
    cursor: default; /* Remove text cursor */
}

.text-box h2 {
    font-size: 1.25rem; /* ~20px */
    font-weight: var(--font-weight-semibold);
    color: var(--text-primary);
    display: inline-flex; /* Align icon and text nicely */
    align-items: center;
    gap: var(--spacing-2);
}

.text-box h2 i {
    color: var(--text-secondary);
    font-size: 1.1em;
}
.input-box h2 i { color: var(--danger-color); }
.output-box h2 i { color: var(--success-color); }


textarea {
    flex-grow: 1; /* Allow textarea to fill vertical space */
    width: 100%;
    padding: var(--spacing-4);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    font-size: 1rem;
    font-family: inherit;
    line-height: inherit;
    background-color: var(--bg-input);
    box-shadow: var(--shadow-xs);
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
    resize: vertical; /* Allow vertical resize only */
    min-height: 350px; /* Generous minimum height */
}

textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px var(--focus-ring-color);
}

textarea[readonly] {
    background-color: var(--bg-input-readonly);
    cursor: default;
    color: var(--text-muted);
}
textarea[readonly]:focus {
    box-shadow: var(--shadow-xs); /* Don't show focus ring on readonly */
    border-color: var(--border-color);
}

/* --- Action Bar & Status --- */
.action-bar {
    display: flex;
    justify-content: center; /* Center button */
    align-items: center;
    gap: var(--spacing-4);
    padding: var(--spacing-4) 0;
    border-top: 1px solid var(--border-color-light);
    border-bottom: 1px solid var(--border-color-light);
}

.status-message {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-style: italic;
}

/* --- Buttons --- */
.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-2);
    padding: var(--spacing-3) var(--spacing-6);
    border: 1px solid transparent;
    border-radius: var(--border-radius-lg);
    font-family: inherit;
    font-size: 1rem;
    font-weight: var(--font-weight-medium);
    cursor: pointer;
    text-align: center;
    white-space: nowrap;
    transition: all 0.2s ease-in-out;
    box-shadow: var(--shadow-sm);
}
.button i {
    font-size: 1.1em;
}

.button:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-1px);
}
.button:active {
    transform: translateY(0px);
    box-shadow: var(--shadow-xs);
}
.button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    box-shadow: none;
    transform: none;
}

.button-primary {
    background-color: var(--primary-color);
    color: var(--text-on-primary);
    border-color: var(--primary-color);
}
.button-primary:hover {
    background-color: var(--primary-hover);
    border-color: var(--primary-hover);
}

.button-success {
    background-color: var(--success-color);
    color: var(--text-on-success);
    border-color: var(--success-color);
}
.button-success:hover {
    background-color: var(--success-hover);
    border-color: var(--success-hover);
}


/* --- Suggestions Area --- */
.suggestions-container {
    background-color: var(--bg-subtle);
    border-radius: var(--border-radius-xl);
    padding: var(--spacing-6);
    border: 1px solid var(--border-color-light);
    box-shadow: var(--shadow-inner, inset 0 2px 4px 0 rgb(0 0 0 / 0.05)); /* Inner shadow */
}

.suggestions-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline; /* Align text baselines */
    flex-wrap: wrap;
    gap: var(--spacing-4);
    margin-bottom: var(--spacing-4);
    padding-bottom: var(--spacing-4);
    border-bottom: 1px solid var(--border-color-light);
}

.suggestions-header h2 {
    font-size: 1.25rem;
    font-weight: var(--font-weight-semibold);
    color: var(--primary-color);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-2);
}

.suggestions-list {
    max-height: 450px;
    overflow-y: auto;
    padding: var(--spacing-1); /* Add padding for focus rings */
    margin: calc(-1 * var(--spacing-1)); /* Counteract padding for visual alignment */
}
/* Style scrollbar */
.suggestions-list::-webkit-scrollbar { width: 8px; }
.suggestions-list::-webkit-scrollbar-track { background: var(--bg-subtle); border-radius: 4px; }
.suggestions-list::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 4px; }
.suggestions-list::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

.suggestions-list .placeholder-text {
    padding: var(--spacing-8) 0;
    text-align: center;
    color: var(--text-muted);
    font-style: italic;
}

.suggestion-item {
    background-color: var(--bg-content);
    padding: var(--spacing-4);
    margin-bottom: var(--spacing-3);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--border-color-light);
    display: flex;
    align-items: flex-start; /* Align checkbox to top */
    gap: var(--spacing-4);
    box-shadow: var(--shadow-xs);
    transition: box-shadow 0.2s ease;
}
.suggestion-item:hover {
    box-shadow: var(--shadow-sm);
}

.suggestion-item input[type="checkbox"] {
    flex-shrink: 0;
    margin-top: var(--spacing-1); /* Align checkbox slightly better */
    accent-color: var(--primary-color);
    width: 18px;
    height: 18px;
    cursor: pointer;
    border-radius: var(--border-radius-sm);
    border: 1px solid var(--border-color);
}
.suggestion-item input[type="checkbox"]:focus {
    outline: none;
    box-shadow: 0 0 0 3px var(--focus-ring-color);
}


.suggestion-content {
    flex-grow: 1;
}

.suggestion-context {
    font-style: italic;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-2);
    border-left: 3px solid var(--border-color);
    padding-left: var(--spacing-3);
    font-size: 0.9rem;
    white-space: pre-wrap;
    word-wrap: break-word;
    background-color: var(--bg-subtle); /* Subtle background for context */
    padding-top: var(--spacing-1);
    padding-bottom: var(--spacing-1);
    border-radius: 0 var(--border-radius-sm) var(--border-radius-sm) 0;
}
.suggestion-context strong { /* Bolded original phrase in context */
    font-style: normal;
    color: var(--danger-color);
    font-weight: var(--font-weight-medium);
}

.suggestion-change {
    font-size: 1rem;
}

.suggestion-change strong { /* Original phrase */
    color: var(--danger-color);
    font-weight: var(--font-weight-normal);
    text-decoration: line-through; /* Strike through original */
    margin-right: var(--spacing-1);
}

.suggestion-change span:not(.arrow) { /* Replacement */
    color: var(--success-color);
    font-weight: var(--font-weight-medium);
    background-color: #ecfdf5; /* Light green background */
    padding: 0 var(--spacing-1);
    border-radius: var(--border-radius-sm);
}

.suggestion-change .arrow {
    color: var(--text-muted);
    margin: 0 var(--spacing-2);
    font-weight: var(--font-weight-bold);
}

.suggestions-footer {
    margin-top: var(--spacing-6);
    text-align: right; /* Align apply button to the right */
    padding-top: var(--spacing-4);
    border-top: 1px solid var(--border-color-light);
}

/* --- Footer --- */
.app-footer {
    margin-top: var(--spacing-10);
    padding-top: var(--spacing-4);
    text-align: center;
    font-size: 0.9rem;
    color: var(--text-muted);
    border-top: 1px solid var(--border-color-light);
}

.app-footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: var(--font-weight-medium);
    transition: color 0.2s ease;
}

.app-footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}
.app-footer i {
    margin-right: var(--spacing-1);
}


/* --- Responsiveness --- */
@media (max-width: 1024px) {
    .app-container {
        margin: var(--spacing-4);
        padding: var(--spacing-4) var(--spacing-6);
    }
    .text-io-grid {
        grid-template-columns: 1fr; /* Stack columns */
        gap: var(--spacing-6);
    }
    textarea {
        min-height: 250px; /* Reduce min height on smaller screens */
    }
}

@media (max-width: 640px) {
     html { font-size: 15px; } /* Slightly smaller base font */
    .app-container {
        margin: var(--spacing-2);
        padding: var(--spacing-3) var(--spacing-4);
        border-radius: var(--border-radius-lg);
    }
    .app-header h1 { font-size: 1.75rem; }
    .app-header .subtitle { font-size: 1rem; }
    .text-io-grid { gap: var(--spacing-4); }
    .action-bar { flex-direction: column; text-align: center; gap: var(--spacing-3); }
    .button { width: 100%; padding: var(--spacing-3) var(--spacing-4); } /* Make buttons full width */
    .suggestions-header { flex-direction: column; align-items: flex-start; }
    .suggestions-footer { text-align: center; }
    .suggestion-item { flex-direction: column; align-items: flex-start; } /* Stack checkbox and content */
    .suggestion-item input[type="checkbox"] { margin-bottom: var(--spacing-2); }
}