:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-color: #f3f4f6;
    --card-bg: #ffffff;
    --text-color: #1f2937;
    --text-secondary: #4b5563;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --success-bg: #ecfdf5;
    --error-color: #ef4444;
    --error-bg: #fef2f2;
}

html.dark-mode {
    --primary-color: #60a5fa;
    --primary-hover: #93c5fd;
    --bg-color: #111827;
    --card-bg: #1f2937;
    --text-color: #f3f4f6;
    --text-secondary: #9ca3af;
    --border-color: #374151;
    --success-color: #34d399;
    --success-bg: #064e3b;
    --error-color: #f87171;
    --error-bg: #7f1d1d;
}

/* Dark Mode Toggle */
.theme-switch-wrapper {
    display: flex;
    align-items: center;
    margin-left: 1rem;
}

.theme-switch {
    display: inline-block;
    height: 26px;
    position: relative;
    width: 50px;
}

.theme-switch input {
    display: none;
}

.slider {
    background-color: #ccc;
    bottom: 0;
    cursor: pointer;
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    transition: .4s;
    border-radius: 34px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 5px;
}

.slider:before {
    background-color: #fff;
    bottom: 3px;
    content: "";
    height: 20px;
    left: 3px;
    position: absolute;
    transition: .4s;
    width: 20px;
    border-radius: 50%;
    z-index: 2;
}

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

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

.slider .icon {
    font-size: 14px;
    line-height: 1;
    z-index: 1;
}

.slider .sun {
    color: #f59e0b;
}

.slider .moon {
    color: #f3f4f6;
}

input:checked + .slider .sun {
    opacity: 0;
}

input:checked + .slider .moon {
    opacity: 1;
}

/* Refactored classes from inline styles */
.alert-box-info {
    background-color: #e3f2fd;
    padding: 15px;
    border-radius: 8px;
    margin: 20px 0;
    border-left: 5px solid #2196f3;
    color: #1f2937; /* Force dark text on light bg in light mode */
}

html.dark-mode .alert-box-info {
    background-color: #1e3a8a;
    border-left-color: #60a5fa;
    color: #e5e7eb;
}

.btn-danger {
    background: #ef5350;
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
}

.btn-danger:hover {
    background: #d32f2f;
}

html.dark-mode .btn-danger {
    background: #b91c1c;
}

html.dark-mode .btn-danger:hover {
    background: #991b1b;
}

.chart-box {
    flex: 1;
    min-width: 300px;
    background: var(--card-bg);
    padding: 15px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.problem-item {
    background: var(--card-bg);
    padding: 15px;
    margin-bottom: 10px;
    border-left: 4px solid var(--error-color);
    border-radius: 4px;
    border: 1px solid var(--border-color);
}

.problem-item-header {
    font-weight: bold;
    color: var(--error-color);
}

.problem-item-stats {
    font-size: 0.9em;
    color: var(--text-secondary);
}

.chart-legend {
    margin-top: 10px;
    font-size: 0.8em;
    color: var(--text-secondary);
}

.tag-badge {
    font-size: 0.85em;
    padding: 4px 8px;
    background: var(--bg-color);
    border-radius: 4px;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

.exam-history-item {
    background: var(--card-bg);
    padding: 15px;
    margin-bottom: 10px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    box-shadow: 0 1px 2px rgba(0,0,0,0.05);
}

.exam-date {
    font-weight: 600;
    color: var(--text-color);
}

.exam-score {
    font-weight: bold;
}

.exam-score.success {
    color: var(--success-color);
}

.exam-score.failure {
    color: var(--error-color);
}

.btn-delete {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--error-color);
    padding: 4px;
    display: flex;
    align-items: center;
}

.btn-recalculate {
    background: none;
    border: none;
    color: var(--text-secondary);
    text-decoration: underline;
    cursor: pointer;
    font-size: 0.9em;
}


body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    margin: 0;
    padding: 0;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

header {
    background: var(--card-bg);
    padding: 1rem 2rem;
    border-radius: 12px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

header h1 {
    margin: 0;
    font-size: 1.5rem;
    color: var(--primary-color);
}

nav {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

nav button {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid transparent;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

nav button:hover {
    background: var(--bg-color);
    color: var(--primary-color);
}

.nav-icon {
    width: 18px;
    height: 18px;
    margin-right: 6px;
    vertical-align: text-bottom;
    stroke-width: 2;
}

.card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    margin-bottom: 2rem;
}

.question-block {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    margin-bottom: 2rem;
    border: 1px solid var(--border-color);
    transition: transform 0.2s;
    position: relative; /* For absolute positioning of badge */
}

.category-header {
    margin-top: 3rem;
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0.5rem;
    font-size: 1.25rem;
}

.category-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background-color: var(--bg-color);
    color: var(--text-secondary);
    padding: 0.25rem 0.75rem;
    border-radius: 999px;
    font-size: 0.8rem;
    font-weight: 600;
    border: 1px solid var(--border-color);
}

.question-text {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-color);
    line-height: 1.5;
}

.question-img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    margin-bottom: 1.5rem;
    display: block;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    background-color: transparent;
}

/* Chat Styles */
.chat-section {
    margin-top: 30px;
    border-top: 1px solid var(--border-color);
    padding-top: 20px;
}

.chat-history {
    max-height: 400px;
    overflow-y: auto;
    margin-bottom: 15px;
    padding: 10px;
    background: var(--bg-color);
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.chat-message {
    padding: 10px 15px;
    border-radius: 12px;
    max-width: 85%;
    line-height: 1.5;
    font-size: 0.95rem;
}

.chat-message.user {
    align-self: flex-end;
    background-color: var(--primary-color);
    color: white;
    border-bottom-right-radius: 2px;
}

.chat-message.model {
    align-self: flex-start;
    background-color: var(--card-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-bottom-left-radius: 2px;
}

.chat-message.loading span {
    display: inline-block;
    animation: bounce 1.4s infinite ease-in-out both;
    margin: 0 2px;
    font-size: 1.5rem;
    line-height: 10px;
}

.chat-message.loading span:nth-child(1) { animation-delay: -0.32s; }
.chat-message.loading span:nth-child(2) { animation-delay: -0.16s; }

@keyframes bounce {
    0%, 80%, 100% { transform: scale(0); }
    40% { transform: scale(1); }
}

.chat-input-area {
    display: flex;
    gap: 10px;
    align-items: flex-end;
}

.chat-input-area textarea {
    flex: 1;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--card-bg);
    color: var(--text-color);
    resize: none;
    min-height: 44px;
    max-height: 150px;
    font-family: inherit;
}

.chat-input-area textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.chat-input-area button {
    height: 44px;
    width: 44px;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
}

html.dark-mode .question-img {
    filter: invert(1) hue-rotate(180deg);
}

.options {
    display: grid;
    gap: 0.75rem;
}

.options label {
    display: flex;
    align-items: flex-start;
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    background: var(--card-bg);
    position: relative;
    color: var(--text-color);
}

.options label:hover {
    border-color: var(--primary-hover);
    background-color: var(--bg-color);
}

/* Custom Radio Button */
.options input[type="radio"] {
    appearance: none;
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-radius: 50%;
    margin-right: 1rem;
    margin-top: 0.2rem;
    flex-shrink: 0;
    display: grid;
    place-content: center;
    transition: all 0.2s;
    background-color: var(--card-bg);
}

.options input[type="radio"]::before {
    content: "";
    width: 10px;
    height: 10px;
    border-radius: 50%;
    transform: scale(0);
    transition: 0.2s transform ease-in-out;
    box-shadow: inset 1em 1em var(--primary-color);
}

.options input[type="radio"]:checked {
    border-color: var(--primary-color);
}

.options input[type="radio"]:checked::before {
    transform: scale(1);
}

/* Highlight selected label */
.options label:has(input:checked) {
    border-color: var(--primary-color);
    background-color: rgba(37, 99, 235, 0.1); /* Light blue with opacity for dark mode compatibility */
}

.answer-content {
    flex: 1;
    font-size: 1rem;
    color: var(--text-color);
}

.answer-img {
    max-width: 180px;
    height: auto;
    display: block;
    margin-top: 0.75rem;
    border-radius: 4px;
    border: 1px solid var(--border-color);
    padding: 4px;
    background: transparent;
}

html.dark-mode .answer-img {
    filter: invert(1) hue-rotate(180deg);
}

.btn {
    background-color: var(--primary-color);
    color: white;
    padding: 0.75rem 2rem;
    border-radius: 8px;
    font-weight: 600;
    border: none;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 1rem;
    display: inline-block;
    box-shadow: 0 2px 4px rgba(37, 99, 235, 0.2);
}

.btn:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 6px rgba(37, 99, 235, 0.3);
}

.btn:active {
    transform: translateY(0);
}

/* Regenerate Button */
.btn-regenerate {
    margin-left: 0.5rem;
    border-color: var(--text-secondary);
    color: var(--text-secondary);
}

.btn-regenerate:hover {
    background-color: #f3f4f6;
    color: var(--text-color);
}

/* Feedback Styles */
.options label.correct {
    border-color: var(--success-color);
    background-color: var(--success-bg);
}

.options label.correct input[type="radio"] {
    border-color: var(--success-color);
    box-shadow: inset 1em 1em var(--success-color); /* Fill circle */
}
.options label.correct input[type="radio"]::before {
    box-shadow: inset 1em 1em white; /* White dot */
}

.options label.incorrect {
    border-color: var(--error-color);
    background-color: var(--error-bg);
    opacity: 0.8;
}

.options label.incorrect input[type="radio"] {
    border-color: var(--error-color);
}

.feedback-box {
    margin-top: 1rem;
    padding: 1rem;
    border-radius: 8px;
    font-weight: 500;
    animation: fadeIn 0.3s ease;
}

.feedback-box.success {
    background-color: var(--success-bg);
    color: var(--success-color);
    border: 1px solid var(--success-color);
}

.feedback-box.error {
    background-color: var(--error-bg);
    color: var(--error-color);
    border: 1px solid var(--error-color);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-5px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Stats */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.5rem;
}

.stat-card {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    text-align: center;
    transition: transform 0.2s;
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin: 0.5rem 0;
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 600;
}

.exam-controls {
    background: var(--card-bg);
    padding: 1rem 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.15);
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: relative;
    width: 100%;
    box-sizing: border-box;
    z-index: 100;
    transition: transform 0.3s ease;
    /* Ensure initial transform matches the Y-axis logic to prevent jumps, 
       though 'none' is usually fine if we only animate Y later. */
    transform: translateY(0);
}

.exam-controls.sticky-mode {
    position: fixed;
    /* Center without translateX to avoid horizontal animation jump */
    left: 0;
    right: 0;
    margin: 0 auto;
    top: 10px;
    width: calc(100% - 2rem);
    max-width: 868px;
    transform: translateY(0);
    margin-bottom: 0;
}

.exam-controls.sticky-mode.hide-bar {
    transform: translateY(-150%);
}

.exam-controls-placeholder {
    display: none;
    height: 72px;
    margin-bottom: 2rem;
}

.exam-controls-placeholder.active {
    display: block;
}

.btn-hilfsmittel {
    width: 40px;
    height: 40px;
    padding: 0;
    border-radius: 8px;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
    flex-shrink: 0;
}

.btn-hilfsmittel:hover {
    background: var(--primary-color);
    border-color: var(--primary-color);
}

.btn-hilfsmittel:hover svg {
    stroke: white;
}

.btn-hilfsmittel svg {
    width: 22px;
    height: 22px;
    stroke: var(--text-secondary);
    transition: stroke 0.2s;
}

.toggle-switch {
    display: flex;
    align-items: center;
    cursor: pointer;
    gap: 0.75rem;
}

.toggle-switch input {
    display: none;
}

.toggle-switch .toggle-slider {
    width: 40px;
    height: 24px;
    background-color: #d1d5db; /* Darker grey for better visibility in light mode */
    border-radius: 999px;
    position: relative;
    transition: all 0.3s ease;
    display: block;
}

html.dark-mode .toggle-switch .toggle-slider {
    background-color: #4b5563;
}

.toggle-switch:hover .toggle-slider {
    background-color: #9ca3af;
}

html.dark-mode .toggle-switch:hover .toggle-slider {
    background-color: #6b7280;
}

.toggle-switch .toggle-slider::before {
    content: "";
    position: absolute;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background-color: white;
    top: 2px;
    left: 2px;
    transition: left 0.3s cubic-bezier(0.4, 0.0, 0.2, 1);
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

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

.toggle-switch:hover input:checked + .toggle-slider {
    background-color: var(--primary-hover);
}

.toggle-switch input:checked + .toggle-slider::before {
    left: 18px;
}

.toggle-switch .label-text {
    font-weight: 600;
    color: var(--text-color);
}

.explanation-controls {
    margin-top: 1rem;
    text-align: right;
}

.btn-explain {
    background-color: var(--card-bg);
    border: 1px solid var(--primary-color);
    color: var(--primary-color);
    padding: 0.5rem 1rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.2s;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.btn-explain:hover {
    background-color: #eff6ff;
}

html.dark-mode .btn-explain:hover {
    background-color: rgba(96, 165, 250, 0.1);
}

.btn-explain:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.explanation-content {
    margin-top: 1rem;
    padding: 1rem;
    background-color: #f8fafc;
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
    font-size: 0.95rem;
    line-height: 1.6;
    color: var(--text-color);
    animation: fadeIn 0.3s ease;
}

html.dark-mode .explanation-content {
    background-color: var(--bg-color);
}

.explanation-content p {
    margin: 0 0 0.5rem 0;
}

.explanation-content p:last-child {
    margin-bottom: 0;
}

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

@media (max-width: 640px) {
    .container {
        padding: 0.5rem;
    }
    
    header {
        padding: 1rem;
        flex-direction: column;
        text-align: center;
        gap: 0.5rem;
        margin-bottom: 1rem;
    }

    header h1 {
        font-size: 1.25rem;
        margin-bottom: 0.5rem;
    }

    nav {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 0.5rem;
    }

    nav button {
        padding: 0.5rem 0.75rem;
        font-size: 0.9rem;
        width: auto;
        flex: 1;
        white-space: nowrap;
    }

    .card {
        padding: 1.25rem;
        margin-bottom: 1rem;
    }

    .question-block {
        padding: 1.25rem;
        margin-bottom: 1rem;
        border-radius: 8px;
    }

    .question-text {
        font-size: 1rem;
        margin-bottom: 1rem;
    }

    .options label {
        padding: 0.75rem;
        margin-bottom: 0.5rem;
    }

    .btn {
        width: 100%;
        padding: 1rem;
        text-align: center;
        font-size: 1.1rem;
        /* Removed sticky positioning */
    }
    
    .stat-value {
        font-size: 2rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
}

/* Modal styles */
.modal {
    display: none; 
    position: fixed; 
    z-index: 1000; 
    left: 0;
    top: 0;
    width: 100%; 
    height: 100%; 
    overflow: hidden; 
    background-color: rgba(0,0,0,0.9); 
    cursor: pointer;
    align-items: center;
    justify-content: center;
}

.modal-content {
    margin: auto;
    display: block;
    background-color: white;
    padding: 10px;
    border-radius: 8px;
    
    /* Ensure image fits within the box if aspect ratio is forced */
    object-fit: contain;
    
    /* Default for mobile/portrait: maximize width */
    width: 95vw;
    height: auto;
    max-height: 90vh;

    animation-name: zoom;
    animation-duration: 0.3s;
    box-shadow: 0 4px 6px rgba(0,0,0,0.3);
}

html.dark-mode .modal-content {
    filter: invert(1) hue-rotate(180deg);
}

/* For landscape screens (desktop/laptop), maximize height */
@media (min-aspect-ratio: 1/1) {
    .modal-content {
        height: 90vh;
        width: auto;
        max-width: 90vw;
    }
}

.pdf-modal-content {
    margin: auto;
    display: block;
    background-color: #525659; /* Dark grey background like PDF viewers */
    width: 90vw;
    height: 90vh;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.3);
    position: relative;
    overflow-y: auto; /* Enable vertical scrolling */
    padding: 20px;
    box-sizing: border-box;
    text-align: center; /* Center the pages */
}

.pdf-page-canvas {
    margin-bottom: 20px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
    max-width: 100%;
    height: auto !important; /* Maintain aspect ratio */
}

@keyframes zoom {
  from {transform:scale(0)} 
  to {transform:scale(1)}
}

.close {
    position: absolute;
    top: 15px;
    right: 35px;
    color: #f1f1f1;
    font-size: 40px;
    font-weight: bold;
    transition: 0.3s;
    z-index: 1001;
}

.close:hover,
.close:focus {
    color: #bbb;
    text-decoration: none;
    cursor: pointer;
}

/* Add cursor pointer to images to indicate they are clickable */
.question-img, .answer-img {
    cursor: pointer;
    transition: transform 0.2s;
}

.question-img:hover, .answer-img:hover {
    transform: scale(1.02);
}

/* Config Section */
.config-section {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
}

.input-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.input-group label {
    font-weight: 600;
    color: var(--text-color);
    font-size: 1rem;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.input-wrapper input {
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1.1rem;
    width: 80px;
    text-align: center;
    transition: border-color 0.2s;
    outline: none;
}

#searchQuestionInput {
    width: 160px;
}

.input-wrapper input:focus {
    border-color: var(--primary-color);
}

.input-hint {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.btn-large {
    padding: 1rem 3rem;
    font-size: 1.1rem;
    width: 100%;
    max-width: 300px;
}