/* ==========================================================================
   118 · 螺栓拧紧扭矩计算
   视觉概念：机械图纸 / 装配手册 —— 石墨灰 + 工业黄 + 钢蓝，网格底，表盘式读数
   ========================================================================== */

:root {
    --bt-bg: #f4f5f2;
    --bt-card: #ffffff;
    --bt-card-2: #ebeee9;
    --bt-ink: #191d1a;
    --bt-ink-2: #414a44;
    --bt-muted: #79847d;
    --bt-line: #d9ddd7;
    --bt-line-2: #c6ccc4;
    --bt-grid-line: rgba(25, 29, 26, .05);
    --bt-yellow: #b58900;
    --bt-yellow-soft: #fbf3d9;
    --bt-steel: #37596e;
    --bt-steel-soft: #e7eff5;
    --bt-bad: #a83a2b;
    --bt-bad-soft: #fbeceA;
    --bt-ok: #2c6b4a;
    --bt-shadow: 0 20px 40px -38px rgba(25, 29, 26, .55);
    --bt-sans: system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
    --bt-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

:root[data-theme="dark"] {
    --bt-bg: #0e1210;
    --bt-card: #161b18;
    --bt-card-2: #1c2320;
    --bt-ink: #e8ebe6;
    --bt-ink-2: #b0bab3;
    --bt-muted: #7c877f;
    --bt-line: #262f2a;
    --bt-line-2: #33403a;
    --bt-grid-line: rgba(232, 235, 230, .045);
    --bt-yellow: #e2b433;
    --bt-yellow-soft: #2a2313;
    --bt-steel: #7fb3d0;
    --bt-steel-soft: #132630;
    --bt-bad: #e08a7c;
    --bt-bad-soft: #2c1714;
    --bt-ok: #5fbf8e;
    --bt-shadow: 0 20px 44px -36px rgba(0, 0, 0, .9);
}

/* ---------------- 首屏 ---------------- */
.bt-hero {
    position: relative;
    padding: 28px 0 0;
    background-image:
        linear-gradient(var(--bt-grid-line) 1px, transparent 1px),
        linear-gradient(90deg, var(--bt-grid-line) 1px, transparent 1px);
    background-size: 24px 24px;
    background-position: 0 0, 0 0;
}
.bt-hero-in {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 290px;
    gap: 34px;
    align-items: center;
    padding-bottom: 28px;
}
.bt-crumb {
    display: flex;
    align-items: center;
    gap: 7px;
    margin-bottom: 14px;
    font-size: 12.5px;
    color: var(--bt-muted);
}
.bt-crumb a { color: var(--bt-muted); text-decoration: none; }
.bt-crumb a:hover { color: var(--bt-steel); }
.bt-crumb i { font-style: normal; opacity: .5; }

.bt-eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 11px;
    font-family: var(--bt-mono);
    font-size: 11px;
    letter-spacing: .18em;
    text-transform: uppercase;
    color: var(--bt-yellow);
}
.bt-eyebrow::before {
    content: "";
    width: 18px;
    height: 3px;
    background: currentColor;
}
.bt-h1 {
    margin: 0 0 12px;
    font-family: var(--bt-sans);
    font-size: clamp(27px, 3.1vw, 38px);
    line-height: 1.24;
    font-weight: 800;
    letter-spacing: -.03em;
    color: var(--bt-ink);
}
.bt-h1 em {
    font-style: normal;
    color: var(--bt-steel);
    position: relative;
    z-index: 0;
}
.bt-h1 em::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    bottom: 2px;
    height: 7px;
    background: color-mix(in srgb, var(--bt-yellow) 26%, transparent);
    z-index: -1;
}
.bt-sub {
    margin: 0;
    max-width: 52ch;
    font-size: 15px;
    line-height: 1.88;
    color: var(--bt-ink-2);
}
.bt-sub b { color: var(--bt-ink); font-weight: 600; white-space: nowrap; }

.bt-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 16px;
}
.bt-meta span {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 5px 10px;
    border: 1px solid var(--bt-line);
    border-radius: 4px;
    background: var(--bt-card);
    font-family: var(--bt-mono);
    font-size: 11.5px;
    color: var(--bt-ink-2);
}
.bt-meta span i {
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--bt-yellow);
    font-style: normal;
}

.bt-theme {
    display: inline-flex;
    gap: 2px;
    margin-top: 14px;
    padding: 3px;
    border: 1px solid var(--bt-line);
    border-radius: 6px;
    background: var(--bt-card-2);
}
.bt-theme button {
    appearance: none;
    border: 0;
    background: transparent;
    color: var(--bt-muted);
    font: inherit;
    font-size: 12px;
    padding: 5px 11px;
    border-radius: 4px;
    cursor: pointer;
}
.bt-theme button:hover { color: var(--bt-ink); }
.bt-theme button[aria-pressed="true"] {
    background: var(--bt-steel);
    color: #fff;
    font-weight: 600;
}

/* 首屏右侧小铭牌 */
.bt-plate {
    padding: 16px 18px;
    border: 1px solid var(--bt-line-2);
    border-radius: 6px;
    background:
        linear-gradient(var(--bt-card), var(--bt-card)) padding-box,
        repeating-linear-gradient(135deg, var(--bt-yellow) 0 8px, transparent 8px 16px) border-box;
    box-shadow: var(--bt-shadow);
}
.bt-plate h2 {
    margin: 0 0 10px;
    font-family: var(--bt-mono);
    font-size: 10.5px;
    letter-spacing: .16em;
    text-transform: uppercase;
    color: var(--bt-muted);
}
.bt-plate-row {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 10px;
    padding: 6px 0;
    border-bottom: 1px dashed var(--bt-line);
    font-size: 12.5px;
    color: var(--bt-ink-2);
}
.bt-plate-row:last-of-type { border-bottom: 0; }
.bt-plate-row b {
    font-family: var(--bt-mono);
    font-size: 13.5px;
    color: var(--bt-ink);
    font-variant-numeric: tabular-nums;
}
.bt-plate p {
    margin: 10px 0 0;
    font-size: 11px;
    line-height: 1.7;
    color: var(--bt-muted);
}

/* ---------------- 工作台 ---------------- */
.bt-work {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.06fr);
    gap: 16px;
    align-items: start;
}
.bt-card {
    border: 1px solid var(--bt-line);
    border-radius: 8px;
    background: var(--bt-card);
    box-shadow: var(--bt-shadow);
}
.bt-card-head {
    display: flex;
    align-items: center;
    gap: 9px;
    padding: 11px 16px;
    border-bottom: 1px solid var(--bt-line);
    background: var(--bt-card-2);
    border-radius: 8px 8px 0 0;
}
.bt-card-head h2 {
    margin: 0;
    font-family: var(--bt-mono);
    font-size: 11.5px;
    font-weight: 700;
    letter-spacing: .12em;
    text-transform: uppercase;
    color: var(--bt-ink);
}
.bt-card-head .bt-side {
    margin-left: auto;
    font-family: var(--bt-mono);
    font-size: 11px;
    color: var(--bt-muted);
}
.bt-card-head::before {
    content: "";
    width: 3px;
    height: 13px;
    background: var(--bt-yellow);
    border-radius: 1px;
}

/* 表单 */
.bt-form { padding: 14px 16px 16px; }
.bt-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 11px 13px;
}
.bt-field { display: grid; gap: 5px; min-width: 0; }
.bt-field.is-wide { grid-column: 1 / -1; }
.bt-field > label {
    font-family: var(--bt-mono);
    font-size: 10.5px;
    letter-spacing: .08em;
    text-transform: uppercase;
    color: var(--bt-muted);
}
.bt-input,
.bt-select {
    width: 100%;
    box-sizing: border-box;
    border: 1px solid var(--bt-line-2);
    border-radius: 5px;
    background: var(--bt-card);
    color: var(--bt-ink);
    font-family: var(--bt-mono);
    font-size: 14px;
    padding: 8px 10px;
    outline: none;
    font-variant-numeric: tabular-nums;
    transition: border-color .15s, box-shadow .15s;
}
.bt-input:focus,
.bt-select:focus {
    border-color: var(--bt-steel);
    box-shadow: 0 0 0 3px color-mix(in srgb, var(--bt-steel) 12%, transparent);
}
.bt-input.is-bad { border-color: var(--bt-bad); background: var(--bt-bad-soft); }
.bt-select { font-family: var(--bt-sans); font-size: 13px; cursor: pointer; }

/* 摩擦系数预设 */
.bt-presets {
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
    margin-top: 7px;
}
.bt-presets button {
    appearance: none;
    border: 1px solid var(--bt-line-2);
    background: var(--bt-card);
    color: var(--bt-ink-2);
    font-family: var(--bt-mono);
    font-size: 11px;
    padding: 4px 8px;
    border-radius: 4px;
    cursor: pointer;
    transition: border-color .15s, background .15s, color .15s;
}
.bt-presets button:hover { border-color: var(--bt-steel); color: var(--bt-steel); }
.bt-presets button[aria-pressed="true"] {
    background: var(--bt-steel);
    border-color: var(--bt-steel);
    color: #fff;
    font-weight: 600;
}

.bt-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    align-items: center;
    margin-top: 15px;
    padding-top: 13px;
    border-top: 1px solid var(--bt-line);
}
.bt-btn {
    appearance: none;
    font: inherit;
    font-size: 13px;
    padding: 8px 15px;
    border-radius: 5px;
    border: 1px solid var(--bt-line-2);
    background: var(--bt-card);
    color: var(--bt-ink-2);
    cursor: pointer;
    white-space: nowrap;
    transition: border-color .15s, color .15s, background .15s;
}
.bt-btn:hover { border-color: var(--bt-ink); color: var(--bt-ink); }
.bt-btn.is-primary {
    background: var(--bt-yellow);
    border-color: var(--bt-yellow);
    color: #1d1a05;
    font-weight: 700;
}
.bt-btn.is-primary:hover { background: color-mix(in srgb, var(--bt-yellow) 88%, #000); }
.bt-btn.is-ghost { background: transparent; }
.bt-actions .bt-spacer { flex: 1 1 auto; }

.bt-demos {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    align-items: center;
    margin-top: 11px;
}
.bt-demos > span { font-size: 11.5px; color: var(--bt-muted); }
.bt-demos button {
    appearance: none;
    border: 1px dashed var(--bt-line-2);
    background: transparent;
    color: var(--bt-ink-2);
    font: inherit;
    font-size: 11.8px;
    padding: 4px 9px;
    border-radius: 4px;
    cursor: pointer;
}
.bt-demos button:hover { border-color: var(--bt-yellow); color: var(--bt-yellow); }

.bt-note {
    margin: 11px 0 0;
    padding: 9px 12px;
    border-left: 3px solid var(--bt-yellow);
    border-radius: 4px;
    background: var(--bt-yellow-soft);
    font-size: 12px;
    line-height: 1.75;
    color: var(--bt-ink-2);
}
.bt-note.is-bad { border-left-color: var(--bt-bad); background: var(--bt-bad-soft); }
.bt-note b { color: var(--bt-ink); }

/* ---------------- 表盘 ---------------- */
.bt-result { position: sticky; top: 14px; }
.bt-gauge-wrap {
    position: relative;
    padding: 16px 16px 6px;
    border-bottom: 1px solid var(--bt-line);
}
.bt-gauge { width: 100%; height: auto; display: block; overflow: visible; }
.bt-gauge-track {
    fill: none;
    stroke: var(--bt-card-2);
    stroke-width: 14;
    stroke-linecap: round;
}
.bt-gauge-fill {
    fill: none;
    stroke: url(#btGrad);
    stroke-width: 14;
    stroke-linecap: round;
    stroke-dasharray: 283;
    stroke-dashoffset: 283;
    transition: stroke-dashoffset .45s cubic-bezier(.22, .8, .3, 1);
}
.bt-tick { stroke: var(--bt-line-2); stroke-width: 1.2; }
.bt-tick.is-major { stroke: var(--bt-ink-2); stroke-width: 1.8; }
.bt-tick-label {
    font-family: var(--bt-mono);
    font-size: 7.5px;
    fill: var(--bt-muted);
}
.bt-needle line { stroke: var(--bt-ink); stroke-width: 2.2; stroke-linecap: round; }
.bt-needle { transform-origin: 110px 108px; transition: transform .45s cubic-bezier(.22, .8, .3, 1); }
.bt-hub { fill: var(--bt-ink); }
.bt-hub-in { fill: var(--bt-card); }

.bt-readout {
    position: absolute;
    left: 0;
    right: 0;
    bottom: 34px;
    text-align: center;
    pointer-events: none;
}
.bt-readout-num {
    font-family: var(--bt-mono);
    font-size: clamp(28px, 3.6vw, 36px);
    font-weight: 700;
    line-height: 1;
    color: var(--bt-ink);
    letter-spacing: -.03em;
    font-variant-numeric: tabular-nums;
}
.bt-readout-num small { font-size: 13px; font-weight: 500; color: var(--bt-muted); margin-left: 3px; }
.bt-readout-label {
    margin-top: 3px;
    font-family: var(--bt-mono);
    font-size: 10px;
    letter-spacing: .12em;
    text-transform: uppercase;
    color: var(--bt-muted);
}

/* 关键数据 */
.bt-facts {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1px;
    background: var(--bt-line);
    border-bottom: 1px solid var(--bt-line);
}
.bt-fact {
    padding: 11px 14px;
    background: var(--bt-card);
}
.bt-fact span {
    display: block;
    font-family: var(--bt-mono);
    font-size: 10px;
    letter-spacing: .08em;
    text-transform: uppercase;
    color: var(--bt-muted);
    margin-bottom: 3px;
}
.bt-fact b {
    font-family: var(--bt-mono);
    font-size: 16px;
    color: var(--bt-ink);
    font-variant-numeric: tabular-nums;
}
.bt-fact b small { font-size: 11px; font-weight: 500; color: var(--bt-muted); margin-left: 2px; }

/* 扭矩分配 */
.bt-split { padding: 13px 16px 15px; }
.bt-split h3 {
    margin: 0 0 8px;
    font-family: var(--bt-mono);
    font-size: 10.5px;
    letter-spacing: .1em;
    text-transform: uppercase;
    color: var(--bt-muted);
}
.bt-split-bar {
    display: flex;
    height: 10px;
    border-radius: 3px;
    overflow: hidden;
    background: var(--bt-card-2);
}
.bt-split-bar i { display: block; height: 100%; width: 0; transition: width .35s ease; }
.bt-split-bar i:nth-child(1) { background: var(--bt-steel); }
.bt-split-bar i:nth-child(2) { background: var(--bt-yellow); }
.bt-split-bar i:nth-child(3) { background: var(--bt-muted); }
.bt-split-legend {
    display: flex;
    flex-wrap: wrap;
    gap: 6px 14px;
    margin-top: 8px;
    font-size: 11.5px;
    color: var(--bt-ink-2);
}
.bt-split-legend span { display: inline-flex; align-items: center; gap: 5px; }
.bt-split-legend i { width: 7px; height: 7px; border-radius: 1px; }
.bt-split-legend b { font-family: var(--bt-mono); color: var(--bt-ink); }

/* 利用率对照 */
.bt-scale { padding: 0 16px 16px; }
.bt-scale table { width: 100%; border-collapse: collapse; font-size: 12.4px; }
.bt-scale th,
.bt-scale td { padding: 6px 0; text-align: left; border-bottom: 1px dashed var(--bt-line); }
.bt-scale th {
    font-family: var(--bt-mono);
    font-size: 10.5px;
    letter-spacing: .06em;
    text-transform: uppercase;
    color: var(--bt-muted);
    font-weight: 600;
}
.bt-scale td:last-child,
.bt-scale th:last-child { text-align: right; font-family: var(--bt-mono); font-variant-numeric: tabular-nums; }
.bt-scale tr.is-cur td { color: var(--bt-steel); font-weight: 700; background: var(--bt-steel-soft); }
.bt-scale tr.is-cur td:first-child { padding-left: 6px; border-radius: 3px 0 0 3px; }
.bt-scale tr.is-cur td:last-child { padding-right: 6px; border-radius: 0 3px 3px 0; }

/* ---------------- 批量表 ---------------- */
.bt-batch { margin-top: 16px; padding: 14px 16px 16px; }
.bt-batch-head {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 10px;
}
.bt-batch-head h2 {
    margin: 0;
    font-family: var(--bt-mono);
    font-size: 11.5px;
    letter-spacing: .12em;
    text-transform: uppercase;
    color: var(--bt-ink);
}
.bt-batch-head span { font-size: 12px; color: var(--bt-muted); }
.bt-batch-head .bt-btn { margin-left: auto; padding: 6px 12px; font-size: 12px; }
.bt-batch-wrap { overflow-x: auto; }
.bt-batch table { width: 100%; min-width: 560px; border-collapse: collapse; font-size: 12.4px; }
.bt-batch th,
.bt-batch td {
    padding: 7px 9px;
    text-align: left;
    border-bottom: 1px dashed var(--bt-line);
    font-variant-numeric: tabular-nums;
}
.bt-batch th {
    font-family: var(--bt-mono);
    font-size: 10.5px;
    letter-spacing: .06em;
    text-transform: uppercase;
    color: var(--bt-muted);
    font-weight: 600;
    white-space: nowrap;
}
.bt-batch td { color: var(--bt-ink-2); font-family: var(--bt-mono); }
.bt-batch tbody tr:hover td { background: var(--bt-card-2); }
.bt-batch .bt-cur td { color: var(--bt-steel); font-weight: 700; background: var(--bt-steel-soft); }

/* ---------------- 说明 ---------------- */
.bt-doc { margin-top: 30px; }
.bt-doc-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
.bt-doc-block {
    padding: 16px 18px;
    border: 1px solid var(--bt-line);
    border-radius: 8px;
    background: var(--bt-card);
}
.bt-doc-block h2 {
    margin: 0 0 9px;
    font-size: 15.5px;
    font-weight: 700;
    color: var(--bt-ink);
}
.bt-doc-block p,
.bt-doc-block li { font-size: 13.2px; line-height: 1.95; color: var(--bt-ink-2); }
.bt-doc-block p { margin: 0 0 8px; }
.bt-doc-block p:last-child { margin-bottom: 0; }
.bt-doc-block ol,
.bt-doc-block ul { margin: 0; padding-left: 19px; }
.bt-doc-block li + li { margin-top: 4px; }
.bt-doc-block b { color: var(--bt-ink); }
.bt-doc-block code {
    font-family: var(--bt-mono);
    font-size: 12px;
    padding: 1px 5px;
    border-radius: 3px;
    background: var(--bt-card-2);
    color: var(--bt-steel);
}
.bt-formula {
    margin: 9px 0 0;
    padding: 11px 13px;
    border: 1px dashed var(--bt-line-2);
    border-radius: 5px;
    background: var(--bt-card-2);
    font-family: var(--bt-mono);
    font-size: 11.8px;
    line-height: 1.95;
    color: var(--bt-ink-2);
    overflow-x: auto;
}

.bt-toast {
    position: fixed;
    left: 50%;
    bottom: 24px;
    transform: translate(-50%, 10px);
    z-index: 90;
    max-width: min(88vw, 440px);
    padding: 10px 18px;
    border-radius: 5px;
    background: var(--bt-ink);
    color: var(--bt-card);
    font-size: 13px;
    line-height: 1.6;
    box-shadow: 0 16px 32px -20px rgba(0, 0, 0, .7);
    opacity: 0;
    pointer-events: none;
    transition: opacity .2s, transform .2s;
}
.bt-toast.is-show { opacity: 1; transform: translate(-50%, 0); }

/* ---------------- 响应式 ---------------- */
@media (max-width: 1020px) {
    .bt-hero-in { grid-template-columns: minmax(0, 1fr); gap: 20px; }
    .bt-plate { max-width: 420px; }
    .bt-work { grid-template-columns: minmax(0, 1fr); }
    .bt-result { position: static; }
    .bt-doc-grid { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 620px) {
    .bt-hero { padding-top: 20px; }
    .bt-h1 { font-size: 25px; }
    .bt-sub { font-size: 14px; line-height: 1.85; max-width: none; }
    .bt-plate { display: none; }
    .bt-meta { margin-top: 12px; }
    .bt-grid { grid-template-columns: minmax(0, 1fr); }
    .bt-field.is-wide { grid-column: auto; }
    .bt-btn { flex: 1 1 auto; text-align: center; }
    .bt-actions .bt-spacer { display: none; }
    .bt-facts { grid-template-columns: minmax(0, 1fr); }
    .bt-form { padding: 12px; }
    .bt-gauge-wrap { padding: 12px 10px 4px; }
    .bt-readout { bottom: 26px; }
    .bt-readout-num { font-size: 26px; }
}