.chapter-mission-page {
    position: relative;
    width: 100vw;
    height: 100vh;
    overflow: hidden;
    background: var(--color-bg-dark);
    color: var(--color-text-light);
    font-family: var(--font-body);
    animation: cm-fade-in 0.8s ease-out;
}

@keyframes cm-fade-in {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.cm-background {
    position: absolute;
    inset: 0;
    z-index: var(--z-background);
}

.cm-bg-video {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.cm-bg-gradient {
    position: absolute;
    inset: 0;
    background: linear-gradient(
        160deg,
        rgba(var(--color-bg-dark-rgb), 0.9) 0%,
        rgba(var(--color-bg-medium-rgb), 0.75) 30%,
        rgba(var(--color-bg-warm-rgb), 0.8) 60%,
        rgba(var(--color-bg-dark-rgb), 0.92) 100%
    );
}

.cm-paper-texture {
    position: absolute;
    inset: 0;
    background-image:
        repeating-linear-gradient(
            0deg,
            transparent,
            transparent 2px,
            rgba(212, 165, 116, 0.008) 2px,
            rgba(212, 165, 116, 0.008) 4px
        ),
        repeating-linear-gradient(
            90deg,
            transparent,
            transparent 3px,
            rgba(212, 165, 116, 0.005) 3px,
            rgba(212, 165, 116, 0.005) 6px
        );
    mix-blend-mode: overlay;
    pointer-events: none;
}

.cm-overlay {
    position: absolute;
    inset: 0;
    z-index: var(--z-overlay);
    background: radial-gradient(ellipse at 25% 45%, rgba(74, 48, 32, 0.15) 0%, transparent 60%);
}

.cm-back-btn {
    position: absolute;
    top: var(--spacing-lg);
    left: var(--spacing-lg);
    z-index: var(--z-header);
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-top-color: var(--glass-border-highlight);
    border-radius: 50%;
    color: var(--glass-text);
    cursor: pointer;
    transition: transform, opacity, background-color, border-color, color, filter, box-shadow var(--transition-normal);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    box-shadow: var(--glass-shadow), var(--glass-shadow-inset);
}

.cm-back-btn:hover {
    background: var(--glass-bg-light);
    border-color: var(--glass-border-highlight);
    transform: scale(1.08);
    filter: brightness(1.1);
    box-shadow: var(--glass-shadow), 0 0 1.5rem rgba(255, 255, 255, 0.12);
}

.cm-back-btn:active {
    transform: scale(0.94);
}

.cm-content {
    position: absolute;
    left: clamp(5%, 8%, 12%);
    top: 48%;
    transform: translateY(-50%);
    z-index: var(--z-content);
    max-width: clamp(0px, 45vw, 35rem);
}

.cm-chapter-intro {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: var(--spacing-sm);
}

.cm-chapter-intro.fade-in > * {
    animation: cm-slide-up 0.5s ease-out forwards;
    opacity: 0;
}

.cm-chapter-intro.fade-in > *:nth-child(1) { animation-delay: 0.05s; }
.cm-chapter-intro.fade-in > *:nth-child(2) { animation-delay: 0.12s; }
.cm-chapter-intro.fade-in > *:nth-child(3) { animation-delay: 0.2s; }
.cm-chapter-intro.fade-in > *:nth-child(4) { animation-delay: 0.28s; }
.cm-chapter-intro.fade-in > *:nth-child(5) { animation-delay: 0.36s; }
.cm-chapter-intro.fade-in > *:nth-child(6) { animation-delay: 0.44s; }

@keyframes cm-slide-up {
    from {
        opacity: 0;
        transform: translateY(1rem);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.ornament-svg {
    width: clamp(0px, 12vw, 7.5rem);
    height: auto;
    opacity: 0.6;
}

.cm-ornament-top {
    margin-bottom: var(--spacing-xs);
}

.cm-ornament-bottom {
    margin-top: var(--spacing-xs);
}

.cm-unlock-hint {
    font-family: var(--font-elegant);
    font-size: clamp(0px, 1vw, 0.875rem);
    color: var(--glass-text-muted);
    letter-spacing: 2px;
    padding: clamp(0px, 1vh, 0.625rem) clamp(0px, 2vw, 1.375rem);
    border: 1px solid var(--glass-border);
    border-radius: var(--glass-radius-full);
    display: inline-block;
    margin-top: var(--spacing-sm);
    animation: cm-slide-up 0.4s ease-out 0.5s forwards;
    opacity: 0;
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    box-shadow: var(--glass-shadow), var(--glass-shadow-inset);
}

.cm-chapter-number {
    font-family: var(--font-elegant);
    font-size: clamp(0px, 1.4vw, 1.125rem);
    letter-spacing: 6px;
    color: var(--theme-primary);
    text-transform: uppercase;
    opacity: 0.7;
}

.cm-chapter-title {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin: var(--spacing-sm) 0;
    padding: 0;
    border: none;
}

.cm-title-text {
    font-family: var(--font-display);
    font-size: clamp(0px, 5.5vw, 4.5rem);
    font-weight: 700;
    color: #fff;
    line-height: 1.1;
    text-shadow: 0 2px 16px rgba(0, 0, 0, 0.6), 0 0 40px rgba(212, 165, 116, 0.08);
    letter-spacing: 2px;
}

.cm-chapter-desc {
    font-family: var(--font-body);
    font-size: clamp(0px, 1.3vw, 1.0625rem);
    line-height: 1.9;
    color: var(--color-neon-cyan);
    opacity: 0.7;
    margin: var(--spacing-sm) 0;
    max-width: 26.25rem;
}

.cm-episode-count {
    font-family: var(--font-elegant);
    font-size: clamp(0px, 1.1vw, 0.9375rem);
    letter-spacing: 4px;
    color: var(--color-neon-sky);
    opacity: 0.5;
}

.cm-start-area {
    position: absolute;
    bottom: 18%;
    left: 50%;
    transform: translateX(-50%);
    z-index: var(--z-content);
}

.cm-start-btn {
    position: relative;
    padding: 0;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--glass-radius-full);
    cursor: pointer;
    transition: transform, opacity, background-color, border-color, color, filter, box-shadow var(--transition-normal);
    overflow: visible;
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    box-shadow: var(--glass-shadow), var(--glass-shadow-inset);
}

.cm-start-btn:active:not(:disabled):not(.loading) {
    transform: scale(0.97);
}

.cm-start-btn:hover:not(:disabled):not(.loading) {
    background: var(--glass-bg-light);
    border-color: var(--glass-border-highlight);
    transform: scale(1.05);
    filter: brightness(1.08);
    box-shadow: var(--glass-shadow), 0 0 1.5rem rgba(255, 255, 255, 0.12);
}

.cm-seal-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.375rem;
    position: relative;
}

.wax-seal-svg {
    transition: transform, opacity, background-color, border-color, color, filter, box-shadow var(--transition-slow);
    filter: drop-shadow(0 4px 12px rgba(139, 32, 32, 0.4));
}

.cm-start-btn:hover:not(:disabled):not(.loading) .wax-seal-svg {
    transform: scale(1.08) rotate(-3deg);
    filter: drop-shadow(0 6px 20px rgba(139, 32, 32, 0.5));
}

.cm-start-btn:hover:not(:disabled):not(.loading) .wax-seal-svg circle:first-of-type {
    animation: wax-melt 0.6s ease-in-out;
}

@keyframes wax-melt {
    0% { transform: scale(1); }
    50% { transform: scale(1.04); }
    100% { transform: scale(1); }
}

.cm-start-btn:disabled {
    cursor: not-allowed;
    opacity: 0.5;
    pointer-events: none;
    filter: grayscale(0.4);
}

.cm-start-btn:disabled .wax-seal-svg {
    filter: grayscale(0.4) drop-shadow(0 2px 6px rgba(0, 0, 0, 0.3));
}

.cm-start-btn.loading {
    pointer-events: none;
}

.cm-start-btn.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 1.5rem;
    height: 1.5rem;
    margin: -0.75rem 0 0 -0.75rem;
    border: 2px solid transparent;
    border-top-color: var(--glass-text);
    border-radius: 50%;
    animation: cm-spin 0.8s linear infinite;
    z-index: 2;
}

@keyframes cm-spin {
    to { transform: rotate(360deg); }
}

.cm-start-text {
    font-family: var(--font-display);
    font-size: clamp(0px, 1.8vw, 1.375rem);
    letter-spacing: 10px;
    color: var(--glass-text);
    text-shadow: 0 0 16px rgba(255, 255, 255, 0.2);
    transition: opacity var(--transition-normal);
    margin-top: 0.25rem;
}

.cm-start-btn.loading .cm-start-text {
    opacity: 0.5;
}

.cm-chapter-selector {
    position: absolute;
    bottom: clamp(0px, 4vh, 3.125rem);
    left: 50%;
    transform: translateX(-50%);
    z-index: var(--z-content);
    display: flex;
    gap: clamp(0px, 1.5vw, 1rem);
    padding: 0 var(--spacing-md);
}

.cm-chapter-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-xs);
    padding: clamp(0px, 1.2vh, 0.75rem) clamp(0px, 1.5vw, 1rem);
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-top-color: var(--glass-border-highlight);
    border-radius: var(--glass-radius-lg);
    cursor: pointer;
    transition: transform, opacity, background-color, border-color, color, filter, box-shadow var(--transition-normal);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    box-shadow: var(--glass-shadow), var(--glass-shadow-inset);
    min-width: clamp(0px, 9vw, 5rem);
    position: relative;
    overflow: hidden;
    animation: cm-card-flip-in 0.5s ease-out forwards;
    opacity: 0;
    transform-origin: center bottom;
}

@keyframes cm-card-flip-in {
    0% {
        opacity: 0;
        transform: perspective(600px) rotateX(-15deg) translateY(1.25rem);
    }
    60% {
        opacity: 1;
        transform: perspective(600px) rotateX(2deg) translateY(-0.25rem);
    }
    100% {
        opacity: 1;
        transform: perspective(600px) rotateX(0deg) translateY(0);
    }
}

.cm-card-envelope-bg {
    position: absolute;
    inset: 0;
    opacity: 0.15;
    pointer-events: none;
    transition: opacity var(--transition-normal);
}

.cm-card-envelope-bg svg {
    width: 100%;
    height: 100%;
}

.cm-chapter-card:hover:not(.locked) {
    background: var(--glass-bg-light);
    border-color: var(--glass-border-highlight);
    transform: translateY(-0.375rem);
    box-shadow: var(--glass-shadow), 0 0 1.5rem rgba(255, 255, 255, 0.1);
}

.cm-chapter-card:hover:not(.locked) .cm-card-envelope-bg {
    opacity: 0.25;
}

.cm-chapter-card.active {
    background: rgba(255, 255, 255, 0.12);
    border-color: var(--glass-border-highlight);
    box-shadow: var(--glass-shadow), inset 0 0 12px rgba(255, 255, 255, 0.08);
}

.cm-chapter-card.locked {
    cursor: not-allowed;
    opacity: 0.35;
}

.cm-chapter-card.locked .cm-card-content {
    filter: blur(0.5px);
}

.cm-chapter-card.custom {
    border-style: dashed;
    border-color: var(--glass-border);
}

.cm-chapter-card.custom:hover:not(.locked) {
    border-color: var(--glass-border-highlight);
}

.cm-card-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.125rem;
    position: relative;
    z-index: 1;
}

.cm-card-number {
    font-family: var(--font-elegant);
    font-size: clamp(0px, 0.9vw, 0.75rem);
    color: var(--glass-text-muted);
    letter-spacing: 2px;
    opacity: 0.6;
}

.cm-card-label {
    font-family: var(--font-chinese);
    font-size: clamp(0px, 1vw, 0.875rem);
    color: var(--glass-text-muted);
    opacity: 0.5;
    margin-top: 0.125rem;
}

.cm-card-title {
    font-family: var(--font-display);
    font-size: clamp(0px, 1.2vw, 0.9375rem);
    color: var(--glass-text);
    text-align: center;
    font-weight: 500;
    margin-top: 0.125rem;
    transition: color var(--transition-normal);
}

.cm-chapter-card.active .cm-card-title {
    color: #fff;
    text-shadow: 0 0 8px rgba(255, 255, 255, 0.15);
}

.cm-card-quill {
    margin-top: 0.25rem;
    opacity: 0.7;
}

.quill-svg {
    transition: transform var(--transition-normal);
}

.cm-chapter-card:hover:not(.locked) .quill-svg {
    transform: rotate(-10deg) scale(1.1);
}

.cm-card-wax-seal {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    opacity: 0.6;
    transition: opacity var(--transition-normal);
}

.cm-chapter-card.locked .cm-card-wax-seal {
    opacity: 0.8;
}

.cm-card-indicator {
    width: 0.25rem;
    height: 0.25rem;
    border-radius: 50%;
    background: var(--glass-border);
    transition: transform, opacity, background-color, border-color, color, filter, box-shadow var(--transition-normal);
    margin-top: 0.25rem;
}

.cm-chapter-card.active .cm-card-indicator {
    background: var(--glass-text);
    box-shadow: 0 0 8px rgba(255, 255, 255, 0.5);
    transform: scale(1.8);
}

.cm-message-area {
    position: absolute;
    bottom: clamp(0px, 2vh, 1.25rem);
    left: 50%;
    transform: translateX(-50%);
    z-index: var(--z-content);
    font-family: var(--font-elegant);
    font-size: clamp(0px, 1vw, 0.875rem);
    color: var(--theme-primary);
    opacity: 0.5;
    text-align: center;
    letter-spacing: 2px;
}

.chapter-mission-modal {
    position: fixed;
    inset: 0;
    z-index: 9999;
    display: block;
    background: rgba(0, 0, 0, 0.45);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.5s ease, visibility 0.5s ease;
    backdrop-filter: var(--glass-blur-heavy);
    -webkit-backdrop-filter: var(--glass-blur-heavy);
}

.chapter-mission-modal.active {
    opacity: 1;
    visibility: visible;
}

.chapter-mission-modal .mission-content {
    position: relative;
    width: 100%;
    height: 100%;
    overflow: hidden;
}

/* ===== Task 4: 章节任务可读性补充 ===== */
.cm-chapter-number,
.cm-chapter-title,
.cm-chapter-desc,
.cm-episode-count {
    text-shadow: 0 1px 3px rgba(0, 0, 0, 0.5);
}

.cm-chapter-desc,
.cm-episode-count {
    color: var(--glass-text-muted);
}


.cm-back-btn,
.cm-unlock-hint,
.cm-start-btn,
.cm-chapter-card,
.chapter-mission-modal {
    isolation: isolate;
}

.cm-back-btn > *:not(svg):not(img):not(video):not(canvas):not(iframe),
.cm-unlock-hint > *:not(svg):not(img):not(video):not(canvas):not(iframe),
.cm-start-btn > *:not(svg):not(img):not(video):not(canvas):not(iframe),
.cm-chapter-card > *:not(svg):not(img):not(video):not(canvas):not(iframe),
.chapter-mission-modal > *:not(svg):not(img):not(video):not(canvas):not(iframe),
.cm-chapter-number,
.cm-title-text,
.cm-chapter-desc,
.cm-episode-count,
.cm-start-text,
.cm-card-number,
.cm-card-label,
.cm-card-title,
.cm-message-area {
    -webkit-font-smoothing: subpixel-antialiased;
    text-rendering: optimizeLegibility;
    transform: translateZ(0);
}

/* Performance: disable backdrop-filter on mobile */
@media (max-width: 768px) {
    [class*="glass-"], .mission-card, .mission-item, .chapter-mission-panel {
        backdrop-filter: none !important;
        -webkit-backdrop-filter: none !important;
    }
}

/* ===== Mobile adaptation for chapter mission modal (≤480px) ===== */
@media (max-width: 480px) {
    .chapter-mission-modal,
    .chapter-mission-modal .mission-content {
        overflow: hidden;
    }

    .chapter-mission-modal .mission-content {
        position: relative;
        top: auto;
        left: auto;
        right: auto;
        bottom: auto;
        transform: none;
        width: 100%;
        height: 100%;
        max-height: none;
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: flex-start;
        overflow-y: auto;
        -webkit-overflow-scrolling: touch;
        padding-top: env(safe-area-inset-top);
        padding-bottom: env(safe-area-inset-bottom);
    }

    .cm-back-btn {
        top: max(var(--spacing-md), env(safe-area-inset-top));
        left: max(var(--spacing-md), env(safe-area-inset-left));
        width: 44px;
        height: 44px;
    }

    .cm-content {
        position: relative;
        left: auto;
        top: auto;
        transform: none;
        max-width: 92vw;
        margin: calc(env(safe-area-inset-top) + 3.5rem) auto 0.5rem;
        text-align: center;
    }

    .cm-chapter-intro {
        align-items: center;
        gap: 0.375rem;
    }

    .ornament-svg {
        width: clamp(4rem, 20vw, 7rem);
    }

    .cm-chapter-number {
        font-size: clamp(0.75rem, 3vw, 1rem);
        letter-spacing: 3px;
    }

    .cm-title-text {
        font-size: clamp(1.75rem, 8vw, 2.5rem);
    }

    .cm-chapter-desc {
        font-size: clamp(0.8125rem, 3.5vw, 1rem);
        line-height: 1.7;
        max-width: 90vw;
        margin: 0.25rem 0;
    }

    .cm-episode-count {
        font-size: clamp(0.75rem, 3vw, 0.9375rem);
    }

    .cm-start-area {
        position: relative;
        bottom: auto;
        left: auto;
        transform: none;
        margin: 0.5rem 0;
    }

    .cm-start-text {
        font-size: clamp(1rem, 4vw, 1.25rem);
        letter-spacing: 6px;
    }

    .cm-chapter-selector {
        position: relative;
        bottom: auto;
        left: auto;
        transform: none;
        width: 100%;
        max-width: 100vw;
        justify-content: flex-start;
        gap: clamp(0.5rem, 2vw, 0.875rem);
        padding: 0.5rem 0.75rem;
        overflow-x: auto;
        overflow-y: hidden;
        -webkit-overflow-scrolling: touch;
        box-sizing: border-box;
    }

    .cm-chapter-card {
        flex: 0 0 auto;
        min-width: 4.75rem;
        padding: clamp(0.5rem, 2vh, 0.75rem) clamp(0.5rem, 2vw, 0.75rem);
    }

    .cm-card-number,
    .cm-card-label {
        font-size: clamp(0.625rem, 2.5vw, 0.75rem);
    }

    .cm-card-title {
        font-size: clamp(0.75rem, 3.2vw, 0.875rem);
    }

    .cm-message-area {
        position: relative;
        bottom: auto;
        left: auto;
        transform: none;
        margin: 0.25rem 0 0.75rem;
        font-size: clamp(0.625rem, 2.5vw, 0.75rem);
    }
}

#chapterMissionModal {
    overscroll-behavior: contain;
}