:root {
    color-scheme: light;
    --tool-bg: #f3f6fb;
    --tool-card: #ffffff;
    --tool-text: #101827;
    --tool-muted: #5f6b7a;
    --tool-border: #d9e1ec;
    --tool-soft: #eef4ff;
    --tool-primary: #101827;
    --tool-blue: #1457d9;
}

* { box-sizing: border-box; }

body.etabs-steel-tool-body {
    margin: 0;
    background: var(--tool-bg);
    color: var(--tool-text);
    font-family: Inter, "Segoe UI", system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
}

.etabs-steel-tool {
    width: min(1440px, calc(100% - 32px));
    margin: 0 auto;
    padding: 32px 0 42px;
}

.tool-header {
    display: flex;
    justify-content: space-between;
    gap: 24px;
    align-items: flex-start;
    margin-bottom: 24px;
}

.back-link {
    display: inline-flex;
    color: var(--tool-muted);
    text-decoration: none;
    font-weight: 700;
    margin-bottom: 18px;
}

.back-link:hover { color: var(--tool-primary); }

.eyebrow {
    margin: 0 0 8px;
    color: var(--tool-blue);
    font-weight: 800;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    font-size: 0.78rem;
}

h1 {
    margin: 0;
    font-size: clamp(2rem, 4vw, 4.2rem);
    line-height: 0.96;
    max-width: 900px;
}

.lede {
    margin: 16px 0 0;
    max-width: 760px;
    color: var(--tool-muted);
    font-size: 1.05rem;
    line-height: 1.55;
}

.tool-header-actions {
    display: inline-flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 12px;
}

.full-structure-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 42px;
    padding: 10px 16px;
    border-radius: 999px;
    background: var(--tool-primary);
    color: #fff;
    text-decoration: none;
    font-weight: 900;
    box-shadow: 0 14px 28px rgba(15, 23, 42, 0.14);
}

.full-structure-button:hover {
    transform: translateY(-1px);
}

.language-switcher {
    display: inline-flex;
    gap: 6px;
    padding: 6px;
    background: #fff;
    border: 1px solid var(--tool-border);
    border-radius: 999px;
    box-shadow: 0 10px 24px rgba(15, 23, 42, 0.08);
}

.language-switch-button {
    border: 0;
    border-radius: 999px;
    padding: 8px 12px;
    background: transparent;
    cursor: pointer;
    font-weight: 800;
    color: var(--tool-muted);
}

.language-switch-button.is-active {
    background: var(--tool-primary);
    color: #fff;
}

.tool-grid-layout {
    display: grid;
    grid-template-columns: minmax(320px, 420px) minmax(0, 1fr);
    gap: 22px;
    align-items: start;
}

.tool-panel {
    display: grid;
    gap: 16px;
}

.import-card,
.viewer-card {
    background: var(--tool-card);
    border: 1px solid var(--tool-border);
    border-radius: 26px;
    box-shadow: 0 18px 42px rgba(15, 23, 42, 0.09);
}

.import-card {
    padding: 20px;
}

.import-card-header {
    display: flex;
    gap: 14px;
    align-items: flex-start;
    margin-bottom: 14px;
}

.step-badge {
    width: 34px;
    height: 34px;
    display: inline-grid;
    place-items: center;
    border-radius: 50%;
    background: var(--tool-soft);
    color: var(--tool-blue);
    font-weight: 900;
    flex: 0 0 auto;
}

.import-card h2 {
    margin: 0;
    font-size: 1.15rem;
}

.import-card p {
    margin: 6px 0 0;
    color: var(--tool-muted);
    line-height: 1.45;
}

.instruction-details {
    margin: 12px 0 18px;
    border: 1px solid var(--tool-border);
    border-radius: 16px;
    background: #fbfdff;
    overflow: hidden;
}

.instruction-details summary {
    cursor: pointer;
    padding: 12px 14px;
    color: #243044;
    font-weight: 900;
    list-style-position: inside;
}

.instruction-details summary:hover {
    background: var(--tool-soft);
}

.instruction-list {
    margin: 0;
    padding: 0 18px 16px 36px;
    color: #243044;
    line-height: 1.45;
    font-size: 0.94rem;
}

.instruction-list li + li { margin-top: 7px; }

.field-label {
    display: block;
    font-weight: 800;
    font-size: 0.86rem;
    color: #2c3749;
    margin-bottom: 8px;
}

.unit-select,
.frame-picker-wrap select {
    width: 100%;
    border: 1px solid var(--tool-border);
    border-radius: 14px;
    padding: 11px 12px;
    background: #fff;
    color: var(--tool-text);
    font-weight: 700;
}

.primary-action,
.secondary-action {
    width: 100%;
    margin-top: 14px;
    border: 0;
    border-radius: 16px;
    padding: 13px 16px;
    font-weight: 900;
    cursor: pointer;
}

.primary-action {
    background: var(--tool-primary);
    color: #fff;
}

.secondary-action {
    background: var(--tool-blue);
    color: #fff;
}

.primary-action:disabled,
.secondary-action:disabled,
.nav-button:disabled {
    cursor: not-allowed;
    opacity: 0.45;
}

.status-line {
    min-height: 22px;
    font-size: 0.9rem;
}

.status-line.is-error { color: #ad1f1f; }
.status-line.is-success { color: #176b35; }

.viewer-card {
    padding: 18px;
    min-width: 0;
}

.viewer-toolbar {
    display: grid;
    grid-template-columns: 52px minmax(0, 1fr) 52px auto;
    gap: 12px;
    align-items: end;
    margin-bottom: 12px;
}

.nav-button {
    height: 50px;
    border: 1px solid var(--tool-border);
    border-radius: 16px;
    background: #fff;
    font-size: 2rem;
    line-height: 1;
    cursor: pointer;
}

.zoom-controls {
    display: inline-flex;
    gap: 8px;
    justify-content: flex-end;
}

.zoom-button {
    min-height: 42px;
    border: 1px solid var(--tool-border);
    border-radius: 14px;
    background: #fff;
    color: var(--tool-primary);
    cursor: pointer;
    font-weight: 900;
    padding: 0 12px;
}

.zoom-button:hover,
.nav-button:hover {
    border-color: var(--tool-primary);
}

.frame-picker-wrap label {
    display: block;
    margin-bottom: 6px;
    font-weight: 900;
}

.viewer-meta {
    color: var(--tool-muted);
    font-size: 0.94rem;
    margin: 6px 0 12px;
}

.canvas-shell {
    width: 100%;
    min-height: 560px;
    border: 1px solid #cfd8e6;
    border-radius: 22px;
    overflow: hidden;
    background: #fff;
}

#frame-canvas {
    display: block;
    width: 100%;
    height: 640px;
    background: #fff;
    cursor: grab;
    touch-action: none;
}

#frame-canvas.is-panning {
    cursor: grabbing;
}

@media (max-width: 980px) {
    .tool-header,
    .tool-grid-layout { grid-template-columns: 1fr; }
    .tool-header { display: grid; }
    .tool-header-actions { align-items: flex-start; }
    .viewer-toolbar { grid-template-columns: 52px minmax(0, 1fr) 52px; }
    .zoom-controls { grid-column: 1 / -1; justify-content: flex-start; flex-wrap: wrap; }
}

@media (max-width: 640px) {
    .etabs-steel-tool { width: min(100% - 20px, 1440px); padding-top: 20px; }
    .viewer-toolbar { grid-template-columns: 44px minmax(0, 1fr) 44px; }
    .zoom-controls { grid-column: 1 / -1; }
    .zoom-button { flex: 1 1 auto; }
    #frame-canvas { height: 520px; }
}