/* ──────────────────────────────────────────────────────────────────────
   Reset, typography, and the "desk" the notebook sits on.
   ────────────────────────────────────────────────────────────────────── */

*,
*::before,
*::after { box-sizing: border-box; }

* { margin: 0; padding: 0; }

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

body {
  min-height: 100dvh;
  font-family: var(--font-ui);
  font-size: var(--text-base);
  line-height: var(--leading-normal);
  color: var(--ink);
  background: var(--desk-2);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: var(--leading-tight);
  letter-spacing: -0.015em;
}

button, input, select, textarea {
  font: inherit;
  color: inherit;
}

button { background: none; border: none; cursor: pointer; }

a { color: var(--accent); text-decoration: none; }

code, kbd, pre { font-family: var(--font-mono); }

::selection {
  background: var(--highlighter);
  color: var(--ink);
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

.skip-link {
  position: absolute;
  left: -999px;
  top: var(--space-2);
  z-index: 200;
  padding: var(--space-2) var(--space-4);
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-pop);
}
.skip-link:focus { left: var(--space-4); }

/* Visually hidden but available to assistive tech. */
.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

/* ── The desk ─────────────────────────────────────────────────────────
   A fixed backdrop: warm gradient, two slow-drifting light pools, and a
   procedural grain layer so large flat areas never look like dead pixels. */

.desk {
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(120% 90% at 12% -10%, var(--desk-1) 0%, transparent 55%),
    radial-gradient(120% 110% at 100% 0%, var(--desk-3) 0%, transparent 60%),
    linear-gradient(170deg, var(--desk-2) 0%, var(--desk-1) 48%, var(--desk-3) 100%);
}

.desk__grain {
  position: absolute;
  inset: -50%;
  opacity: var(--grain-opacity);
  mix-blend-mode: soft-light;
  pointer-events: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='220' height='220'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.86' numOctaves='3' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='220' height='220' filter='url(%23n)' opacity='0.5'/%3E%3C/svg%3E");
}

.desk__glow {
  position: absolute;
  width: 48vw;
  height: 48vw;
  border-radius: 50%;
  filter: blur(90px);
  opacity: 0.35;
  pointer-events: none;
}
.desk__glow--a {
  top: -14vw;
  left: -8vw;
  background: radial-gradient(circle, var(--accent-soft) 0%, transparent 70%);
}
.desk__glow--b {
  bottom: -18vw;
  right: -10vw;
  background: radial-gradient(circle, var(--highlighter) 0%, transparent 70%);
}

/* ── Top bar ──────────────────────────────────────────────────────── */

.topbar {
  position: sticky;
  top: 0;
  z-index: 60;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
  padding: var(--space-3) clamp(var(--space-4), 4vw, var(--space-6));
  background: color-mix(in srgb, var(--paper) 78%, transparent);
  backdrop-filter: blur(14px) saturate(1.3);
  border-bottom: 1px solid var(--border);
}

.topbar__brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-width: 0;
}

.topbar__mark {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  flex-shrink: 0;
  border-radius: var(--radius-md);
  color: var(--paper);
  background: linear-gradient(145deg, var(--accent) 0%, var(--accent-ink) 100%);
  box-shadow: var(--shadow-card);
}

.topbar__titles { min-width: 0; }

.topbar__title {
  font-size: var(--text-md);
  font-weight: 700;
  letter-spacing: -0.02em;
  white-space: nowrap;
}

.topbar__sub {
  font-size: var(--text-xs);
  color: var(--ink-3);
  font-variant-numeric: tabular-nums;
}

.topbar__actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-wrap: wrap;
}

@media (max-width: 640px) {
  .topbar { padding: var(--space-2) var(--space-3); }
  .topbar__actions .btn__label { display: none; }
}