:root {
    --bg-color: #e0e0e0;
    --card-bg-color: #303030;
    --header-card-bg-color: #f7f7f7;
    --text-color: #000000;
    --text-color-2: #ffffff;
    --accent-color: #008653;
    --accent-color-2: #00b46f;
    --medium-gray: #757575;
    --button-gray: #505050;
    --font-logo: 'knewave', cursive;
    --font-body: 'Roboto', sans-serif;
    --underline-color: #ffffff;

    /* GAME VARIABLES */
    --game-bg-color: #3a3a3a;
    --sentence-success-bg: #4CAF50;
    --sentence-fail-bg: #D32F2F;
    --pronoun-noun-bg: #fdf2d0;
    --pronoun-noun-border: #e2c050;
    --game-correct-color: #2E7D32;
    --game-incorrect-color: #D32F2F;
}



/* ----------------------------- Navbar and Title Card ----------------------------- */



body {
    margin: 0;
    font-family: var(--font-body);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    max-width: 100%;
    overflow-x: hidden;
}

.font-container {
    font-size: 16px;
}

.page-container {
    max-width: clamp(320px, 1200px, 90vw);
    margin: 0 auto;
    box-sizing: border-box;
}

header {
    height: auto;
    min-height: 70px;
    background-color: var(--card-bg-color);
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    padding: 15px 5vw;
    margin-bottom: 3em;
}

.logo {
    font-family: var(--font-logo);
    font-size: clamp(1.8em, 4vw, 2.5em);
    color: var(--accent-color-2);
    margin-right: 20px;
}

nav a {
    color: white;
    text-decoration: none;
    margin-left: clamp(15px, 3vw, 30px);
    font-size: clamp(1em, 2.5vw, 1.5em);
    transition: color 0.3s ease;
}

nav a:hover {
    color: var(--accent-color);
}

.chapter-title-card {
    background-color: var(--card-bg-color);
    padding: clamp(1em, 3vw, 2em) clamp(1.5em, 4vw, 2.6em);
    border-radius: 1.5em;
    margin-bottom: 3em;
    text-align: center;
}

.chapter-title-card h2 {
    margin: 0;
    font-size: clamp(1.5em, 4vw, 2.5em);
    color: var(--accent-color-2);
    font-weight: 500;
}



/* ----------------------------- Read & Listen Card ----------------------------- */



.collapsible-card {
    background-color: var(--header-card-bg-color);
    border-radius: 1.5em;
    margin-bottom: 25px;
    overflow: hidden;
}

.collapsible-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: clamp(1em, 3vw, 1.8em) clamp(1.5em, 4vw, 2.6em);
    cursor: pointer;
    background-color: var(--card-bg-color);
}

.collapsible-header h3 {
    margin: 0;
    font-size: clamp(1.8em, 4.5vw, 2.8em);
    font-weight: 500;
    color: var(--text-color-2);
}

.toggle-button {
    background-color: #4a4a4a;
    border: 1px solid #666;
    color: white;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    font-weight: bold;
    cursor: pointer;
    padding: 0;
    line-height: 1;
    transition: background-color 0.3s ease;
    flex-shrink: 0;
}

.toggle-button:hover {
    background-color: #5a5a5a;
}

.collapsible-content-wrapper {
    max-height: 10000px;
    opacity: 1;
    overflow: hidden;
    transition: max-height 0.7s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.5s ease-out 0.1s;
}

.collapsible-content-wrapper.collapsed {
    max-height: 0;
    opacity: 0;
    transition: max-height 0.5s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.3s ease-in;
}

.collapsible-content-inner {
    padding: 2em clamp(1.5em, 5vw, 4em);
}

.story-image {
    display: block;
    width: 100%;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    height: auto;
    border-radius: 1em;
    margin-bottom: 25px;
}

.content-block {
    border-radius: 1em;
    background-color: #ffffff;
    padding: clamp(1em, 3vw, 2em);
    margin-bottom: 25px;
    position: relative;
}
.content-block:last-child {
    margin-bottom: 0;
}

.content-block h4 {
    font-size: clamp(1.5em, 3.5vw, 2.2em);
    color: var(--text-color);
    margin-top: 0;
    margin-bottom: 0.75em;
    font-weight: 500;
    position: relative;
    padding-bottom: 0.5em;
}


.content-block h4::after {
    content: '';
    display: block;
    width: 100%;
    height: 1px;
    background-color: var(--underline-color);
    position: absolute;
    bottom: 0;
    left: 0;
}

.story-text-section p {
    margin-bottom: 10px;
    font-size: clamp(1em, 2vw, 1.3em);
}



/* ----------------------------- Listen Part ----------------------------- */



.audio-player-section {
    margin-bottom: 2em !important;
}

.audio-controls {
    display: flex;
    gap: 15px;
    margin-bottom: 20px;
    flex-wrap: wrap;
    align-items: center;
}

.audio-btn {
    padding: 10px 18px;
    border: none;
    border-radius: 25px;
    font-size: clamp(0.9em, 2vw, 1em);
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.1s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
}
.audio-btn:active {
    transform: scale(0.95);
}

.play-pause-btn {
    background-color: var(--accent-color);
    color: white;
    padding: 12px;
    min-width: 50px;
    height: 50px;
    border-radius: 50%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
}
.play-pause-btn:hover {
    background-color: #cc8e11;
}

.play-pause-btn svg.icon {
    width: 24px;
    height: 24px;
}

.play-pause-btn .icon-play {
    display: inline-block;
}
.play-pause-btn .icon-pause {
    display: none;
}

.play-pause-btn.playing .icon-play {
    display: none;
}
.play-pause-btn.playing .icon-pause {
    display: inline-block;
}

.stop-btn {
    background-color: var(--button-gray);
    color: var(--text-color-2);
    padding: 10px 20px;
    height: 50px;
}
.stop-btn:hover {
    background-color: #505050;
}

.audio-progress {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 10px;
}

.time-display {
    font-size: clamp(0.85em, 1.8vw, 1em);
    color: var(--light-gray);
    min-width: 40px;
    text-align: center;
}

.progress-bar-container {
    flex-grow: 1;
    height: 10px;
    border-radius: 5px;
    position: relative;
}

#progressBar {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 10px;
    border-radius: 5px;
    cursor: pointer;
    margin: 0;
    padding: 0;
    outline: none;
    background: var(--medium-gray);
    border: none;
    display: block;
}

#progressBar::-webkit-slider-runnable-track {
    width: 100%;
    height: 10px;
    background: transparent;
    border: none;
    border-radius: 5px;
}

#progressBar::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 20px;
    height: 20px;
    background: var(--accent-color);
    border-radius: 50%;
    border: 2px solid var(--card-bg-color);
    cursor: pointer;
    margin-top: -5px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}

#progressBar::-moz-range-track {
    width: 100%;
    height: 10px;
    background: var(--medium-gray);
    border: none;
    border-radius: 5px;
}

#progressBar::-moz-range-progress {
    background-color: var(--accent-color);
    height: 10px;
    border-radius: 5px;
}

#progressBar::-moz-range-thumb {
    width: 20px;
    height: 20px;
    background: var(--accent-color);
    border-radius: 50%;
    border: 2px solid var(--card-bg-color);
    cursor: pointer;
    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}

.audio-status {
    font-size: clamp(0.8em, 1.6vw, 0.9em);
    color: #bebebe;
    margin: 0;
}


/* ----------------------------- Learn Rules Card (Sound Change / Rhyming) ----------------------------- */


#learn-rules-section .collapsible-content-inner {
    background-color: #fdfdfd;
    color: #333;
    padding: clamp(1.5em, 4vw, 3em);
    font-size: clamp(1rem, 2.2vw, 1.1rem);
    line-height: 1.6;
}

.rules-soundchange-container {
    display: flex;
    flex-direction: column;
    gap: 2.5em;
    max-width: 800px;
    margin: 0 auto;
}

.soundchange-header,
.soundchange-middle,
.soundchange-bottom {
    display: flex;
    gap: 2em;
}

/* Top Section */
.soundchange-header {
    justify-content: space-between;
    align-items: flex-start;
}
.soundchange-text ul {
    list-style: none;
    padding: 0;
    margin: 0;
}
.soundchange-text li {
    padding-left: 20px;
    position: relative;
    margin-bottom: 1em;
}
.soundchange-text li::before {
    content: '•';
    position: absolute;
    left: 0;
    top: -2px;
    font-size: 1.8em;
    color: #2e3d4f;
    line-height: 1;
}
.soundchange-text li:last-child {
    margin-bottom: 0;
}
.soundchange-book-img {
    flex-shrink: 0;
    width: 250px;
}

.soundchange-book-img img {
    width: 250px;
}

.soundchange-book-img img,
.soundchange-figure-img img,
.soundchange-examples-img img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* Middle Section */
.soundchange-middle {
    align-items: center;
}
.soundchange-figure-img {
    flex-basis: 45%;
    flex-shrink: 0;
}
.soundchange-middle-text {
    flex-basis: 55%;
    font-size: clamp(1.2em, 3vw, 1.5em);
    font-weight: 500;
    color: #333;
}
.soundchange-middle-text p {
    margin: 0.2em 0;
}
.soundchange-middle-text strong {
    font-weight: 700;
}

/* Bottom Section */
.soundchange-bottom {
    align-items: flex-start;
}
.soundchange-examples-text {
    flex-basis: 35%;
}
.soundchange-examples-text h3 {
    font-weight: bold;
    font-size: 1.25em;
    margin: 0 0 0.5em 0;
}
.soundchange-examples-text p {
    margin: 0.2em 0;
    font-size: 1.1em;
}
.soundchange-examples-img {
    flex-basis: 65%;
}

/* ----------------------------- RHYMING GAME STYLES (NEW) ----------------------------- */

.game-container { text-align: center; padding-bottom: 2em; }
.game-title { font-size: clamp(2em, 5vw, 3em); color: var(--accent-color); margin-bottom: 0.4em; }
.game-instructions { font-size: clamp(1em, 2.2vw, 1.2em); color: black; margin-bottom: 2em; max-width: 550px; margin-left: auto; margin-right: auto; line-height: 1.5; }
.game-instructions span { color: var(--accent-color); font-weight: 700; }
.game-area { background-color: #f0f0f0; border-radius: 20px; padding: 30px clamp(15px, 4vw, 40px); box-shadow: inset 0 2px 8px rgba(0,0,0,0.1); max-width: 700px; margin: 0 auto;}

#game-content-main {
    max-height: none !important;
}

.singular-word-display {
    font-size: clamp(2em, 5vw, 3.5em);
    font-weight: 700;
    color: #333;
    background-color: #fff;
    padding: 15px 30px;
    border-radius: 15px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    display: inline-block;
    margin: 0.5em 0;
    min-height: 1.5em;
    min-width: 250px;
}
.game-feedback-display { min-height: 3.5em; display: flex; justify-content: center; align-items: center; perspective: 500px; margin-bottom: 1em; }
.game-feedback-display p { font-size: clamp(1.4em, 3.5vw, 2em); color: var(--text-color-2); font-weight: bold; padding: 12px 25px; border-radius: 12px; box-shadow: 0 4px 10px rgba(0,0,0,0.25); display: inline-block; opacity: 0; transform: translateY(30px) rotateX(-30deg) scale(0.8); transition: opacity 0.6s ease-out, transform 0.6s cubic-bezier(0.175, 0.885, 0.32, 1.275); cursor: default; }
.game-feedback-display p.show { opacity: 1; transform: translateY(0) rotateX(0deg) scale(1); }
.game-feedback-display p.correct { background: linear-gradient(135deg, var(--game-correct-color), #388E3C); }
.game-feedback-display p.incorrect { background: linear-gradient(135deg, var(--game-incorrect-color), #C62828); }

.plural-choices-container { display: flex; justify-content: center; gap: 15px; flex-wrap: wrap; }
.game-choice-btn {
    padding: 12px 25px;
    font-size: clamp(1.1em, 2.8vw, 1.4em);
    font-weight: 500;
    border: 2px solid var(--card-bg-color);
    background-color: white;
    color: var(--card-bg-color);
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
    box-shadow: 0 3px 6px rgba(0,0,0,0.1);
}
.game-choice-btn:hover:not(:disabled) { background-color: var(--card-bg-color); color: white; transform: translateY(-3px) scale(1.02); }
.game-choice-btn:disabled { opacity: 0.5; cursor: not-allowed; }

@keyframes shake { 10%, 90% { transform: translate3d(-1px, 0, 0); } 20%, 80% { transform: translate3d(2px, 0, 0); } 30%, 50%, 70% { transform: translate3d(-4px, 0, 0); } 40%, 60% { transform: translate3d(4px, 0, 0); } }
.shake { animation: shake 0.7s cubic-bezier(.36,.07,.19,.97) both; }


/* ----------------------------- Mobile Layout Adjustments ----------------------------- */

@media (max-width: 768px) {
    .soundchange-header,
    .soundchange-middle,
    .soundchange-bottom {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }

    .soundchange-text {
        text-align: left;
        width: 100%;
    }

    .soundchange-book-img {
        order: -1;
        width: 120px;
        margin-bottom: 1.5em;
    }
    
    .soundchange-middle {
        gap: 1.5em;
    }

    .soundchange-examples-text {
        text-align: left;
        margin-bottom: 1.5em;
    }
}


@media (max-width: 600px) {
    header { flex-direction: column; gap: 15px; padding-top: 20px; padding-bottom: 20px; }
    .logo { margin-right: 0; }
    nav { display: flex; justify-content: center; gap: 25px; width: 100%; }
    nav a { margin-left: 0; }
}

/* ===================== NEXT CHAPTER BUTTON STYLES ===================== */
.next-chapter-container {
    text-align: center;
    margin: 4em 0 6em 0; /* Adds space above and below the button */
    padding: 0 20px; /* Prevents button from touching screen edges on mobile */
}

.next-chapter-btn {
    display: inline-block;
    background-color: var(--accent-color);
    color: white;
    padding: 16px 35px;
    font-size: clamp(1.1em, 3vw, 1.4em);
    font-weight: 700;
    text-decoration: none;
    border-radius: 50px; /* A pill shape to match other buttons */
    transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.next-chapter-btn:hover {
    background-color: var(--accent-color-2);
    transform: translateY(-3px) scale(1.03);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.25);
}