/* 扩展下载页 — 更开阔的尺度 + 圆角 */
.extend-page {
    --ex-ink: #0a0a0a;
    --ex-ink-soft: #2a2a2a;
    --ex-muted: #6b6b6b;
    --ex-line: #e8e8e6;
    --ex-surface: #ffffff;
    --ex-wash: #f3f3f1;
    --ex-radius: 18px;
    --ex-radius-sm: 12px;
    position: relative;
    margin: -1.5rem -1rem 0;
    padding: 0 1rem 2.5rem;
}

.extend-top {
    position: relative;
    padding: 0 0 1rem;
    margin-bottom: 3.5rem;
    background: none;
}

.extend-hero {
    text-align: center;
    padding: 3.25rem 1rem 2.5rem;
}

.extend-hero__brand {
    display: inline-block;
    font-size: 0.82rem;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    color: var(--ex-muted);
    margin-bottom: 1.15rem;
}

.extend-hero h1 {
    color: var(--ex-ink);
    font-weight: 700;
    font-size: clamp(2.4rem, 5vw, 3.5rem);
    letter-spacing: -0.035em;
    line-height: 1.08;
    margin-bottom: 1rem;
}

.extend-hero p {
    color: var(--ex-muted);
    font-size: clamp(1.05rem, 1.6vw, 1.25rem);
    max-width: 38rem;
    margin: 0 auto;
    line-height: 1.55;
}

.extend-download {
    max-width: 1120px;
    margin: 0 auto;
    background: var(--ex-surface);
    border: 1px solid var(--ex-line);
    border-radius: var(--ex-radius);
    padding: 2.5rem 2.75rem 2.15rem;
}

.extend-download__grid {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr auto;
    gap: 1.35rem 1.4rem;
    align-items: end;
}

.extend-field label {
    display: block;
    font-size: 0.9rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    color: var(--ex-ink-soft);
    margin-bottom: 0.65rem;
}

.extend-field .form-select {
    height: 56px;
    border-radius: var(--ex-radius-sm);
    border-color: #d2d2d0;
    background-color: #fafafa;
    color: var(--ex-ink);
    font-size: 1rem;
    padding: 0.65rem 1rem;
    transition: border-color 0.2s ease, background-color 0.2s ease, box-shadow 0.2s ease;
}

.extend-field .form-select:hover:not(:disabled) {
    border-color: #aeaeae;
    background-color: #fff;
}

.extend-field .form-select:focus {
    border-color: var(--ex-ink);
    background-color: #fff;
    box-shadow: 0 0 0 4px rgba(0, 0, 0, 0.07);
}

.extend-field .form-select:disabled {
    opacity: 0.55;
    cursor: not-allowed;
}

.extend-download__action {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    align-items: stretch;
}

.extend-download__action .btn {
    height: 56px;
    min-width: 156px;
    border-radius: var(--ex-radius-sm);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.55rem;
    padding: 0 1.7rem;
    font-size: 1.05rem;
    font-weight: 600;
    transition: background-color 0.2s ease, opacity 0.2s ease;
}

.extend-download__action .btn img {
    width: 18px;
    height: 18px;
}

.extend-download__script-btn i {
    display: inline-block;
    font-size: 1.15rem;
    line-height: 1;
}

.extend-selection {
    margin-top: 1.6rem;
    padding: 1.1rem 1.35rem;
    background: var(--ex-wash);
    border-radius: var(--ex-radius-sm);
    border: 1px solid transparent;
    border-left: 4px solid var(--ex-ink);
    display: flex;
    flex-wrap: wrap;
    gap: 0.45rem 0.85rem;
    align-items: baseline;
    transition: background-color 0.25s ease;
}

.extend-selection.is-updating {
    background: #e9e9e6;
}

.extend-selection__label {
    font-size: 0.9rem;
    color: var(--ex-muted);
}

.extend-selection__value {
    font-size: 1.05rem;
    font-weight: 650;
    color: var(--ex-ink);
    letter-spacing: -0.015em;
}

.extend-section {
    max-width: 1120px;
    margin: 0 auto 2.5rem;
    padding: 0;
}

.extend-section:not(:last-child) {
    margin-bottom: 4.5rem;
}

.extend-section__head {
    text-align: center;
    margin-bottom: 2.25rem;
}

.extend-section__head h2 {
    font-size: clamp(1.65rem, 2.6vw, 2.05rem);
    font-weight: 700;
    color: var(--ex-ink);
    letter-spacing: -0.025em;
    margin-bottom: 0.55rem;
}

.extend-section__head p {
    color: var(--ex-muted);
    margin: 0;
    font-size: 1.05rem;
}

.extend-steps {
    list-style: none;
    margin: 0;
    padding: 0rem;
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    position: relative;
    gap: 1.5rem;
}

.extend-steps::before {
    content: "";
    position: absolute;
    top: 1.25rem;
    left: calc(3.5rem + 1.25rem);
    right: calc(3.5rem + 1.25rem);
    height: 1px;
    background: var(--ex-line);
}

.extend-step {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    flex: 0 1 auto;
    width: 30%;
    max-width: 16rem;
    padding: 0;
    background: none;
    border: none;
    border-radius: 0;
}

.extend-step__marker {
    position: relative;
    z-index: 2;
    margin-bottom: 1.25rem;
    background: #ffffff;
    padding: 0 0.45rem;
}

.extend-step__index {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 2.5rem;
    height: 2.5rem;
    border-radius: 50%;
    background: var(--ex-ink);
    color: #fff;
    font-size: 0.95rem;
    font-weight: 700;
    letter-spacing: 0;
    line-height: 1;
    margin-bottom: 0;
}

.extend-step__body h3 {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--ex-ink);
    margin-bottom: 0.45rem;
    letter-spacing: -0.02em;
}

.extend-step__body p {
    margin: 0;
    color: var(--ex-muted);
    font-size: 1rem;
    line-height: 1.5;
}

.extend-compat {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.25rem;
}

.extend-compat__item {
    padding: 2rem 1.35rem;
    border: 1px solid var(--ex-line);
    border-radius: var(--ex-radius);
    background: var(--ex-surface);
    text-align: center;
}

.extend-compat__item i {
    font-size: 1.85rem;
    color: var(--ex-ink);
    margin-bottom: 1rem;
    display: block;
}

.extend-compat__item h3 {
    font-size: 1.05rem;
    font-weight: 700;
    color: var(--ex-ink);
    margin-bottom: 0.55rem;
}

.extend-compat__item p {
    margin: 0;
    font-size: 0.92rem;
    color: var(--ex-muted);
    line-height: 1.55;
}

@media (max-width: 991.98px) {
    .extend-download {
        padding: 2rem 1.5rem 1.75rem;
    }

    .extend-download__grid {
        grid-template-columns: 1fr 1fr;
    }

    .extend-download__action {
        grid-column: 1 / -1;
    }

    .extend-download__action .btn {
        width: 100%;
    }

    .extend-steps {
        flex-direction: column;
        gap: 0;
        padding: 0 0 0 0.25rem;
    }

    .extend-steps::before {
        left: calc(0.25rem + 1.25rem);
        right: auto;
        width: 1px;
        top: 1.25rem;
        bottom: 1.25rem;
        height: auto;
    }

    .extend-step {
        flex-direction: row;
        align-items: flex-start;
        text-align: left;
        width: auto;
        max-width: none;
        gap: 1rem;
        padding: 0 0 1.75rem 0;
    }

    .extend-step:last-child {
        padding-bottom: 0;
    }

    .extend-step__marker {
        margin-bottom: 0;
        padding: 0.35rem 0;
        flex-shrink: 0;
    }

    .extend-compat {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 575.98px) {
    .extend-page {
        padding-bottom: 3.5rem;
    }

    .extend-top {
        padding-bottom: 0.5rem;
        margin-bottom: 2.5rem;
    }

    .extend-hero {
        padding: 2.5rem 0.5rem 2rem;
    }

    .extend-download {
        padding: 1.5rem 1.2rem 1.35rem;
    }

    .extend-download__grid {
        grid-template-columns: 1fr;
    }

    .extend-section {
        margin-bottom: 2rem;
    }

    .extend-section:not(:last-child) {
        margin-bottom: 3.5rem;
    }

    .extend-compat {
        grid-template-columns: 1fr;
    }
}