:root {
    --primary-color: #1E90FF;
    --primary-dark-color: #1C86EE;
    --secondary-color: #f4f7fa;
    --border-color: #e1e5eb;
    --text-color: #333;
    --light-text-color: #777;
    --card-bg-color: #ffffff;
    --answer-color: #d32f2f;
    --correct-color: #28a745;
    --incorrect-color: #dc3545;
    --selected-color: #a5d6a7;
}

[data-theme="dark"] {
    --primary-color: #4f88f3;
    --primary-dark-color: #3569d7;
    --secondary-color: #2a3142;
    --border-color: rgba(255, 255, 255, 0.12);
    --text-color: #e8eef7;
    --text-secondary: #c4cddc;
    --light-text-color: #9aa3b8;
    --bs-code-color: #e8ecf8;
    --card-bg-color: rgba(20, 26, 38, 0.95);
    --answer-color: #ff8080;
    --correct-color: #39b54a;
    --incorrect-color: #ee6363;
    --selected-color: rgba(82, 153, 118, 0.3);
}

body {
    background: transparent;
}

main {
    background-color: transparent;
    border: none;
    max-width: 800px;
    margin-top: 0 !important;
    box-shadow: none;
}

footer {
    margin-top: 0;
}

.redsheet-container {
    min-height: calc(100vh - 56px);
    display: flex;
    justify-content: center;
    align-items: flex-start;
    background: transparent;
    padding: 20px;
    margin-bottom: 20px;
}

.redsheet-card {
    max-width: 1200px;
    width: 100%;
    background: var(--glass-bg) !important;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    box-shadow: 0 4px 20px var(--glass-shadow);
    padding: 25px;
    overflow: hidden;
}

.tab-nav {
    display: flex;
    background-color: transparent;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 20px;
}

.tab-button {
    flex-grow: 1;
    padding: 15px 10px;
    border: none;
    background-color: transparent;
    font-size: 16px;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
    position: relative;
}

.tab-button.active {
    color: var(--accent-blue);
}

.tab-button.active::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 0;
    right: 0;
    height: 3px;
    background-color: var(--accent-blue);
}

.tab-content {
    display: none;
    padding: 0;
}

.tab-content.active {
    display: block;
    animation: fadeIn 0.4s;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

h2 {
    text-align: left;
    margin-top: 0;
    color: var(--text-primary);
}

p, label {
    color: var(--text-secondary);
    font-size: 15px;
}

.section-box {
    border: 1px solid var(--border-color);
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 20px;
    background-color: var(--card-bg-color);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

textarea, input, input[type="number"] {
    width: 100%;
    padding: 12px;
    margin-bottom: 10px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 16px;
    transition: border-color 0.2s, box-shadow 0.2s;
    background-color: var(--card-bg-color);
    color: var(--text-primary);
}

textarea:focus, input:focus, input[type="number"]:focus {
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
    outline: none;
}

button, .file-label {
    background-color: var(--primary-color);
    color: #fff;
    border: none;
    padding: 12px 18px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 500;
    transition: background-color 0.2s;
    text-align: center;
    margin: 2px;
    display: inline-block;
}

button:hover, .file-label:hover {
    background-color: var(--primary-dark-color);
}

button:disabled {
    background-color: #aaa;
    cursor: not-allowed;
}

.button-secondary {
    background-color: #6c757d;
}

.button-secondary:hover {
    background-color: #5a6268;
}

#question-list {
    list-style-type: none;
    padding: 0;
    margin-top: 20px;
}

.question-item {
    background-color: var(--card-bg-color);
    border: 1px solid var(--border-color);
    padding: 15px 20px;
    margin-bottom: 15px;
    border-radius: 8px;
    box-shadow: 0 4px 15px var(--glass-shadow);
    transition: box-shadow 0.2s, transform 0.2s;
}

.question-item:hover {
    box-shadow: 0 6px 20px var(--glass-shadow);
    transform: translateY(-2px);
}

.question-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.question-text {
    font-weight: 500;
    margin-bottom: 10px;
    flex-grow: 1;
    word-wrap: break-word;
}

.answer-text {
    cursor: pointer;
    transition: all 0.2s;
    padding: 5px;
    border-radius: 3px;
    color: var(--answer-color);
    font-weight: 500;
}

.answer-text.hidden {
    background-color: var(--answer-color);
    user-select: none;
    color: var(--answer-color);
}

.question-item .actions button {
    background-color: var(--glass-bg-alt);
    color: var(--text-primary);
    padding: 6px 10px;
    font-size: 12px;
    border: 1px solid var(--glass-border);
}

.question-item .actions button:hover {
    background-color: var(--glass-bg-hover);
}

.modal-overlay {
    position: fixed;
    inset: 0;
    background-color: rgba(0, 0, 0, 0.75);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 9999;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s, visibility 0.3s;
}

.modal-card {
    position: relative;
    z-index: 10000;
    background-color: var(--card-bg-color);
    width: 90%;
    max-width: 700px;
    max-height: 90vh;
    border-radius: 12px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.2);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transform: scale(0.95);
    opacity: 0;
    transition: transform 0.3s, opacity 0.3s;
}

.modal-overlay.visible {
    opacity: 1;
    visibility: visible;
}

.modal-overlay.visible .modal-card {
    transform: scale(1);
    opacity: 1;
}

.modal-header {
    padding: 15px 20px;
    background-color: var(--secondary-color);
    flex-shrink: 0;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h3 {
    margin: 0;
    font-size: 18px;
}

.modal-body {
    padding: 25px;
    overflow-y: auto;
    flex-grow: 1;
}

.modal-footer {
    padding: 15px 20px;
    background-color: var(--secondary-color);
    flex-shrink: 0;
    border-top: 1px solid var(--border-color);
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    gap: 10px;
}

.focus-body .answer-area {
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px dashed var(--border-color);
    color: var(--answer-color);
    visibility: hidden;
}

.focus-body .answer-area.visible {
    visibility: visible;
}

.quiz-options {
    display: grid;
    grid-template-columns: 1fr;
    gap: 10px;
    margin-top: 20px;
}

.quiz-option-container {
    display: flex;
    flex-direction: column;
    position: relative;
}

.quiz-option-button {
    width: 100%;
    padding: 15px;
    font-size: 16px;
    background-color: var(--card-bg-color);
    color: var(--text-primary);
    text-align: left;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
}

.quiz-option-button:hover {
    background-color: rgba(59, 130, 246, 0.08);
}

.quiz-option-button::before {
    content: attr(data-key) ". ";
    font-weight: bold;
    margin-right: 5px;
}

.quiz-option-button.correct {
    background-color: var(--correct-color) !important;
    color: white;
    border-color: var(--correct-color);
}

.quiz-option-button.incorrect {
    background-color: var(--incorrect-color) !important;
    color: white;
    border-color: var(--incorrect-color);
}

.quiz-option-button:disabled {
    opacity: 0.8;
    cursor: not-allowed;
}

.quiz-explanation {
    font-size: 0.8em;
    color: #555;
    padding-left: 15px;
    margin-top: 2px;
}

#quiz-next-button {
    display: none;
}

.matching-container {
    display: flex;
    justify-content: space-between;
    gap: 20px;
    height: 400px;
}

.matching-list {
    list-style: none;
    padding: 0;
    width: 48%;
    display: flex;
    flex-direction: column;
    gap: 10px;
    overflow-y: auto;
    overflow-x: hidden;
    max-height: 100%;
}

.matching-item {
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    word-wrap: break-word;
    min-height: 50px;
    display: flex;
    align-items: center;
    flex-shrink: 0;
    background-color: var(--card-bg-color);
    color: var(--text-primary);
}

.matching-item.selected {
    background-color: var(--selected-color);
    border-color: var(--correct-color);
    transform: scale(1.03);
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
}

.matching-item.matched {
    opacity: 0.3;
    text-decoration: line-through;
    pointer-events: none;
}

.matching-item.incorrect-flash {
    animation: shake 0.5s;
    background-color: var(--incorrect-color);
}

@keyframes shake {
    0%, 100% {
        transform: translateX(0);
    }
    25% {
        transform: translateX(-5px);
    }
    75% {
        transform: translateX(5px);
    }
}

.file-input {
    display: none;
}

.toast-notification {
    position: fixed;
    bottom: -100px;
    left: 50%;
    transform: translateX(-50%);
    background-color: rgba(0,0,0,0.75);
    color: white;
    padding: 12px 20px;
    border-radius: 25px;
    font-size: 15px;
    z-index: 2000;
    transition: bottom 0.5s ease-in-out;
}

.toast-notification.show {
    bottom: 30px;
}

@media (min-width: 600px) {
    .quiz-options {
        grid-template-columns: 1fr 1fr;
    }
}

.quiz-result {
    margin-top: 20px;
    padding: 16px;
    border-radius: 12px;
    background-color: rgba(255, 255, 255, 0.92);
    border: 1px solid rgba(0, 0, 0, 0.08);
    color: var(--text-primary);
    line-height: 1.6;
}

.quiz-result.hidden {
    display: none;
}

@media print {
    html,
    body,
    .page-content,
    .redsheet-card,
    .redsheet-container {
        background: #fff !important;
        color: #000 !important;
        box-shadow: none !important;
        border: none !important;
        border-color: white !important;
    }

    .no-print,
    .tab-nav,
    .section-box,
    .controls,
    .modal-overlay,
    .modal-card,
    .quiz-options,
    .file-label,
    input,
    textarea,
    button,
    .button-secondary,
    .toast-notification,
    .quiz-result,
    .answer-text.hidden,
    header,
    footer,
    #learn-tab,
    #manage-tab {
        display: none !important;
    }

    * {
        border-color: white !important;
    }

    main {
        padding-top: 0 !important;
        box-shadow: none !important;
    }

    .tab-content {
        display: block !important;
        padding: 0;
    }

    #question-list {
        margin-top: 0;
    }

    .question-item {
        background: transparent !important;
        border: none !important;
        box-shadow: none !important;
        page-break-inside: avoid;
    }

    .question-text,
    .answer-text {
        color: #000 !important;
        background: transparent !important;
    }
}

body.modal-open {
    overflow: hidden;
}