:root {
    --bg: #0f1115;
    --bg-soft: #14171d;
    --panel: #171a21;
    --panel-2: #1d2129;
    --border: #2a2f3a;
    --border-strong: #3a4150;
    --text: #e7eaf0;
    --muted: #9aa1af;
    --accent: #7c5cff;
    --accent-2: #4aa8ff;
    --accent-soft: rgba(124, 92, 255, 0.14);
    --ok: #39a339;
    --err: #e5534b;
    --radius: 14px;
    --radius-sm: 9px;
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
    --canvas-bg: #ffffff;
    --canvas-text: #1a1d24;
    --canvas-border: #e2e5ea;
}

html[data-theme="light"] {
    --bg: #f4f5f7;
    --bg-soft: #eceef1;
    --panel: #ffffff;
    --panel-2: #f6f7f9;
    --border: #e2e5ea;
    --border-strong: #cfd4dc;
    --text: #1a1d24;
    --muted: #6b7280;
    --accent: #6a4bff;
    --accent-2: #2f8cff;
    --accent-soft: rgba(106, 75, 255, 0.1);
    --shadow: 0 10px 30px rgba(20, 24, 34, 0.08);
    --canvas-bg: #ffffff;
    --canvas-text: #1a1d24;
    --canvas-border: #e2e5ea;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
        "Microsoft Yahei", "Helvetica Neue", Helvetica, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.5;
    min-height: 100vh;
    font-size: 15px;
}

.hidden { display: none !important; }

/* ---------- 顶栏 ---------- */
.topbar {
    max-width: none;
    margin: 0 auto;
    padding: 40px 32px 8px;
    text-align: center;
    position: relative;
}
.topbar h1 {
    font-size: 34px;
    font-weight: 800;
    letter-spacing: -0.02em;
    background: linear-gradient(120deg, var(--accent), var(--accent-2));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}
.topbar .subtitle {
    margin-top: 6px;
    color: var(--muted);
    font-size: 14px;
}
.toolbar {
    position: absolute;
    top: 40px;
    right: 24px;
    display: flex;
    gap: 8px;
}
.lang-toggle {
    border: 1px solid var(--border);
    background: var(--panel);
    color: var(--text);
    font-size: 13px;
    padding: 7px 14px;
    border-radius: 999px;
    cursor: pointer;
    transition: border-color 0.15s, background 0.15s;
}
.lang-toggle:hover {
    border-color: var(--accent);
    background: var(--accent-soft);
}

/* ---------- 布局 ---------- */
.layout {
    max-width: none;
    margin: 0 auto;
    padding: 20px 32px 40px;
    display: grid;
    grid-template-columns: minmax(320px, 400px) minmax(0, 1fr);
    gap: 24px;
    align-items: start;
}

.panel {
    background: var(--panel);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 22px;
    box-shadow: var(--shadow);
}

.output {
    position: sticky;
    top: 20px;
    display: flex;
    flex-direction: column;
    gap: 18px;
}

/* ---------- 表单 ---------- */
.block { border: none; margin: 0 0 20px; }
.block:last-child { margin-bottom: 0; }
.block legend {
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--muted);
    padding: 0;
    margin-bottom: 10px;
}

.type-options {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
}
.type-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    padding: 14px 8px;
    background: var(--panel-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: border-color 0.15s, background 0.15s, transform 0.05s;
}
.type-btn:hover { border-color: var(--border-strong); }
.type-btn:active { transform: scale(0.97); }
.type-btn .type-icon {
    font-size: 20px;
    line-height: 1;
    color: var(--muted);
    transition: color 0.15s;
}
.type-btn.active {
    border-color: var(--accent);
    background: var(--accent-soft);
}
.type-btn.active .type-icon { color: var(--accent); }

.unit-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 14px;
    flex-wrap: wrap;
}
.unit-options {
    display: inline-flex;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    overflow: hidden;
}
.unit-btn {
    padding: 8px 20px;
    background: var(--panel-2);
    border: none;
    color: var(--text);
    font-size: 14px;
    font-weight: 700;
    cursor: pointer;
    text-transform: uppercase;
    transition: background 0.15s, color 0.15s;
}
.unit-btn + .unit-btn { border-left: 1px solid var(--border); }
.unit-btn.active { background: var(--accent); color: #fff; }

.root-font {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: var(--muted);
}
.root-font input {
    width: 58px;
    padding: 7px 8px;
    text-align: center;
    background: var(--panel-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-size: 14px;
    font-weight: 700;
}
.root-font input:focus { border-color: var(--accent); outline: none; }

/* ---------- 字段网格 ---------- */
.field-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}
.field {
    display: flex;
    flex-direction: column;
    gap: 6px;
}
.field-label { font-size: 13px; color: var(--muted); font-weight: 600; }
.field-input {
    display: flex;
    align-items: center;
    gap: 6px;
}
.field-input input {
    width: 100%;
    min-width: 0;
    padding: 9px 12px;
    background: var(--panel-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-size: 15px;
    font-weight: 700;
    transition: border-color 0.15s;
}
.field-input input:focus { border-color: var(--accent); outline: none; }
.unit-hint {
    font-size: 12px;
    color: var(--muted);
    font-weight: 700;
    min-width: 26px;
    text-transform: lowercase;
}
.field-error {
    margin-top: 12px;
    font-size: 13px;
    color: var(--err);
    font-weight: 600;
}

/* ---------- 结果 ---------- */
.result-block {
    background: var(--panel-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    overflow: hidden;
}
.result-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 14px;
    border-bottom: 1px solid var(--border);
}
.result-label {
    font-size: 12px;
    font-weight: 700;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}
.copy-btn {
    background: var(--accent);
    color: #fff;
    border: none;
    font-size: 13px;
    font-weight: 700;
    padding: 6px 16px;
    border-radius: 7px;
    cursor: pointer;
    transition: opacity 0.15s;
}
.copy-btn:hover { opacity: 0.88; }
.copy-btn.copied { background: var(--ok); }
.result-code {
    display: block;
    padding: 14px 16px;
    font-family: "SF Mono", "Fira Code", "Consolas", "Menlo", monospace;
    font-size: 16px;
    font-weight: 600;
    color: var(--accent-2);
    word-break: break-all;
    user-select: all;
}

.formula-block {
    font-size: 13px;
    color: var(--muted);
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}
.formula-code {
    font-family: "SF Mono", "Consolas", monospace;
    color: var(--text);
    background: var(--panel-2);
    padding: 3px 9px;
    border-radius: 6px;
    border: 1px solid var(--border);
}

/* ---------- 预览 ---------- */
.preview-block {
    display: flex;
    flex-direction: column;
    gap: 12px;
}
.preview-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    flex-wrap: wrap;
    font-size: 14px;
    font-weight: 700;
}
.preview-readout {
    font-size: 13px;
    color: var(--muted);
    font-weight: 500;
}
.preview-readout b {
    color: var(--accent-2);
    font-family: "SF Mono", "Consolas", monospace;
    font-weight: 700;
}
.preview-text-row {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 13px;
    color: var(--muted);
    font-weight: 600;
}
.preview-text-row input {
    flex: 1;
    min-width: 0;
    padding: 8px 12px;
    background: var(--panel-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-size: 14px;
    transition: border-color 0.15s;
}
.preview-text-row input:focus { border-color: var(--accent); outline: none; }
.preview-text-row input::placeholder { color: var(--muted); opacity: 0.7; }

.viewport-canvas-wrap {
    width: 100%;
    overflow: hidden;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background:
        linear-gradient(45deg, var(--bg-soft) 25%, transparent 25%),
        linear-gradient(-45deg, var(--bg-soft) 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, var(--bg-soft) 75%),
        linear-gradient(-45deg, transparent 75%, var(--bg-soft) 75%);
    background-size: 20px 20px;
    background-position: 0 0, 0 10px, 10px -10px, -10px 0;
    background-color: var(--bg);
    position: relative;
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.03);
}
.viewport-canvas {
    width: 100%;
    background: var(--canvas-bg);
    color: var(--canvas-text);
    position: relative;
    overflow: hidden;
    transition: height 0.2s ease;
}
.viewport-canvas .vp-badge {
    position: absolute;
    top: 8px;
    left: 10px;
    z-index: 2;
    font-size: 10px;
    font-weight: 700;
    color: #fff;
    background: rgba(26, 29, 36, 0.55);
    padding: 2px 8px;
    border-radius: 999px;
    font-family: "SF Mono", "Consolas", monospace;
    letter-spacing: 0.02em;
    pointer-events: none;
}

/* 字号预览 */
.vp-font {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    padding: 20px;
    font-weight: 800;
    line-height: 1.1;
    text-align: center;
    color: #1a1d24;
    transition: font-size 90ms linear;
}
/* 边距预览 */
.vp-spacing {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    padding: 16px;
}
.vp-spacing-box {
    width: 100%;
    height: 100%;
    background: #eef0ff;
    border: 2px dashed #7c5cff;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: padding 90ms linear, gap 90ms linear;
}
.vp-spacing-box .vp-cell {
    background: #7c5cff;
    border-radius: 6px;
    flex: 1 1 0;
    height: 60%;
}
/* 通用预览 */
.vp-generic {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    width: 100%;
    height: 100%;
    padding: 16px;
}
.vp-generic-bar {
    background: linear-gradient(90deg, #7c5cff, #4aa8ff);
    border-radius: 8px;
    height: 50%;
    transition: width 90ms linear;
}

.slider-row {
    display: flex;
    align-items: center;
    gap: 12px;
}
.slider-min, .slider-max {
    font-size: 12px;
    color: var(--muted);
    font-family: "SF Mono", "Consolas", monospace;
    min-width: 34px;
}
.slider-max { text-align: right; }
input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    flex: 1;
    height: 6px;
    border-radius: 999px;
    background: linear-gradient(to right,
        var(--accent) 0%, var(--accent-2) var(--fill, 50%),
        var(--border-strong) var(--fill, 50%), var(--border-strong) 100%);
    cursor: pointer;
}
input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: #fff;
    border: 2px solid var(--accent);
    box-shadow: 0 0 0 4px var(--accent-soft), 0 2px 8px rgba(0, 0, 0, 0.3);
    cursor: grab;
    transition: box-shadow 0.15s;
}
input[type="range"]::-webkit-slider-thumb:hover {
    box-shadow: 0 0 0 6px var(--accent-soft), 0 2px 10px rgba(0, 0, 0, 0.35);
}
input[type="range"]::-webkit-slider-thumb:active { cursor: grabbing; }
input[type="range"]::-moz-range-thumb {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: #fff;
    border: 2px solid var(--accent);
    box-shadow: 0 0 0 4px var(--accent-soft);
    cursor: grab;
}
input[type="range"]::-moz-range-track {
    height: 6px;
    border-radius: 999px;
    background: var(--border-strong);
}
input[type="range"]::-moz-range-progress {
    height: 6px;
    border-radius: 999px;
    background: linear-gradient(90deg, var(--accent), var(--accent-2));
}
.slider-hint {
    font-size: 12px;
    color: var(--muted);
}

/* ---------- 曲线图 ---------- */
.chart-block svg {
    width: 100%;
    height: 160px;
    display: block;
    background: var(--panel-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    overflow: hidden;
}
.chart-legend {
    display: flex;
    gap: 16px;
    margin-top: 10px;
    font-size: 12px;
    color: var(--muted);
}
.chart-legend span { display: inline-flex; align-items: center; gap: 5px; }
.dot { width: 10px; height: 10px; border-radius: 3px; display: inline-block; }
.dot-min { background: var(--accent-2); }
.dot-pref { background: var(--accent); }
.dot-max { background: #b08cff; }

/* ---------- 反向推算 ---------- */

.reverse h2 {
    font-size: 18px;
    font-weight: 800;
    margin-bottom: 4px;
}
.reverse p { color: var(--muted); font-size: 13px; margin-bottom: 12px; }
.reverse-input {
    width: 100%;
    max-width: 460px;
    padding: 11px 14px;
    background: var(--panel-2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-size: 15px;
    font-family: "SF Mono", "Consolas", monospace;
    transition: border-color 0.15s;
}
.reverse-input:focus { border-color: var(--accent); outline: none; }
.reverse-result {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 14px;
    flex-wrap: wrap;
    font-size: 14px;
    color: var(--muted);
}
.reverse-result b {
    color: var(--accent-2);
    font-size: 20px;
    font-weight: 800;
    font-family: "SF Mono", "Consolas", monospace;
}
.reverse-result .sep { color: var(--border-strong); }
.reverse-result .apply-btn {
    background: var(--accent);
    color: #fff;
    border: none;
    font-size: 13px;
    font-weight: 700;
    padding: 6px 14px;
    border-radius: 7px;
    cursor: pointer;
    transition: opacity 0.15s;
    margin-left: 4px;
}
.reverse-result .apply-btn:hover { opacity: 0.88; }
.reverse-result .apply-btn.applied { background: var(--ok); }
.reverse-error { margin-top: 12px; color: var(--err); font-size: 13px; font-weight: 600; }

/* ---------- 页脚 ---------- */
.footer {
    text-align: center;
    color: var(--muted);
    font-size: 12px;
    padding: 8px 32px 40px;
}

/* ---------- 响应式 ---------- */
@media (max-width: 860px) {
    .layout { grid-template-columns: 1fr; }
    .output { position: static; }
    .toolbar { position: static; margin-top: 12px; justify-content: center; }
    .topbar h1 { font-size: 28px; }
}
@media (max-width: 480px) {
    .field-grid { grid-template-columns: 1fr; }
    .type-options { grid-template-columns: 1fr; }
    .type-btn { flex-direction: row; gap: 8px; }
    .topbar { padding: 28px 16px 4px; }
    .layout { padding: 16px 16px 32px; }
}

/* ---------- 2026 体验增强 ---------- */
:root {
    --bg: #0a0c10;
    --bg-soft: #11151b;
    --panel: rgba(20, 23, 30, 0.88);
    --panel-2: #1a1e27;
    --border: rgba(255, 255, 255, 0.09);
    --border-strong: rgba(255, 255, 255, 0.18);
    --text: #f4f5f8;
    --muted: #98a0b0;
    --accent: #8b6cff;
    --accent-2: #59b7ff;
    --accent-soft: rgba(139, 108, 255, 0.16);
    --ok: #33b86b;
    --radius: 18px;
    --radius-sm: 11px;
    --shadow: 0 18px 60px rgba(0, 0, 0, 0.28);
    --chart-grid: rgba(255, 255, 255, 0.09);
    --chart-marker: rgba(255, 255, 255, 0.28);
    --chart-cursor: #ffffff;
    --chart-label: #aeb5c3;
    --chart-min-zone: rgba(89, 183, 255, 0.035);
    --chart-fluid-zone: rgba(139, 108, 255, 0.07);
    --chart-max-zone: rgba(192, 132, 252, 0.035);
}

html { scroll-behavior: smooth; }

body {
    background:
        radial-gradient(circle at 7% 0%, rgba(89, 183, 255, 0.11), transparent 27rem),
        radial-gradient(circle at 92% 8%, rgba(139, 108, 255, 0.14), transparent 32rem),
        var(--bg);
    letter-spacing: -0.006em;
    overflow-x: auto;
}

button, input { font: inherit; }
button { -webkit-tap-highlight-color: transparent; }
::selection { background: rgba(139, 108, 255, 0.36); color: #fff; }

:where(button, input, [tabindex]):focus-visible {
    outline: 3px solid rgba(89, 183, 255, 0.46);
    outline-offset: 3px;
}

.topbar {
    width: 100%;
    max-width: none;
    padding: 36px clamp(20px, 2vw, 40px) 16px;
    display: flex;
    align-items: center;
    gap: 18px;
    text-align: left;
}

.hero-copy { min-width: 0; }
.section-kicker {
    display: block;
    color: var(--accent-2);
    font-size: 11px;
    font-weight: 800;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.topbar h1 {
    margin-top: 3px;
    font-size: clamp(30px, 4vw, 42px);
    line-height: 1.08;
    letter-spacing: -0.045em;
}

.topbar .subtitle {
    max-width: 600px;
    margin-top: 7px;
    font-size: 14px;
}

.toolbar {
    position: static;
    margin-left: auto;
    flex: 0 0 auto;
}

.lang-toggle {
    min-height: 38px;
    padding: 8px 15px;
    backdrop-filter: blur(12px);
}

.layout {
    width: 100%;
    max-width: none;
    padding: 16px clamp(20px, 2vw, 40px) 46px;
    grid-template-columns: minmax(310px, 350px) minmax(0, 1fr);
    gap: 20px;
}

@media (min-width: 1900px) {
    .layout { grid-template-columns: 360px minmax(0, 1fr); }
    .preview-block { padding: 22px; }
}

.panel {
    border-color: var(--border);
    background: linear-gradient(160deg, rgba(25, 29, 38, 0.94), rgba(16, 19, 25, 0.94));
    box-shadow: var(--shadow), inset 0 1px 0 rgba(255, 255, 255, 0.035);
    backdrop-filter: blur(18px);
}

.config { position: sticky; top: 18px; }
.output { position: static; gap: 16px; }

.panel-intro {
    display: flex;
    align-items: center;
    gap: 11px;
    padding-bottom: 18px;
    margin-bottom: 20px;
    border-bottom: 1px solid var(--border);
}

.panel-intro .step-number {
    display: grid;
    place-items: center;
    width: 34px;
    height: 34px;
    flex: 0 0 auto;
    border: 1px solid rgba(139, 108, 255, 0.42);
    border-radius: 10px;
    background: var(--accent-soft);
    color: #b6a5ff;
    font: 800 11px/1 "SF Mono", "Consolas", monospace;
}

.panel-intro h2 {
    font-size: 15px;
    line-height: 1.25;
    letter-spacing: -0.015em;
}

.panel-intro p {
    margin-top: 3px;
    color: var(--muted);
    font-size: 12px;
}

.output-intro { margin-bottom: 0; }

.type-btn,
.unit-btn,
.field-input input,
.root-font input,
.preview-text-row input,
.reverse-input {
    transition: border-color 150ms ease, background 150ms ease, box-shadow 150ms ease, transform 100ms ease;
}

.type-btn:hover,
.field-input input:hover,
.preview-text-row input:hover,
.reverse-input:hover { border-color: var(--border-strong); }

input[aria-invalid="true"] {
    border-color: rgba(229, 83, 75, 0.78) !important;
    box-shadow: 0 0 0 3px rgba(229, 83, 75, 0.1);
}

.type-btn.active {
    border-color: rgba(139, 108, 255, 0.7);
    box-shadow: inset 0 0 0 1px rgba(139, 108, 255, 0.12), 0 8px 22px rgba(32, 19, 80, 0.16);
}

.result-block {
    position: relative;
    border-color: rgba(139, 108, 255, 0.28);
    background: linear-gradient(130deg, rgba(139, 108, 255, 0.11), rgba(89, 183, 255, 0.035));
}

.result-head { padding: 11px 13px 10px 15px; }
.result-label { display: inline-flex; align-items: center; gap: 7px; }
.status-dot {
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: var(--ok);
    box-shadow: 0 0 0 4px rgba(51, 184, 107, 0.12), 0 0 14px rgba(51, 184, 107, 0.5);
}

.copy-btn {
    min-width: 70px;
    min-height: 34px;
    background: #f3f1ff;
    color: #251b4f;
    box-shadow: 0 6px 18px rgba(0, 0, 0, 0.18);
}

.copy-btn:hover { opacity: 1; transform: translateY(-1px); background: #fff; }
.copy-btn:active { transform: translateY(0); }
.copy-btn.copied { color: #fff; }

.result-code {
    padding: 18px;
    color: #8acaff;
    font-size: clamp(14px, 1.7vw, 17px);
    line-height: 1.55;
}

.formula-block { padding-inline: 2px; }

.preview-block {
    gap: 15px;
    padding: 20px;
    border: 1px solid var(--border);
    border-radius: 16px;
    background: rgba(8, 10, 14, 0.38);
    overflow: visible;
}

.preview-head {
    align-items: flex-start;
    flex-wrap: nowrap;
}

.preview-head h2 {
    margin-top: 2px;
    font-size: 22px;
    letter-spacing: -0.03em;
}

.preview-actions {
    display: flex;
    align-items: center;
    gap: 7px;
}

.scale-btn {
    display: inline-flex;
    align-items: center;
    gap: 7px;
    min-height: 36px;
    padding: 7px 11px;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.035);
    color: var(--muted);
    font-size: 11px;
    cursor: pointer;
    transition: 150ms ease;
}

.scale-btn span {
    color: #e1e4eb;
    font: 800 10px/1 "SF Mono", "Consolas", monospace;
}

.scale-btn b { font-size: 11px; white-space: nowrap; }
.scale-btn:hover { border-color: var(--border-strong); color: var(--text); }
.scale-btn.active { border-color: var(--accent-2); background: rgba(89, 183, 255, 0.12); color: #b9dfff; }

.play-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    min-height: 36px;
    padding: 8px 13px;
    border: 1px solid rgba(139, 108, 255, 0.36);
    border-radius: 10px;
    background: var(--accent-soft);
    color: #d8d0ff;
    font-size: 12px;
    font-weight: 750;
    cursor: pointer;
    transition: 150ms ease;
}

.play-btn:hover { border-color: var(--accent); background: rgba(139, 108, 255, 0.24); }
.play-btn.playing { background: var(--accent); border-color: var(--accent); color: #fff; }
.play-icon { width: 12px; font-size: 10px; text-align: center; }

.preview-controls {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 14px;
}

.preview-text-row {
    flex: 1 1 320px;
    max-width: 450px;
    flex-direction: column;
    align-items: stretch;
    gap: 6px;
}

.preview-text-row input { min-height: 38px; }

.viewport-presets {
    display: grid;
    grid-template-columns: repeat(3, minmax(78px, 1fr));
    gap: 6px;
    margin-left: auto;
}

.viewport-presets button {
    min-height: 52px;
    padding: 7px 9px;
    display: grid;
    grid-template-columns: auto 1fr;
    grid-template-rows: 1fr 1fr;
    column-gap: 7px;
    align-items: center;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: var(--panel-2);
    color: var(--muted);
    cursor: pointer;
    transition: 150ms ease;
}

.viewport-presets button > span {
    grid-row: 1 / 3;
    color: #c7cbd4;
    font-size: 17px;
}

.viewport-presets b { align-self: end; color: var(--text); font-size: 11px; text-align: left; }
.viewport-presets small { align-self: start; font: 600 9px/1.2 "SF Mono", "Consolas", monospace; text-align: left; }
.viewport-presets button:hover { border-color: var(--border-strong); transform: translateY(-1px); }
.viewport-presets button.active { border-color: var(--accent); background: var(--accent-soft); }
.viewport-presets button.active > span { color: #b8a8ff; }

.preview-readouts {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
}

.preview-readouts > span {
    min-width: 0;
    padding: 10px 12px;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.025);
}

.preview-readouts small {
    display: block;
    margin-bottom: 2px;
    color: var(--muted);
    font-size: 10px;
    font-weight: 700;
    letter-spacing: 0.04em;
}

.preview-readouts b {
    display: block;
    overflow: hidden;
    color: #f5f6fa;
    font: 750 14px/1.35 "SF Mono", "Consolas", monospace;
    text-overflow: ellipsis;
    white-space: nowrap;
}

#valueReadout { color: #7fc8ff; }
#phaseReadout[data-phase="fluid"] { color: #b7a7ff; }
#phaseReadout[data-phase="min"] { color: #79c7ff; }
#phaseReadout[data-phase="max"] { color: #d2a3ff; }

.viewport-canvas-wrap {
    min-height: 500px;
    padding: 34px 16px 48px;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    isolation: isolate;
    overflow: hidden;
    border-color: rgba(255, 255, 255, 0.12);
    border-radius: 13px;
    background: #090b0f;
    cursor: col-resize;
    touch-action: none;
    user-select: none;
}

.stage-grid {
    position: absolute;
    inset: 0;
    z-index: -1;
    opacity: 0.65;
    background:
        linear-gradient(rgba(255,255,255,.035) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,.035) 1px, transparent 1px),
        radial-gradient(circle at 50% 0%, rgba(139, 108, 255, 0.15), transparent 56%);
    background-size: 24px 24px, 24px 24px, 100% 100%;
}

.viewport-canvas {
    flex: 0 0 auto;
    width: calc(100% - 32px);
    min-width: 0;
    border: 1px solid rgba(255, 255, 255, 0.24);
    border-radius: 12px;
    background: #fff;
    box-shadow: 0 24px 55px rgba(0, 0, 0, 0.48), 0 0 0 5px rgba(255, 255, 255, 0.035);
    transition: width 130ms ease-out, transform 130ms ease-out, height 200ms ease;
    container-type: inline-size;
}

.viewport-canvas-wrap:active .viewport-canvas { transition: height 200ms ease; }

.viewport-canvas-wrap.actual-size {
    width: max-content;
    min-width: 100%;
    justify-content: flex-start;
    overflow: visible;
    cursor: default;
}

.viewport-canvas-wrap.actual-size .viewport-canvas { flex-shrink: 0; }
.viewport-canvas-wrap.actual-size .stage-hint { opacity: 0; }

.browser-chrome {
    height: 50px;
    padding: 0 14px;
    display: grid;
    grid-template-columns: auto minmax(120px, 420px) auto;
    justify-content: space-between;
    align-items: center;
    gap: 14px;
    border-bottom: 1px solid #dfe2e7;
    background: linear-gradient(#f7f8fa, #eff1f4);
    color: #656c78;
    font: 650 12px/1 "SF Mono", "Consolas", monospace;
}

.window-dots { display: flex; gap: 7px; }
.window-dots i {
    width: 11px;
    height: 11px;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: 50%;
    background: #c5c8cf;
    box-shadow: inset 0 -1px 1px rgba(0, 0, 0, 0.09);
}
.window-dots i:first-child { background: #ff796e; }
.window-dots i:nth-child(2) { background: #f6c557; }
.window-dots i:last-child { background: #5acb76; }
.fake-address {
    min-width: 0;
    height: 30px;
    padding: 0 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    border: 1px solid #e0e3e8;
    border-radius: 8px;
    background: rgba(255, 255, 255, 0.9);
    color: #656c78;
    text-align: center;
    text-overflow: ellipsis;
    white-space: nowrap;
    box-shadow: 0 1px 2px rgba(20, 24, 34, 0.04);
}
.chrome-value {
    padding: 7px 9px;
    border-radius: 7px;
    background: #e9e5ff;
    color: #5643bd;
    font-size: 12px;
    font-weight: 850;
    white-space: nowrap;
}

.preview-surface {
    position: relative;
    overflow: hidden;
    background:
        radial-gradient(circle at 88% 12%, rgba(139, 108, 255, 0.15), transparent 36%),
        linear-gradient(145deg, #ffffff, #f4f5f9);
    color: #171921;
    transition: height 200ms ease;
    container-type: inline-size;
}

.resize-grip {
    position: absolute;
    right: 3px;
    top: 50%;
    z-index: 3;
    width: 5px;
    height: 42px;
    transform: translateY(-30%);
    border: solid rgba(64, 51, 122, 0.35);
    border-width: 0 1px;
}

.stage-hint {
    position: absolute;
    left: 16px;
    right: 16px;
    bottom: 15px;
    color: #7c8390;
    font-size: 10px;
    font-weight: 650;
    text-align: center;
    pointer-events: none;
}

.vp-font {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    padding: 0;
    text-align: left;
}

.vp-demo-nav {
    min-height: 54px;
    padding: 0 clamp(24px, 4cqw, 54px);
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid rgba(28, 30, 38, 0.08);
}

.vp-demo-brand {
    color: #1a1c24;
    font-size: 13px;
    font-weight: 850;
    letter-spacing: -0.02em;
}

.vp-demo-nav-meta {
    color: #8a8f99;
    font: 750 9px/1 "SF Mono", "Consolas", monospace;
    letter-spacing: 0.1em;
}

.vp-font-layout {
    min-height: 0;
    flex: 1;
    padding: clamp(24px, 4cqw, 54px);
    display: grid;
    grid-template-columns: minmax(0, 1.65fr) minmax(210px, 0.7fr);
    align-items: center;
    gap: clamp(24px, 5cqw, 72px);
}

.vp-font-copy { min-width: 0; }

.vp-eyebrow {
    color: #6d5bd0;
    font-size: 10px;
    font-weight: 850;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.vp-font-title {
    display: block;
    max-width: 880px;
    margin-top: 12px;
    color: #171921;
    font-weight: 820;
    line-height: 1.02;
    letter-spacing: -0.045em;
    overflow-wrap: anywhere;
    transition: font-size 80ms linear;
}

.vp-font p {
    max-width: 520px;
    margin-top: 16px;
    color: #6d7280;
    font-size: 13px;
    line-height: 1.6;
}

.vp-demo-actions {
    margin-top: 20px;
    display: flex;
    align-items: center;
    gap: 13px;
}

.vp-demo-cta {
    padding: 10px 14px;
    border-radius: 9px;
    background: #1d2029;
    color: #fff;
    font-size: 11px;
    font-weight: 750;
    box-shadow: 0 8px 20px rgba(25, 28, 38, 0.14);
}

.vp-range-values {
    color: #6d5bd0;
    font: 750 10px/1 "SF Mono", "Consolas", monospace;
    white-space: nowrap;
}

.vp-demo-card {
    padding: clamp(18px, 2.4cqw, 30px);
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    border: 1px solid rgba(109, 91, 208, 0.16);
    border-radius: 18px;
    background: rgba(255, 255, 255, 0.72);
    box-shadow: 0 20px 50px rgba(59, 44, 125, 0.1);
}

.vp-demo-card small {
    color: #858a95;
    font-size: 9px;
    font-weight: 800;
    letter-spacing: .09em;
    text-transform: uppercase;
}

.vp-current-value {
    margin-top: 8px;
    color: #5e4ac4;
    font: 850 clamp(20px, 2.3cqw, 34px)/1 "SF Mono", "Consolas", monospace;
}

.vp-demo-meter {
    width: 100%;
    height: 7px;
    margin-top: 18px;
    display: grid;
    grid-template-columns: .6fr 1.7fr .8fr;
    gap: 3px;
}

.vp-demo-meter i { border-radius: 99px; background: #dcefff; }
.vp-demo-meter i:nth-child(2) { background: linear-gradient(90deg, #8b6cff, #59b7ff); }
.vp-demo-meter i:last-child { background: #eadcff; }
.vp-demo-card p { margin-top: 16px; color: #767b87; font-size: 10px; line-height: 1.55; }
}

.vp-spacing { padding: clamp(22px, 3cqw, 42px); }
.vp-spacing-shell {
    width: min(100%, 900px);
    display: flex;
    flex-direction: column;
    gap: 16px;
}
.vp-spacing-heading { display: flex; flex-direction: column; gap: 4px; }
.vp-spacing-heading small { color: #6d5bd0; font-size: 9px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.vp-spacing-heading strong { max-width: 520px; color: #1b1e27; font-size: clamp(18px, 2.2cqw, 27px); letter-spacing: -.025em; }
.vp-spacing-box {
    max-width: 720px;
    height: auto;
    min-height: 120px;
    border: 1px solid #d7d2f6;
    border-radius: 16px;
    background: rgba(255, 255, 255, 0.94);
    box-shadow: 0 18px 42px rgba(59, 44, 125, 0.12);
}

.vp-spacing-metrics { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.vp-spacing-metrics > span {
    padding: 10px 12px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border: 1px solid #e2e4ea;
    border-radius: 10px;
    background: rgba(255,255,255,.66);
}
.vp-spacing-metrics small { color: #858a95; font-size: 9px; font-weight: 700; }
.vp-spacing-metrics b { color: #5e4ac4; font: 800 10px/1 "SF Mono", "Consolas", monospace; }

.vp-avatar {
    display: grid;
    place-items: center;
    width: 44px;
    height: 44px;
    flex: 0 0 auto;
    border-radius: 13px;
    background: linear-gradient(145deg, #8b6cff, #59b7ff);
    color: #fff;
    font-size: 12px;
    font-weight: 850;
}

.vp-card-copy { display: flex; min-width: 0; flex: 1; flex-direction: column; gap: 4px; }
.vp-card-copy small { color: #868b96; font-size: 9px; font-weight: 750; text-transform: uppercase; letter-spacing: .08em; }
.vp-card-copy b { color: #1d2028; font-size: 13px; line-height: 1.3; }
.vp-card-action {
    display: grid;
    place-items: center;
    width: 34px;
    height: 34px;
    flex: 0 0 auto;
    border-radius: 50%;
    background: #f0edff;
    color: #6d5bd0;
    font-weight: 800;
}

.vp-generic {
    flex-direction: column;
    align-items: stretch;
    justify-content: center;
    padding: clamp(28px, 5cqw, 64px);
}

.vp-generic > strong { margin-top: 6px; font-size: 20px; }
.vp-generic > p { max-width: 560px; margin-top: 10px; color: #747a87; font-size: 12px; line-height: 1.55; }
.vp-generic-track {
    height: 28px;
    margin-top: 20px;
    overflow: hidden;
    border-radius: 8px;
    background: #e6e8ef;
}
.vp-generic-bar { height: 100%; min-width: 4px; border-radius: 8px; }
.vp-generic-value { margin-top: 9px; color: #5f4dc5; font: 800 12px/1 "SF Mono", "Consolas", monospace; }
.vp-generic-ticks { margin-top: 7px; display: flex; justify-content: space-between; color: #999eaa; font: 700 8px/1 "SF Mono", "Consolas", monospace; letter-spacing: .08em; }

@container (max-width: 640px) {
    .vp-font-layout { grid-template-columns: 1fr; }
    .vp-demo-card { display: none; }
}

@container (max-width: 420px) {
    .browser-chrome {
        grid-template-columns: auto 1fr;
        gap: 10px;
        padding-inline: 12px;
    }
    .fake-address { display: none; }
    .chrome-value { justify-self: end; }
    .vp-demo-nav { padding-inline: 22px; }
    .vp-demo-nav-meta { display: none; }
    .vp-font-layout { padding: 24px 22px; }
    .vp-font p { font-size: 12px; }
    .vp-demo-actions { align-items: flex-start; flex-direction: column; gap: 10px; }
    .vp-spacing-shell { gap: 12px; }
    .vp-spacing-metrics { grid-template-columns: 1fr; }
}

.slider-group { padding: 7px 4px 18px; }
.slider-row { gap: 11px; }
.slider-min, .slider-max { min-width: 53px; font-size: 10px; }
input[type="range"] { height: 8px; }
input[type="range"]::-webkit-slider-thumb { width: 21px; height: 21px; border-width: 3px; }
input[type="range"]::-moz-range-thumb { width: 17px; height: 17px; border-width: 3px; }

.breakpoint-track {
    position: relative;
    height: 16px;
    margin: 4px 64px 0;
}

.breakpoint-track > span {
    position: absolute;
    top: 0;
    transform: translateX(-50%);
}

.breakpoint-track i { display: block; width: 1px; height: 7px; margin: 0 auto; background: var(--border-strong); }
.breakpoint-track b {
    display: block;
    margin-top: 1px;
    color: #777f8e;
    font: 600 8px/1 "SF Mono", "Consolas", monospace;
    white-space: nowrap;
}
.slider-hint { margin-top: -8px; text-align: center; }

.chart-block {
    padding-top: 16px;
    border-top: 1px solid var(--border);
}

.chart-head {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 10px;
}

.chart-head > div:first-child { display: flex; flex-direction: column; gap: 2px; }
.chart-head b { font-size: 13px; }
.chart-head > div:first-child span { color: var(--muted); font-size: 10px; }
.chart-block svg {
    height: 160px;
    border-color: rgba(255, 255, 255, 0.1);
    background: rgba(255, 255, 255, 0.025);
    cursor: ew-resize;
    touch-action: none;
}
.chart-legend { margin-top: 0; gap: 12px; font-size: 10px; white-space: nowrap; }
.dot { width: 7px; height: 7px; border-radius: 50%; }

.reverse {
    padding: 20px 22px;
    background: linear-gradient(120deg, rgba(89, 183, 255, 0.06), rgba(139, 108, 255, 0.035));
}
.reverse h2 { font-size: 16px; }
.reverse-input { max-width: 620px; }

@media (max-width: 1040px) {
    .layout { grid-template-columns: 1fr; }
    .config { position: static; }
    .output { position: static; }
}

@media (max-width: 700px) {
    .topbar { padding: 28px 18px 12px; align-items: flex-start; }
    .toolbar { position: absolute; top: 26px; right: 18px; }
    .hero-copy { padding-right: 64px; }
    .topbar .subtitle { font-size: 13px; }
    .layout { padding: 14px 16px 34px; }
    .panel { padding: 18px; }
    .preview-block { padding: 16px; }
    .preview-controls { align-items: stretch; flex-direction: column; }
    .preview-text-row { max-width: none; flex-basis: auto; }
    .preview-readouts { grid-template-columns: 1fr 1fr; }
    .viewport-presets { width: 100%; margin-left: 0; }
    .viewport-canvas-wrap { min-height: 500px; }
    .chart-head { align-items: flex-start; flex-direction: column; }
}

@media (max-width: 480px) {
    .hero-copy { padding-right: 62px; }
    .topbar h1 { font-size: 29px; }
    .panel-intro { padding-bottom: 15px; margin-bottom: 16px; }
    .type-options { grid-template-columns: repeat(3, 1fr); }
    .type-btn { flex-direction: column; gap: 5px; padding: 11px 5px; }
    .field-grid { grid-template-columns: 1fr 1fr; }
    .preview-head h2 { font-size: 19px; }
    .play-btn { padding-inline: 10px; }
    .scale-btn b { display: none; }
    .viewport-presets button { min-width: 0; padding-inline: 6px; }
    .viewport-presets button > span { display: none; }
    .viewport-presets button { grid-template-columns: 1fr; }
    .viewport-canvas-wrap { min-height: 500px; padding-inline: 10px; }
    .viewport-canvas { max-width: none; }
    .fake-address { visibility: hidden; }
    .breakpoint-track { margin-inline: 63px; }
    .chart-legend { width: 100%; justify-content: space-between; gap: 6px; }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 0.01ms !important; }
}

/* ================= 顶栏精简 / 侧栏布局 / 数值输入 ================= */

/* ---- 顶栏：单行紧凑，去掉图标块 ---- */
.topbar {
    display: flex;
    align-items: center;
    gap: 18px;
    padding: 22px clamp(20px, 2vw, 40px) 4px;
    text-align: left;
}

.hero-copy {
    display: flex;
    align-items: baseline;
    flex-wrap: wrap;
    gap: 2px 13px;
    min-width: 0;
}

.topbar h1 {
    margin-top: 0;
    font-size: clamp(21px, 1.9vw, 27px);
    line-height: 1.2;
    letter-spacing: -0.035em;
}

.topbar .subtitle {
    margin-top: 0;
    padding-left: 13px;
    border-left: 1px solid var(--border);
    color: var(--muted);
    font-size: 13px;
    line-height: 1.35;
}

.toolbar { margin-left: auto; align-self: center; }

/* ---- 左侧栏：配置 + 反向推算，跟随滚动 ---- */
.layout { padding-top: 10px; }

.side-stack {
    display: flex;
    flex-direction: column;
    gap: 18px;
    min-width: 0;
    position: sticky;
    top: 16px;
    align-self: start;
}

.config { position: static; }

/* 视口不够高时不粘，避免底部被截断 */
@media (max-height: 860px) {
    .side-stack { position: static; }
}

/* ---- 反向推算：适配窄栏 ---- */
.reverse { padding: 20px; }
.reverse-intro { padding-bottom: 14px; margin-bottom: 14px; }
.reverse-intro h2 { font-size: 15px; }
.reverse-intro p { margin-bottom: 0; }

.reverse-input {
    width: 100%;
    max-width: none;
    padding: 10px 12px;
    font-size: 13px;
}

.reverse-result {
    display: grid;
    grid-template-columns: 1fr 1fr;
    align-items: stretch;
    gap: 9px;
    margin-top: 12px;
}

.rev-stat {
    display: flex;
    flex-direction: column;
    gap: 2px;
    padding: 8px 10px;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: rgba(255, 255, 255, 0.03);
}

.rev-stat small {
    color: var(--muted);
    font: 800 9px/1.4 inherit;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.rev-stat b {
    color: var(--accent-2);
    font: 800 17px/1.2 "SF Mono", "Consolas", monospace;
}

.reverse-result .apply-btn {
    grid-column: 1 / -1;
    width: 100%;
    min-height: 34px;
    margin-left: 0;
}

.reverse-error { margin-top: 10px; }

/* ---- 复制成功态必须压过 hover（hover 定义在后面，特异性相同） ---- */
.copy-btn.copied,
.copy-btn.copied:hover,
.copy-btn.copied:active {
    background: var(--ok);
    color: #fff;
    opacity: 1;
}

/* ---- 数值输入：text 类型，去掉原生上下箭头 ---- */
.num-input {
    font-variant-numeric: tabular-nums;
    letter-spacing: 0.01em;
}

.num-input::-webkit-outer-spin-button,
.num-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }

.field-input { position: relative; }

.field-input .kbd-hint {
    position: absolute;
    right: 8px;
    top: 50%;
    transform: translateY(-50%);
    display: none;
    color: var(--muted);
    font: 700 9px/1 "SF Mono", "Consolas", monospace;
    letter-spacing: 0.04em;
    pointer-events: none;
    opacity: 0.55;
}

.field-input:focus-within .kbd-hint { display: block; }
.field-input:focus-within .unit-hint { opacity: 0; }

/* ---- 断点 ---- */
@media (max-width: 1040px) {
    .side-stack { display: contents; }
    .reverse { order: 1; }
}

@media (max-width: 700px) {
    .topbar { align-items: flex-start; padding: 22px 18px 6px; }
    .hero-copy { padding-right: 84px; }
    .topbar .subtitle { padding-left: 0; border-left: none; }
    .toolbar { position: absolute; top: 20px; right: 18px; }
    .reverse-result { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 480px) {
    .topbar h1 { font-size: 22px; }
    .hero-copy { padding-right: 78px; }
}

/* ================= 常见问题（FAQPage 结构化数据的可见内容） ================= */
.faq {
    width: 100%;
    padding: 4px clamp(20px, 2vw, 40px) 26px;
}

.faq > h2 {
    margin-bottom: 13px;
    font-size: 16px;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.faq-list {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    align-items: start;
    gap: 10px;
}

@media (max-width: 1300px) {
    .faq-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

.faq-item {
    padding: 0 16px;
    border: 1px solid var(--border);
    border-radius: 14px;
    background: linear-gradient(160deg, rgba(25, 29, 38, 0.72), rgba(16, 19, 25, 0.72));
    transition: border-color 150ms ease;
}

.faq-item[open],
.faq-item:hover { border-color: var(--border-strong); }

.faq-item summary {
    position: relative;
    padding: 13px 26px 13px 0;
    font-size: 14px;
    font-weight: 700;
    line-height: 1.45;
    list-style: none;
    cursor: pointer;
}

.faq-item summary::-webkit-details-marker { display: none; }

.faq-item summary::after {
    content: "+";
    position: absolute;
    top: 50%;
    right: 0;
    transform: translateY(-50%);
    color: var(--muted);
    font: 400 18px/1 "SF Mono", "Consolas", monospace;
    transition: color 150ms ease;
}

.faq-item[open] summary::after { content: "\2212"; color: var(--accent-2); }

.faq-item p {
    padding: 0 0 15px;
    color: var(--muted);
    font-size: 13px;
    line-height: 1.75;
}

@media (max-width: 760px) {
    .faq { padding-inline: 16px; }
    .faq-list { grid-template-columns: 1fr; }
}

/* ================= 首帧抑制过渡 ================= */
/* JS 初始化时会把画布宽度从 CSS 的 calc(100% - 32px) 改成模拟视口宽度，
   若此时 transition 已生效，页面一打开就会看到画布从满宽收缩到 800px。
   is-booting 由 index.html 内联写死，init() 里双 rAF 后移除。 */
html.is-booting *,
html.is-booting *::before,
html.is-booting *::after {
    transition: none !important;
    animation: none !important;
}