/* Twincoal 官網的「組裝說明書」視覺系統。
   插圖由 scripts/iso-figures.py 產生；版面與元件都在這一支。
   舊頁面（尚未改版者）仍用 styles.css，改版完成後移除。 */

:root {
    --paper: #fdfdfb;
    --panel: #e4f1fb;
    --panel-dot: rgba(42, 111, 168, .16);
    --ink: #17191c;
    --ink-2: #353b43;
    --ink-3: #555d67;
    --hair: #d6dee6;
    --orange: #f2711f;
    --orange-hover: #ff8a3d;
    --orange-soft: #ffe6d4;
    --orange-ink: #b9500c;
    --yellow: #f5c518;
    --yellow-soft: #fff3c4;
    --sky: #4f9fdc;
    --sky-deep: #24679c;
    --ok: #1d8a4b;

    --font-zh: "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", system-ui, sans-serif;
    --font-num: "Rubik", "Noto Sans TC", system-ui, sans-serif;

    --container: 1336px;
    --gutter: clamp(20px, 4vw, 52px);
    --keyline: 2px;
    --radius: 16px;
    --radius-s: 10px;
    --space-section: clamp(72px, 9vw, 128px);
    /* 區塊上緣（墨線）到標題的距離：各區塊統一用組裝說明原本的間距（2026-11-05） */
    --space-section-top: clamp(56px, 6vw, 72px);
    --ease-out: cubic-bezier(.16, 1, .3, 1);
    --ease-settle: cubic-bezier(.22, 1, .36, 1);
}

/* ── 基礎 ─────────────────────────────────────────────── */

*, *::before, *::after { box-sizing: border-box; }

html {
    scroll-behavior: smooth;
    scroll-padding-top: 96px;
    -webkit-text-size-adjust: 100%;
    scrollbar-color: var(--ink-3) var(--paper);
}

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
}

body {
    margin: 0;
    background: var(--paper);
    color: var(--ink);
    font-family: var(--font-zh);
    font-size: 17px;
    line-height: 1.75;
    text-rendering: optimizeLegibility;
    -webkit-font-smoothing: antialiased;
    caret-color: var(--orange);
}

::selection { background: var(--yellow); color: var(--ink); }

img, svg { display: block; max-width: 100%; }

[hidden] { display: none !important; }

.nb { white-space: nowrap; }

a { color: inherit; text-underline-offset: .22em; text-decoration-thickness: 2px; }

h1, h2, h3, p, ol, ul { margin: 0; }

h1, h2, h3 { font-weight: 900; line-height: 1.25; text-wrap: balance; letter-spacing: -.005em; }

p { text-wrap: pretty; }

:focus-visible { outline: 3px solid var(--sky-deep); outline-offset: 3px; border-radius: 6px; }

.container { width: min(100% - 2 * var(--gutter), var(--container)); margin-inline: auto; }

.skip-link {
    position: absolute; left: 16px; top: -60px; z-index: 50;
    padding: 10px 16px; background: var(--ink); color: #fff; border-radius: var(--radius-s); text-decoration: none;
}
.skip-link:focus { top: 12px; }

.num { font-family: var(--font-num); font-variant-numeric: tabular-nums; }

.icon { width: 1.1em; height: 1.1em; flex: none; }

/* ── 按鈕：一塊帶描邊、有厚度的零件 ─────────────────────── */

.btn {
    --depth: 6px;
    display: inline-flex; align-items: center; justify-content: center; gap: 12px;
    min-height: 58px; padding: 0 26px;
    border: var(--keyline) solid var(--ink); border-bottom-width: var(--depth); border-radius: var(--radius-s);
    background: var(--orange); color: var(--ink);
    font: 700 18px/1.2 var(--font-zh); text-decoration: none;
    transition: background-color .18s ease, translate .16s var(--ease-out), border-bottom-width .16s var(--ease-out), margin-bottom .16s var(--ease-out);
}
/* 按壓：底邊（零件厚度）變薄、按鈕往下沉；外距補回同樣的高度，旁邊的元素不會跟著動 */
.btn:hover { background: var(--orange-hover); border-bottom-width: calc(var(--depth) - 2px); margin-bottom: 2px; translate: 0 2px; }
.btn:active { border-bottom-width: var(--keyline); margin-bottom: calc(var(--depth) - var(--keyline)); translate: 0 calc(var(--depth) - var(--keyline)); }
.btn--paper { background: #fff; }
.btn--paper:hover { background: var(--yellow-soft); }
/* 加 LINE 好友的動作一律用 LINE 綠，墨字（對比 7.9:1） */
.btn--line { background: #06c755; }
.btn--line:hover { background: #2fd472; }
.btn--ink { background: var(--ink); color: #fff; }
.btn--ink:hover { background: #33373d; }
.btn--large { min-height: 64px; padding: 0 30px; font-size: 19px; }

.sr-only {
    position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
    overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

/* 勾選框：包含是黃底墨勾，不包含是白底墨橫線；用畫的，不用文字符號 */
.mark {
    display: inline-block; flex: none; width: 20px; height: 20px; vertical-align: -4px;
    border: var(--keyline) solid var(--ink); border-radius: 5px; background: #fff no-repeat center / 14px 14px;
}
.mark--yes { background-color: var(--yellow); background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 14 14'%3E%3Cpath d='M2.5 7.3l2.9 2.9 6-6.2' fill='none' stroke='%2317191c' stroke-width='2.2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E"); }
.mark--no { background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 14 14'%3E%3Cpath d='M3.5 7h7' fill='none' stroke='%2317191c' stroke-width='2.2' stroke-linecap='round'/%3E%3C/svg%3E"); }

.text-link {
    position: relative; display: inline-flex; align-items: center; gap: 8px;
    font-weight: 700; text-decoration: underline; text-decoration-color: var(--orange);
}
/* 點擊範圍往外擴 8px（上下左右），版面與間距不動；字高約 30px，擴完約 46px（2026-11-05） */
.text-link::before { content: ""; position: absolute; inset: -8px; }
.text-link:hover { text-decoration-color: var(--ink); }

/* ── 頁首 ─────────────────────────────────────────────── */

.site-header {
    position: sticky; top: 0; z-index: 30;
    background: rgba(253, 253, 251, .96);
    border-bottom: var(--keyline) solid var(--ink);
}

.nav-wrap { display: flex; align-items: center; gap: 24px; min-height: 72px; }

.brand { display: inline-flex; align-items: center; gap: 12px; font-weight: 900; font-size: 20px; text-decoration: none; letter-spacing: -.01em; }
.brand svg { width: 36px; height: 36px; }
/* 產品標誌一律不加墨線外框（2026-11-05 起）：Twinco 照原圖、Twinchat 用無框的 v4。 */
.brand img { width: 36px; height: 36px; }

.site-nav { margin-left: auto; display: flex; align-items: center; gap: 30px; font-size: 16px; font-weight: 500; }
.site-nav a { text-decoration: none; }
.site-nav a:not(.btn) { padding: 6px 0; border-bottom: 2px solid transparent; }
.site-nav a:not(.btn):hover { border-bottom-color: var(--orange); }
.site-nav .nav-cta, .nav-wrap > .nav-cta { --depth: 4px; padding: 0 16px; min-height: 44px; font-size: 16px; }
/* 產品頁的主要行動（例如加入 LINE）放在選單外面，手機上也一直看得到；漢堡鈕緊貼在它右邊 */
.nav-wrap > .nav-cta ~ .menu-toggle { margin-left: 0; }

.menu-toggle {
    display: none; margin-left: auto;
    width: 46px; height: 46px; padding: 0; border: var(--keyline) solid var(--ink); border-radius: var(--radius-s);
    background: #fff; cursor: pointer;
}
.menu-toggle span { display: block; width: 20px; height: 2px; margin: 5px auto; background: var(--ink); transition: transform .2s var(--ease-out); }
.menu-toggle[aria-expanded="true"] span:first-child { transform: translateY(3.5px) rotate(45deg); }
.menu-toggle[aria-expanded="true"] span:last-child { transform: translateY(-3.5px) rotate(-45deg); }

/* ── 區塊標題 ─────────────────────────────────────────── */

.section { padding-block: var(--space-section-top) var(--space-section); }

.section-head { display: grid; grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr); gap: 24px 64px; align-items: end; margin-bottom: clamp(36px, 5vw, 64px); }
.section-head h2 { font-size: clamp(32px, 3.6vw, 50px); }
.section-head p { color: var(--ink-2); max-width: 34em; }

/* ── 首屏 ─────────────────────────────────────────────── */

.hero { padding-block: clamp(32px, 4vw, 48px); }

/* 桌機：首屏剛好填滿第一個視窗，下緣落在組裝說明的分隔線上 */
@media (min-width: 1181px) {
    .hero { min-height: calc(100svh - 74px); display: grid; align-items: center; }
}

.hero-layout { display: grid; grid-template-columns: minmax(0, 540px) minmax(0, 1fr); gap: clamp(32px, 4vw, 56px); align-items: center; }

.hero-copy h1 { font-size: min(clamp(32px, 3.7vw, 53px), 8.6vw); line-height: 1.2; }
.hero-lead { margin-top: 24px; font-size: 18px; line-height: 1.8; color: var(--ink-2); max-width: 30em; }
.hero-actions { margin-top: 36px; display: flex; flex-wrap: wrap; align-items: center; gap: 18px 28px; }

.hero-figure {
    display: grid; grid-template-columns: minmax(0, 1fr) 216px; gap: 8px; align-items: center;
    padding: 24px 24px 24px 12px;
    background-color: var(--panel);
    background-image: radial-gradient(var(--panel-dot) 1.5px, transparent 1.7px);
    background-size: 22px 22px;
    border-radius: 24px;
}

.hero-diagram > svg { width: 100%; height: auto; max-height: 600px; }

/* 圖例軌：上面是四個模組的編號圖例，下面夾著品質檢查表 */
.hero-rail { display: flex; flex-direction: column; justify-content: space-between; gap: 28px; padding-block: 8px; }

.hero-parts { list-style: none; padding: 0; display: grid; gap: 10px; }
.hero-parts a {
    display: flex; align-items: center; gap: 10px; min-height: 44px; padding: 4px 14px 4px 6px;
    background: #fff; border: var(--keyline) solid var(--ink); border-radius: 999px;
    font-size: 15px; font-weight: 700; line-height: 1.3; text-decoration: none;
}
.hero-parts a:hover { background: var(--yellow-soft); }
.badge {
    display: grid; place-items: center; flex: none; width: 30px; height: 30px;
    border: var(--keyline) solid var(--ink); border-radius: 50%; background: #fff;
    font-weight: 700; font-size: 15px; line-height: 1;
}

/* 品質檢查表：夾在板子上的一張單子 */
.qc-sheet {
    position: relative;
    padding: 24px 16px 12px; background: #fff;
    border: var(--keyline) solid var(--ink); border-radius: var(--radius);
}
.qc-sheet::before {
    content: ""; position: absolute; top: -12px; left: 50%; width: 76px; height: 22px; transform: translateX(-50%);
    background: var(--yellow); border: var(--keyline) solid var(--ink); border-radius: 8px;
}
.qc-sheet h2 { font-size: 20px; }
.qc-sheet .qc-note { margin-top: 2px; font-size: 14px; line-height: 1.5; color: var(--ink-3); }
.qc-list { list-style: none; padding: 0; margin-top: 8px; display: grid; }
.qc-list li { display: flex; align-items: center; gap: 10px; padding: 6px 0; border-top: 1px solid var(--hair); font-size: 16px; font-weight: 700; }
.qc-list svg { width: 24px; height: 24px; flex: none; }

/* ── 組裝說明 ─────────────────────────────────────────── */

.process { background: #fff; border-block: var(--keyline) solid var(--ink); }

.steps { list-style: none; padding: 0; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 28px; counter-reset: step; }

.step { position: relative; display: flex; flex-direction: column; }
.step-head { display: flex; align-items: baseline; gap: 14px; }
.step-no { font-family: var(--font-num); font-weight: 800; font-size: clamp(56px, 6vw, 84px); line-height: .9; color: var(--ink); transition: color .6s ease .5s; }
.step h3 { font-size: 23px; }
.step-figure {
    margin: 18px 0 16px; padding: 14px; aspect-ratio: 4 / 3; display: grid; place-items: center;
    background: var(--panel); border-radius: var(--radius);
}
.step-figure svg { width: 100%; height: 100%; overflow: visible; }
.step p { color: var(--ink-2); font-size: 16px; line-height: 1.75; }

.step:not(:last-child)::after {
    content: ""; position: absolute; top: clamp(150px, 15vw, 190px); right: -24px; width: 20px; height: 20px;
    background: no-repeat center / contain url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20'%3E%3Cpath d='M2 10h13M10 4l6 6-6 6' fill='none' stroke='%2317191c' stroke-width='2.2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
}

/* 招牌互動：零件落下、卡進定位。預設就是組好的樣子；JS 只在允許動態時先把零件抬起來。 */
.steps .drop { transform-box: fill-box; transition: transform 1.4s var(--ease-settle); }
.steps.is-armed .drop { transform: translateY(-42px); }
.steps.is-armed .step.is-built .drop { transform: none; }
/* 第一步的方塊組好後離面板上緣只剩約 1px，抬高會凸出面板；改成淡入加小幅下降，落定後才出現指向底板的虛線箭頭。 */
.steps .step:first-child .drop { transition: transform 1.4s var(--ease-settle), opacity .7s ease; }
.steps.is-armed .step:first-child .drop { transform: translateY(-24px); opacity: 0; }
.steps.is-armed .step:first-child.is-built .drop { transform: none; opacity: 1; }
.steps .cue { transition: opacity .5s ease; }
.steps.is-armed .cue { opacity: 0; }
.steps.is-armed .step.is-built .cue { opacity: 1; transition-delay: .9s; }
/* 第二步：先畫出一格格預定位置的藍色虛線，再讓虛線方塊落下 */
.steps .slot { transition: opacity .5s ease; }
.steps.is-armed .slot { opacity: 0; }
.steps.is-armed .step.is-built .slot { opacity: 1; }
.steps.is-armed .step.is-built .slot:nth-of-type(2) { transition-delay: .15s; }
.steps.is-armed .step.is-built .slot:nth-of-type(3) { transition-delay: .3s; }
.steps.is-armed .step.is-built .slot:nth-of-type(4) { transition-delay: .45s; }
.steps.is-armed .step.is-built .step-no { color: var(--orange-ink); }

/* ── 零件清單 ─────────────────────────────────────────── */

.parts { list-style: none; padding: 0; border-top: var(--keyline) solid var(--ink); }
.part-row {
    display: grid; grid-template-columns: 220px minmax(0, 1.3fr) minmax(0, 1fr); gap: 20px 48px; align-items: center;
    padding-block: 32px; border-bottom: 1px solid var(--hair);
}
.part-row:last-child { border-bottom: var(--keyline) solid var(--ink); }

.callout {
    position: relative; display: grid; place-items: center; aspect-ratio: 4 / 3; padding: 18px;
    background: #fff; border: var(--keyline) solid var(--ink); border-radius: var(--radius);
}
.callout svg { width: 100%; height: 100%; }
.callout-tag {
    position: absolute; top: 10px; right: 10px; padding: 0 8px; min-height: 26px; display: grid; place-items: center;
    border: var(--keyline) solid var(--ink); border-radius: 7px; background: #fff;
    font-family: var(--font-num); font-size: 14px; font-weight: 700; line-height: 1; white-space: nowrap;
}

.part-body h3 { font-size: 26px; }
.part-body p { margin-top: 8px; color: var(--ink-2); }

.spec { list-style: none; padding: 0; display: grid; gap: 8px; }
.spec li { display: flex; align-items: baseline; gap: 12px; font-size: 16px; }
.spec li::before { content: ""; flex: none; width: 9px; height: 9px; translate: 0 -2px; background: var(--orange); border: 1.5px solid var(--ink); border-radius: 2px; }

/* ── 完成品 ───────────────────────────────────────────── */

.products { background: var(--panel); border-top: var(--keyline) solid var(--ink); }

.product-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 28px; }

.product-card {
    display: grid; grid-template-columns: minmax(0, 220px) minmax(0, 1fr); gap: 8px 28px; align-items: start;
    padding: 28px; background: #fff; border: var(--keyline) solid var(--ink); border-radius: 20px;
    text-decoration: none; transition: transform .25s var(--ease-out);
}
.product-card:hover { transform: translateY(-4px); }
.product-card:hover .text-link { text-decoration-color: var(--ink); }
.product-model svg { width: 100%; height: auto; }
.product-name { display: flex; align-items: center; gap: 12px; }
.product-name img { width: 48px; height: 48px; }
.product-name h3 { font-size: 30px; font-family: var(--font-num); font-weight: 800; letter-spacing: -.01em; }
.status {
    display: inline-flex; align-items: center; gap: 8px; margin-top: 12px; padding: 2px 12px;
    border: 1.5px solid var(--ink); border-radius: 999px; background: #fff;
    font-size: 15px; font-weight: 700;
}
.status i { width: 10px; height: 10px; border-radius: 50%; background: var(--ok); border: 1.5px solid var(--ink); }
.product-card p { margin-top: 12px; color: var(--ink-2); font-size: 16px; }
.product-card .text-link { margin-top: 14px; }
.product-card .live-note { margin-top: 10px; font-size: 15px; color: var(--ink-3); }

.care { margin-top: 56px; display: grid; grid-template-columns: 220px repeat(3, minmax(0, 1fr)); gap: 24px 36px; padding-top: 28px; border-top: var(--keyline) solid var(--ink); }
.care h3 { font-size: 24px; }
.care-item h4 { display: flex; align-items: center; gap: 10px; margin: 0; font-size: 18px; font-weight: 900; line-height: 1.4; }
.care-item h4 svg { width: 26px; height: 26px; flex: none; }
.care-item p { margin-top: 8px; color: var(--ink-2); font-size: 16px; }

.product-more { margin-top: 40px; display: flex; flex-wrap: wrap; gap: 14px 28px; }

/* ── 封底：聯絡 ───────────────────────────────────────── */

.back-cover { background: var(--orange); border-top: var(--keyline) solid var(--ink); }
.back-cover .container { display: grid; grid-template-columns: auto minmax(0, 1fr) minmax(0, 380px); gap: 16px 48px; align-items: center; }
.back-figure svg { width: 100%; height: auto; }
.back-cover .step-no { font-size: clamp(120px, 16vw, 220px); line-height: .8; color: var(--ink); }
.back-cover h2 { font-size: clamp(34px, 4.6vw, 64px); }
.back-cover p { margin-top: 16px; font-size: 19px; max-width: 30em; }
.back-cover .btn { margin-top: 28px; font-family: var(--font-num); font-weight: 700; }
.reply-note { margin-top: 14px; font-size: 16px; font-weight: 500; }

/* ── 頁尾 ─────────────────────────────────────────────── */

.site-footer { padding-block: 40px 48px; border-top: var(--keyline) solid var(--ink); background: var(--paper); }
.footer-inner { display: flex; flex-wrap: wrap; align-items: center; gap: 16px 40px; }
.footer-links { display: flex; flex-wrap: wrap; gap: 8px 28px; font-size: 16px; }
.footer-links a { text-decoration: none; }
.footer-links a:hover { text-decoration: underline; text-decoration-color: var(--orange); }
.copyright { margin-left: auto; font-size: 15px; color: var(--ink-3); }

/* ── 內頁開場（產品目錄等）──────────────────────────────── */

.page-hero { min-height: 0 !important; }
.page-hero-layout { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.3fr); gap: clamp(32px, 4vw, 64px); align-items: center; }
.page-hero .status { margin-top: 24px; }

.catalog-figure {
    padding: 28px 28px 22px;
    background-color: var(--panel);
    background-image: radial-gradient(var(--panel-dot) 1.5px, transparent 1.7px);
    background-size: 22px 22px;
    border-radius: 24px;
}
.catalog-figure > svg { width: 100%; height: auto; }
.catalog-legend { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 16px; }

/* ── 產品展示列：真實畫面＋說明 ─────────────────────────── */

.showcase {
    display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr); gap: 24px clamp(32px, 4vw, 64px); align-items: center;
    padding-block: 40px; border-top: var(--keyline) solid var(--ink);
}
.showcase + .showcase { margin-top: 8px; }
.showcase--flip .showcase-photo { order: 2; }
.showcase-photo {
    position: relative; display: block; overflow: hidden; aspect-ratio: 3 / 2;
    background-color: var(--panel);
    background-image: radial-gradient(var(--panel-dot) 1.5px, transparent 1.7px);
    background-size: 22px 22px;
    border: var(--keyline) solid var(--ink); border-radius: 20px;
    transition: transform .25s var(--ease-out);
}
.showcase-photo:hover { transform: translateY(-4px); }
/* 截圖自帶外框（手機、瀏覽器），完整縮放進看板裡，不另加描邊 */
.showcase-photo img { position: absolute; inset: 20px; width: calc(100% - 40px); height: calc(100% - 40px); object-fit: contain; }
.showcase-body .product-name h3 { font-size: 34px; }
.showcase-body > p { margin-top: 14px; color: var(--ink-2); }
.showcase-body .spec { margin-top: 18px; }
.showcase-body .text-link { margin-top: 22px; }

/* ── 下一個：還空著的位置 ─────────────────────────────── */

.next-layout { display: grid; grid-template-columns: minmax(0, 360px) minmax(0, 1fr); gap: 24px clamp(32px, 5vw, 80px); align-items: center; }
.next-figure svg { width: 100%; height: auto; }
.next h2 { font-size: clamp(30px, 3.4vw, 46px); }
.next p { margin-top: 16px; color: var(--ink-2); max-width: 32em; }
.next .text-link { margin-top: 22px; }

/* ── 常見問題（各頁共用） ─────────────────────────────── */
.faq { background: #fff; border-top: var(--keyline) solid var(--ink); }
.faq-layout { display: grid; grid-template-columns: minmax(0, 340px) minmax(0, 1fr); gap: 32px clamp(40px, 6vw, 96px); align-items: start; }
.faq-heading { position: sticky; top: 100px; }
.faq-heading h2 { font-size: clamp(28px, 3vw, 40px); }
.faq-heading > p { margin-top: 12px; color: var(--ink-2); font-size: 16px; }
.faq-list details { border-bottom: 1px solid var(--hair); }
.faq-list summary {
    position: relative; list-style: none; cursor: pointer; padding: 18px 44px 18px 0; font-size: 17px; font-weight: 700;
}
.faq-list summary::-webkit-details-marker { display: none; }
.faq-list summary::after {
    content: ""; position: absolute; right: 4px; top: 50%; width: 22px; height: 22px; translate: 0 -50%;
    border: var(--keyline) solid var(--ink); border-radius: 6px;
    background: #fff no-repeat center / 12px 12px url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 12'%3E%3Cpath d='M6 1.5v9M1.5 6h9' fill='none' stroke='%2317191c' stroke-width='2' stroke-linecap='round'/%3E%3C/svg%3E");
}
.faq-list details[open] summary::after { background-color: var(--yellow); background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 12 12'%3E%3Cpath d='M1.5 6h9' fill='none' stroke='%2317191c' stroke-width='2' stroke-linecap='round'/%3E%3C/svg%3E"); }
.faq-list details > :not(summary) { margin-bottom: 14px; color: var(--ink-2); font-size: 16px; }
.faq-list details ul { padding-left: 1.2em; display: grid; gap: 6px; }

/* ── 響應式 ───────────────────────────────────────────── */

@media (max-width: 1180px) {
    .hero-layout { grid-template-columns: minmax(0, 1fr); }
    .hero-copy { max-width: 640px; }
    .care { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .care > h3 { grid-column: 1 / -1; }
}

@media (max-width: 960px) {
    .steps { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 40px 28px; }
    .step:nth-child(2)::after { display: none; }
    .part-row { grid-template-columns: 180px minmax(0, 1fr); }
    .part-row .spec { grid-column: 2; }
    .product-grid { grid-template-columns: minmax(0, 1fr); }
    .section-head { grid-template-columns: minmax(0, 1fr); }
    .faq-layout { grid-template-columns: minmax(0, 1fr); }
    .faq-heading { position: static; }
    .back-cover .container { grid-template-columns: auto minmax(0, 1fr); }
    .back-figure { display: none; }
    .page-hero-layout { grid-template-columns: minmax(0, 1fr); }
    .showcase { grid-template-columns: minmax(0, 1fr); }
    .showcase--flip .showcase-photo { order: 0; }
    .next-layout { grid-template-columns: minmax(0, 1fr); }
    .next-figure { max-width: 280px; }
}

@media (max-width: 800px) {
    .menu-toggle { display: block; }
    .site-nav {
        position: absolute; top: 100%; left: 0; right: 0; display: none;
        flex-direction: column; align-items: stretch; gap: 0; padding: 8px var(--gutter) 20px;
        background: var(--paper); border-bottom: var(--keyline) solid var(--ink);
    }
    .site-nav.open { display: flex; }
    .site-nav a:not(.btn) { padding: 14px 0; border-bottom: 1px solid var(--hair); font-size: 17px; }
    .site-nav .nav-cta { margin-top: 14px; justify-content: center; }
    .nav-wrap > .nav-cta { margin-left: auto; }

    .hero-figure { grid-template-columns: minmax(0, 1fr); padding: 20px; }
    .hero-parts { grid-template-columns: repeat(2, minmax(0, 1fr)); margin-top: 8px; }
    .qc-sheet { margin-top: 8px; }
}

@media (max-width: 420px) {
    .nav-wrap { gap: 12px; }
    .nav-wrap > .nav-cta { padding: 0 12px; font-size: 15px; }
}

@media (max-width: 640px) {
    body { font-size: 16px; }
    .hero-lead { font-size: 17px; }
    .hero-actions .btn { width: 100%; }
    .steps { grid-template-columns: minmax(0, 1fr); gap: 28px; }
    .step { display: grid; grid-template-columns: 112px minmax(0, 1fr); grid-template-areas: "fig head" "fig text"; column-gap: 16px; align-content: start; }
    .step::after { display: none; }
    .step-figure { grid-area: fig; margin: 0; padding: 8px; aspect-ratio: 1; border-radius: var(--radius-s); }
    .step-head { grid-area: head; gap: 10px; }
    .step-no { font-size: 44px; }
    .step h3 { font-size: 20px; }
    .step p { grid-area: text; margin-top: 4px; font-size: 15px; }
    .part-row { grid-template-columns: 112px minmax(0, 1fr); gap: 12px 16px; padding-block: 24px; }
    .callout { padding: 26px 8px 8px; border-radius: var(--radius-s); aspect-ratio: auto; }
    .callout-tag { top: 6px; right: 6px; min-height: 22px; padding: 0 6px; font-size: 12px; border-width: 1.5px; }
    .part-body h3 { font-size: 22px; }
    .part-body p { font-size: 15px; }
    .part-row .spec { grid-column: 1 / -1; }
    .product-card { grid-template-columns: minmax(0, 1fr); padding: 22px; }
    .product-model { max-width: 220px; margin-inline: auto; }
    .care { grid-template-columns: minmax(0, 1fr); }
    .hero-parts { grid-template-columns: minmax(0, 1fr); }
    .back-cover .container { grid-template-columns: minmax(0, 1fr); }
    .back-cover .btn { width: 100%; font-size: 17px; }
    .copyright { margin-left: 0; }
}