/* ============================================================
   练琴搭子 · 官网设计系统
   复用小程序的「纸张手绘」视觉基因
   ============================================================ */

/* ---------- 字体加载 ---------- */
@font-face {
    font-family: "JasonHandwriting8";
    src: url("../fonts/site-handwriting.woff2") format("woff2");
    font-weight: normal;
    font-style: normal;
    font-display: swap;
    unicode-range: U+20-7E, U+266F; /* ASCII + ♯，其余中文用子集 */
}

/* ---------- 设计变量 ---------- */
:root {
    /* 配色（与小程序 app.wxss 完全一致） */
    --paper: #EFE9E2;
    --paper-shadow: #ECE3CC;
    --paper-card: rgba(255, 255, 255, 0.45);
    --ink: #292929;
    --ink-soft: #77736C;
    --accent: #E48A19;
    --accent-soft: #D4A52C;
    --success: #4E9B55;
    --danger: #C75A3C;
    --disabled: #B9B3A9;

    /* 线条与圆角 */
    --line: 2px;
    --line-bold: 3px;
    --radius: 8px;
    --radius-lg: 14px;

    /* 字体栈 */
    --font-hand: "JasonHandwriting8", "KaiTi", "STKaiti", "楷体", cursive;
    --font-body: -apple-system, BlinkMacSystemFont, "PingFang SC",
                 "Helvetica Neue", "Hiragino Sans GB", "Microsoft YaHei",
                 sans-serif;

    /* 硬投影（手绘招牌效果） */
    --shadow-sm: 3px 3px 0 rgba(41, 41, 41, 0.08);
    --shadow: 5px 5px 0 rgba(41, 41, 41, 0.12);
    --shadow-lg: 7px 7px 0 rgba(41, 41, 41, 0.15);
    --shadow-accent: 5px 5px 0 rgba(228, 138, 25, 0.25);

    --maxw: 1080px;
}

/* ---------- 重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
    margin: 0;
    font-family: var(--font-body);
    font-size: 16px;
    line-height: 1.6;
    color: var(--ink);
    background-color: var(--paper);
    /* 水墨晕染 + 纸张颗粒 */
    background-image:
        radial-gradient(circle at 12% 18%, rgba(120, 100, 60, 0.06) 0, transparent 90px),
        radial-gradient(circle at 78% 62%, rgba(120, 100, 60, 0.05) 0, transparent 110px),
        radial-gradient(circle at 38% 88%, rgba(120, 100, 60, 0.06) 0, transparent 130px),
        radial-gradient(circle at 62% 32%, rgba(120, 100, 60, 0.05) 0, transparent 100px),
        radial-gradient(circle at 88% 8%, rgba(120, 100, 60, 0.04) 0, transparent 80px),
        url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='180' height='180'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/><feColorMatrix values='0 0 0 0 0.4 0 0 0 0 0.35 0 0 0 0 0.25 0 0 0 0.04 0'/></filter><rect width='100%25' height='100%25' filter='url(%23n)'/></svg>");
    background-size: 600px 600px, 720px 720px, 540px 540px, 480px 480px, auto, 180px 180px;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
h1, h2, h3, h4 { margin: 0; font-weight: 700; line-height: 1.3; }

/* ---------- 手写体工具类 ---------- */
.hand {
    font-family: var(--font-hand);
    letter-spacing: 1px;
}
.hand-xl { font-size: clamp(40px, 7vw, 72px); font-weight: 700; }
.hand-lg { font-size: clamp(28px, 4.5vw, 42px); }
.hand-md { font-size: clamp(20px, 3vw, 28px); }
.hand-sm { font-size: clamp(16px, 2.2vw, 20px); }
.text-ink { color: var(--ink); }
.text-soft { color: var(--ink-soft); }
.text-accent { color: var(--accent); }
.text-success { color: var(--success); }
.center-text { text-align: center; }

/* ---------- 布局 ---------- */
.wrap {
    width: 100%;
    max-width: var(--maxw);
    margin: 0 auto;
    padding: 0 24px;
}
.section { padding: 64px 0; }
.section-tight { padding: 40px 0; }
.center-col {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}
.eyebrow {
    display: inline-block;
    padding: 4px 14px;
    border: var(--line) solid var(--ink);
    border-radius: 999px;
    font-size: 13px;
    color: var(--ink-soft);
    background: rgba(255, 255, 255, 0.4);
    margin-bottom: 18px;
    letter-spacing: 1px;
}
.h-section {
    font-family: var(--font-hand);
    font-size: clamp(28px, 4.5vw, 40px);
    margin-bottom: 12px;
}
.h-section-sub {
    color: var(--ink-soft);
    font-size: clamp(15px, 2vw, 18px);
    margin-bottom: 40px;
}

/* ---------- 卡片（草图描边 + 硬投影） ---------- */
.card {
    border: var(--line) solid var(--ink);
    border-radius: var(--radius);
    background: var(--paper-card);
    box-shadow: var(--shadow);
    padding: 28px;
}
.card-bold {
    border-width: var(--line-bold);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    padding: 32px;
}
.card-hover { transition: transform .25s ease, box-shadow .25s ease; }
.card-hover:hover {
    transform: translate(-2px, -2px);
    box-shadow: var(--shadow-lg);
}

/* ---------- 按钮 ---------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 14px 28px;
    border: var(--line) solid var(--ink);
    border-radius: var(--radius);
    background: rgba(255, 255, 255, 0.5);
    color: var(--ink);
    font-size: 16px;
    font-weight: 600;
    line-height: 1;
    cursor: pointer;
    box-shadow: var(--shadow-sm);
    transition: transform .15s ease, box-shadow .15s ease;
}
.btn:hover { transform: translate(-1px, -1px); box-shadow: var(--shadow); }
.btn:active { transform: translate(1px, 1px); box-shadow: 2px 2px 0 rgba(41,41,41,.08); }
.btn-primary {
    background: var(--ink);
    color: var(--paper);
}
.btn-accent {
    border-color: var(--accent);
    color: var(--accent);
    background: rgba(228, 138, 25, 0.08);
    box-shadow: var(--shadow-accent);
}
.btn-lg { padding: 18px 36px; font-size: 18px; }

/* ---------- 小程序码 ---------- */
.qr-box {
    width: 140px;
    height: 140px;
    border: var(--line-bold) solid var(--ink);
    border-radius: var(--radius);
    padding: 5px;
    background: #fff;
    box-shadow: var(--shadow);
    object-fit: contain;
    flex-shrink: 0;
}
.scan-conversion {
    display: flex;
    align-items: center;
    gap: 18px;
    margin-top: 24px;
    padding-top: 24px;
    border-top: 1px dashed rgba(41, 41, 41, 0.28);
}
.qr-box.qr-conversion-code {
    width: 116px;
    height: 116px;
    box-shadow: var(--shadow-sm);
}
.scan-copy {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 3px;
}
.scan-copy strong {
    font-size: 20px;
}
.scan-copy span {
    color: var(--ink-soft);
    font-size: 13px;
}
.scan-copy small {
    margin-top: 5px;
    color: var(--accent);
    font-size: 12px;
}

/* ---------- 顶部导航 ---------- */
.nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(239, 233, 226, 0.88);
    backdrop-filter: blur(8px);
    border-bottom: var(--line) solid var(--ink);
}
.nav-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}
.nav-brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-family: var(--font-hand);
    font-size: 22px;
    font-weight: 700;
    color: var(--ink);
}
.nav-brand-mark {
    width: 32px;
    height: 32px;
    border: var(--line) solid var(--ink);
    border-radius: 6px;
    display: grid;
    place-items: center;
    background: var(--ink);
    color: var(--paper);
    font-size: 18px;
    box-shadow: 2px 2px 0 rgba(41,41,41,.15);
}
.nav-links {
    display: flex;
    align-items: center;
    gap: 28px;
}
.nav-links a {
    font-size: 15px;
    color: var(--ink-soft);
    transition: color .15s;
}
.nav-links a:hover { color: var(--ink); }
.nav-cta { padding: 8px 18px; font-size: 14px; }
@media (max-width: 640px) {
    .nav-links { gap: 16px; }
    .nav-links a:not(.nav-cta) { display: none; }
}

/* ---------- 吸底 CTA ---------- */
.cta-bar {
    position: fixed;
    left: 0; right: 0; bottom: 0;
    z-index: 90;
    background: rgba(239, 233, 226, 0.95);
    backdrop-filter: blur(8px);
    border-top: var(--line) solid var(--ink);
    box-shadow: 0 -4px 20px rgba(41, 41, 41, 0.06);
}
.cta-inner {
    max-width: var(--maxw);
    margin: 0 auto;
    padding: 12px 24px;
    display: flex;
    align-items: center;
    gap: 16px;
}
.cta-mini-qr {
    width: 44px;
    height: 44px;
    border: var(--line) solid var(--ink);
    border-radius: 6px;
    background: #fff;
    position: relative;
    overflow: hidden;
    flex-shrink: 0;
    object-fit: cover;
    background: #fff;
}
.cta-mini-mark {
    width: 44px;
    height: 44px;
    border: var(--line) solid var(--ink);
    border-radius: 50%;
    display: grid;
    place-items: center;
    flex-shrink: 0;
    background: var(--ink);
    color: var(--paper);
    font-size: 15px;
    font-weight: 700;
    box-shadow: var(--shadow-sm);
}
.cta-text { flex: 1; min-width: 0; }
.cta-title {
    font-family: var(--font-hand);
    font-size: 18px;
    font-weight: 700;
    color: var(--ink);
    line-height: 1.2;
}
.cta-sub { font-size: 12px; color: var(--ink-soft); }
.cta-btn { padding: 12px 22px; white-space: nowrap; }
@media (max-width: 480px) {
    .cta-inner { gap: 10px; padding: 10px 16px; }
    .cta-mini-qr { width: 38px; height: 38px; }
    .cta-title { font-size: 15px; }
    .cta-sub { font-size: 11px; }
    .cta-btn { padding: 10px 14px; font-size: 13px; }
}

/* ---------- 乐器卡片网格 ---------- */
.grid {
    display: grid;
    gap: 18px;
}
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 900px) {
    .grid-4 { grid-template-columns: repeat(2, 1fr); }
    .grid-3 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 560px) {
    .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

/* 乐器入口卡片 */
.tuner-card {
    display: block;
    padding: 24px;
    text-align: center;
    position: relative;
}
.tuner-card .icon {
    width: 88px;
    height: 65px;
    margin: 0 auto 14px;
    display: flex;
    align-items: center;
    justify-content: center;
}
.tuner-card .icon img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    /* 轻微浮动入场，hover 放大 */
    transition: transform .25s ease;
}
.tuner-card:hover .icon img { transform: scale(1.08); }
.tuner-card .name {
    font-family: var(--font-hand);
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 4px;
}
.tuner-card .sub { font-size: 13px; color: var(--ink-soft); }
.card-status {
    position: absolute;
    top: 12px;
    right: 12px;
    padding: 3px 9px;
    border-radius: 999px;
    background: var(--success);
    color: #fff;
    font-size: 11px;
    font-weight: 700;
}
.tuner-card.is-coming {
    opacity: 0.56;
    box-shadow: 3px 3px 0 rgba(41, 41, 41, 0.06);
}
.tuner-card.is-coming::after {
    content: "即将上线";
    display: block;
    width: fit-content;
    margin: 12px auto 0;
    padding: 2px 8px;
    border: 1px dashed var(--ink-soft);
    border-radius: 999px;
    color: var(--ink-soft);
    font-size: 11px;
}

/* ============================================================
   首屏动态装置：调音指针表盘
   ============================================================ */
.tuner-stage {
    position: relative;
    width: min(420px, 86vw);
    aspect-ratio: 2 / 1.15;
    margin: 0 auto;
}
/* 刻度盘 */
.gauge {
    position: absolute;
    inset: 0;
    border: var(--line-bold) solid var(--ink);
    border-radius: 220px 220px 0 0;
    background: var(--paper-card);
    box-shadow: var(--shadow-lg);
}
.gauge-fill {
    position: absolute;
    inset: 8px;
    border-radius: 212px 212px 0 0;
    background:
        linear-gradient(90deg,
            rgba(199,90,60,0.10) 0%,
            rgba(199,90,60,0.04) 35%,
            rgba(78,155,85,0.12) 45%,
            rgba(78,155,85,0.12) 55%,
            rgba(199,90,60,0.04) 65%,
            rgba(199,90,60,0.10) 100%);
}
/* 刻度线 */
.gauge-ticks {
    position: absolute;
    bottom: 0; left: 0; right: 0;
    height: 100%;
}
.tick {
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 2px;
    background: var(--ink);
    transform-origin: bottom center;
    opacity: 0.5;
}
.tick-major { height: 28px; opacity: 0.8; }
.tick-minor { height: 14px; }
.tick-label {
    position: absolute;
    bottom: 8px;
    font-size: 15px;
    color: var(--ink-soft);
    font-weight: 700;
    font-family: var(--font-hand);
    letter-spacing: 1px;
}
.tick-label.center {
    left: 50%;
    bottom: 36px;
    transform: translateX(-50%);
    color: var(--success);
    font-size: 18px;
}
/* 指针 */
.needle-wrap {
    position: absolute;
    bottom: 12px;
    left: 50%;
    width: 6px;
    height: 78%;
    transform-origin: bottom center;
    transform: translateX(-50%) rotate(var(--angle, 0deg));
    animation: needle-sweep 6s cubic-bezier(.4,0,.6,1) infinite;
    z-index: 3;
}
.needle {
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 100%;
    background: var(--ink);
    border-radius: 4px 4px 0 0;
}
.needle::before {
    /* 指针尖小红点 */
    content: "";
    position: absolute;
    top: -6px;
    left: 50%;
    transform: translateX(-50%);
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--accent);
    box-shadow: 0 0 0 2px var(--paper);
}
.needle-hub {
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: var(--ink);
    box-shadow: 0 2px 0 rgba(41,41,41,.2);
    z-index: 4;
}
@keyframes needle-sweep {
    0%   { transform: translateX(-50%) rotate(-42deg); }
    20%  { transform: translateX(-50%) rotate(-8deg); }
    28%  { transform: translateX(-50%) rotate(2deg); }
    32%  { transform: translateX(-50%) rotate(0deg); }
    40%  { transform: translateX(-50%) rotate(0deg); }
    55%  { transform: translateX(-50%) rotate(18deg); }
    72%  { transform: translateX(-50%) rotate(38deg); }
    85%  { transform: translateX(-50%) rotate(-12deg); }
    100% { transform: translateX(-50%) rotate(-42deg); }
}
/* 调准瞬间：表盘绿光脉冲 */
.gauge.tuned-flash .gauge-fill {
    animation: tuned-pulse 6s linear infinite;
}
@keyframes tuned-pulse {
    0%, 26%, 34%, 100% { box-shadow: inset 0 0 0 0 transparent; }
    28% { box-shadow: inset 0 0 60px 10px rgba(78,155,85,0.35); }
    32% { box-shadow: inset 0 0 40px 4px rgba(78,155,85,0.2); }
}
/* 信号词 */
.signal-word {
    position: absolute;
    top: 18%;
    left: 50%;
    transform: translateX(-50%);
    font-family: var(--font-hand);
    font-size: 16px;
    color: var(--ink-soft);
    letter-spacing: 2px;
    z-index: 2;
}

/* ============================================================
   首屏布局
   ============================================================ */
.hero {
    padding: 56px 0 48px;
    position: relative;
}
.hero-grid {
    display: grid;
    grid-template-columns: 1.05fr 1fr;
    gap: 48px;
    align-items: center;
}
@media (max-width: 820px) {
    .hero-grid { grid-template-columns: 1fr; gap: 36px; text-align: center; }
    .hero-copy .eyebrow { margin-left: auto; margin-right: auto; }
}
.hero-title {
    font-family: var(--font-hand);
    font-size: clamp(44px, 8vw, 84px);
    font-weight: 700;
    line-height: 1.05;
    margin-bottom: 16px;
    letter-spacing: 2px;
}
.hero-title-accent {
    color: var(--accent);
    position: relative;
}
.hero-title-accent::after {
    content: "";
    position: absolute;
    left: 2%;
    right: -2%;
    bottom: 2px;
    height: 7px;
    border-top: 3px solid currentColor;
    border-radius: 50%;
    opacity: 0.45;
    transform: rotate(-1deg);
}
.hero-sub {
    font-size: clamp(17px, 2.4vw, 22px);
    color: var(--ink-soft);
    margin-bottom: 32px;
}
.hero-cta-row {
    display: flex;
    align-items: center;
    gap: 20px;
    flex-wrap: wrap;
}
@media (max-width: 820px) {
    .hero-cta-row { justify-content: center; }
}
.hero-stats {
    display: flex;
    gap: 36px;
    margin-top: 40px;
    flex-wrap: wrap;
}
@media (max-width: 820px) { .hero-stats { justify-content: center; } }
.stat-num {
    font-family: var(--font-hand);
    font-size: 36px;
    font-weight: 700;
    color: var(--accent);
    line-height: 1;
}
.stat-label { font-size: 13px; color: var(--ink-soft); margin-top: 4px; }

/* ---------- 首页首屏：产品先于宣传 ---------- */
.home-hero {
    padding-top: 72px;
}
.home-hero::before {
    content: "A  440";
    position: absolute;
    top: 24px;
    right: max(24px, calc((100vw - var(--maxw)) / 2));
    font-family: var(--font-hand);
    color: var(--ink-soft);
    opacity: 0.28;
    letter-spacing: 5px;
    transform: rotate(3deg);
}
.home-hero-grid {
    grid-template-columns: 0.92fr 1.08fr;
    gap: 72px;
}
.home-hero .hero-sub {
    max-width: 560px;
    margin-top: 22px;
}
.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    align-items: center;
}
.trust-list {
    display: flex;
    flex-wrap: wrap;
    gap: 12px 20px;
    padding: 0;
    margin: 22px 0 0;
    list-style: none;
    color: var(--ink-soft);
    font-size: 13px;
}
.trust-list span {
    color: var(--success);
    font-weight: 800;
    margin-right: 4px;
}
.demo-panel {
    display: block;
    position: relative;
    overflow: hidden;
    color: var(--ink);
    background:
        radial-gradient(circle at 50% 42%, rgba(228, 138, 25, 0.11), transparent 42%),
        rgba(255, 255, 255, 0.58);
    transform: rotate(0.5deg);
    transition: transform .25s ease, box-shadow .25s ease;
}
.demo-panel:hover {
    transform: rotate(0deg) translate(-2px, -2px);
    box-shadow: 10px 10px 0 rgba(41, 41, 41, 0.14);
}
.demo-topline {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: var(--ink-soft);
}
.live-dot {
    width: 9px;
    height: 9px;
    border-radius: 50%;
    background: var(--success);
    box-shadow: 0 0 0 4px rgba(78, 155, 85, 0.12);
}
.demo-mode {
    margin-left: auto;
    padding: 3px 9px;
    border: 1px solid var(--ink-soft);
    border-radius: 999px;
    font-size: 11px;
}
.demo-note {
    margin-top: 14px;
    text-align: center;
    font-size: clamp(48px, 8vw, 78px);
    font-weight: 700;
    line-height: 1;
}
.demo-hz {
    text-align: center;
    color: var(--ink-soft);
    font-size: 13px;
}
.demo-gauge {
    width: min(360px, 78vw);
    margin-top: 18px;
}
.demo-gauge .signal-word {
    width: 100%;
    text-align: center;
    top: 16%;
    font-size: 13px;
    color: var(--success);
}
.demo-result {
    display: flex;
    justify-content: center;
    align-items: baseline;
    gap: 10px;
    margin-top: 16px;
}
.demo-result strong {
    color: var(--accent);
    font-size: 18px;
}
.demo-result span {
    color: var(--ink-soft);
    font-size: 13px;
}
.demo-link {
    margin-top: 20px;
    padding-top: 16px;
    border-top: 1px dashed rgba(41, 41, 41, 0.28);
    text-align: center;
    font-weight: 700;
}
.proof-strip {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    margin-top: 64px;
    border-top: var(--line) solid var(--ink);
    border-bottom: var(--line) solid var(--ink);
}
.proof-strip div {
    display: flex;
    align-items: baseline;
    justify-content: center;
    gap: 8px;
    padding: 20px 12px;
}
.proof-strip div + div {
    border-left: 1px dashed rgba(41, 41, 41, 0.25);
}
.proof-strip strong {
    font-family: var(--font-hand);
    color: var(--accent);
    font-size: 27px;
}
.proof-strip span {
    color: var(--ink-soft);
    font-size: 12px;
}
.home-faq {
    background: rgba(236, 227, 204, 0.55);
}
@media (max-width: 820px) {
    .home-hero {
        padding-top: 48px;
    }
    .home-hero-grid {
        grid-template-columns: 1fr;
        gap: 44px;
    }
    .home-hero .hero-copy {
        text-align: center;
    }
    .home-hero .hero-sub {
        margin-left: auto;
        margin-right: auto;
    }
    .hero-actions,
    .trust-list {
        justify-content: center;
    }
    .scan-conversion {
        justify-content: center;
        text-align: left;
    }
    .proof-strip {
        grid-template-columns: repeat(2, 1fr);
        margin-top: 48px;
    }
    .proof-strip div:nth-child(3) {
        border-left: 0;
        border-top: 1px dashed rgba(41, 41, 41, 0.25);
    }
    .proof-strip div:nth-child(4) {
        border-top: 1px dashed rgba(41, 41, 41, 0.25);
    }
}
@media (max-width: 480px) {
    .home-hero::before { display: none; }
    .hero-actions {
        display: grid;
        grid-template-columns: 1fr;
    }
    .hero-actions .btn { width: 100%; }
    .demo-panel { padding: 22px 18px; }
    .demo-result { flex-direction: column; align-items: center; gap: 0; }
    .proof-strip strong { font-size: 23px; }
    .scan-conversion {
        align-items: center;
        gap: 14px;
    }
    .qr-box.qr-conversion-code {
        width: 96px;
        height: 96px;
    }
    .scan-copy strong { font-size: 17px; }
    .scan-copy span { font-size: 12px; }
}

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    .needle-wrap,
    .gauge.tuned-flash .gauge-fill,
    .metro-pendulum,
    .beat { animation: none !important; }
}

/* ---------- 卖点列表 ---------- */
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
@media (max-width: 820px) { .feature-grid { grid-template-columns: 1fr; } }
.feature-card { text-align: center; }
.feature-card .ico {
    width: 56px; height: 56px; margin: 0 auto 16px;
    border: var(--line) solid var(--ink);
    border-radius: 50%;
    display: grid; place-items: center;
    font-size: 24px; font-family: var(--font-hand); font-weight: 700;
    background: rgba(228,138,25,0.08); color: var(--accent);
    box-shadow: var(--shadow-sm);
}
.feature-card h3 { font-family: var(--font-hand); font-size: 22px; margin-bottom: 8px; }
.feature-card p { font-size: 14px; color: var(--ink-soft); margin: 0; }

/* ---------- 步骤教程 ---------- */
.steps { display: grid; gap: 20px; }
.step {
    display: flex;
    gap: 20px;
    align-items: flex-start;
}
.step-num {
    flex-shrink: 0;
    width: 44px; height: 44px;
    border: var(--line) solid var(--ink);
    border-radius: 50%;
    display: grid; place-items: center;
    font-family: var(--font-hand); font-size: 20px; font-weight: 700;
    background: var(--ink); color: var(--paper);
    box-shadow: var(--shadow-sm);
}
.step-body h4 { font-size: 18px; margin-bottom: 4px; }
.step-body p { font-size: 14px; color: var(--ink-soft); margin: 0; }

/* ---------- 调式标签 ---------- */
.scheme-tags { display: flex; flex-wrap: wrap; gap: 10px; }
.scheme-tag {
    display: inline-block;
    padding: 8px 16px;
    border: var(--line) solid var(--ink);
    border-radius: 999px;
    font-size: 14px;
    background: rgba(255,255,255,0.5);
    box-shadow: var(--shadow-sm);
}
.scheme-tag .dot { color: var(--accent); margin-right: 4px; }

/* ---------- FAQ ---------- */
.faq-item {
    border: var(--line) solid var(--ink);
    border-radius: var(--radius);
    background: var(--paper-card);
    box-shadow: var(--shadow-sm);
    margin-bottom: 14px;
    overflow: hidden;
}
.faq-q {
    width: 100%;
    text-align: left;
    padding: 18px 22px;
    background: none;
    border: none;
    font: inherit;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--ink);
}
.faq-q::after {
    content: "+";
    font-family: var(--font-hand);
    font-size: 22px;
    color: var(--accent);
    transition: transform .2s;
}
.faq-item[open] .faq-q::after { content: "−"; }
.faq-a {
    padding: 0 22px 18px;
    font-size: 14px;
    color: var(--ink-soft);
    line-height: 1.7;
}

/* ---------- 页脚 ---------- */
.footer {
    border-top: var(--line) solid var(--ink);
    background: var(--paper-shadow);
    padding: 48px 0 96px; /* 底部留白给吸底 CTA */
}
.footer-grid {
    display: grid;
    grid-template-columns: 1.4fr 1fr 1fr;
    gap: 32px;
    margin-bottom: 32px;
}
@media (max-width: 720px) { .footer-grid { grid-template-columns: 1fr; } }
.footer h4 {
    font-family: var(--font-hand);
    font-size: 18px;
    margin-bottom: 12px;
}
.footer ul { list-style: none; padding: 0; margin: 0; }
.footer li { margin-bottom: 8px; }
.footer a { font-size: 14px; color: var(--ink-soft); }
.footer a:hover { color: var(--ink); }
.footer-bottom {
    padding-top: 24px;
    border-top: 1px dashed rgba(41,41,41,0.2);
    font-size: 13px;
    color: var(--ink-soft);
    text-align: center;
}

/* ---------- 乐器专属：古筝 21 弦可视化 ---------- */
.guzheng-board {
    position: relative;
    width: min(380px, 80vw);
    margin: 0 auto;
    padding: 20px 16px 22px;
    border: var(--line-bold) solid var(--ink);
    border-radius: var(--radius-lg);
    background:
        linear-gradient(180deg, rgba(228,138,25,0.04), rgba(228,138,25,0) 30%),
        var(--paper-card);
    box-shadow: var(--shadow-lg);
}
.guzheng-board .board-label {
    text-align: center;
    font-size: 18px;
    color: var(--ink-soft);
    margin-bottom: 12px;
    letter-spacing: 2px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}
.guzheng-board .board-label::before,
.guzheng-board .board-label::after {
    content: "";
    width: 28px;
    height: 1px;
    background: var(--ink-soft);
    opacity: 0.4;
}
.guzheng-board .board-hint {
    text-align: center;
    font-size: 13px;
    color: var(--accent);
    margin-top: 14px;
    letter-spacing: 1px;
}
.strings {
    display: flex;
    flex-direction: column;
    gap: 8px;
    position: relative;
    /* 右侧岳山：一道粗墨梁 */
    padding-right: 8px;
    border-right: 4px solid var(--ink);
    margin-right: 4px;
}
.string-row {
    display: grid;
    grid-template-columns: 28px 1fr 40px;
    align-items: center;
    gap: 10px;
}
.string-row .str-num {
    font-family: var(--font-hand);
    font-size: 13px;
    color: var(--ink-soft);
    text-align: right;
    opacity: 0.7;
}
.string-row .str-line {
    background: linear-gradient(180deg, #3a3a3a, #1a1a1a);
    border-radius: 3px;
    position: relative;
    box-shadow: 0 1px 0 rgba(255,255,255,0.3);
}
.string-row .str-note {
    font-size: 15px;
    font-weight: 700;
    color: var(--ink);
    text-align: left;
    position: relative;
}
/* 音名下的小琴码（菱形暗示） */
.string-row .str-note::before {
    content: "";
    position: absolute;
    left: -8px;
    top: 50%;
    transform: translateY(-50%) rotate(45deg);
    width: 5px;
    height: 5px;
    background: var(--ink-soft);
    opacity: 0.6;
}
/* 弦宽从高音（细）到低音（粗）明显渐变 */
.string-row:nth-child(1) .str-line { height: 2px; }
.string-row:nth-child(2) .str-line { height: 3px; }
.string-row:nth-child(3) .str-line { height: 3px; }
.string-row:nth-child(4) .str-line { height: 4px; }
.string-row:nth-child(5) .str-line { height: 4px; }
.string-row:nth-child(6) .str-line { height: 5px; }
.string-row:nth-child(7) .str-line { height: 5px; }
.string-row:nth-child(8) .str-line { height: 6px; }
.string-row:nth-child(9) .str-line { height: 6px; }
.string-row:nth-child(10) .str-line { height: 7px; }
.string-row:nth-child(11) .str-line { height: 8px; }

.hero-stage { display: flex; align-items: center; justify-content: center; }

/* ============================================================
   通用调音器表盘装置（chromatic 落地页）
   ============================================================ */
.gauge-board {
    position: relative;
    width: min(320px, 80vw);
    margin: 0 auto;
    padding: 22px 18px 22px;
    border: var(--line-bold) solid var(--ink);
    border-radius: var(--radius-lg);
    background:
        radial-gradient(ellipse at 50% 0%, rgba(228,138,25,0.05), transparent 60%),
        var(--paper-card);
    box-shadow: var(--shadow-lg);
}
.gauge-board .board-label {
    text-align: center;
    font-size: 16px;
    color: var(--ink-soft);
    margin-bottom: 16px;
    letter-spacing: 2px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}
.gauge-board .board-label::before,
.gauge-board .board-label::after {
    content: "";
    width: 24px;
    height: 1px;
    background: var(--ink-soft);
    opacity: 0.4;
}
.gauge-board .board-hint {
    text-align: center;
    font-size: 13px;
    color: var(--accent);
    margin-top: 14px;
    letter-spacing: 1px;
}
.gauge-mini { margin: 0 auto; }

/* ============================================================
   拇指琴键位装置
   ============================================================ */
.kalimba-board {
    position: relative;
    width: min(340px, 82vw);
    margin: 0 auto;
    padding: 22px 14px 22px;
    border: var(--line-bold) solid var(--ink);
    border-radius: var(--radius-lg);
    background:
        radial-gradient(ellipse at 50% 100%, rgba(228,138,25,0.06), transparent 60%),
        var(--paper-card);
    box-shadow: var(--shadow-lg);
}
.kalimba-board .board-label {
    text-align: center;
    font-size: 17px;
    color: var(--ink-soft);
    margin-bottom: 14px;
    letter-spacing: 2px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}
.kalimba-board .board-label::before,
.kalimba-board .board-label::after {
    content: "";
    width: 24px;
    height: 1px;
    background: var(--ink-soft);
    opacity: 0.4;
}
.kalimba-board .board-hint {
    text-align: center;
    font-size: 13px;
    color: var(--accent);
    margin-top: 14px;
    letter-spacing: 1px;
}
/* 键位容器：横向排列，底部对齐（中间键最高） */
.kalimba-keys {
    display: flex;
    align-items: flex-end;
    justify-content: center;
    gap: 3px;
    height: 150px;
}
.kalimba-key {
    /* 键宽固定，高度由 nth-child 动态控制（模拟扇形） */
    width: 15px;
    background: linear-gradient(180deg, #3a3a3a, #1a1a1a);
    border-radius: 3px 3px 0 0;
    border: 1.5px solid var(--ink);
    box-shadow: inset 0 2px 0 rgba(255,255,255,0.25);
    position: relative;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding-top: 3px;
}
.kalimba-key .key-note {
    font-size: 9px;
    color: var(--paper);
    font-weight: 700;
    writing-mode: vertical-rl;
    line-height: 1;
    letter-spacing: 0;
}
/* 中央根音键（C4）：橙色高亮，最长 */
.kalimba-key.key-root {
    background: linear-gradient(180deg, var(--accent), #b87015);
    box-shadow: inset 0 2px 0 rgba(255,255,255,0.3), 0 0 0 2px rgba(228,138,25,0.2);
}
.kalimba-key.key-root .key-note { color: #fff; }

/* 17 键扇形高度：中间最高，向两侧递减
   索引 0-16，中央 = 8（根音 C4） */
.kalimba-keys .kalimba-key:nth-child(1)  { height: 62px; }
.kalimba-keys .kalimba-key:nth-child(2)  { height: 74px; }
.kalimba-keys .kalimba-key:nth-child(3)  { height: 86px; }
.kalimba-keys .kalimba-key:nth-child(4)  { height: 98px; }
.kalimba-keys .kalimba-key:nth-child(5)  { height: 110px; }
.kalimba-keys .kalimba-key:nth-child(6)  { height: 122px; }
.kalimba-keys .kalimba-key:nth-child(7)  { height: 134px; }
.kalimba-keys .kalimba-key:nth-child(8)  { height: 142px; }
.kalimba-keys .kalimba-key:nth-child(9)  { height: 148px; }
.kalimba-keys .kalimba-key:nth-child(10) { height: 142px; }
.kalimba-keys .kalimba-key:nth-child(11) { height: 134px; }
.kalimba-keys .kalimba-key:nth-child(12) { height: 122px; }
.kalimba-keys .kalimba-key:nth-child(13) { height: 110px; }
.kalimba-keys .kalimba-key:nth-child(14) { height: 98px; }
.kalimba-keys .kalimba-key:nth-child(15) { height: 86px; }
.kalimba-keys .kalimba-key:nth-child(16) { height: 74px; }
.kalimba-keys .kalimba-key:nth-child(17) { height: 62px; }

/* ============================================================
   首屏双工具并立
   ============================================================ */
.duo-tools {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}
@media (max-width: 820px) {
    .duo-tools { grid-template-columns: 1fr; }
}
.tool-card {
    display: flex;
    flex-direction: column;
    padding: 28px 28px 24px;
    text-align: center;
    position: relative;
}
.tool-card-head { margin-bottom: 8px; }
.tool-tag {
    display: inline-block;
    padding: 3px 12px;
    border: var(--line) solid var(--ink);
    border-radius: 999px;
    font-size: 11px;
    letter-spacing: 2px;
    color: var(--ink-soft);
    background: rgba(255,255,255,0.5);
    margin-bottom: 12px;
}
.tool-tag-accent {
    color: var(--accent);
    border-color: var(--accent);
    background: rgba(228,138,25,0.08);
}
.tool-name {
    font-size: clamp(28px, 4vw, 36px);
    margin-bottom: 6px;
}
.tool-desc {
    font-size: 14px;
    color: var(--ink-soft);
    margin: 0;
}
.tool-stage {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 16px 0;
    min-height: 200px;
}
.tool-cta {
    display: inline-block;
    margin-top: auto;
    padding: 10px 24px;
    border: var(--line) solid var(--ink);
    border-radius: 999px;
    font-size: 16px;
    background: var(--ink);
    color: var(--paper);
    box-shadow: var(--shadow-sm);
    align-self: center;
}
.tool-card:hover .tool-cta { box-shadow: var(--shadow); }

/* 调音表盘缩小版 */
.tuner-stage.mini {
    width: min(280px, 70vw);
    aspect-ratio: 2 / 1.1;
}
.tuner-stage.mini .gauge { border-width: var(--line); box-shadow: var(--shadow); }
.tuner-stage.mini .needle-wrap { height: 72%; }
.tuner-stage.mini .signal-word { font-size: 12px; top: 14%; }

/* ============================================================
   节拍器摆锤装置（机械节拍器造型）
   ============================================================ */
.metro-stage {
    position: relative;
    width: min(200px, 60vw);
    height: 240px;
    margin: 0 auto;
}
/* 节拍器外壳（梯形木质机身，摆杆从中伸出） */
.metro-base {
    position: absolute;
    bottom: 28px;
    left: 50%;
    transform: translateX(-50%);
    width: 130px;
    height: 150px;
    background:
        /* 正面 BPM 刻度槽（中央竖向刻度线） */
        linear-gradient(90deg, transparent 46%, rgba(41,41,41,0.18) 46%, rgba(41,41,41,0.18) 47%, transparent 47%, transparent 53%, rgba(41,41,41,0.18) 53%, rgba(41,41,41,0.18) 54%, transparent 54%),
        /* 刻度横线 */
        repeating-linear-gradient(0deg, transparent 0 14px, rgba(41,41,41,0.12) 14px 15px),
        var(--paper-card);
    border: var(--line-bold) solid var(--ink);
    /* 梯形：顶窄底宽，模拟金字塔形节拍器外壳 */
    clip-path: polygon(30% 0, 70% 0, 100% 100%, 0 100%);
    border-radius: 4px 4px 0 0;
    box-shadow: var(--shadow);
    z-index: 1;
}
/* 外壳顶部的小开口（摆杆穿出处） */
.metro-base::before {
    content: "";
    position: absolute;
    top: -2px;
    left: 50%;
    transform: translateX(-50%);
    width: 24px;
    height: 6px;
    background: var(--ink);
    border-radius: 0 0 4px 4px;
    z-index: 2;
}
/* 摆杆：轴心固定在机身下部，杆尖始终收在机身轮廓内 */
.metro-pendulum {
    position: absolute;
    top: 62px;
    left: 50%;
    width: 8px;
    height: 128px;
    transform-origin: bottom center;
    transform: translateX(-50%);
    animation: metro-swing .5s cubic-bezier(.42,0,.58,1) infinite alternate;
    z-index: 3;
}
@keyframes metro-swing {
    0%   { transform: translateX(-50%) rotate(-14deg); }
    100% { transform: translateX(-50%) rotate(14deg); }
}
.pendulum-arm {
    position: absolute;
    inset: 0;
    width: 3px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--ink);
    border-radius: 2px;
}
.pendulum-weight {
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 20px;
    background: var(--accent);
    border: 2px solid var(--ink);
    border-radius: 50%;
    box-shadow: var(--shadow-sm);
}
/* 拍点指示（4 拍，第 1 拍强拍高亮） */
.metro-beats {
    position: absolute;
    bottom: 6px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 7px;
    z-index: 4;
}
.beat {
    --beat-rgb: 41, 41, 41;
    width: 9px;
    height: 9px;
    border-radius: 50%;
    border: 2px solid var(--ink);
    background: rgba(255,255,255,0.7);
}
.beat-accent { --beat-rgb: 228, 138, 25; }
/* 四个拍点以 120 BPM 依次闪烁；每四拍回到强拍 */
.beat-pulse-1,
.beat-pulse-2,
.beat-pulse-3,
.beat-pulse-4 {
    animation: beat-flash 2s ease-out infinite;
}
.beat-pulse-1 { animation-delay: 0s; }
.beat-pulse-2 { animation-delay: .5s; }
.beat-pulse-3 { animation-delay: 1s; }
.beat-pulse-4 { animation-delay: 1.5s; }
@keyframes beat-flash {
    0% {
        background: rgb(var(--beat-rgb));
        box-shadow: 0 0 0 5px rgba(var(--beat-rgb), .25);
        transform: scale(1.35);
    }
    10%, 100% {
        background: rgba(255,255,255,.7);
        box-shadow: 0 0 0 0 rgba(var(--beat-rgb), 0);
        transform: scale(1);
    }
}
.metro-bpm {
    position: absolute;
    bottom: -32px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 20px;
    font-weight: 700;
    white-space: nowrap;
}

/* 节拍器落地页：大版摆锤装置 */
.metro-stage-lg {
    width: min(280px, 75vw);
    height: 360px;
}
.metro-stage-lg .metro-base { width: 180px; height: 220px; }
.metro-stage-lg .metro-pendulum { height: 194px; top: 112px; }
.metro-stage-lg .pendulum-weight { bottom: -11px; width: 28px; height: 28px; }
.metro-stage-lg .metro-beats-lg { bottom: 10px; gap: 11px; }
.metro-stage-lg .metro-beats-lg .beat { width: 13px; height: 13px; }
.metro-stage-lg .metro-bpm { bottom: -42px; font-size: 26px; }

/* ---------- 可访问性 ---------- */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.001ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.001ms !important;
        scroll-behavior: auto !important;
    }
}