/* MathPrint — app.css : builder + library UI */

:root {
  --ink:    #1c2433;
  --paper:  #f7f6f2;
  --line:   #d9d5cc;
  --brand:  #2f6f4f;
  --brand-d:#245840;
  --accent: #c9622e;
  --muted:  #6b7280;
  --card:   #ffffff;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--paper);
  color: var(--ink);
  line-height: 1.5;
}

/* ── Header ─────────────────────────────────────────────────── */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  height: 58px;
  background: var(--ink);
  color: #fff;
}
.app-logo { font-size: 20px; font-weight: 400; letter-spacing: -0.3px; }
.app-logo b { font-weight: 800; color: #7fc4a0; }
.app-nav a {
  color: #c9cdd4;
  text-decoration: none;
  margin-left: 22px;
  font-size: 14px;
  font-weight: 600;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
}
.app-nav a:hover { color: #fff; }
.app-nav a.active { color: #fff; border-bottom-color: var(--accent); }

/* ── Builder layout ─────────────────────────────────────────── */
.builder, .library {
  max-width: 880px;
  margin: 0 auto;
  padding: 32px 24px 64px;
}
.builder-intro, .lib-head { margin-bottom: 28px; }
.builder-intro h1, .lib-head h1 {
  font-size: 26px;
  font-weight: 800;
  letter-spacing: -0.4px;
  margin-bottom: 6px;
}
.builder-intro p, .lib-head p { color: var(--muted); font-size: 15px; }

.fld { margin-bottom: 28px; }
.fld-title {
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  color: var(--muted);
  margin-bottom: 12px;
}

/* ── Grade buttons ──────────────────────────────────────────── */
.grade-row { display: flex; gap: 8px; flex-wrap: wrap; }
.grade-btn {
  width: 52px;
  height: 52px;
  border: 2px solid var(--line);
  background: var(--card);
  border-radius: 10px;
  font-size: 19px;
  font-weight: 700;
  color: var(--ink);
  cursor: pointer;
  transition: all 0.12s ease;
}
.grade-btn:hover { border-color: var(--brand); }
.grade-btn.on {
  background: var(--brand);
  border-color: var(--brand);
  color: #fff;
}

/* ── Topic cards ────────────────────────────────────────────── */
.topic-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 10px;
}
.topic-card {
  position: relative;
  display: block;
  padding: 14px 14px 14px 42px;
  background: var(--card);
  border: 2px solid var(--line);
  border-radius: 10px;
  cursor: pointer;
  transition: border-color 0.12s ease;
}
.topic-card:hover { border-color: var(--brand); }
.topic-card input {
  position: absolute;
  left: 14px;
  top: 16px;
  width: 18px;
  height: 18px;
  accent-color: var(--brand);
  cursor: pointer;
}
.topic-card:has(input:checked) {
  border-color: var(--brand);
  background: #f0f6f2;
}
.topic-name { display: block; font-weight: 700; font-size: 15px; }
.topic-desc { display: block; color: var(--muted); font-size: 13px; margin-top: 2px; }
.topic-card.disabled {
  opacity: 0.4;
  cursor: not-allowed;
  background: #f0efec;
}
.topic-card.disabled:hover { border-color: var(--line); }

/* ── Options grid ───────────────────────────────────────────── */
.opt-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 14px;
}
.opt { display: flex; flex-direction: column; }
.opt-label {
  font-size: 13px;
  font-weight: 600;
  color: var(--muted);
  margin-bottom: 4px;
}
.opt input, .opt select {
  padding: 8px 10px;
  border: 1.5px solid var(--line);
  border-radius: 7px;
  font-size: 14px;
  font-family: inherit;
  background: var(--card);
  color: var(--ink);
}
.opt input:focus, .opt select:focus {
  outline: none;
  border-color: var(--brand);
}

/* ── Actions ────────────────────────────────────────────────── */
.builder-actions {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-top: 8px;
}
.btn-primary {
  background: var(--brand);
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 12px 24px;
  font-size: 15px;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.12s ease;
}
.btn-primary:hover { background: var(--brand-d); }
.btn-primary:disabled { opacity: 0.55; cursor: default; }
.gen-status { font-size: 14px; font-weight: 600; }
.gen-status.err { color: #b4392b; }
.gen-status.ok  { color: var(--brand); }

/* ── Library ────────────────────────────────────────────────── */
.lib-filter {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-bottom: 22px;
}
.filter-chip {
  padding: 6px 12px;
  border: 1.5px solid var(--line);
  border-radius: 20px;
  font-size: 13px;
  font-weight: 600;
  color: var(--muted);
  text-decoration: none;
  background: var(--card);
}
.filter-chip:hover { border-color: var(--brand); color: var(--ink); }
.filter-chip.on {
  background: var(--brand);
  border-color: var(--brand);
  color: #fff;
}

.lib-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(248px, 1fr));
  gap: 14px;
}
.lib-card {
  background: var(--card);
  border: 1.5px solid var(--line);
  border-radius: 10px;
  padding: 16px;
}
.lib-card-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}
.lib-grade {
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--brand);
}
.lib-date { font-size: 12px; color: var(--muted); }
.lib-card-title { font-size: 16px; font-weight: 700; margin-bottom: 4px; }
.lib-card-topics { font-size: 13px; color: var(--muted); margin-bottom: 6px; }
.lib-card-prints { font-size: 12px; color: var(--accent); margin-bottom: 8px; }
.lib-card-actions {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px solid var(--line);
}
.lib-btn {
  padding: 5px 10px;
  border: 1.5px solid var(--line);
  border-radius: 6px;
  font-size: 12px;
  font-weight: 600;
  color: var(--ink);
  text-decoration: none;
  background: var(--card);
  cursor: pointer;
  font-family: inherit;
}
.lib-btn:hover { border-color: var(--brand); }
.lib-btn-del { color: #b4392b; border-color: #e3c4bf; }
.lib-btn-del:hover { border-color: #b4392b; }
.lib-del { display: inline; margin: 0; }

.lib-empty {
  text-align: center;
  padding: 56px 20px;
  color: var(--muted);
}
.lib-empty .btn-primary {
  display: inline-block;
  margin-top: 14px;
  text-decoration: none;
}

.lib-pager {
  display: flex;
  gap: 6px;
  justify-content: center;
  margin-top: 28px;
}
.pager-link {
  min-width: 34px;
  text-align: center;
  padding: 6px 8px;
  border: 1.5px solid var(--line);
  border-radius: 6px;
  font-size: 13px;
  font-weight: 600;
  color: var(--ink);
  text-decoration: none;
  background: var(--card);
}
.pager-link.on {
  background: var(--brand);
  border-color: var(--brand);
  color: #fff;
}

/* ── Footer ─────────────────────────────────────────────────── */
.app-footer {
  text-align: center;
  padding: 24px;
  color: var(--muted);
  font-size: 13px;
  border-top: 1px solid var(--line);
}