/* ==========================================================
 * 多功能节拍器 /tools/metronome
 *
 * 设计系统（三端优化版）
 *   · 配色：语义化 token 分层（背景 / 表面 / 边框 / 文字 / 主色 / 状态色），
 *     深色为默认舞台配色，浅色主题下整组覆盖，保证两种主题都满足 WCAG AA 对比度
 *   · 排版：8px 基准栅格，桌面双栏（主控区 + 面板侧栏）、平板单列宽卡、手机纵向单手操作
 *   · 交互：触区 ≥40px、焦点可见、hover/active 有反馈、尊重 prefers-reduced-motion
 * ========================================================== */

.mt-page {
    /* ---- 主色 ---- */
    --mt-primary: #14b8a6;
    --mt-primary-hover: #0d9488;
    --mt-primary-soft: rgba(20, 184, 166, .14);
    --mt-primary-ring: rgba(20, 184, 166, .35);
    --mt-on-primary: #ffffff;

    /* ---- 中性（深色）---- */
    --mt-surface-0: rgba(2, 6, 23, .55);
    --mt-surface-1: rgba(17, 24, 39, .72);
    --mt-surface-2: rgba(30, 41, 59, .55);
    --mt-surface-3: rgba(51, 65, 85, .48);
    --mt-border: rgba(148, 163, 184, .18);
    --mt-border-strong: rgba(148, 163, 184, .34);
    --mt-text: #e8eef7;
    --mt-text-2: #a9b7cc;
    --mt-text-3: #7f8ea6;

    /* ---- 状态 ---- */
    --mt-ok: #22c55e;
    --mt-warn: #f59e0b;
    --mt-bad: #ef4444;

    /* ---- 形状 / 尺度 ---- */
    --mt-r-xl: 20px;
    --mt-r-lg: 16px;
    --mt-r-md: 12px;
    --mt-r-sm: 10px;
    --mt-gap: 16px;

    position: relative;
    width: 100%;
    max-width: 1180px;
    margin: 0 auto;
    padding: 16px 16px 40px;
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    gap: var(--mt-gap);
    align-items: start;
    color: var(--mt-text);
    font-size: 15px;
    line-height: 1.5;
}

/* 浅色主题：整组覆盖，保持同一套语义 */
[data-theme="light"] .mt-page {
    --mt-primary: #0d9488;
    --mt-primary-hover: #0f766e;
    --mt-primary-soft: rgba(13, 148, 136, .12);
    --mt-primary-ring: rgba(13, 148, 136, .32);
    --mt-surface-0: #ffffff;
    --mt-surface-1: #ffffff;
    --mt-surface-2: #f4f6fa;
    --mt-surface-3: #e9eef6;
    --mt-border: rgba(15, 23, 42, .10);
    --mt-border-strong: rgba(15, 23, 42, .22);
    --mt-text: #0f172a;
    --mt-text-2: #475569;
    --mt-text-3: #64748b;
}

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

.mt-page h1, .mt-page h2, .mt-page h3, .mt-page h4, .mt-page h5 { margin: 0; font-weight: 800; }
.mt-page button { font-family: inherit; color: inherit; border: 0; background: none; cursor: pointer; }
.mt-page select, .mt-page input { font-family: inherit; }
.mt-page [hidden] { display: none !important; }
.mt-page .mt-mono { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-variant-numeric: tabular-nums; }
.mt-page .mt-hint { color: var(--mt-text-3); font-size: 11.5px; line-height: 1.5; }
.mt-page .mt-row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.mt-page .mt-grow { flex: 1; min-width: 0; }
.mt-page :focus-visible {
    outline: 2px solid var(--mt-primary);
    outline-offset: 2px;
    border-radius: var(--mt-r-sm);
}

/* 主控区 / 侧栏容器 */
.mt-main { display: flex; flex-direction: column; gap: var(--mt-gap); min-width: 0; }
.mt-side { display: flex; flex-direction: column; gap: var(--mt-gap); min-width: 0; }

/* ---------- 全屏闪烁 ---------- */
.mt-flash {
    position: fixed;
    inset: 0;
    z-index: 0;
    pointer-events: none;
    background: var(--mt-primary, #14b8a6);
    opacity: 0;
    mix-blend-mode: screen;
    transition: opacity 90ms ease-out;
}
.mt-flash.is-on { opacity: .14; transition-duration: 0s; }

/* ---------- 顶栏 ---------- */
.mt-topbar {
    grid-column: 1 / -1;
    z-index: 6;
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 12px;
    margin: 0 -4px;
    border-radius: var(--mt-r-lg);
    background: var(--mt-surface-1);
    border: 1px solid var(--mt-border);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}
.mt-brand { flex: 1; min-width: 0; }
.mt-brand__name {
    display: block;
    font-size: clamp(15px, 2.2vw, 19px);
    font-weight: 900;
    letter-spacing: -.01em;
    color: var(--mt-text);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
.mt-brand__badge {
    display: inline-block;
    margin-top: 2px;
    padding: 1px 7px;
    border-radius: 999px;
    background: var(--mt-primary-soft);
    color: var(--mt-primary);
    font-family: ui-monospace, Menlo, Consolas, monospace;
    font-size: 9px;
    font-weight: 700;
    letter-spacing: .14em;
}
.mt-topbar__actions { display: flex; gap: 8px; flex-shrink: 0; }

.mt-icon-btn {
    display: grid;
    place-items: center;
    width: 42px;
    height: 42px;
    border-radius: var(--mt-r-md);
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    color: var(--mt-text-2);
    transition: background .15s, color .15s, border-color .15s, transform .12s;
}
.mt-icon-btn:hover { color: var(--mt-primary); border-color: var(--mt-primary); transform: translateY(-1px); }
.mt-icon-btn.is-active {
    background: var(--mt-primary);
    border-color: var(--mt-primary);
    color: var(--mt-on-primary);
    box-shadow: 0 6px 18px -8px var(--mt-primary);
}
.mt-icon-btn svg { width: 19px; height: 19px; }

.mt-btn--tap {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 3px;
    min-width: 66px;
    height: 42px;
    padding: 0 12px;
    border-radius: var(--mt-r-md);
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    color: var(--mt-text-2);
    font-size: 11px;
    font-weight: 800;
    letter-spacing: .16em;
    transition: .12s;
}
.mt-btn--tap:hover { color: var(--mt-primary); border-color: var(--mt-primary); }
.mt-btn--tap:active, .mt-btn--tap.is-hit {
    border-color: var(--mt-primary);
    color: var(--mt-primary);
    background: var(--mt-primary-soft);
    transform: scale(.96);
}
.mt-tap-dots { display: flex; gap: 3px; }
.mt-tap-dots i { width: 4px; height: 4px; border-radius: 50%; background: var(--mt-border-strong); }
.mt-tap-dots i.on { background: var(--mt-primary); }

/* ---------- 通用控件 ---------- */
.mt-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 7px;
    min-height: 38px;
    padding: 9px 16px;
    border-radius: var(--mt-r-sm);
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    color: var(--mt-text);
    font-size: 12.5px;
    font-weight: 700;
    transition: background .15s, border-color .15s, color .15s, transform .12s;
}
.mt-btn:hover { border-color: var(--mt-primary); color: var(--mt-primary); }
.mt-btn:active { transform: scale(.97); }
.mt-btn:disabled { opacity: .38; cursor: not-allowed; transform: none; }
.mt-btn svg { width: 15px; height: 15px; }
.mt-btn > span[data-icon] { display: flex; }
.mt-btn--primary {
    background: var(--mt-primary);
    border-color: var(--mt-primary);
    color: var(--mt-on-primary);
    box-shadow: 0 8px 22px -12px var(--mt-primary);
}
.mt-btn--primary:hover { background: var(--mt-primary-hover); border-color: var(--mt-primary-hover); color: var(--mt-on-primary); }
.mt-btn--danger { color: #fca5a5; }
.mt-btn--danger:hover { background: rgba(239, 68, 68, .12); border-color: var(--mt-bad); color: #fca5a5; }
.mt-btn--sm { min-height: 32px; padding: 6px 12px; font-size: 11.5px; }
.mt-btn--sm svg { width: 13px; height: 13px; }
.mt-btn--dashed { border-style: dashed; border-color: var(--mt-border-strong); color: var(--mt-text-2); }

.mt-card {
    background: var(--mt-surface-1);
    border: 1px solid var(--mt-border);
    border-radius: var(--mt-r-lg);
    padding: 16px;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}
.mt-card__label {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 12px;
    font-size: 10px;
    font-weight: 800;
    letter-spacing: .1em;
    text-transform: uppercase;
    color: var(--mt-text-2);
}
.mt-card__label::before {
    content: "";
    width: 3px;
    height: 12px;
    border-radius: 2px;
    background: var(--mt-primary);
}
.mt-grid2 { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: var(--mt-gap); }

/* 分段按钮 */
.mt-seg { display: flex; flex-wrap: wrap; gap: 6px; }
.mt-seg__btn {
    flex: 1 1 auto;
    min-width: 52px;
    min-height: 40px;
    padding: 8px 8px;
    border-radius: var(--mt-r-sm);
    background: var(--mt-surface-2);
    border: 1px solid transparent;
    color: var(--mt-text-2);
    font-size: 13px;
    font-weight: 800;
    transition: background .13s, color .13s, border-color .13s;
}
.mt-seg__btn:hover { background: var(--mt-surface-3); color: var(--mt-text); }
.mt-seg__btn.is-active {
    background: var(--mt-primary);
    border-color: var(--mt-primary);
    color: var(--mt-on-primary);
    box-shadow: 0 6px 18px -10px var(--mt-primary);
}
.mt-seg__btn small { display: block; font-size: 9px; font-weight: 600; opacity: .8; }

/* 滑块 */
.mt-page input[type=range] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 24px;
    background: transparent;
    cursor: pointer;
}
.mt-page input[type=range]::-webkit-slider-runnable-track {
    height: 6px;
    border-radius: 999px;
    background: var(--mt-surface-3);
    border: 1px solid var(--mt-border);
}
.mt-page input[type=range]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    margin-top: -8px;
    border-radius: 50%;
    border: 2px solid var(--mt-surface-0);
    background: var(--mt-primary);
    box-shadow: 0 0 0 3px var(--mt-primary-ring), 0 2px 8px -2px rgba(0, 0, 0, .5);
}
.mt-page input[type=range]::-moz-range-track {
    height: 6px;
    border-radius: 999px;
    background: var(--mt-surface-3);
    border: 1px solid var(--mt-border);
}
.mt-page input[type=range]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    border: 2px solid var(--mt-surface-0);
    background: var(--mt-primary);
    box-shadow: 0 0 0 3px var(--mt-primary-ring);
}
.mt-page input[type=range].mt-tall { height: 34px; }
.mt-page input[type=range].mt-tall::-webkit-slider-runnable-track { height: 8px; }
.mt-page input[type=range].mt-tall::-webkit-slider-thumb { width: 24px; height: 24px; margin-top: -9px; }

/* 输入 / 下拉 */
.mt-page input[type=number], .mt-page input[type=text], .mt-page select {
    width: 100%;
    min-height: 38px;
    padding: 8px 10px;
    border-radius: var(--mt-r-sm);
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    color: var(--mt-text);
    font-size: 13px;
    font-weight: 700;
    outline: none;
    transition: border-color .15s, box-shadow .15s;
}
.mt-page input:focus, .mt-page select:focus {
    border-color: var(--mt-primary);
    box-shadow: 0 0 0 3px var(--mt-primary-ring);
}
.mt-page select {
    appearance: none;
    -webkit-appearance: none;
    padding-right: 28px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%237f8ea6' stroke-width='2.5'%3E%3Cpath d='m6 9 6 6 6-6'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 9px center;
    background-size: 14px;
}

/* 开关 */
.mt-switch { display: inline-flex; align-items: center; gap: 8px; cursor: pointer; min-height: 32px; }
.mt-switch input { position: absolute; opacity: 0; width: 0; height: 0; }
.mt-switch__track {
    position: relative;
    width: 40px;
    height: 22px;
    border-radius: 999px;
    background: var(--mt-surface-3);
    border: 1px solid var(--mt-border-strong);
    transition: background .2s, border-color .2s;
    flex-shrink: 0;
}
.mt-switch__track::after {
    content: "";
    position: absolute;
    top: 2px;
    left: 2px;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--mt-text-3);
    transition: transform .2s, background .2s;
}
.mt-switch input:checked + .mt-switch__track { background: var(--mt-primary); border-color: var(--mt-primary); }
.mt-switch input:checked + .mt-switch__track::after { transform: translateX(18px); background: #fff; }
.mt-switch__text { font-size: 12px; font-weight: 700; color: var(--mt-text-2); }
.mt-switch input:checked ~ .mt-switch__text { color: var(--mt-text); }

.mt-field { margin-bottom: 14px; }
.mt-field:last-child { margin-bottom: 0; }
.mt-field__head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    margin-bottom: 6px;
    font-size: 11.5px;
    font-weight: 700;
    color: var(--mt-text-2);
}
.mt-field__val { font-family: ui-monospace, Menlo, Consolas, monospace; font-weight: 800; color: var(--mt-primary); }
.mt-disabled { opacity: .4; pointer-events: none; }

/* ---------- 节拍可视化 ---------- */
.mt-stage {
    background: var(--mt-surface-0);
    border: 1px solid var(--mt-border);
    border-radius: var(--mt-r-xl);
    padding: 18px 16px 14px;
}
.mt-beats {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    gap: 14px;
    min-height: 88px;
}
.mt-beat {
    position: relative;
    display: grid;
    place-items: center;
    border-radius: 50%;
    font-family: ui-monospace, Menlo, Consolas, monospace;
    font-weight: 800;
    cursor: pointer;
    transition: transform .09s ease-out, background .09s, box-shadow .09s, border-color .09s, color .09s;
}
.mt-beat--strong {
    width: 60px; height: 60px; font-size: 16px;
    border: 2px solid var(--mt-primary);
    color: var(--mt-primary);
    background: var(--mt-primary-soft);
}
.mt-beat--medium {
    width: 50px; height: 50px; font-size: 14px;
    border: 2px solid var(--mt-border-strong);
    color: var(--mt-text-2);
    background: var(--mt-surface-2);
}
.mt-beat--weak {
    width: 42px; height: 42px; font-size: 13px;
    border: 1px solid var(--mt-border);
    color: var(--mt-text-3);
    background: var(--mt-surface-2);
}
.mt-beat--mute {
    width: 42px; height: 42px; font-size: 13px;
    border: 1px dashed rgba(239, 68, 68, .45);
    color: #b96868;
    background: transparent;
    opacity: .65;
}
[data-theme="light"] .mt-beat--mute { color: #b91c1c; }
.mt-beat--strong.is-active {
    background: var(--mt-primary);
    border-color: var(--mt-on-primary);
    color: var(--mt-on-primary);
    box-shadow: 0 0 0 6px var(--mt-primary-soft), 0 0 30px -2px var(--mt-primary);
    transform: scale(1.12);
}
.mt-beat--medium.is-active {
    background: var(--mt-primary);
    border-color: var(--mt-on-primary);
    color: var(--mt-on-primary);
    box-shadow: 0 0 0 5px var(--mt-primary-soft);
    transform: scale(1.1);
}
.mt-beat--weak.is-active {
    background: var(--mt-text-2);
    border-color: var(--mt-text);
    color: var(--mt-surface-0);
    transform: scale(1.1);
}
.mt-beat--mute.is-active { border-color: var(--mt-bad); color: var(--mt-bad); opacity: 1; }
.mt-beat__subdots { position: absolute; bottom: -11px; display: flex; gap: 4px; }
.mt-beat__subdots i { width: 4px; height: 4px; border-radius: 50%; background: var(--mt-border-strong); transition: background .08s; }
.mt-beat__subdots i.on { background: var(--mt-primary); }

.mt-stage__meta {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-top: 20px;
    padding-top: 12px;
    border-top: 1px solid var(--mt-border);
    font-size: 11.5px;
    color: var(--mt-text-3);
    flex-wrap: wrap;
}
.mt-stat {
    display: inline-flex;
    align-items: baseline;
    gap: 5px;
    padding: 4px 10px;
    border-radius: 999px;
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
}
.mt-stat b { font-family: ui-monospace, Menlo, Consolas, monospace; font-size: 13px; font-weight: 800; color: var(--mt-text); }
.mt-badge {
    padding: 3px 9px;
    border-radius: 999px;
    font-size: 10px;
    font-weight: 800;
    border: 1px solid;
}
.mt-badge--mute { color: var(--mt-bad); border-color: rgba(239, 68, 68, .5); background: rgba(239, 68, 68, .1); }
.mt-badge--count { color: var(--mt-warn); border-color: rgba(245, 158, 11, .5); background: rgba(245, 158, 11, .1); }
.mt-badge--ramp { color: var(--mt-primary); border-color: var(--mt-primary-ring); background: var(--mt-primary-soft); }

/* ---------- 走带 ---------- */
.mt-transport {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    align-items: center;
    gap: 26px;
    background: var(--mt-surface-1);
    border: 1px solid var(--mt-border);
    border-radius: var(--mt-r-xl);
    padding: 20px 22px;
    box-shadow: 0 24px 60px -40px rgba(0, 0, 0, .8);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
}
[data-theme="light"] .mt-transport { box-shadow: 0 18px 40px -34px rgba(15, 23, 42, .45); }

.mt-play-btn {
    display: grid;
    place-items: center;
    width: 116px;
    height: 116px;
    border-radius: 50%;
    background: linear-gradient(145deg, var(--mt-primary), var(--mt-primary-hover));
    color: var(--mt-on-primary);
    box-shadow: 0 16px 40px -16px var(--mt-primary), inset 0 0 0 4px rgba(255, 255, 255, .14);
    transition: transform .12s, box-shadow .2s, filter .15s;
}
.mt-play-btn:hover { transform: scale(1.04); filter: brightness(1.05); }
.mt-play-btn:active { transform: scale(.95); }
.mt-play-btn svg { width: 46px; height: 46px; }
.mt-play-btn.is-playing { box-shadow: 0 16px 44px -12px var(--mt-primary), inset 0 0 0 4px rgba(255, 255, 255, .2); }

.mt-tempo { min-width: 0; }
.mt-tempo__top { display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap; }
.mt-tempo__bpm {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: clamp(54px, 8.5vw, 84px);
    font-weight: 800;
    letter-spacing: -.055em;
    line-height: .95;
    font-variant-numeric: tabular-nums;
    color: var(--mt-text);
}
.mt-tempo__unit { font-size: 14px; font-weight: 800; letter-spacing: .12em; color: var(--mt-primary); }
.mt-tempo__term {
    margin-left: auto;
    padding: 5px 12px;
    border-radius: 999px;
    background: var(--mt-primary-soft);
    border: 1px solid var(--mt-primary-ring);
    text-align: right;
    line-height: 1.25;
}
.mt-tempo__term b { display: block; font-size: 13px; color: var(--mt-primary); }
.mt-tempo__term span { font-size: 10.5px; color: var(--mt-text-3); }
.mt-tempo__scale {
    display: flex;
    justify-content: space-between;
    font-family: ui-monospace, Menlo, Consolas, monospace;
    font-size: 9.5px;
    font-weight: 700;
    color: var(--mt-text-3);
    margin-top: 2px;
}
.mt-fine { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 6px; margin-top: 10px; }
.mt-fine__btn {
    min-height: 40px;
    padding: 8px 0;
    border-radius: var(--mt-r-sm);
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    color: var(--mt-text-2);
    font-family: ui-monospace, Menlo, Consolas, monospace;
    font-size: 12.5px;
    font-weight: 800;
    transition: color .12s, border-color .12s, background .12s, transform .1s;
}
.mt-fine__btn:hover { color: var(--mt-primary); border-color: var(--mt-primary); background: var(--mt-primary-soft); }
.mt-fine__btn:active { transform: scale(.95); }

.mt-stepper { display: flex; align-items: center; gap: 8px; }
.mt-stepper__btn {
    width: 38px;
    height: 38px;
    display: grid;
    place-items: center;
    border-radius: var(--mt-r-sm);
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    color: var(--mt-text-2);
    font-size: 17px;
    font-weight: 800;
    line-height: 1;
    transition: .15s;
}
.mt-stepper__btn:hover { color: var(--mt-primary); border-color: var(--mt-primary); }
.mt-stepper__btn:active { transform: scale(.94); }
.mt-stepper__val { flex: 1; text-align: center; font-family: ui-monospace, Menlo, Consolas, monospace; font-size: 19px; font-weight: 800; }

/* ---------- 面板 ---------- */
.mt-panel {
    background: var(--mt-surface-1);
    border: 1px solid var(--mt-border);
    border-radius: var(--mt-r-xl);
    padding: 18px;
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    animation: mt-slide-in .18s ease-out;
}
@keyframes mt-slide-in { from { opacity: 0; transform: translateY(-8px); } to { opacity: 1; transform: none; } }
.mt-panel__head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--mt-border);
}
.mt-panel__head h2 { font-size: 14.5px; display: flex; align-items: center; gap: 8px; color: var(--mt-text); }
.mt-panel__head h2 svg { width: 16px; height: 16px; color: var(--mt-primary); }
.mt-section { margin-bottom: 18px; }
.mt-section:last-child { margin-bottom: 0; }
.mt-section__title {
    display: flex;
    align-items: center;
    gap: 7px;
    margin-bottom: 10px;
    font-size: 10.5px;
    font-weight: 800;
    letter-spacing: .09em;
    text-transform: uppercase;
    color: var(--mt-text-3);
}
.mt-section__title svg { width: 13px; height: 13px; }
.mt-box {
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    border-radius: var(--mt-r-lg);
    padding: 14px;
}

/* 主题色 */
.mt-swatches { display: flex; gap: 10px; flex-wrap: wrap; }
.mt-swatch {
    width: 38px;
    height: 38px;
    border-radius: 50%;
    border: 3px solid transparent;
    display: grid;
    place-items: center;
    transition: transform .15s, border-color .15s;
}
.mt-swatch:hover { transform: scale(1.12); }
.mt-swatch.is-active { border-color: var(--mt-text); box-shadow: 0 4px 14px -4px currentColor; }
.mt-swatch svg { width: 16px; height: 16px; color: #fff; opacity: 0; }
.mt-swatch.is-active svg { opacity: 1; }

/* ---------- 音色引擎 ---------- */
.mt-tabs { display: flex; border-bottom: 1px solid var(--mt-border); }
.mt-tab {
    flex: 1;
    min-height: 44px;
    padding: 10px 4px;
    font-size: 12.5px;
    font-weight: 800;
    color: var(--mt-text-3);
    border-bottom: 2px solid transparent;
    transition: color .15s, border-color .15s;
}
.mt-tab:hover { color: var(--mt-text-2); }
.mt-tab.is-active { color: var(--mt-primary); border-bottom-color: var(--mt-primary); }

.mt-layer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    padding: 10px 12px;
    margin-bottom: 7px;
    border-radius: var(--mt-r-md);
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    transition: border-color .15s;
}
.mt-layer:hover { border-color: var(--mt-border-strong); }
.mt-layer__idx {
    width: 22px;
    height: 22px;
    flex-shrink: 0;
    display: grid;
    place-items: center;
    border-radius: 50%;
    background: var(--mt-surface-3);
    font-family: ui-monospace, Menlo, Consolas, monospace;
    font-size: 10px;
    font-weight: 800;
    color: var(--mt-text-2);
}
.mt-layer__name { display: flex; align-items: center; gap: 6px; font-size: 12.5px; font-weight: 700; color: var(--mt-text); }
.mt-layer__name svg { width: 13px; height: 13px; }
.mt-layer__meta { margin-top: 2px; font-size: 10.5px; color: var(--mt-text-3); display: flex; gap: 8px; align-items: center; }
.mt-layer__acts { display: flex; gap: 2px; flex-shrink: 0; }
.mt-layer__acts button {
    width: 32px;
    height: 32px;
    display: grid;
    place-items: center;
    border-radius: 8px;
    color: var(--mt-text-3);
    transition: background .15s, color .15s;
}
.mt-layer__acts button:hover { background: var(--mt-surface-3); color: var(--mt-text); }
.mt-layer__acts button.mt-del:hover { color: var(--mt-bad); }
.mt-layer__acts svg { width: 15px; height: 15px; }
.mt-empty { padding: 26px 0; text-align: center; color: var(--mt-text-3); font-size: 12.5px; display: grid; gap: 8px; justify-items: center; }
.mt-empty svg { width: 26px; height: 26px; opacity: .35; }

.mt-wave-box {
    position: relative;
    height: 150px;
    border-radius: var(--mt-r-md);
    overflow: hidden;
    background: var(--mt-surface-0);
    border: 1px solid var(--mt-border);
}
.mt-wave-box canvas { display: block; width: 100%; height: 100%; }
.mt-wave-box__overlay { position: absolute; inset: 0; display: grid; place-items: center; font-size: 12px; color: var(--mt-text-3); }
.mt-rec-dot { color: var(--mt-bad); font-weight: 800; }

/* ---------- 曲目库 ---------- */
.mt-song {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 11px 13px;
    margin-bottom: 7px;
    border-radius: var(--mt-r-md);
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    transition: border-color .15s, background .15s;
}
.mt-song:hover { border-color: var(--mt-primary); background: var(--mt-primary-soft); }
.mt-song__info { flex: 1; min-width: 0; }
.mt-song__name { font-size: 13px; font-weight: 800; color: var(--mt-text); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.mt-song__tags { margin-top: 2px; font-size: 10.5px; color: var(--mt-text-3); font-family: ui-monospace, Menlo, Consolas, monospace; }
.mt-song__bpm { font-family: ui-monospace, Menlo, Consolas, monospace; font-size: 20px; font-weight: 800; color: var(--mt-primary); }

/* ---------- 调音器 ---------- */
.mt-tuner-display { display: flex; align-items: center; justify-content: center; gap: 18px; padding: 8px 0 4px; }
.mt-tuner-note {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 70px;
    font-weight: 800;
    line-height: 1;
    letter-spacing: -.04em;
    min-width: 124px;
    text-align: center;
    color: var(--mt-text);
    transition: color .2s;
}
.mt-tuner-note sub { font-size: 24px; color: var(--mt-text-3); vertical-align: baseline; }
.mt-tuner-note.is-ok { color: var(--mt-ok); }
.mt-tuner-readout .big { font-family: ui-monospace, Menlo, Consolas, monospace; font-size: 20px; font-weight: 800; color: var(--mt-text); }
.mt-tuner-readout .sub { font-size: 11px; color: var(--mt-text-3); }

.mt-meter { position: relative; height: 64px; margin: 8px 0 4px; }
.mt-meter__scale { position: absolute; inset: auto 0 16px; height: 22px; display: flex; justify-content: space-between; align-items: flex-end; }
.mt-meter__scale i { width: 1px; height: 8px; background: var(--mt-border-strong); }
.mt-meter__scale i.major { height: 15px; background: var(--mt-text-3); }
.mt-meter__zone {
    position: absolute;
    left: 50%;
    bottom: 16px;
    width: 9%;
    height: 22px;
    transform: translateX(-50%);
    background: rgba(34, 197, 94, .16);
    border-left: 1px solid rgba(34, 197, 94, .5);
    border-right: 1px solid rgba(34, 197, 94, .5);
}
.mt-meter__needle {
    position: absolute;
    bottom: 10px;
    left: 50%;
    width: 4px;
    height: 36px;
    margin-left: -2px;
    border-radius: 3px;
    background: var(--mt-warn);
    box-shadow: 0 0 12px -1px var(--mt-warn);
    transition: left .07s linear, background .2s, box-shadow .2s, opacity .2s;
}
.mt-meter__needle.is-ok { background: var(--mt-ok); box-shadow: 0 0 14px -1px var(--mt-ok); }
.mt-meter__needle.is-off { opacity: .25; }
.mt-meter__labels {
    position: absolute;
    inset: auto 0 0;
    display: flex;
    justify-content: space-between;
    font-family: ui-monospace, Menlo, Consolas, monospace;
    font-size: 9.5px;
    color: var(--mt-text-3);
}

.mt-strings { display: flex; flex-wrap: wrap; gap: 7px; justify-content: center; margin: 12px 0; }
.mt-chip {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1px;
    min-width: 56px;
    min-height: 44px;
    padding: 7px 10px;
    border-radius: var(--mt-r-md);
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border);
    font-family: ui-monospace, Menlo, Consolas, monospace;
    font-size: 13px;
    font-weight: 800;
    color: var(--mt-text-2);
    transition: border-color .15s, color .15s, background .15s;
}
.mt-chip small { font-size: 9px; font-weight: 600; color: var(--mt-text-3); }
.mt-chip:hover { border-color: var(--mt-border-strong); color: var(--mt-text); }
.mt-chip.is-target { border-color: var(--mt-primary); color: var(--mt-primary); background: var(--mt-primary-soft); }
.mt-chip.is-tuned { border-color: var(--mt-ok); color: var(--mt-ok); background: rgba(34, 197, 94, .12); }

.mt-level { height: 5px; border-radius: 999px; background: var(--mt-surface-3); overflow: hidden; }
.mt-level__fill { height: 100%; width: 0%; background: var(--mt-primary); transition: width .08s linear; }

/* ---------- 指南 & 页脚 ---------- */
.mt-guide { grid-column: 1 / -1; border-top: 1px solid var(--mt-border); padding-top: 18px; }
.mt-guide__grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 12px 28px; }
.mt-guide h5 { margin: 0 0 6px; font-size: 12px; color: var(--mt-text-2); font-weight: 800; }
.mt-guide ul { margin: 0 0 14px; padding-left: 17px; }
.mt-guide li { font-size: 11.5px; color: var(--mt-text-3); line-height: 1.7; margin-bottom: 3px; }
.mt-guide b { color: var(--mt-text-2); font-weight: 700; }
.mt-page kbd {
    display: inline-block;
    min-width: 20px;
    padding: 1px 5px;
    border-radius: 5px;
    background: var(--mt-surface-2);
    border: 1px solid var(--mt-border-strong);
    border-bottom-width: 2px;
    font-family: ui-monospace, Menlo, Consolas, monospace;
    font-size: 10px;
    font-weight: 700;
    color: var(--mt-text-2);
    text-align: center;
}
.mt-foot { margin-top: 16px; text-align: center; font-size: 11.5px; color: var(--mt-text-3); }

.mt-toast {
    position: fixed;
    left: 50%;
    bottom: calc(24px + env(safe-area-inset-bottom, 0px));
    z-index: 90;
    transform: translate(-50%, 20px);
    max-width: min(92vw, 460px);
    padding: 11px 20px;
    border-radius: 999px;
    background: var(--mt-surface-1);
    border: 1px solid var(--mt-border-strong);
    box-shadow: 0 16px 40px -16px rgba(0, 0, 0, .6);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    font-size: 13px;
    font-weight: 700;
    color: var(--mt-text);
    text-align: center;
    opacity: 0;
    pointer-events: none;
    transition: .22s ease-out;
}
.mt-toast.is-on { opacity: 1; transform: translate(-50%, 0); }
.mt-toast.is-err { border-color: var(--mt-bad); color: #fca5a5; }

/* ==========================================================
 * 响应式
 * ========================================================== */

/* 大桌面：核心控件一屏可见 + 右侧面板（面板打开时） */
@media (min-width: 1200px) {
    .mt-page { max-width: 1280px; padding: 20px 20px 48px; }
    .mt-topbar { position: sticky; top: 0; }

    /* 未打开面板：节拍台与走带并排，拍号 / 划分横跨两列 */
    .mt-page:not(.mt-has-panel) .mt-main {
        display: grid;
        grid-template-columns: minmax(0, 1fr) minmax(320px, 380px);
        column-gap: var(--mt-gap);
        align-items: start;
    }
    .mt-page:not(.mt-has-panel) .mt-stage { grid-column: 1; min-height: 232px; }
    .mt-page:not(.mt-has-panel) .mt-transport {
        grid-column: 2;
        grid-template-columns: minmax(0, 1fr);
        justify-items: stretch;
        gap: 16px;
        padding: 20px 18px;
    }
    .mt-page:not(.mt-has-panel) .mt-play-btn { margin: 0 auto; }
    .mt-page:not(.mt-has-panel) .mt-tempo__top { justify-content: center; }
    .mt-page:not(.mt-has-panel) .mt-fine { grid-template-columns: repeat(3, minmax(0, 1fr)); width: 100%; }
    .mt-page:not(.mt-has-panel) .mt-grid2 { grid-column: 1 / -1; }

    /* 打开面板：右侧面板栏 + 主控区纵向 */
    .mt-page.mt-has-panel {
        grid-template-columns: minmax(0, 1fr) minmax(360px, 420px);
        column-gap: 20px;
    }
    .mt-page.mt-has-panel .mt-side {
        position: sticky;
        top: 76px;
        max-height: calc(100vh - 100px);
        overflow-y: auto;
        padding-right: 4px;
    }
    .mt-page.mt-has-panel .mt-side .mt-grid2 { grid-template-columns: minmax(0, 1fr); }
    .mt-transport { padding: 22px 26px; gap: 30px; }
    .mt-beats { min-height: 96px; gap: 16px; }
}
@media (min-width: 981px) {
    .mt-topbar { position: sticky; top: 0; }
}

/* 中等桌面 / 平板横屏：单列，卡片保持两列 */
@media (min-width: 981px) and (max-width: 1199px) {
    .mt-page { max-width: 980px; }
    .mt-play-btn { width: 104px; height: 104px; }
}

/* 平板竖屏 */
@media (max-width: 980px) {
    .mt-page { max-width: 100%; padding: 14px 12px 36px; gap: 14px; }
    .mt-grid2 { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
    .mt-transport { grid-template-columns: auto minmax(0, 1fr); padding: 18px; gap: 22px; }
    .mt-play-btn { width: 100px; height: 100px; }
    .mt-play-btn svg { width: 42px; height: 42px; }
    .mt-guide__grid { grid-template-columns: minmax(0, 1fr); }
}

/* 手机：走带置顶（先看到播放与速度），节拍台紧随其后 */
@media (max-width: 700px) {
    .mt-page {
        padding: 10px 10px calc(28px + env(safe-area-inset-bottom, 0px));
        gap: 12px;
    }
    .mt-topbar { padding: 8px 10px; gap: 8px; border-radius: var(--mt-r-md); }
    .mt-topbar__actions { gap: 6px; }
    .mt-icon-btn { width: 40px; height: 40px; }
    .mt-btn--tap { min-width: 58px; height: 40px; }
    .mt-main { gap: 12px; }
    .mt-transport { order: 1; }
    .mt-stage { order: 2; }
    .mt-transport {
        grid-template-columns: minmax(0, 1fr);
        justify-items: stretch;
        gap: 14px;
        padding: 16px 14px;
    }
    .mt-play-btn { width: 88px; height: 88px; margin: 0 auto; }
    .mt-play-btn svg { width: 38px; height: 38px; }
    .mt-tempo { width: 100%; }
    .mt-tempo__top { justify-content: center; gap: 8px; }
    .mt-tempo__term { margin-left: 0; }
    .mt-fine { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .mt-grid2 { grid-template-columns: minmax(0, 1fr); }
    .mt-beats { gap: 10px; min-height: 76px; }
    .mt-beat--strong { width: 50px; height: 50px; font-size: 14px; }
    .mt-beat--medium { width: 44px; height: 44px; font-size: 13px; }
    .mt-beat--weak, .mt-beat--mute { width: 38px; height: 38px; font-size: 12px; }
    .mt-stage__meta { gap: 8px; }
    .mt-panel { padding: 14px; border-radius: var(--mt-r-lg); }
    .mt-tuner-display { gap: 12px; }
    .mt-tuner-note { font-size: 54px; min-width: 96px; }
    .mt-song__bpm { font-size: 18px; }
}

/* 超小屏 */
@media (max-width: 400px) {
    .mt-brand__badge { display: none; }
    .mt-btn--tap { min-width: 52px; padding: 0 8px; }
    .mt-fine { grid-template-columns: repeat(3, minmax(0, 1fr)); }
    .mt-fine__btn { font-size: 12px; min-height: 38px; }
    .mt-beats { gap: 8px; }
    .mt-beat--strong { width: 46px; height: 46px; }
    .mt-beat--medium { width: 40px; height: 40px; }
    .mt-beat--weak, .mt-beat--mute { width: 34px; height: 34px; }
    .mt-stat { padding: 3px 8px; font-size: 11px; }
}

/* 无障碍：减少动效 */
@media (prefers-reduced-motion: reduce) {
    .mt-page *, .mt-flash, .mt-toast { transition-duration: .01ms !important; animation-duration: .01ms !important; }
}