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

:root {
    --primary-color: #0b0b0f;
    --secondary-color: #101016;
    --accent-color: #fbbf24;
    --success-color: #4ade80;
    --error-color: #f87171;
    --text-primary: #f4f4f6;
    --text-secondary: #a2a2b0;
    --card-bg: #14141b;
    --hover-color: #24242f;
}

body {
    font-family: 'Inter', 'Segoe UI', system-ui, -apple-system, sans-serif;
    -webkit-font-smoothing: antialiased;
    background-color: var(--primary-color);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
}

header {
    background-color: var(--secondary-color);
    padding: 1rem 1.5rem;
    box-shadow: 0 2px 10px rgba(255, 255, 255, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.brand {
    display: flex;
    align-items: center;
    gap: 10px;
}

.brand h1 {
    font-size: 1.2rem;
    margin-bottom: 0.2rem;
    color: var(--text-primary);
}

.brand .course-name {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 300;
}

.back-link {
    text-decoration: none;
    font-size: 1.4rem;
    color: #fff;
    font-weight: 700;
    margin-right: 10px;
}

.screen {
    display: none;
    animation: fadeIn 0.3s ease-in-out;
}

.screen.active {
    display: block;
}

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

.dashboard-container {
    max-width: 700px;
    margin: 0 auto;
    padding: 1.5rem;
}

.welcome-message h2 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    text-align: center;
}

.progress-section {
    margin-bottom: 1.5rem;
}

.progress-card {
    background-color: var(--secondary-color);
    padding: 1.2rem;
    border-radius: 12px;
    border: 1px solid rgba(255, 255, 255, 0.08);
}

.progress-card h3 {
    font-size: 1rem;
    margin-bottom: 0.8rem;
    color: var(--text-secondary);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 0.5rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #d97706, var(--accent-color));
    border-radius: 4px;
    transition: width 0.5s ease;
}

.main-actions {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1rem;
}

.dashboard-btn {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    padding: 1rem;
    background-color: var(--secondary-color);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 12px;
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.2s;
    text-align: left;
    width: 100%;
}

.dashboard-btn:hover {
    background-color: var(--hover-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.dashboard-btn.primary {
    background: linear-gradient(135deg, #d97706, var(--accent-color));
    color: #111;
    border: none;
}

.dashboard-btn.success {
    background: rgba(74, 222, 128, 0.1);
    border-color: rgba(74, 222, 128, 0.3);
}

.dashboard-btn.known-idioms-btn {
    background: linear-gradient(135deg, rgba(74, 222, 128, 0.11), rgba(22, 101, 52, 0.05));
    border-color: rgba(74, 222, 128, 0.24);
}

.dashboard-btn.practice-idioms-btn {
    background: linear-gradient(135deg, rgba(251, 191, 36, 0.12), rgba(217, 119, 6, 0.05));
    border-color: rgba(251, 191, 36, 0.28);
}

.categories-container {
    width: min(760px, calc(100% - 2rem));
    margin: 0 auto;
    padding: 1rem 0 3rem;
}

.category-column {
    min-width: 0;
    padding: 1rem;
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 18px;
    background: rgba(18, 18, 24, 0.82);
}

.known-column {
    border-color: rgba(74, 222, 128, 0.18);
}

.practice-column {
    border-color: rgba(251, 191, 36, 0.22);
}

.category-column-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 1rem;
    padding: 0.2rem 0.15rem 0.9rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.category-column-head h3 {
    margin: 0.2rem 0 0;
    font-size: 1.2rem;
}

.category-kicker {
    color: var(--text-secondary);
    font-size: 0.68rem;
    font-weight: 700;
    letter-spacing: 0.11em;
    text-transform: uppercase;
}

.known-column .category-kicker {
    color: var(--success-color);
}

.practice-column .category-kicker {
    color: var(--accent-color);
}

.category-total {
    display: grid;
    place-items: center;
    min-width: 42px;
    height: 42px;
    padding: 0 0.7rem;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.06);
    font-size: 1rem;
    font-weight: 800;
}

.category-list {
    display: grid;
    gap: 0.65rem;
}

.category-idiom-row {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.85rem;
    border: 1px solid rgba(255, 255, 255, 0.07);
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.025);
}

.category-idiom-copy {
    display: grid;
    flex: 1;
    min-width: 0;
    gap: 0.25rem;
}

.category-idiom-copy strong {
    color: var(--text-primary);
    font-size: 0.9rem;
    line-height: 1.3;
}

.category-idiom-copy span {
    color: var(--text-secondary);
    font-size: 0.75rem;
    line-height: 1.45;
}

.category-idiom-copy small {
    color: rgba(251, 191, 36, 0.8);
    font-size: 0.66rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

.now-known-btn,
.forgot-it-btn {
    flex: 0 0 auto;
    padding: 0.55rem 0.7rem;
    border-radius: 8px;
    font-family: inherit;
    font-size: 0.7rem;
    font-weight: 700;
    cursor: pointer;
    transition: background 0.2s, transform 0.2s;
}

.now-known-btn {
    border: 1px solid rgba(74, 222, 128, 0.32);
    background: rgba(74, 222, 128, 0.08);
    color: #86efac;
}

.forgot-it-btn {
    border: 1px solid rgba(251, 191, 36, 0.3);
    background: rgba(251, 191, 36, 0.07);
    color: #fbbf24;
}

.now-known-btn:hover {
    transform: translateY(-1px);
    background: rgba(74, 222, 128, 0.15);
}

.forgot-it-btn:hover {
    transform: translateY(-1px);
    background: rgba(251, 191, 36, 0.14);
}

.practice-group {
    display: grid;
    gap: 0.55rem;
    padding: 0.75rem;
    border: 1px solid rgba(251, 191, 36, 0.16);
    border-radius: 14px;
    background: rgba(251, 191, 36, 0.025);
}

.practice-group-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.15rem 0.1rem 0.35rem;
}

.practice-group-head strong {
    color: var(--accent-color);
    font-size: 0.78rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
}

.practice-group-head span {
    color: var(--text-secondary);
    font-size: 0.72rem;
}

.practice-these-btn {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    margin-top: 0.2rem;
    padding: 0.8rem 0.95rem;
    border: 0;
    border-radius: 10px;
    background: linear-gradient(135deg, #fbbf24, #d97706);
    color: #171109;
    font-family: inherit;
    font-size: 0.82rem;
    font-weight: 800;
    cursor: pointer;
}

.category-empty {
    padding: 2rem 1rem;
    border: 1px dashed rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    color: var(--text-secondary);
    font-size: 0.82rem;
    line-height: 1.5;
    text-align: center;
}

.category-quiz-open {
    overflow: hidden;
}

.category-quiz-overlay {
    position: fixed;
    inset: 0;
    z-index: 10020;
    display: grid;
    place-items: center;
    padding: 1rem;
    background: rgba(3, 3, 6, 0.86);
    backdrop-filter: blur(10px);
}

.category-quiz-overlay.hidden {
    display: none;
}

.category-quiz-modal {
    position: relative;
    width: min(600px, 100%);
    max-height: min(88vh, 760px);
    overflow-y: auto;
    padding: 1.25rem;
    border: 1px solid rgba(251, 191, 36, 0.3);
    border-radius: 20px;
    background: #121218;
    box-shadow: 0 28px 80px rgba(0, 0, 0, 0.55);
}

.category-quiz-close {
    position: absolute;
    top: 0.65rem;
    right: 0.75rem;
    z-index: 1;
    width: 36px;
    height: 36px;
    border: 0;
    background: transparent;
    color: var(--text-secondary);
    font-size: 1.7rem;
    cursor: pointer;
}

.category-quiz-head {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 1rem;
    padding: 0.2rem 2.4rem 1rem 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.category-quiz-head span,
.category-quiz-results > span {
    color: var(--accent-color);
    font-size: 0.68rem;
    font-weight: 800;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.category-quiz-head h2 {
    margin: 0.3rem 0 0;
    font-size: 1.25rem;
}

.category-quiz-head > strong {
    color: var(--text-secondary);
    font-size: 0.8rem;
}

.category-quiz-question {
    padding: 1.4rem 0 1rem;
    color: var(--text-primary);
    font-size: 1.05rem;
    font-weight: 600;
    line-height: 1.55;
}

.category-quiz-options {
    display: grid;
    gap: 0.6rem;
}

.category-quiz-options button {
    width: 100%;
    padding: 0.8rem 0.9rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.035);
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.85rem;
    line-height: 1.4;
    text-align: left;
    cursor: pointer;
}

.category-quiz-options button:not(:disabled):hover {
    border-color: rgba(251, 191, 36, 0.45);
    background: rgba(251, 191, 36, 0.08);
}

.category-quiz-options button.correct {
    border-color: rgba(74, 222, 128, 0.55);
    background: rgba(74, 222, 128, 0.14);
}

.category-quiz-options button.incorrect {
    border-color: rgba(239, 68, 68, 0.55);
    background: rgba(239, 68, 68, 0.14);
}

.category-quiz-feedback {
    display: grid;
    gap: 0.35rem;
    margin-top: 0.85rem;
    padding: 0.8rem;
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.04);
}

.category-quiz-feedback.hidden,
.category-quiz-next.hidden,
.category-quiz-results.hidden {
    display: none;
}

.category-quiz-feedback strong {
    color: var(--accent-color);
    font-size: 0.85rem;
}

.category-quiz-feedback span {
    color: var(--text-secondary);
    font-size: 0.78rem;
    line-height: 1.5;
}

.category-quiz-feedback b {
    color: var(--text-primary);
}

.category-quiz-next,
.category-quiz-results button {
    width: 100%;
    margin-top: 0.85rem;
    padding: 0.85rem;
    border: 0;
    border-radius: 10px;
    background: linear-gradient(135deg, #fbbf24, #d97706);
    color: #171109;
    font-family: inherit;
    font-size: 0.85rem;
    font-weight: 800;
    cursor: pointer;
}

.category-quiz-results {
    display: grid;
    justify-items: center;
    gap: 0.65rem;
    padding: 2.5rem 0.25rem 0.5rem;
    text-align: center;
}

.category-quiz-results strong {
    color: var(--accent-color);
    font-size: 3.2rem;
}

.category-quiz-results p {
    margin: 0;
    color: var(--text-secondary);
    font-size: 0.85rem;
}

@media (max-width: 760px) {
    .category-column {
        padding: 0.8rem;
    }
}

@media (max-width: 480px) {
    .category-idiom-row {
        align-items: flex-start;
    }

    .now-known-btn,
    .forgot-it-btn {
        padding: 0.5rem 0.55rem;
        font-size: 0.64rem;
    }

    .category-quiz-modal {
        padding: 1rem;
        border-radius: 16px;
    }
}

.categorize-actions {
    display: grid;
    gap: 0.75rem;
    max-width: 420px;
    margin: 1.5rem auto 0;
}

.categorize-actions[hidden] {
    display: none;
}

.categorize-action {
    display: flex;
    align-items: center;
    gap: 0.85rem;
    width: 100%;
    min-height: 66px;
    padding: 0.8rem 1rem;
    border-radius: 14px;
    color: var(--text-primary);
    font-family: inherit;
    text-align: left;
    cursor: pointer;
    transition: transform 0.2s, border-color 0.2s, background 0.2s, box-shadow 0.2s;
}

.categorize-action:hover {
    transform: translateY(-2px);
}

.categorize-action:focus-visible {
    outline: 2px solid var(--accent-color);
    outline-offset: 3px;
}

.categorize-action-primary {
    border: 1px solid rgba(251, 191, 36, 0.55);
    background: linear-gradient(135deg, #fbbf24, #d97706);
    color: #111;
    box-shadow: 0 10px 28px rgba(217, 119, 6, 0.2);
}

.categorize-action-primary:hover {
    box-shadow: 0 14px 34px rgba(217, 119, 6, 0.3);
}

.categorize-action-secondary {
    border: 1px solid rgba(255, 255, 255, 0.12);
    background: rgba(255, 255, 255, 0.035);
    color: var(--text-secondary);
}

.categorize-action-secondary:hover {
    border-color: rgba(255, 255, 255, 0.25);
    background: rgba(255, 255, 255, 0.065);
    color: var(--text-primary);
}

.categorize-action-icon {
    display: grid;
    flex: 0 0 42px;
    place-items: center;
    width: 42px;
    height: 42px;
    border-radius: 11px;
    background: rgba(0, 0, 0, 0.14);
}

.categorize-action-secondary .categorize-action-icon {
    background: rgba(251, 191, 36, 0.08);
    color: var(--accent-color);
}

.categorize-action-icon svg {
    width: 22px;
    height: 22px;
}

.categorize-action > span:nth-child(2) {
    display: grid;
    flex: 1;
    gap: 2px;
}

.categorize-action strong {
    font-size: 0.95rem;
}

.categorize-action small {
    font-size: 0.72rem;
    font-weight: 500;
    opacity: 0.72;
}

.categorize-action-arrow {
    width: 19px;
    height: 19px;
    transition: transform 0.2s;
}

.categorize-action-primary:hover .categorize-action-arrow {
    transform: translateX(3px);
}

.btn-icon {
    font-size: 1.5rem;
}

.btn-content {
    display: flex;
    flex-direction: column;
}

.btn-title {
    font-size: 0.95rem;
    font-weight: 700;
}

.btn-desc {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-top: 2px;
}

.secondary-info {
    display: flex;
    gap: 1rem;
}

.cert-btn {
    max-width: 300px;
    margin: 0 auto;
}

.lessons-container {
    max-width: 700px;
    margin: 0 auto;
    padding: 1rem;
}

.lessons-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 1rem;
}

.lesson-card {
    background-color: var(--secondary-color);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 12px;
    padding: 1.2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    position: relative;
}

.lesson-card:hover {
    background-color: var(--hover-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.lesson-card.completed {
    border-color: rgba(74, 222, 128, 0.4);
}

.lesson-num {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--accent-color);
    margin-bottom: 0.3rem;
}

.lesson-title {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.lesson-check {
    position: absolute;
    top: 8px;
    right: 8px;
    color: var(--success-color);
    font-size: 1rem;
}

.screen-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.back-btn {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.2rem;
    cursor: pointer;
    padding: 4px 8px;
}

.lesson-container {
    max-width: 700px;
    margin: 0 auto;
}

.quiz-container {
    padding: 1rem;
    max-width: 600px;
    margin: 0 auto;
}

.question-card {
    background-color: var(--secondary-color);
    padding: 1rem;
    border-radius: 10px;
    margin-bottom: 1rem;
}

.question-text {
    font-size: 0.95rem;
    margin-bottom: 0.8rem;
    line-height: 1.4;
}

.options-container {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.option {
    padding: 0.7rem;
    background-color: var(--secondary-color);
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.9rem;
    color: var(--text-primary);
}

.option:hover {
    border-color: rgba(255, 255, 255, 0.3);
}

.option.correct {
    background-color: rgba(74, 222, 128, 0.2);
    border-color: var(--success-color);
}

.option.incorrect {
    background-color: rgba(239, 68, 68, 0.2);
    border-color: var(--error-color);
}

.idk-btn {
    margin-top: 10px;
    padding: 8px 16px;
    background: transparent;
    border: 1px solid rgba(255, 255, 255, 0.15);
    color: var(--text-secondary);
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.85rem;
    width: 100%;
}

.idk-btn:hover {
    border-color: var(--accent-color);
    color: var(--accent-color);
}

.feedback-card {
    background-color: var(--secondary-color);
    padding: 1rem;
    border-radius: 10px;
    margin-top: 1rem;
}

.feedback-content {
    text-align: center;
}

.feedback-explanation {
    margin: 0.5rem 0;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.next-btn {
    width: 100%;
    padding: 12px 0;
    border: none;
    border-radius: 12px;
    font-size: 1rem;
    font-weight: 700;
    background: linear-gradient(135deg, #d97706, var(--accent-color));
    color: #111;
    cursor: pointer;
    margin-top: 12px;
}

.quiz-results {
    text-align: center;
    padding: 2rem;
}

.score-display {
    margin-bottom: 1.5rem;
}

.score-value {
    font-size: 4rem;
    font-weight: 800;
    color: var(--accent-color);
}

.score-label {
    font-size: 1rem;
    color: var(--text-secondary);
}

.review-container {
    padding: 1rem;
    max-width: 600px;
    margin: 0 auto;
}

.review-list {
    max-width: 700px;
    margin: 0 auto;
    padding: 1rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.review-item {
    background-color: var(--secondary-color);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 12px;
    padding: 1rem;
    transition: all 0.3s ease;
}

.review-question-text {
    font-size: 0.95rem;
    margin-bottom: 0.8rem;
    line-height: 1.4;
    color: var(--text-primary);
}

.review-options {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.review-opt {
    padding: 0.7rem;
    background-color: var(--secondary-color);
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.9rem;
    color: var(--text-primary);
    text-align: left;
}

.review-opt:hover {
    border-color: rgba(255, 255, 255, 0.3);
}

.review-opt.correct {
    background-color: rgba(74, 222, 128, 0.2);
    border-color: var(--success-color);
}

.review-opt.incorrect {
    background-color: rgba(239, 68, 68, 0.2);
    border-color: var(--error-color);
}

.review-opt:disabled {
    cursor: not-allowed;
    opacity: 0.8;
}

.review-feedback {
    margin-top: 0.8rem;
    padding: 0.8rem;
    background: rgba(255, 255, 255, 0.03);
    border-radius: 8px;
    font-size: 0.9rem;
    line-height: 1.5;
}

.review-feedback.hidden {
    display: none;
}

.no-mistakes, .review-complete {
    text-align: center;
    padding: 2rem;
}

.no-mistakes h2, .review-complete h2 {
    margin-bottom: 1rem;
}

.certificate-container {
    max-width: 700px;
    margin: 0 auto;
    padding: 1rem;
}

.certificate {
    background: linear-gradient(135deg, #1a1a1a, #0a0a0a);
    border: 2px solid rgba(251, 191, 36, 0.3);
    border-radius: 16px;
    padding: 2rem;
    margin-bottom: 1.5rem;
}

.certificate-border {
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
}

.certificate-header h2 {
    color: var(--accent-color);
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
}

.cert-text {
    color: var(--text-secondary);
    font-size: 1rem;
    margin-bottom: 0.5rem;
}

.cert-name {
    font-size: 2rem;
    font-weight: 800;
    color: var(--text-primary);
    margin: 0.5rem 0;
    min-height: 2.6rem;
    outline: none;
    border-bottom: 1px dashed transparent;
    transition: border-color .15s;
}

.cert-name:empty::before {
    content: attr(data-placeholder);
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 1.15rem;
    opacity: .75;
}

.cert-name:hover,
.cert-name:focus {
    border-bottom-color: var(--accent-color);
}

@media print {
    .cert-name { border-bottom-color: transparent; min-height: 0; }
    .cert-name:empty::before { content: ''; }
}

.cert-course {
    font-size: 1.3rem;
    color: var(--accent-color);
    margin: 0.5rem 0;
}

.cert-description {
    max-width: 520px;
    margin: 0.25rem auto 0.65rem;
    color: var(--text-secondary);
    font-size: 0.88rem;
    line-height: 1.5;
}

.cert-brand {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.cert-details {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-top: 1.5rem;
}

.cert-detail {
    display: flex;
    flex-direction: column;
    gap: 0.3rem;
}

.cert-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.no-certificate {
    text-align: center;
    padding: 2rem;
}

.no-certificate h2 {
    margin-bottom: 1rem;
}

.index-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

.index-search-bar {
    margin: 20px 0;
}

.index-search-bar input {
    width: 100%;
    padding: 12px 16px;
    font-size: 1rem;
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    background: var(--card-bg);
    color: var(--text-primary);
    outline: none;
    transition: border-color 0.2s;
}

.index-search-bar input:focus {
    border-color: var(--accent-color);
}

.index-list {
    display: flex;
    flex-direction: column;
    gap: 6px;
    max-height: 65vh;
    overflow-y: auto;
}

.index-row {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 14px;
    background: var(--card-bg);
    border-radius: 8px;
    border: 1px solid rgba(255, 255, 255, 0.08);
}

.index-num {
    min-width: 36px;
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-align: right;
}

.index-verb {
    flex: 1;
    font-weight: 600;
    color: var(--text-primary);
}

.index-lesson-btn {
    padding: 5px 14px;
    background: linear-gradient(135deg, #d97706, var(--accent-color));
    color: #111;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 700;
    white-space: nowrap;
    transition: opacity 0.2s;
}

.index-lesson-btn:hover {
    opacity: 0.85;
}

.no-results {
    text-align: center;
    color: var(--text-secondary);
    padding: 30px;
}

.hidden {
    display: none !important;
}

@media (max-width: 768px) {
    header {
        padding: 1rem;
    }
    .brand h1 {
        font-size: 1.2rem;
    }
    .main-actions {
        grid-template-columns: 1fr;
    }
    .lessons-grid {
        grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    }
    .cert-details {
        flex-direction: column;
        gap: 1rem;
    }
}

/* ===== COURSE COMPLETION MESSAGE ===== */
.completion-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.85);
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    animation: fadeIn 0.5s ease;
}
.completion-overlay.hidden {
    display: none !important;
}
.completion-modal {
    background: var(--card-bg);
    border: 2px solid var(--accent-color);
    border-radius: 16px;
    max-width: 640px;
    width: 100%;
    max-height: 85vh;
    overflow-y: auto;
    padding: 2.5rem 2rem;
    position: relative;
    animation: slideUp 0.5s ease;
}
.completion-close {
    position: absolute;
    top: 12px;
    right: 16px;
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 1.8rem;
    cursor: pointer;
    line-height: 1;
    transition: color 0.2s;
}
.completion-close:hover {
    color: var(--text-primary);
}
.completion-icon {
    text-align: center;
    font-size: 3.5rem;
    margin-bottom: 0.5rem;
}
.completion-title {
    text-align: center;
    color: var(--accent-color);
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
}
.completion-body {
    color: var(--text-primary);
    font-size: 0.95rem;
    line-height: 1.7;
}
.completion-body p {
    margin-bottom: 0.8rem;
}
.completion-body ul {
    margin: 0.5rem 0 1rem 1.5rem;
    list-style: disc;
}
.completion-body li {
    margin-bottom: 0.5rem;
}
.completion-signature {
    margin-top: 1.5rem;
    text-align: right;
    font-style: italic;
    color: var(--accent-color);
}
.completion-cert-btn {
    display: block;
    width: 100%;
    max-width: 280px;
    margin: 1.5rem auto 0;
    padding: 0.8rem 1.5rem;
    background: var(--accent-color);
    color: #000;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s;
}
.completion-cert-btn:hover {
    opacity: 0.85;
}
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}
@keyframes slideUp {
    from { transform: translateY(40px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

@media (max-width: 480px) {
    html,
    body {
        max-width: 100%;
    }

    .screen {
        width: 100%;
        max-width: 100%;
        overflow-x: clip;
    }

    .screen-header {
        display: grid;
        grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
        gap: 0.35rem;
        width: 100%;
        max-width: 100%;
        padding: 0 0.75rem;
    }

    .screen-header h2 {
        min-width: 0;
        max-width: 100%;
        font-size: clamp(1.05rem, 5vw, 1.25rem);
        line-height: 1.2;
        text-align: center;
        overflow-wrap: anywhere;
    }

    .screen-header .back-btn {
        justify-self: start;
        padding: 0.25rem 0;
        font-size: 1rem;
        white-space: nowrap;
    }

    .screen-header > :last-child {
        justify-self: end;
        min-width: 0;
        max-width: 100%;
        font-size: 0.9rem;
        white-space: nowrap;
    }

    .screen-header > div[style*="width:100px"] {
        width: 0 !important;
    }

    .lesson-container,
    .match-wrap,
    .quiz-container,
    .review-container,
    .index-container,
    .certificate-container {
        width: 100%;
        max-width: 100%;
        padding-left: 0.75rem;
        padding-right: 0.75rem;
    }

    .ls-stepper {
        width: 100%;
        max-width: 100%;
        padding-left: 0.5rem;
        padding-right: 0.5rem;
    }

    .ls-step {
        min-width: 0;
    }

    .ls-step-line {
        min-width: 4px;
    }

    .ls-step-label {
        font-size: 0.53rem;
        letter-spacing: 0.15px;
    }

    .context-sentence {
        padding: 0.65rem 0.75rem;
        font-size: 1.05rem;
        overflow-wrap: anywhere;
    }

    .context-options,
    .ctx-opt-btn {
        min-width: 0;
        max-width: 100%;
        overflow-wrap: anywhere;
    }

    .match-columns {
        gap: 0.6rem;
    }

    .match-col {
        min-width: 0;
    }

    .match-chip {
        min-width: 0;
        padding: 0.75rem 0.5rem;
        font-size: 0.85rem;
        overflow-wrap: anywhere;
    }

    .match-blanks-row {
        gap: 0.4rem;
    }

    .match-blank-cell {
        flex: 1;
        min-width: 0;
    }

    .match-blank {
        width: 100%;
        min-width: 0;
        max-width: 90px;
    }

    .index-row {
        gap: 0.5rem;
        padding: 0.65rem;
    }

    .index-num {
        min-width: 30px;
    }

    .index-verb {
        min-width: 0;
        overflow-wrap: anywhere;
    }

    .index-lesson-btn {
        padding: 0.4rem 0.55rem;
    }

    .certificate {
        padding: 0.75rem;
    }

    .certificate-border {
        padding: 1rem 0.75rem;
    }

    .completion-modal {
        padding: 2rem 1rem;
    }
}