/* Base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Open Sans', sans-serif;
    background-color: var(--dp-lesson-bg);
    color: var(--dp-text);
}

html, body {
    height: 100%;
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Open Sans', sans-serif;
    background-color: var(--dp-lesson-bg);
    color: var(--dp-text);
}

body {
    display: block;
    min-height: 100%;
}

.mainarea {
    display: flex;
    justify-content: space-between;
    align-items: stretch;
    gap: 1.5rem;
    background-color: var(--dp-lesson-bg);
}

/* Side ad slots — layout and placeholder visuals in platform/site-chrome.css */

/* Lesson content styling */
.lesson-content {
    flex: 1;
    width: 70%;
    min-width: 0;
    min-height: 0;
    background-color: var(--dp-content);
    padding: 20px;
    overflow-y: auto;
    overflow-x: hidden;
}

.lesson-content:has(.lesson-notes) {
    padding-left: 20px;
    padding-right: 20px;
}

/* Apply black background to all divs inside .lesson-content, excluding .option elements */
.lesson-content > div {
    background-color: var(--dp-content);
    padding: 15px;
    border-radius: 10px;
    margin-bottom: 10px;
}

.lesson-content > .quiz-container,
.lesson-content > .score-container {
    background-color: var(--dp-card);
    border-radius: var(--dp-radius-md);
}

.lesson-content > .quiz-container {
    padding: 1.5rem;
}

.lesson-content > .score-container {
    padding: 1.25rem 1.5rem;
}

.videoframe {
    display: flex;
    justify-content: center;
}

.quiz-container {
    width: 90%;
    max-width: 700px;
    margin: 0 auto;
    padding: 1.5rem;
    background-color: var(--dp-card);
    border: 1px solid var(--dp-border);
    border-radius: var(--dp-radius-md);
    box-shadow: var(--dp-shadow-card);
}

.question {
    margin-top: 2rem;
    margin-bottom: 0.75rem;
    font-size: 0.9375rem;
    font-weight: 600;
    line-height: 1.55;
    color: var(--dp-text);
    background-color: transparent;
}

.question:first-child {
    margin-top: 0;
}

.options-container {
    display: grid;
    grid-template-columns: repeat(2, minmax(100px, 1fr));
    gap: 0.65rem;
    justify-content: center;
    background-color: transparent;
    padding-bottom: 2rem;
    margin-bottom: 0;
    border-bottom: 1px solid var(--dp-border);
}

.options-container:last-of-type {
    padding-bottom: 0;
    border-bottom: none;
}

.option {
    padding: 0.75rem 1rem;
    background-color: var(--dp-option-bg);
    border: 1px solid var(--dp-border);
    border-radius: var(--dp-radius-sm);
    cursor: pointer;
    text-align: center;
    font-size: 0.875rem;
    line-height: 1.45;
    transition: background-color 0.2s ease, border-color 0.2s ease;
}

.score-container {
    width: 100%;
    max-width: 600px;
    margin: 1.25rem auto 0;
    padding: 1.25rem 1.5rem;
    background-color: var(--dp-card);
    border: 1px solid var(--dp-border);
    border-radius: var(--dp-radius-md);
    text-align: center;
    box-shadow: var(--dp-shadow-card);
    color: var(--dp-text);
}

.score-container.score-container--pending:not(.score-container--revealed) {
    opacity: 0;
    max-height: 0;
    margin-top: 0;
    padding-top: 0;
    padding-bottom: 0;
    overflow: hidden;
    border-color: transparent;
    box-shadow: none;
    pointer-events: none;
    visibility: hidden;
}

.score-container.score-container--revealed {
    visibility: visible;
    animation: score-container-reveal 0.7s cubic-bezier(0.22, 1, 0.36, 1) forwards;
}

@keyframes score-container-reveal {
    0% {
        opacity: 0;
        max-height: 0;
        margin-top: 0;
        padding-top: 0;
        padding-bottom: 0;
        transform: translateY(14px);
        border-color: transparent;
        box-shadow: none;
    }
    40% {
        opacity: 1;
        max-height: 10rem;
        margin-top: 1.25rem;
        padding-top: 1.25rem;
        padding-bottom: 1.25rem;
        border-color: var(--dp-border);
        box-shadow: var(--dp-shadow-card);
    }
    100% {
        opacity: 1;
        max-height: 12rem;
        margin-top: 1.25rem;
        padding-top: 1.25rem;
        padding-bottom: 1.25rem;
        transform: translateY(0);
        border-color: var(--dp-border);
        box-shadow: var(--dp-shadow-card);
    }
}

.score-container.score-container--revealed #score-text {
    animation: score-text-pop 0.55s cubic-bezier(0.22, 1, 0.36, 1) 0.2s both;
}

@keyframes score-text-pop {
    0% {
        opacity: 0;
        transform: scale(0.45);
    }
    65% {
        transform: scale(1.06);
    }
    100% {
        opacity: 1;
        transform: scale(1);
    }
}

.score-container.score-container--revealed .progress-bar {
    opacity: 0;
    animation: score-progress-in 0.45s ease 0.45s forwards;
}

@keyframes score-progress-in {
    from {
        opacity: 0;
        transform: scaleX(0.85);
    }
    to {
        opacity: 1;
        transform: scaleX(1);
    }
}

@media (prefers-reduced-motion: reduce) {
    .score-container.score-container--pending:not(.score-container--revealed) {
        transition: none;
    }

    .score-container.score-container--revealed,
    .score-container.score-container--revealed #score-text,
    .score-container.score-container--revealed .progress-bar {
        animation: none;
        opacity: 1;
        max-height: none;
        transform: none;
        visibility: visible;
    }
}

#score-text {
    font-size: 2.25rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    background-color: transparent;
    transform-origin: center center;
}

.progress-bar {
    width: 100%;
    height: 20px;
    background-color: var(--dp-mark-wrong);
    border-radius: 10px;
    overflow: hidden;
    position: relative;
    transform-origin: center center;
}

.progress {
    height: 100%;
    width: 0%;
    background-color: var(--dp-mark-correct);
    transition: width 0.5s ease;
}

.lesson-navigation {
    display: flex;
    flex-direction: column;
    gap: 12px;
    margin-top: 20px;
    background-color: var(--dp-content);
}

.lesson-nav-buttons {
    display: flex;
    justify-content: space-between;
    width: 100%;
    background-color: var(--dp-content);
}

.lesson-navigation button {
    padding: 15px 30px; /* Increase padding for larger buttons */
    background-color: var(--dp-card);
    color: #fff;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease;
    font-size: 1.2em; /* Increase font size */
}

.lesson-navigation button:hover {
    background-color: var(--dp-nav-button-hover);
}

    

.option.correct {
    background-color: var(--dp-mark-correct);
    border-color: var(--dp-mark-correct);
}

.option.wrong {
    background-color: var(--dp-mark-wrong);
    border-color: var(--dp-mark-wrong);
}

.option:hover {
    background-color: var(--dp-card-hover);
    border-color: var(--dp-border-strong);
}

footer {
    position: relative;
    bottom: 0;
    width: 100%;
    height: 10vh;
    background-color: transparent;
    color: #fff;
    padding: 20px;
    text-align: center;
}

::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-thumb {
    background-color: var(--dp-scrollbar-thumb);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb:hover {
    background-color: var(--dp-scrollbar-thumb-hover);
}

::-webkit-scrollbar-track {
    background-color: transparent;
    border-radius: none;
}

/* ── Chapter notes (token-only; reusable across chemistry lessons) ── */

.lesson-syllabus {
    display: inline-block;
    width: fit-content;
    max-width: 100%;
    margin-bottom: 1.25rem;
    padding: 0.35rem 0.75rem;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--dp-muted);
    background-color: transparent;
    border: 1px solid var(--dp-border);
    border-radius: var(--dp-radius-sm);
}

.lesson-content > .lesson-notes {
    width: 100%;
    max-width: none;
    margin: 0;
    padding: 0 0 2.5rem;
    background-color: transparent;
    border-radius: 0;
    border-bottom: 2px solid var(--dp-border-strong);
}

/* Notes → quiz transition (chapter pages with lesson notes) */
.lesson-content:has(.lesson-notes) > .quiz-container {
    width: 100%;
    max-width: none;
    margin-top: 2.5rem;
    padding: 1.75rem 1.5rem 1.5rem;
}

.lesson-content:has(.lesson-notes) > .quiz-container::before {
    content: "Practice Questions";
    display: block;
    font-size: 1.0625rem;
    font-weight: 700;
    line-height: 1.4;
    color: var(--dp-text);
    margin-bottom: 0.25rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--dp-border);
    background-color: transparent;
}

.lesson-content:has(.lesson-notes) > .score-container {
    width: 100%;
    max-width: none;
}

.lesson-notes > h1 {
    font-size: clamp(1.375rem, 2.2vw, 1.625rem);
    font-weight: 700;
    line-height: 1.35;
    letter-spacing: -0.02em;
    text-align: left;
    padding: 0 0 1rem;
    margin-bottom: 0.5rem;
    color: var(--dp-text);
    background-color: transparent;
    border: none;
    border-bottom: 2px solid var(--dp-border-strong);
    border-radius: 0;
    box-shadow: none;
}

.lesson-notes__topic {
    font-size: 0.875rem;
    font-weight: 600;
    line-height: 1.5;
    color: var(--dp-muted);
    margin: 0 0 2rem;
    padding: 0 0 1rem;
    background-color: transparent;
    border-bottom: 2px solid var(--dp-border-strong);
}

.lesson-notes section {
    background-color: transparent;
    border: none;
    border-radius: 0;
    padding: 0 0 2rem;
    margin-bottom: 2rem;
    box-shadow: none;
    border-bottom: 1px solid var(--dp-border);
}

.lesson-notes section:last-of-type {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.lesson-notes h2 {
    display: block;
    font-size: 1.0625rem;
    font-weight: 700;
    line-height: 1.4;
    color: var(--dp-text);
    margin: 0 0 0.85rem;
    padding: 0;
    border: none;
    background-color: transparent;
}

.lesson-notes__section-num {
    display: inline;
    min-width: 0;
    height: auto;
    padding: 0;
    margin-right: 0.35rem;
    font-size: inherit;
    font-weight: 700;
    letter-spacing: 0;
    color: var(--dp-text-soft);
    background-color: transparent;
    border: none;
    border-radius: 0;
    box-shadow: none;
}

.lesson-notes__section-num::after {
    content: " ·";
    color: var(--dp-muted);
    font-weight: 400;
}

.lesson-notes p {
    font-size: 0.9375rem;
    line-height: 1.65;
    font-weight: 400;
    color: var(--dp-text-soft);
    margin-bottom: 1rem;
    background-color: transparent;
}

.lesson-notes ul,
.lesson-notes ol {
    margin: 0 0 1rem;
    padding-left: 1.25rem;
    background-color: transparent;
}

.lesson-notes li {
    font-size: 0.9375rem;
    line-height: 1.65;
    font-weight: 400;
    color: var(--dp-text-soft);
    background-color: transparent;
    margin-bottom: 0.5rem;
}

.lesson-notes li:last-child {
    margin-bottom: 0;
}

.lesson-notes strong {
    font-weight: 700;
    color: var(--dp-text);
    background-color: transparent;
}

.lesson-notes dd ul,
.lesson-notes dd ol {
    margin: 0.5rem 0 0;
    padding-left: 1rem;
}

.lesson-notes dl {
    display: grid;
    grid-template-columns: 1fr;
    gap: 0.85rem;
    background-color: transparent;
}

.lesson-notes dt {
    display: block;
    width: auto;
    font-size: 0.9375rem;
    font-weight: 700;
    letter-spacing: 0;
    color: var(--dp-text);
    padding: 0;
    background-color: transparent;
    border: none;
    border-radius: 0;
}

.lesson-notes dd {
    margin: 0.2rem 0 0;
    padding: 0 0 0 0.85rem;
    font-size: 0.9375rem;
    line-height: 1.65;
    font-weight: 400;
    color: var(--dp-text-soft);
    background-color: transparent;
    border: none;
    border-left: 2px solid var(--dp-border-strong);
    border-radius: 0;
    box-shadow: none;
}

.lesson-notes__figure {
    margin-top: 1.25rem;
    padding: 1rem;
    background-color: transparent;
    border: 1px dashed var(--dp-border-strong);
    border-radius: var(--dp-radius-sm);
    overflow: hidden;
}

.lesson-notes__diagram-img,
.lesson-notes img {
    display: block;
    width: auto;
    max-width: min(55%, 28rem);
    height: auto;
    margin: 0 auto;
    background-color: transparent;
}

.lesson-notes__figure figcaption {
    padding: 0.65rem 0.85rem;
    font-size: 0.8125rem;
    line-height: 1.45;
    font-weight: 400;
    font-style: italic;
    text-align: left;
    color: var(--dp-muted);
    background-color: transparent;
}

@media (min-width: 720px) {
    .lesson-notes dl {
        grid-template-columns: 10.5rem 1fr;
        column-gap: 1.5rem;
        row-gap: 0.75rem;
        align-items: start;
    }

    .lesson-notes dt {
        padding-top: 0.1rem;
    }

    .lesson-notes dd {
        margin: 0;
        padding: 0 0 0 0.75rem;
        border-left: 2px solid var(--dp-border-strong);
    }
}

@media (max-width: 640px) {
    .lesson-notes > h1 {
        font-size: 1.25rem;
        margin-bottom: 0.35rem;
    }

    .lesson-notes__topic {
        font-size: 0.8125rem;
        margin-bottom: 1.5rem;
        padding-bottom: 0.75rem;
    }

    .lesson-notes section {
        padding-bottom: 1.5rem;
        margin-bottom: 1.5rem;
    }

    .lesson-notes h2 {
        font-size: 1rem;
    }

    .options-container {
        grid-template-columns: 1fr;
    }

    .lesson-content:has(.lesson-notes) > .quiz-container {
        margin-top: 2rem;
        padding: 1.25rem 1rem 1rem;
    }

    #score-text {
        font-size: 1.75rem;
    }
}