:root {
    /* 優化：改用 Apple 質感的低飽和度、高質感色系 */
    --color-bg-light: #FDFCFB; 
    --color-bg-dark: #0B0B0E; /* 更深邃、不刺眼的純黑變體 */
    --color-text-main: #1D1D1F; /* 柔和但清晰的深灰色 */
    --color-text-muted: #86868B;
    --color-text-light: #A1A1A6;
    --color-primary: #F47AA4;
    --color-white: #F5F5F7;
    
    /* 優化：卡片陰影改為精品級的柔和擴散陰影 */
    --card-shadow: 0 8px 22px rgba(0, 0, 0, 0.035);
    --card-shadow-hover: 0 14px 28px rgba(0, 0, 0, 0.07);
}

body[data-page="milestone"] {
    margin: 0;
    padding: 0;
    background-color: var(--color-bg-light);
    font-family: -apple-system, BlinkMacSystemFont, 'Noto Sans TC', sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale; /* 讓文字渲染更精緻 */
}

.milestone-main-wrapper {
    width: 100%;
    background-color: var(--color-bg-light);
    transition: background-color 1s cubic-bezier(0.25, 1, 0.5, 1);
}

.milestone-main-wrapper.is-dark {
    background-color: var(--color-bg-dark);
}

.milestone-scroll-container {
    position: relative;
    width: 100%;
}

.milestone-stage {
    position: relative;
    width: 100%;
    height: 100vh;
    height: 100svh;
    overflow: hidden;
}

.milestone-scene {
    position: relative;
    width: 100%;
    min-height: auto;
    padding: 96px 24px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    box-sizing: border-box;
    opacity: 1;
    visibility: visible;
}

body.js-enabled .milestone-scene {
    position: absolute;
    inset: 0;
    min-height: 100vh;
    padding: 24px;
    opacity: 0;
    visibility: hidden;
}

body.js-enabled .main-title,
body.js-enabled .genesis-story,
body.js-enabled .meta-10k-panel,
body.js-enabled .horizontal-track,
body.js-enabled .reveal-layer,
body.js-enabled .stacking-heading,
body.js-enabled .final-assembly-wrapper {
    opacity: 0;
}

/* 優化：標題層次、字距、行高 */
.huge-title {
    font-size: clamp(2.8rem, 8vw, 5.5rem);
    font-weight: 800; /* 收斂字重，不使用 900 避免過粗 */
    letter-spacing: -0.02em; /* 緊湊字距，增加成熟感 */
    color: var(--color-text-main);
    text-align: center;
    margin: 0;
    will-change: transform, opacity;
}

.huge-number {
    font-size: clamp(4rem, 15vw, 13rem);
    font-weight: 800;
    letter-spacing: -0.04em;
    color: var(--color-text-main);
    line-height: 1;
    text-align: center;
    margin: 0;
    will-change: transform, opacity;
    font-variant-numeric: tabular-nums; /* 確保滾動時數字等寬，不抖動 */
}

.scene-100k .huge-number, 
.scene-finale .final-assembly {
    color: var(--color-white);
}

.story-year {
    font-size: clamp(3.5rem, 10vw, 8.5rem);
    font-weight: 800;
    letter-spacing: -0.03em;
    color: var(--color-text-main);
    line-height: 1;
}

.story-date {
    font-size: clamp(2rem, 6vw, 4.5rem);
    font-weight: 700;
    color: var(--color-primary);
    margin-top: 16px;
}

.story-desc {
    font-size: 1.25rem;
    font-weight: 500;
    color: var(--color-text-muted);
    text-align: center;
    line-height: 1.6;
    margin-top: 24px;
}

.story-desc small {
    font-size: 0.95rem;
    color: var(--color-text-light);
    font-weight: 400;
    margin-top: 8px;
    display: block;
}

.meta-10k-panel {
    display: flex;
    flex-direction: column;
    align-items: center;
}

body.js-enabled .meta-10k-panel {
    position: absolute;
    transform: translateY(30px);
}

.meta-date {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--color-text-light);
    letter-spacing: 0.05em;
}

.meta-title {
    font-size: clamp(1.8rem, 4vw, 3rem);
    font-weight: 800;
    letter-spacing: -0.02em;
    color: var(--color-text-main);
    margin: 8px 0 0 0;
}

.horizontal-slider {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: flex-start;
}

body.js-enabled .horizontal-slider {
    padding-left: 10vw;
}

.horizontal-track {
    display: flex;
    gap: 40px;
    will-change: transform;
}

body.no-js .horizontal-slider,
body.no-gsap .horizontal-slider {
    overflow-x: auto;
    scroll-snap-type: x mandatory;
    -webkit-overflow-scrolling: touch;
    padding: 24px 0;
}

body.no-js .horizontal-track,
body.no-gsap .horizontal-track {
    padding: 0 24px;
}

/* 優化：卡片圓角、陰影、過渡動畫 */
.horizontal-card {
    flex: 0 0 320px;
    height: 440px;
    background: rgba(255, 255, 255, 0.95);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: 24px; /* 更精緻的圓角比例 */
    padding: 32px;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    box-shadow: var(--card-shadow);
    position: relative;
    overflow: hidden;
    cursor: pointer;
    transition: transform 0.28s cubic-bezier(0.25, 1, 0.5, 1), border-color 0.28s ease, box-shadow 0.28s ease;
}

body.no-js .horizontal-card,
body.no-gsap .horizontal-card {
    scroll-snap-align: center;
}

.card-bg-img {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 0;
    transition: transform 0.8s cubic-bezier(0.2, 0.8, 0.2, 1); /* 更高級的圖片放大曲線 */
}

.card-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(to top, rgba(11, 11, 14, 0.92) 0%, rgba(11, 11, 14, 0.3) 60%, transparent 100%);
    z-index: 1;
    transition: background 0.4s ease;
}

.card-info, .card-media, .stack-info, .stack-media {
    position: relative;
    z-index: 2;
}

/* Hover 效果：克制的高級感 */
.horizontal-card.video-card:hover,
.horizontal-card.video-card:focus-visible,
.stack-card:hover,
.stack-card:focus-visible {
    border-color: rgba(244, 122, 164, 0.3);
    box-shadow: var(--card-shadow-hover);
    transform: translateY(-4px);
}

.horizontal-card.video-card:hover .card-bg-img,
.horizontal-card.video-card:focus-visible .card-bg-img,
.stack-card:hover .card-bg-img,
.stack-card:focus-visible .card-bg-img {
    transform: scale(1.04); /* 降低放大倍率，避免廉價感 */
}

.heading-card {
    background: linear-gradient(135deg, rgba(244, 122, 164, 0.08), rgba(123, 90, 200, 0.05));
    justify-content: center;
    border-color: rgba(244, 122, 164, 0.15);
    cursor: default;
}

.heading-card h2 {
    font-size: 2.2rem;
    font-weight: 800;
    color: var(--color-text-main);
    margin: 0 0 16px;
    letter-spacing: -0.02em;
}

.heading-card p {
    color: var(--color-text-muted);
    margin: 0;
    font-size: 1.05rem;
    line-height: 1.5;
}

/* 優化：毛玻璃 Icon 區塊 */
.card-media {
    position: absolute;
    top: 32px;
    left: 32px;
    width: 52px;
    height: 52px;
    border-radius: 16px;
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(12px); /* 提高毛玻璃模糊度 */
    -webkit-backdrop-filter: blur(12px);
    display: grid;
    place-items: center;
    color: var(--color-white);
    font-size: 1.4rem;
    transition: background 0.4s ease, color 0.4s ease;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.horizontal-card.video-card:hover .card-media {
    background: var(--color-white);
    color: var(--color-primary);
}

.card-info .v-date, .stack-info .v-date {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.85); /* 提高辨識度 */
    font-weight: 600;
    display: block;
    margin-bottom: 8px;
    letter-spacing: 0.02em;
}

.card-info h3, .stack-info h3 {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--color-white);
    margin: 0 0 12px;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: normal;
}

.card-info .v-views, .stack-info .v-views {
    font-size: 1.05rem;
    color: var(--color-primary);
    font-weight: 800;
}

.reveal-layer {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-top: 12px;
}

body.js-enabled .reveal-layer {
    position: absolute;
    transform: translateY(30px);
}

.reveal-num {
    font-size: clamp(3.5rem, 9vw, 7.5rem);
    font-weight: 800;
    color: var(--color-white);
    line-height: 1;
    font-variant-numeric: tabular-nums;
}

.reveal-label {
    font-size: 1.15rem;
    color: var(--color-text-light);
    font-weight: 500;
    margin-top: 16px;
    letter-spacing: 0.05em;
}

.reveal-date {
    font-size: 1.15rem;
    color: var(--color-primary);
    font-weight: 600;
    letter-spacing: 0.05em;
}

.reveal-title {
    font-size: clamp(2.2rem, 5vw, 4rem);
    font-weight: 800;
    letter-spacing: -0.02em;
    color: var(--color-white);
    margin: 12px 0 0 0;
    font-variant-numeric: tabular-nums;
}

.stacking-heading {
    text-align: center;
    margin-bottom: 24px;
}

body.js-enabled .stacking-heading {
    position: absolute;
    top: 8vh;
    z-index: 10;
}

.stacking-heading h2 {
    font-size: 2.4rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    color: var(--color-white);
    margin: 0 0 12px;
}

.stacking-heading p {
    color: var(--color-text-light);
    margin: 0;
    font-size: 1.1rem;
}

.stacking-container {
    position: relative;
    width: min(580px, 90vw);
    height: 420px;
}

body.no-js .stacking-container,
body.no-gsap .stacking-container {
    height: auto;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.stack-card {
    position: absolute;
    inset: 0;
    background: var(--color-bg-dark);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 24px;
    padding: 40px;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    box-shadow: 0 18px 36px rgba(0, 0, 0, 0.32);
    transform-origin: center bottom;
    will-change: transform, opacity;
    cursor: pointer;
    transition: border-color 0.4s ease, transform 0.4s ease;
    overflow: hidden;
}

body.no-js .stack-card,
body.no-gsap .stack-card {
    position: relative;
    min-height: 280px;
}

.stack-media {
    position: absolute;
    top: 40px;
    left: 40px;
    width: 56px;
    height: 56px;
    border-radius: 18px;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    display: grid;
    place-items: center;
    color: var(--color-white);
    font-size: 1.6rem;
    border: 1px solid rgba(255, 255, 255, 0.15);
    transition: background 0.4s ease, border-color 0.4s ease;
}

.stack-card:hover .stack-media {
    background: var(--color-white);
    color: var(--color-bg-dark);
    border-color: var(--color-white);
}

.flash-container {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    overflow: hidden;
}

body.no-js .flash-container,
body.no-gsap .flash-container,
body.no-js .giant-plus,
body.no-gsap .giant-plus {
    display: none;
}

.flash-item {
    position: absolute;
    font-weight: 800;
    color: rgba(255, 255, 255, 0.12);
    line-height: 1;
    opacity: 0;
    will-change: opacity, transform;
}

.flash-1 { font-size: clamp(4rem, 8vw, 8rem); top: 22%; left: 15%; }
.flash-2 { font-size: clamp(5rem, 10vw, 10rem); bottom: 30%; right: 18%; }
.flash-3 { font-size: clamp(3rem, 6vw, 6rem); top: 40%; left: 30%; }
.flash-4 { font-size: clamp(6rem, 12vw, 12rem); top: 15%; right: 15%; }
.flash-5 { font-size: clamp(4.5rem, 9vw, 9rem); bottom: 20%; left: 20%; }
.flash-6 { font-size: clamp(7rem, 14vw, 14rem); top: 35%; right: 25%; }
.flash-7 { font-size: clamp(6rem, 12vw, 12rem); bottom: 35%; left: 10%; color: rgba(255, 255, 255, 0.2); }

.giant-plus {
    position: absolute;
    font-size: clamp(10rem, 35vw, 26rem);
    font-weight: 800;
    color: var(--color-white);
    opacity: 0;
    line-height: 1;
    text-shadow: 0 0 50px rgba(255, 255, 255, 0.1);
}

/* 修正 5：Finale 排版重疊問題。透過 Flex Column + Gap 穩定控制間距 */
.final-assembly-wrapper {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: clamp(16px, 4vh, 32px); /* 在不同裝置下自動收放間距 */
    width: 100%;
    padding: 0 20px;
    box-sizing: border-box;
}

body.js-enabled .final-assembly-wrapper {
    position: absolute;
    z-index: 2;
}

.final-context-top,
.final-context-bottom {
    font-size: 1.1rem;
    color: var(--color-text-light);
    font-weight: 500;
    letter-spacing: 0.05em;
}

.final-assembly {
    font-size: clamp(3rem, 11vw, 8.5rem); /* 微調大小防止手機爆版 */
    font-weight: 800;
    letter-spacing: -0.04em;
    color: var(--color-white);
    line-height: 1.1; /* 避免文字被上下截斷 */
    margin: 0; /* 移除原本的 margin 10px，改由父層 gap 控制 */
    font-variant-numeric: tabular-nums;
}

/* =========================================
   優雅降級模式 (.no-gsap)
   ========================================= */
body.no-gsap .scene-100k,
body.no-gsap .scene-stacking,
body.no-gsap .scene-finale {
    background-color: var(--color-bg-dark);
}

body.no-js .milestone-scene,
body.no-gsap .milestone-scene {
    border-bottom: 1px solid rgba(0,0,0,0.05);
}

body.no-js .scene-100k, body.no-gsap .scene-100k,
body.no-js .scene-stacking, body.no-gsap .scene-stacking,
body.no-js .scene-finale, body.no-gsap .scene-finale {
    border-bottom: 1px solid rgba(255,255,255,0.05);
}

@media (max-width: 680px) {
    .horizontal-card {
        flex: 0 0 280px;
        height: 380px;
        padding: 24px;
    }
    .card-media {
        top: 24px;
        left: 24px;
    }
    .stack-card {
        padding: 24px;
    }
    .stack-media {
        top: 24px;
        left: 24px;
    }
}

/* Performance pass: reduce paint cost during GSAP pinned scrolling. */
.milestone-stage,
.milestone-scene,
.horizontal-track,
.horizontal-card,
.stack-card,
.card-bg-img,
.flash-item,
.giant-plus,
.final-assembly-wrapper {
    backface-visibility: hidden;
    transform: translateZ(0);
}

.horizontal-card,
.stack-card {
    contain: layout paint;
}

.card-bg-img {
    will-change: transform;
}

.num-100k-main,
.final-assembly {
    contain: content;
}

@media (max-width: 760px), (prefers-reduced-motion: reduce) {
    .card-media,
    .stack-media {
        backdrop-filter: none;
        -webkit-backdrop-filter: none;
        background: rgba(255,255,255,.18);
    }

    .horizontal-card.video-card:hover,
    .horizontal-card.video-card:focus-visible,
    .stack-card:hover,
    .stack-card:focus-visible {
        transform: none;
        box-shadow: var(--card-shadow);
    }

    .horizontal-card.video-card:hover .card-bg-img,
    .horizontal-card.video-card:focus-visible .card-bg-img,
    .stack-card:hover .card-bg-img,
    .stack-card:focus-visible .card-bg-img {
        transform: none;
    }

    .flash-item,
    .giant-plus {
        text-shadow: none;
    }
}

@media (prefers-reduced-motion: reduce) {
    .milestone-main-wrapper,
    .horizontal-card,
    .card-bg-img,
    .card-overlay,
    .card-media,
    .stack-card,
    .stack-media {
        transition-duration: 0.01ms !important;
    }
}