/* Scroll story: a sticky stage with a step list on the left and a visual that
   changes as the reader scrolls (the pattern depthfirst.com uses for its
   "security operating system" section). Progressive: without JS, or on narrow
   screens, every step is open and the visuals stack inline. */

.ss { position: relative; --ss-top: 64px; --ss-steps: 4; --ss-ease: cubic-bezier(0.4, 0, 0.2, 1); --ss-dur: 0.6s; }
.ss[data-enhanced="true"] { min-height: calc(var(--ss-steps) * 85vh + 100vh); }
.ss-stage { position: relative; }
.ss[data-enhanced="true"] .ss-stage { position: sticky; top: calc(var(--ss-top) + 24px); min-height: calc(100vh - var(--ss-top) - 48px); height: auto; display: grid; grid-template-rows: auto minmax(0, 1fr); gap: clamp(20px, 3vh, 40px); }
/* short viewports: keep the pinned stage inside the window */
@media (max-height: 820px) { .ss[data-enhanced="true"] .ss-stage { gap: 14px; } .ss[data-enhanced="true"] .ss-visual { zoom: 0.84; } .ss[data-enhanced="true"] .ss-step-btn { padding: 1rem 0 0.55rem; } }
@media (max-height: 720px) { .ss[data-enhanced="true"] .ss-visual { zoom: 0.72; } }
.ss-head { margin: 0; }
.ss-layout { display: grid; grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr); gap: clamp(2.5rem, 5vw, 5rem); align-items: center; min-height: 0; }
.ss-steps { list-style: none; margin: 0; padding: 0; grid-column: 1; grid-row: 1; }
.ss-step { position: relative; }
.ss-step::before, .ss-step::after { content: ""; position: absolute; left: 0; bottom: 0; width: 100%; height: 1px; background: var(--border-soft); }
.ss-step::after { background: var(--ink); transform: scaleX(var(--ss-p, 0)); transform-origin: left center; transition: transform 0.12s linear; }
.ss-step-btn { display: flex; align-items: baseline; gap: 14px; width: 100%; padding: 1.3rem 0 0.7rem; border: 0; background: none; text-align: left; color: var(--muted); font-family: var(--sans); font-size: clamp(18px, 1.6vw, 22px); font-weight: 500; letter-spacing: -0.015em; line-height: 1.25; cursor: pointer; transition: color 0.3s var(--ss-ease); }
.ss-step-btn .ss-n { font-family: var(--mono); font-size: 12px; letter-spacing: 0.04em; color: var(--dim); flex: none; width: 22px; }
.ss-step[data-active="true"] .ss-step-btn, .ss-step-btn:hover { color: var(--ink); }
.ss-step[data-active="true"] .ss-step-btn .ss-n { color: var(--ink); }
.ss-body { display: grid; grid-template-rows: 0fr; opacity: 0; transition: grid-template-rows var(--ss-dur) var(--ss-ease), opacity 0.4s var(--ss-ease); }
.ss-step[data-active="true"] .ss-body { grid-template-rows: 1fr; opacity: 1; }
.ss-body > div { min-height: 0; overflow: hidden; }
.ss-body p { margin: 0 0 0 36px; padding-bottom: 1.4rem; color: var(--text-soft); font-size: 15.5px; line-height: 1.55; max-width: 50ch; }
.ss-visual { position: relative; display: grid; min-width: 0; align-items: center; grid-column: 2; grid-row: 1; }
.ss-panel { grid-area: 1 / 1; min-width: 0; opacity: 0; visibility: hidden; transition: opacity var(--ss-dur) var(--ss-ease), visibility var(--ss-dur); }
.ss-panel[data-active="true"] { opacity: 1; visibility: visible; }
.ss-visual.ss-single .ss-panel { opacity: 1; visibility: visible; }

/* static fallback: no JS, reduced motion, or a narrow screen */
.ss:not([data-enhanced="true"]) .ss-layout { grid-template-columns: minmax(0, 1fr); align-items: start; }
.ss:not([data-enhanced="true"]) .ss-body { grid-template-rows: 1fr; opacity: 1; }
.ss:not([data-enhanced="true"]) .ss-step-btn { color: var(--ink); cursor: default; }
.ss:not([data-enhanced="true"]) .ss-step::after { display: none; }
.ss:not([data-enhanced="true"]) .ss-steps, .ss:not([data-enhanced="true"]) .ss-visual { grid-column: 1; grid-row: auto; }
.ss:not([data-enhanced="true"]) .ss-visual { display: grid; gap: 14px; order: -1; margin-bottom: 8px; }
.ss:not([data-enhanced="true"]) .ss-panel { grid-area: auto; opacity: 1; visibility: visible; }
.ss:not([data-enhanced="true"]) .ss-visual.ss-single .ss-panel + .ss-panel { display: none; }

/* dark variant (section on --df-dark) */
.ss-dark { color: var(--df-ink-inverse); }
.ss-dark .ss-step::before { background: var(--df-dark-line); }
.ss-dark .ss-step::after { background: var(--df-ink-inverse); }
.ss-dark .ss-step-btn { color: var(--df-ink-inverse-soft); }
.ss-dark .ss-step[data-active="true"] .ss-step-btn, .ss-dark .ss-step-btn:hover, .ss-dark .ss-step[data-active="true"] .ss-step-btn .ss-n { color: var(--df-ink-inverse); }
.ss-dark .ss-body p { color: var(--df-ink-inverse-soft); }
.ss-dark:not([data-enhanced="true"]) .ss-step-btn { color: var(--df-ink-inverse); }

@media (prefers-reduced-motion: reduce) { .ss-step-btn, .ss-body, .ss-panel, .ss-step::after { transition: none; } }

/* an element after the stacked panels (e.g. a demo link) sits below them */
.ss-visual > .ss-visual-foot { grid-area: 2 / 1; min-width: 0; }
.ss:not([data-enhanced="true"]) .ss-visual > .ss-visual-foot { grid-area: auto; }