/* FlashRecall app styles — layout, components, responsive. Colors via theme.css vars. */

* { box-sizing: border-box; }
html { font-size: var(--font-size); }
body {
  margin: 0;
  font-family: var(--font-ui);
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}
a { color: var(--accent); text-decoration: none; }
h1, h2, h3, h4 { margin: 0; font-weight: 600; }
p { margin: 0; }
button { font: inherit; color: inherit; background: none; border: none; cursor: pointer; }
input, select, textarea { font: inherit; color: inherit; }
::selection { background: var(--accent-soft); }

/* ---------- layout ---------- */

#app { display: flex; min-height: 100vh; }
.main-wrap { flex: 1; min-width: 0; display: flex; flex-direction: column; }
#main { flex: 1; padding: 24px 28px 64px; max-width: 1240px; width: 100%; margin: 0 auto; }

body[data-view="study"] #sidebar,
body[data-view="study"] #topbar,
body[data-view="study"] #bottomnav,
body[data-view="auth"] #sidebar,
body[data-view="auth"] #topbar,
body[data-view="auth"] #bottomnav { display: none; }
body[data-view="study"] #main,
body[data-view="auth"] #main { max-width: none; padding: 0; }

/* ---------- sidebar ---------- */

#sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  background: var(--bg-elev);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}
.brand { display: flex; align-items: center; gap: 10px; padding: 16px 18px 12px; }
.brand-logo {
  width: 30px; height: 30px; border-radius: 8px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  display: grid; place-items: center; color: var(--accent-contrast); flex-shrink: 0;
  box-shadow: 0 0 14px var(--accent-soft);
}
.brand-name { font-weight: 700; letter-spacing: 0.08em; font-size: 14px; }
.brand-tag { font-size: 10px; color: var(--text-faint); letter-spacing: 0.04em; }

.side-section { padding: 10px 12px 4px; }
.side-label {
  font-size: 11px; letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--text-faint); padding: 0 8px 6px; display: flex; justify-content: space-between;
}
.side-item {
  display: flex; align-items: center; gap: 10px; width: 100%;
  padding: 7px 8px; border-radius: var(--radius-sm);
  color: var(--text-dim); font-size: 13.5px; text-align: left;
  transition: background var(--speed), color var(--speed);
}
.side-item:hover { background: var(--surface-2); color: var(--text); }
.side-item.active { background: var(--accent-soft); color: var(--text); }
.side-item svg { flex-shrink: 0; opacity: 0.85; }
.side-item .count-badge { margin-left: auto; }

.deck-tree { padding: 0 12px; }
.deck-node .side-item { padding-left: 8px; }
.deck-children { margin-left: 14px; border-left: 1px solid var(--border); padding-left: 4px; }
.deck-children.collapsed { display: none; }
.deck-caret { width: 14px; height: 14px; display: grid; place-items: center; color: var(--text-faint); transition: transform var(--speed); }
.deck-caret.open { transform: rotate(90deg); }
.dot { width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0; }
.count-badge {
  font-size: 11px; font-family: var(--font-mono); color: var(--accent-2);
  background: var(--accent-soft); border-radius: 8px; padding: 1px 7px;
  font-variant-numeric: tabular-nums;
}
.count-badge.zero { color: var(--text-faint); background: transparent; }

.side-bottom { margin-top: auto; padding: 12px; border-top: 1px solid var(--border); display: flex; flex-direction: column; gap: 8px; }
.user-chip { display: flex; align-items: center; gap: 9px; padding: 4px; border-radius: var(--radius-sm); }
.user-chip:hover { background: var(--surface-2); }
.avatar {
  width: 28px; height: 28px; border-radius: 50%; flex-shrink: 0;
  background: linear-gradient(135deg, var(--accent), var(--teal));
  color: var(--accent-contrast); font-size: 11px; font-weight: 700;
  display: grid; place-items: center; letter-spacing: 0.03em;
}
.user-name { font-size: 13px; color: var(--text); }
.user-chip .gear { margin-left: auto; color: var(--text-faint); padding: 5px; border-radius: 6px; display: grid; place-items: center; }
.user-chip .gear:hover { color: var(--text); background: var(--surface-3); }

/* ---------- topbar ---------- */

#topbar {
  height: var(--topbar-h); flex-shrink: 0;
  display: flex; align-items: center; gap: 14px;
  padding: 0 22px;
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--bg) 80%, transparent);
  backdrop-filter: blur(8px);
  position: sticky; top: 0; z-index: 30;
}
.hamburger { display: none; padding: 8px; border-radius: 8px; color: var(--text-dim); }
.hamburger:hover { background: var(--surface-2); color: var(--text); }
.search-box {
  flex: 1; max-width: 460px; display: flex; align-items: center; gap: 8px;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 7px 12px; color: var(--text-faint);
  transition: border-color var(--speed);
}
.search-box:focus-within { border-color: var(--accent); }
.search-box input { flex: 1; background: none; border: none; outline: none; color: var(--text); font-size: 13.5px; min-width: 0; }
.kbd {
  font-family: var(--font-mono); font-size: 10.5px; color: var(--text-dim);
  background: var(--surface-3); border: 1px solid var(--border-strong);
  border-radius: 5px; padding: 1px 6px; white-space: nowrap;
}
.topbar-right { margin-left: auto; display: flex; align-items: center; gap: 12px; }
.add-fab {
  width: 32px; height: 32px; border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: var(--accent-contrast); display: grid; place-items: center;
  box-shadow: 0 0 12px var(--accent-soft);
}
.add-fab:hover { filter: brightness(1.1); }

/* ---------- bottom nav (phone) ---------- */

#bottomnav {
  display: none;
  position: fixed; bottom: 0; left: 0; right: 0; z-index: 40;
  background: var(--bg-elev); border-top: 1px solid var(--border);
  padding: 4px 6px calc(4px + env(safe-area-inset-bottom));
}
#bottomnav .bn-item {
  flex: 1; display: flex; flex-direction: column; align-items: center; gap: 2px;
  padding: 7px 0; min-height: 44px; border-radius: 8px;
  color: var(--text-faint); font-size: 10px;
}
#bottomnav .bn-item.active { color: var(--accent-2); }

/* ---------- buttons / chips ---------- */

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 7px;
  border-radius: 999px; padding: 8px 18px; font-size: 13.5px; font-weight: 600;
  border: 1px solid var(--border-strong); color: var(--text-dim);
  background: var(--surface-2); min-height: 36px;
  transition: filter var(--speed), background var(--speed), border-color var(--speed);
}
.btn:hover { color: var(--text); border-color: var(--text-faint); }
.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: var(--accent-contrast); border: none;
  box-shadow: 0 4px 18px var(--accent-soft), 0 0 0 1px color-mix(in srgb, var(--accent) 40%, transparent);
}
.btn-primary:hover { filter: brightness(1.12); color: var(--accent-contrast); }
.btn-ghost { background: transparent; border-color: transparent; }
.btn-ghost:hover { background: var(--surface-2); }
.btn-danger:hover { color: var(--red); border-color: var(--red); }
.btn .kbd { background: rgba(255, 255, 255, 0.18); border-color: transparent; color: inherit; }
.btn:disabled { opacity: 0.5; cursor: default; }

.icon-btn {
  width: 34px; height: 34px; border-radius: 9px; display: grid; place-items: center;
  color: var(--text-dim); transition: background var(--speed), color var(--speed);
}
.icon-btn:hover { background: var(--surface-2); color: var(--text); }
.icon-btn.on { color: var(--yellow); }

.chip {
  display: inline-flex; align-items: center; gap: 4px;
  font-size: 11px; font-family: var(--font-mono); font-variant-numeric: tabular-nums;
  padding: 2px 9px; border-radius: 999px; border: 1px solid var(--border);
  background: var(--surface-2); color: var(--text-dim); white-space: nowrap;
}
.chip.c-new { color: var(--blue); border-color: color-mix(in srgb, var(--blue) 35%, transparent); }
.chip.c-lrn { color: var(--red); border-color: color-mix(in srgb, var(--red) 35%, transparent); }
.chip.c-rev { color: var(--green); border-color: color-mix(in srgb, var(--green) 35%, transparent); }
.chip.c-accent { color: var(--accent-2); border-color: color-mix(in srgb, var(--accent) 40%, transparent); background: var(--accent-soft); }
.tag-chip {
  font-size: 11px; padding: 2px 9px; border-radius: 999px;
  border: 1px solid var(--border-strong); color: var(--text-dim);
  background: transparent; cursor: pointer;
}
.tag-chip:hover { border-color: var(--accent); color: var(--accent-2); }
.tag-chip.leech { color: var(--red); border-color: color-mix(in srgb, var(--red) 40%, transparent); }

.section-label {
  font-size: 11px; letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--text-faint); font-weight: 600;
}

/* ---------- cards / tiles ---------- */

.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px;
}
.card h3 { font-size: 14px; font-weight: 600; }
.card .card-sub { font-size: 11.5px; color: var(--text-faint); margin-top: 2px; }
.card-head { display: flex; align-items: baseline; justify-content: space-between; gap: 10px; margin-bottom: 12px; }

.tiles { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.tile {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 18px; position: relative;
}
.tile .tile-icon {
  position: absolute; top: 14px; right: 14px;
  width: 30px; height: 30px; border-radius: 8px;
  display: grid; place-items: center;
}
.tile .tile-num { font-family: var(--font-mono); font-size: 26px; font-weight: 600; font-variant-numeric: tabular-nums; letter-spacing: -0.02em; }
.tile .tile-label { font-size: 10.5px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--text-faint); margin-top: 3px; }
.tile .tile-sub { font-size: 11px; color: var(--text-faint); position: absolute; bottom: 14px; right: 16px; max-width: 52%; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; text-align: right; }
.tile .tile-sub .up { color: var(--green); }
.tile .tile-sub .down { color: var(--red); }

/* ---------- home ---------- */

.home-greet { font-size: 24px; font-weight: 650; letter-spacing: -0.01em; }
.home-sub { color: var(--text-dim); font-size: 13.5px; margin-top: 5px; }
.home-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; margin-bottom: 20px; flex-wrap: wrap; }
.home-grid { display: grid; grid-template-columns: minmax(0, 1fr) 300px; gap: 18px; margin-top: 20px; align-items: start; }
.home-col { display: flex; flex-direction: column; gap: 14px; }

.deck-row {
  display: flex; align-items: center; gap: 12px;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 13px 16px;
}
.deck-row .deck-meta { min-width: 0; }
.deck-row .deck-name { font-size: 14px; font-weight: 600; }
.deck-row .deck-path { font-size: 11.5px; color: var(--text-faint); margin-top: 2px; }
.deck-row .deck-chips { display: flex; gap: 6px; margin-left: auto; }
.deck-row .btn { padding: 6px 16px; min-height: 32px; font-size: 12.5px; }
.all-caught-up { color: var(--green); display: flex; align-items: center; gap: 8px; font-size: 13.5px; padding: 14px 16px; }

/* ---------- heatmap ---------- */

.heatmap-scroll { overflow-x: auto; padding-bottom: 4px; }
.heatmap { display: grid; grid-auto-flow: column; grid-template-rows: repeat(7, 11px); gap: 3px; width: max-content; }
.hm-cell { width: 11px; height: 11px; border-radius: 3px; background: var(--surface-3); }
.hm-cell.l1 { background: color-mix(in srgb, var(--accent) 30%, var(--surface-3)); }
.hm-cell.l2 { background: color-mix(in srgb, var(--accent) 55%, var(--surface-3)); }
.hm-cell.l3 { background: color-mix(in srgb, var(--accent) 80%, var(--surface-3)); }
.hm-cell.l4 { background: var(--accent); }
.hm-legend { display: flex; align-items: center; gap: 4px; font-size: 10.5px; color: var(--text-faint); margin-top: 8px; }
.hm-legend .hm-cell { width: 9px; height: 9px; }
.hm-best { margin-left: auto; font-family: var(--font-mono); }

/* ---------- bar chart ---------- */

.barchart { display: flex; align-items: flex-end; gap: 4px; height: 110px; }
.bc-bar-wrap { flex: 1; display: flex; flex-direction: column; justify-content: flex-end; height: 100%; min-width: 6px; }
.bc-bar { width: 100%; border-radius: 3px 3px 1px 1px; background: var(--surface-3); min-height: 2px; transition: height var(--speed); }
.bc-bar.today { background: var(--accent); }
.bc-bar.peak { background: var(--teal); }
.bc-ticks { display: flex; justify-content: space-between; font-size: 10px; color: var(--text-faint); font-family: var(--font-mono); margin-top: 6px; }
.bc-foot { font-size: 11px; color: var(--text-faint); margin-top: 8px; text-align: right; font-family: var(--font-mono); }
.callout { font-size: 10.5px; font-family: var(--font-mono); color: var(--text-dim); background: var(--surface-2); border: 1px solid var(--border); border-radius: 999px; padding: 2px 9px; white-space: nowrap; }

/* ---------- study ---------- */

.study-shell { min-height: 100vh; display: flex; flex-direction: column; }
.study-header {
  display: flex; align-items: center; gap: 12px; padding: 14px 20px;
}
.study-header .study-title { display: flex; align-items: center; gap: 10px; font-size: 15px; font-weight: 600; }
.study-progress-text { position: absolute; left: 50%; transform: translateX(-50%); font-family: var(--font-mono); font-size: 14px; color: var(--text-dim); font-variant-numeric: tabular-nums; }
.study-header { position: relative; }
.study-actions { margin-left: auto; display: flex; gap: 4px; }
.study-bar { height: 3px; background: var(--surface-2); }
.study-bar > div { height: 100%; background: linear-gradient(90deg, var(--accent), var(--teal)); transition: width 300ms; }
.study-sub { display: flex; justify-content: space-between; padding: 10px 22px; font-size: 12px; color: var(--text-faint); font-family: var(--font-mono); }
.study-stage { flex: 1; display: flex; flex-direction: column; align-items: center; justify-content: center; padding: 20px; gap: 26px; }
.study-card {
  width: 100%; max-width: 720px; min-height: 320px;
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-lg);
  padding: 22px 28px; position: relative; display: flex; flex-direction: column;
}
.study-card .card-top { display: flex; justify-content: space-between; align-items: flex-start; gap: 10px; }
.study-card .tags-row { display: flex; gap: 6px; flex-wrap: wrap; justify-content: flex-end; }
.study-front {
  font-family: var(--font-jp); font-size: 42px; font-weight: 500; text-align: center;
  margin: auto 0; padding: 30px 0 8px; line-height: 1.3; word-break: break-word;
}
.study-front.small { font-size: 24px; text-align: left; margin: 8px 0 0; padding: 6px 0 14px; }
.study-hint { text-align: center; color: var(--text-faint); font-size: 13px; padding-bottom: 20px; }
.study-source { font-family: var(--font-mono); font-size: 11px; color: var(--text-faint); text-align: center; margin-top: auto; padding-top: 16px; }
.study-divider { border: none; border-top: 1px solid var(--border); margin: 4px 0 14px; }
.answer-section { margin-bottom: 12px; }
.answer-section .section-label { display: block; margin-bottom: 4px; }
.answer-reading { font-family: var(--font-jp); font-size: 21px; color: var(--accent-2); }
.answer-body { font-size: 15.5px; line-height: 1.55; }
.answer-body p { margin: 4px 0; }
.answer-extra {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 13px 16px; margin: 10px 0;
}
.answer-extra .section-label { display: block; margin-bottom: 6px; }
.answer-extra .ex-main { font-family: var(--font-jp); font-size: 15px; line-height: 1.5; }
.answer-extra .ex-note { font-style: italic; color: var(--text-dim); font-size: 13px; margin-top: 5px; }
.answer-note { font-style: italic; color: var(--text-dim); font-size: 13px; margin-top: 6px; }
.play-btn { padding: 3px 12px; min-height: 28px; font-size: 12px; }
.study-front.cloze-reveal { font-size: 26px; }
.study-front.cloze-reveal strong { color: var(--accent-2); }

.grade-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; width: 100%; max-width: 720px; }
.grade-btn {
  border-radius: var(--radius); border: 1.5px solid; background: transparent;
  padding: 14px 10px 10px; text-align: center; position: relative; min-height: 62px;
  transition: background var(--speed), filter var(--speed);
}
.grade-btn:hover { filter: brightness(1.25); }
.grade-btn .g-name { font-size: 16px; font-weight: 650; }
.grade-btn .g-ivl { font-size: 12px; font-family: var(--font-mono); opacity: 0.8; margin-top: 3px; }
.grade-btn .g-key { position: absolute; top: 7px; right: 10px; font-size: 10.5px; font-family: var(--font-mono); opacity: 0.6; }
.grade-btn.g1 { color: var(--red); border-color: var(--red); }
.grade-btn.g2 { color: var(--orange); border-color: var(--orange); }
.grade-btn.g3 { color: var(--green); border-color: var(--green); }
.grade-btn.g4 { color: var(--blue); border-color: var(--blue); }
.study-caption { font-size: 12px; color: var(--text-faint); font-family: var(--font-mono); text-align: center; }
.study-footer { padding: 14px 22px 18px; text-align: center; font-size: 12px; color: var(--text-faint); font-family: var(--font-mono); }
.study-footer .legend { display: flex; justify-content: center; gap: 18px; flex-wrap: wrap; }
.study-session-line { text-align: left; margin-top: 10px; }
.summary-card { max-width: 460px; margin: 12vh auto 0; text-align: center; }
.summary-card .big { font-family: var(--font-mono); font-size: 40px; font-weight: 650; }
.summary-stats { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; margin: 22px 0; }

/* ---------- browse ---------- */

.browse-head { display: flex; align-items: center; gap: 14px; margin-bottom: 14px; flex-wrap: wrap; }
.browse-head h2 { font-size: 20px; }
.browse-head .head-stats { margin-left: auto; font-size: 12px; color: var(--text-faint); font-family: var(--font-mono); }
.browse-query { display: flex; align-items: center; gap: 8px; background: var(--surface); border: 1px solid var(--border); border-radius: 10px; padding: 8px 12px; margin-bottom: 14px; color: var(--text-faint); }
.browse-query:focus-within { border-color: var(--accent); }
.browse-query input { flex: 1; background: none; border: none; outline: none; color: var(--text); font-family: var(--font-mono); font-size: 13px; min-width: 0; }
.pane-tabs { display: none; gap: 6px; margin-bottom: 12px; }
.browse-grid { display: grid; grid-template-columns: 220px minmax(0, 1fr) 320px; gap: 14px; align-items: start; }
.pane { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px; }
.browse-decks .side-item { font-size: 13px; padding: 6px 8px; }
.browse-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.pane-note { font-size: 11px; color: var(--text-faint); margin-top: 10px; line-height: 1.5; }

.card-list { display: flex; flex-direction: column; }
.card-row {
  display: flex; align-items: center; gap: 10px; padding: 9px 8px;
  border-radius: var(--radius-sm); cursor: pointer; border-left: 2px solid transparent;
}
.card-row:hover { background: var(--surface-2); }
.card-row.selected { background: var(--accent-soft); border-left-color: var(--accent); }
.card-row input[type="checkbox"] { accent-color: var(--accent); width: 14px; height: 14px; flex-shrink: 0; }
.card-row .row-front { flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: 13.5px; }
.card-row .row-due { font-size: 11px; font-family: var(--font-mono); width: 64px; text-align: right; flex-shrink: 0; }
.row-due.d-today { color: var(--red); }
.row-due.d-new { color: var(--blue); }
.row-due.d-learning { color: var(--orange); }
.row-due.d-later, .row-due.d-susp { color: var(--text-faint); }
.card-row .row-flag { color: var(--yellow); flex-shrink: 0; display: grid; place-items: center; }
.list-foot { font-size: 11px; color: var(--text-faint); font-family: var(--font-mono); padding: 10px 8px 2px; border-top: 1px solid var(--border); margin-top: 6px; }

.edit-panel h3 { font-size: 14px; margin-bottom: 10px; }
.edit-panel .edit-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 12px; }
.edit-row { display: flex; gap: 8px; margin-bottom: 10px; }
.edit-row select { flex: 1; min-width: 0; }
.toolbar { display: flex; gap: 2px; align-items: center; margin-bottom: 10px; flex-wrap: wrap; }
.toolbar .icon-btn { width: 30px; height: 30px; font-size: 12px; font-weight: 700; }
.toolbar .cloze-btn { font-size: 11px; font-family: var(--font-mono); padding: 5px 10px; border-radius: 7px; color: var(--teal); border: 1px solid color-mix(in srgb, var(--teal) 40%, transparent); }
.toolbar .cloze-btn:hover { background: color-mix(in srgb, var(--teal) 12%, transparent); }
.field-label { font-size: 10.5px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--text-faint); margin: 10px 0 5px; font-weight: 600; }
.edit-actions { display: flex; gap: 8px; margin-top: 14px; }
.edit-actions .spacer { flex: 1; }
.edit-foot { font-size: 11px; color: var(--text-faint); font-family: var(--font-mono); margin-top: 12px; }
.edit-empty { color: var(--text-faint); font-size: 13px; text-align: center; padding: 40px 10px; }

/* ---------- forms ---------- */

input[type="text"], input[type="password"], input[type="number"], select, textarea {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--radius-sm); padding: 9px 12px; color: var(--text);
  outline: none; width: 100%; transition: border-color var(--speed);
}
input:focus, select:focus, textarea:focus { border-color: var(--accent); }
textarea { resize: vertical; min-height: 80px; line-height: 1.5; }
select { appearance: none; background-image: linear-gradient(45deg, transparent 50%, var(--text-faint) 50%), linear-gradient(135deg, var(--text-faint) 50%, transparent 50%); background-position: calc(100% - 16px) 50%, calc(100% - 11px) 50%; background-size: 5px 5px; background-repeat: no-repeat; padding-right: 30px; }
input[type="range"] { width: 100%; accent-color: var(--accent); }
input[type="color"] { width: 42px; height: 30px; border: 1px solid var(--border); border-radius: 8px; background: var(--surface-2); padding: 2px; }
input[type="checkbox"].switch { appearance: none; width: 38px; height: 22px; border-radius: 999px; background: var(--surface-3); position: relative; cursor: pointer; transition: background var(--speed); flex-shrink: 0; }
input[type="checkbox"].switch::after { content: ""; position: absolute; top: 3px; left: 3px; width: 16px; height: 16px; border-radius: 50%; background: var(--text-dim); transition: left var(--speed), background var(--speed); }
input[type="checkbox"].switch:checked { background: var(--accent); }
input[type="checkbox"].switch:checked::after { left: 19px; background: var(--accent-contrast); }

.form-card { max-width: 520px; margin: 0 auto; }
.form-card h2 { font-size: 19px; margin-bottom: 16px; }
.field { margin-bottom: 14px; }
.field label { display: block; font-size: 12px; color: var(--text-dim); margin-bottom: 5px; }
.field .field-hint { font-size: 11px; color: var(--text-faint); margin-top: 4px; }
.form-error { color: var(--red); font-size: 12.5px; margin: 8px 0; min-height: 1em; }

.segmented { display: inline-flex; background: var(--surface-2); border: 1px solid var(--border); border-radius: 999px; padding: 3px; gap: 2px; }
.segmented button { padding: 6px 18px; border-radius: 999px; font-size: 13px; color: var(--text-dim); min-height: 32px; }
.segmented button.active { background: var(--accent); color: var(--accent-contrast); }

.tags-input { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; background: var(--surface-2); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 7px 10px; }
.tags-input:focus-within { border-color: var(--accent); }
.tags-input input { flex: 1; min-width: 90px; background: none; border: none; padding: 2px; }
.tags-input .tag-chip { display: inline-flex; align-items: center; gap: 5px; cursor: default; }
.tags-input .tag-chip button { color: var(--text-faint); font-size: 12px; line-height: 1; padding: 0 2px; }
.tags-input .tag-chip button:hover { color: var(--red); }

/* ---------- auth ---------- */

.auth-wrap { min-height: 100vh; display: grid; place-items: center; padding: 20px; }
.auth-card { width: 100%; max-width: 360px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 30px 28px; }
.auth-card .brand { justify-content: center; padding: 0 0 18px; }
.auth-card h2 { text-align: center; font-size: 17px; margin-bottom: 18px; }
.auth-toggle { text-align: center; font-size: 12.5px; color: var(--text-dim); margin-top: 16px; }

/* ---------- settings ---------- */

.settings-wrap { max-width: 640px; display: flex; flex-direction: column; gap: 16px; }
.settings-wrap h2 { font-size: 20px; }
.setting-row { display: flex; align-items: center; gap: 14px; padding: 10px 0; }
.setting-row + .setting-row { border-top: 1px solid var(--border); }
.setting-row .sr-label { flex: 1; min-width: 0; }
.setting-row .sr-label .sr-name { font-size: 13.5px; }
.setting-row .sr-label .sr-desc { font-size: 11.5px; color: var(--text-faint); margin-top: 2px; }
.setting-row .sr-val { font-family: var(--font-mono); font-size: 12px; color: var(--text-dim); min-width: 44px; text-align: right; }
.setting-row input[type="range"] { width: 160px; }
.setting-row input[type="text"], .setting-row input[type="password"], .setting-row input[type="number"], .setting-row select { width: 190px; }
.theme-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; padding: 8px 0; }
.theme-swatch { border: 2px solid var(--border); border-radius: var(--radius-sm); padding: 8px; cursor: pointer; text-align: center; font-size: 11px; color: var(--text-dim); }
.theme-swatch.active { border-color: var(--accent); color: var(--text); }
.theme-swatch .sw-preview { height: 38px; border-radius: 6px; margin-bottom: 6px; border: 1px solid var(--border); display: flex; align-items: flex-end; padding: 4px; gap: 3px; }
.theme-swatch .sw-dot { width: 10px; height: 10px; border-radius: 3px; }
.tint-row { display: flex; gap: 8px; }
.tint-dot { width: 26px; height: 26px; border-radius: 50%; border: 2px solid var(--border-strong); cursor: pointer; }
.tint-dot.active { border-color: var(--accent); }
.share-row { display: flex; align-items: center; gap: 10px; padding: 9px 0; font-size: 13px; }
.share-row + .share-row { border-top: 1px solid var(--border); }
.share-row .share-meta { flex: 1; min-width: 0; }
.share-row .share-sub { font-size: 11px; color: var(--text-faint); }
.empty-line { color: var(--text-faint); font-size: 12.5px; padding: 8px 0; }

/* ---------- stats ---------- */

.stats-head { display: flex; align-items: center; gap: 14px; margin-bottom: 16px; flex-wrap: wrap; }
.stats-head h2 { font-size: 20px; }
.stats-head .spacer { flex: 1; }
.stats-head select { width: auto; min-width: 140px; }
.stats-grid { display: grid; grid-template-columns: minmax(0, 2fr) minmax(0, 1fr); gap: 14px; margin-top: 14px; align-items: start; }
.stats-col { display: flex; flex-direction: column; gap: 14px; }
.seg-bar { display: flex; height: 14px; border-radius: 7px; overflow: hidden; margin: 8px 0 14px; }
.seg-bar > div { height: 100%; }
.legend-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 6px 14px; font-size: 12.5px; }
.legend-grid .lg { display: flex; align-items: center; gap: 8px; }
.legend-grid .lg .n { margin-left: auto; font-family: var(--font-mono); color: var(--text-dim); }
.grade-bar-row { display: grid; grid-template-columns: 48px 1fr 40px; align-items: center; gap: 10px; padding: 5px 0; font-size: 12.5px; }
.grade-bar-row .gb-track { height: 8px; border-radius: 4px; background: var(--surface-3); overflow: hidden; }
.grade-bar-row .gb-fill { height: 100%; border-radius: 4px; }
.grade-bar-row .gb-n { font-family: var(--font-mono); color: var(--text-dim); text-align: right; font-size: 11.5px; }
.kv-row { display: flex; justify-content: space-between; font-size: 13px; padding: 6px 0; }
.kv-row .v { font-family: var(--font-mono); color: var(--text-dim); }

/* ---------- modal / toast / misc ---------- */

.modal-text { font-size: 13px; color: var(--text-dim); line-height: 1.55; margin-bottom: 12px; }
.btn-danger-solid { background: var(--red); border-color: var(--red); color: var(--accent-contrast); }
.btn-danger-solid:hover { filter: brightness(1.1); color: var(--accent-contrast); }
.icon-btn.icon-danger:hover { color: var(--red); }

/* swatch picker (deck colour) */
.swatch-row { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.swatch {
  width: 26px; height: 26px; border-radius: 50%; border: 2px solid transparent;
  box-shadow: 0 0 0 1px var(--border-strong); cursor: pointer; min-height: 0; flex-shrink: 0;
}
.swatch.on, .swatch-row input[type="color"].on { border-color: var(--surface); box-shadow: 0 0 0 2px var(--accent); }

/* sidebar deck header */
.side-label-link { color: inherit; }
.side-label-link:hover { color: var(--text); }
.side-label-right { display: inline-flex; align-items: center; gap: 8px; }
.side-add {
  width: 18px; height: 18px; border-radius: 5px; display: grid; place-items: center;
  color: var(--text-dim); background: var(--surface-2);
}
.side-add:hover { color: var(--accent-contrast); background: var(--accent); }
.side-item.side-empty { color: var(--text-faint); font-style: italic; }

/* decks page */
.deck-manage-list { display: flex; flex-direction: column; gap: 8px; }
.deck-manage-row { margin-left: calc(var(--depth, 0) * 22px); }
.deck-actions { display: flex; align-items: center; gap: 2px; }
.deck-actions .btn { margin-right: 6px; }
.deck-empty { text-align: center; padding: 40px 20px; max-width: 460px; margin: 20px auto; }
.deck-empty-icon { color: var(--accent-2); display: grid; place-items: center; margin-bottom: 10px; }
.deck-empty h3 { font-size: 16px; margin-bottom: 6px; }
.deck-empty p { font-size: 13px; color: var(--text-dim); line-height: 1.55; margin-bottom: 18px; }
.section-label-row { display: flex; justify-content: space-between; align-items: baseline; }
.inline-link { text-transform: none; letter-spacing: 0; color: var(--accent-2); font-size: 12px; font-weight: 600; background: none; border: none; padding: 0; cursor: pointer; }
.inline-link:hover { text-decoration: underline; }

.modal-overlay {
  position: fixed; inset: 0; z-index: 100; background: var(--scrim);
  display: grid; place-items: center; padding: 18px;
}
.modal {
  width: 100%; max-width: 480px; max-height: 88vh; overflow-y: auto;
  background: var(--surface); border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg); padding: 20px;
}
.modal h3 { margin-bottom: 14px; font-size: 15px; }
.modal-actions { display: flex; justify-content: flex-end; gap: 8px; margin-top: 16px; }

#toasts { position: fixed; bottom: 20px; right: 20px; z-index: 200; display: flex; flex-direction: column; gap: 8px; }
.toast {
  background: var(--surface-3); border: 1px solid var(--border-strong);
  border-radius: 10px; padding: 10px 16px; font-size: 13px; color: var(--text);
  box-shadow: 0 8px 24px var(--shadow); max-width: 320px;
  animation: toast-in 200ms ease;
}
.toast.error { border-color: color-mix(in srgb, var(--red) 50%, transparent); color: var(--red); }
.toast.success { border-color: color-mix(in srgb, var(--green) 50%, transparent); }
@keyframes toast-in { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }

.skeleton { border-radius: var(--radius-sm); background: linear-gradient(90deg, var(--surface-2) 25%, var(--surface-3) 50%, var(--surface-2) 75%); background-size: 200% 100%; animation: shimmer 1.3s infinite; }
@keyframes shimmer { from { background-position: 200% 0; } to { background-position: -200% 0; } }
.spinner { width: 26px; height: 26px; border-radius: 50%; border: 3px solid var(--surface-3); border-top-color: var(--accent); animation: spin 800ms linear infinite; margin: 60px auto; }
@keyframes spin { to { transform: rotate(360deg); } }

.view-empty { text-align: center; color: var(--text-faint); padding: 60px 20px; font-size: 13.5px; }
.md-code { font-family: var(--font-mono); font-size: 0.88em; background: var(--surface-3); border-radius: 4px; padding: 1px 5px; }

/* ---------- responsive ---------- */

@media (max-width: 960px) {
  #sidebar {
    position: fixed; left: 0; top: 0; z-index: 60; height: 100vh;
    transform: translateX(-100%); transition: transform 220ms ease;
    box-shadow: 0 0 40px var(--shadow);
  }
  body.nav-open #sidebar { transform: none; }
  .nav-scrim { position: fixed; inset: 0; z-index: 55; background: var(--scrim); }
  .hamburger { display: grid; place-items: center; }
  #main { padding: 18px 16px 64px; }
  .tiles { grid-template-columns: repeat(2, 1fr); }
  .home-grid { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: 1fr; }
  .browse-grid { grid-template-columns: 200px minmax(0, 1fr); }
  .browse-grid .edit-panel { grid-column: 1 / -1; }
  .study-front { font-size: 34px; }
}

@media (max-width: 640px) {
  .swatch { width: 34px; height: 34px; }
  .deck-manage-row { flex-wrap: wrap; margin-left: calc(var(--depth, 0) * 12px); }
  .deck-manage-row .deck-actions { width: 100%; justify-content: flex-end; }
  .tile .tile-sub { position: static; max-width: none; text-align: left; margin-top: 4px; }
  .study-header { flex-wrap: wrap; row-gap: 4px; }
  .study-header .study-title { min-width: 0; }
  .study-header .study-title > span:nth-child(2) { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
  .study-progress-text { position: static; transform: none; order: 3; width: 100%; text-align: center; font-size: 12px; }
  #main { padding: 14px 12px 90px; }
  #topbar { padding: 0 12px; gap: 8px; }
  #topbar .avatar, .search-box .kbd { display: none; }
  #bottomnav { display: flex; }
  .tiles { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .tile .tile-num { font-size: 21px; }
  .browse-grid { grid-template-columns: 1fr; }
  .pane-tabs { display: flex; }
  .browse-grid .pane { display: none; }
  .browse-grid .pane.pane-active { display: block; }
  .grade-row { grid-template-columns: 1fr 1fr; gap: 10px; }
  .grade-btn { min-height: 56px; padding: 12px 8px 8px; }
  .study-front { font-size: 28px; }
  .study-card { padding: 16px 16px; min-height: 260px; }
  .study-sub { flex-direction: column; gap: 4px; padding: 8px 16px; }
  .theme-grid { grid-template-columns: repeat(2, 1fr); }
  .setting-row input[type="text"], .setting-row input[type="password"], .setting-row input[type="number"], .setting-row select { width: 140px; }
  .home-head { flex-direction: column; }
  .deck-row { flex-wrap: wrap; }
  .deck-row .deck-chips { margin-left: 0; }
  #toasts { left: 12px; right: 12px; }
  .toast { max-width: none; }
  button, .side-item, .card-row, .bn-item { min-height: 44px; }
}
.heatmap-scroll { scrollbar-width: thin; scrollbar-color: var(--border-strong) transparent; }
.heatmap-scroll::-webkit-scrollbar { height: 6px; }
.heatmap-scroll::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 3px; }

/* ---------- practice test / study guide ---------- */

.summary-actions { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }
.test-setup .segmented { flex-wrap: wrap; }
.test-inline { display: flex; align-items: center; justify-content: space-between; }
.test-inline label { margin: 0; }
.test-setup-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 6px; flex-wrap: wrap; }

.test-head { display: flex; align-items: flex-end; justify-content: space-between; gap: 12px; flex-wrap: wrap; margin-bottom: 12px; }
.test-head h2 { font-size: 20px; }
.test-head-meta { display: flex; align-items: center; gap: 14px; font-family: var(--font-mono); font-size: 12.5px; color: var(--text-dim); }
.test-clock { color: var(--text-faint); }
.test-progress {
  position: sticky; top: var(--topbar-h); z-index: 5; height: 3px; border-radius: 3px;
  background: var(--surface-2); margin-bottom: 16px; overflow: hidden;
}
.test-progress > div { height: 100%; background: linear-gradient(90deg, var(--accent), var(--teal)); transition: width 420ms var(--ease-out, ease); }

.test-list { display: flex; flex-direction: column; gap: 12px; max-width: 820px; margin: 0 auto; }
.test-q {
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 18px; transition: border-color var(--speed), box-shadow var(--speed);
}
.test-q:focus-within { border-color: color-mix(in srgb, var(--accent) 55%, transparent); box-shadow: 0 0 0 3px var(--accent-soft); }
.test-q-head { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-bottom: 8px; }
.test-num {
  width: 26px; height: 26px; border-radius: 50%; display: grid; place-items: center; flex-shrink: 0;
  background: var(--surface-2); border: 1px solid var(--border-strong);
  font-family: var(--font-mono); font-size: 12px; color: var(--text-dim);
}
.test-prompt { font-size: 17px; line-height: 1.5; margin: 4px 0 12px; word-break: break-word; }
.test-prompt p { margin: 2px 0; }
.choice-list { display: grid; gap: 8px; }
.choice {
  display: flex; align-items: center; gap: 10px; cursor: pointer; min-height: 44px;
  padding: 9px 12px; border: 1px solid var(--border); border-radius: var(--radius-sm);
  background: var(--surface-2); transition: border-color var(--speed), background var(--speed), transform 140ms ease;
}
.choice:hover { border-color: var(--border-strong); }
.choice:active { transform: scale(0.99); }
.choice input { position: absolute; opacity: 0; pointer-events: none; }
.choice-key {
  width: 24px; height: 24px; border-radius: 6px; display: grid; place-items: center; flex-shrink: 0;
  border: 1px solid var(--border-strong); font-family: var(--font-mono); font-size: 11.5px; color: var(--text-dim);
  transition: background var(--speed), color var(--speed), border-color var(--speed);
}
.choice-text p { margin: 0; }
.choice:has(input:checked) { border-color: var(--accent); background: var(--accent-soft); }
.choice:has(input:checked) .choice-key { background: var(--accent); border-color: var(--accent); color: var(--accent-contrast); }
.choice:has(input:focus-visible) { box-shadow: 0 0 0 3px var(--accent-soft); }

.test-submit-bar {
  position: sticky; bottom: 0; z-index: 5; display: flex; justify-content: flex-end; gap: 10px;
  max-width: 820px; margin: 16px auto 0; padding: 12px 0 18px;
  background: linear-gradient(to top, var(--bg) 70%, transparent);
}

.score-card { display: flex; align-items: center; gap: 26px; max-width: 820px; margin: 0 auto 14px; flex-wrap: wrap; }
.score-ring { position: relative; width: 128px; height: 128px; flex-shrink: 0; }
.ring-svg { width: 100%; height: 100%; transform: rotate(-90deg); }
.ring-bg { fill: none; stroke: var(--surface-3); stroke-width: 10; }
.ring-fg {
  fill: none; stroke: var(--score-color, var(--accent)); stroke-width: 10; stroke-linecap: round;
  transition: stroke-dashoffset 900ms var(--ease-out, ease), stroke 400ms ease;
}
.score-pct { position: absolute; inset: 0; display: grid; place-items: center; font-family: var(--font-mono); font-size: 28px; font-weight: 700; }
.score-meta { flex: 1; min-width: 220px; }
.score-meta h2 { font-size: 20px; }
.score-count { font-size: 15px; margin-top: 8px; }
.score-note { font-size: 12.5px; color: var(--text-faint); margin-top: 4px; }
.score-actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 14px; }
.test-filter { max-width: 820px; margin: 0 auto 12px; }

.test-q.result { border-left: 3px solid var(--border-strong); }
.test-q.result.is-right { border-left-color: var(--green); }
.test-q.result.is-wrong { border-left-color: var(--red); }
.verdict-reason { font-size: 12px; color: var(--text-faint); }
.override-btn { margin-left: auto; padding: 4px 12px; min-height: 30px; font-size: 12px; }
.answer-compare { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.answer-compare .section-label { display: block; margin-bottom: 3px; }
.answer-compare .given { font-size: 15px; word-break: break-word; }
.answer-compare .given.blank { color: var(--text-faint); font-style: italic; }
.is-wrong .answer-compare .given:not(.blank) { color: var(--red); text-decoration: line-through; text-decoration-thickness: 1px; }
.answer-compare .expected { font-size: 15px; color: var(--green); font-weight: 600; }
.answer-compare .expected p { margin: 0; }
.answer-more {
  margin-top: 10px; padding: 10px 12px; border-radius: var(--radius-sm);
  background: var(--surface-2); font-size: 13.5px; color: var(--text-dim); line-height: 1.5;
}
.answer-more p { margin: 2px 0; }
.answer-more.extra { font-style: italic; }

.guide-list { display: flex; flex-direction: column; gap: 10px; max-width: 820px; margin: 0 auto; }
.guide-item { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px 18px; }
.guide-q { display: flex; gap: 10px; align-items: flex-start; font-weight: 600; font-size: 15.5px; }
.guide-q p { margin: 2px 0; }
.guide-a { margin: 8px 0 0 36px; color: var(--text-dim); font-size: 14.5px; line-height: 1.55; }
.guide-a p { margin: 2px 0; }
.guide-extra { margin: 6px 0 0 36px; font-size: 13px; font-style: italic; color: var(--text-faint); }

@media (max-width: 640px) {
  .answer-compare { grid-template-columns: 1fr; gap: 8px; }
  .score-card { gap: 16px; }
  .score-ring { width: 100px; height: 100px; }
  .score-pct { font-size: 22px; }
  .test-submit-bar { bottom: 60px; }
  .override-btn { margin-left: 0; }
}

/* Printing a study guide or graded test: plain black on white, no chrome. */
@media print {
  #sidebar, #topbar, #bottomnav, #toasts, .no-print, .override-btn { display: none !important; }
  :root, body, #main, .main-wrap { background: #fff !important; color: #000 !important; }
  #main { padding: 0 !important; max-width: none !important; }
  #main * { animation: none !important; box-shadow: none !important; }
  .test-q, .guide-item, .score-card, .answer-more {
    background: #fff !important; color: #000 !important; border-color: #bbb !important; break-inside: avoid;
  }
  .guide-a, .guide-extra, .card-sub, .score-note, .verdict-reason { color: #333 !important; }
}

/* ---------- motion ---------- */
/* Everything below is switched off by [data-motion="reduced"] in theme.css. */

:root {
  --ease-out: cubic-bezier(0.2, 0.8, 0.2, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes view-in { from { opacity: 0; transform: translateY(12px); } }
@keyframes view-out { to { opacity: 0; transform: translateY(-8px); } }
@keyframes rise-in { from { opacity: 0; transform: translateY(14px) scale(0.98); } }
@keyframes fade-in { from { opacity: 0; } }
@keyframes fade-out { to { opacity: 0; } }
@keyframes modal-in { from { opacity: 0; transform: translateY(16px) scale(0.95); } }
@keyframes modal-out { to { opacity: 0; transform: translateY(10px) scale(0.97); } }
@keyframes pop { 0% { transform: scale(1); } 40% { transform: scale(1.22); } 100% { transform: scale(1); } }

/* page transitions: incoming view rises in, outgoing fades up (router adds .view-exit) */
#main > * { animation: view-in 360ms var(--ease-out) backwards; }
#main > *:nth-child(2) { animation-delay: 50ms; }
#main > *:nth-child(3) { animation-delay: 100ms; }
#main > *:nth-child(4) { animation-delay: 150ms; }
#main.view-exit > * { animation: view-out 150ms ease-in forwards; }

/* staggered lists and grids */
.tiles > *, .deck-manage-list > *, .home-col > .deck-row, .stagger > *, .grade-row > * { animation: rise-in 420ms var(--ease-out) backwards; }
.tiles > *:nth-child(2), .deck-manage-list > *:nth-child(2), .home-col > .deck-row:nth-child(2), .stagger > *:nth-child(2), .grade-row > *:nth-child(2) { animation-delay: 45ms; }
.tiles > *:nth-child(3), .deck-manage-list > *:nth-child(3), .home-col > .deck-row:nth-child(3), .stagger > *:nth-child(3), .grade-row > *:nth-child(3) { animation-delay: 90ms; }
.tiles > *:nth-child(4), .deck-manage-list > *:nth-child(4), .home-col > .deck-row:nth-child(4), .stagger > *:nth-child(4), .grade-row > *:nth-child(4) { animation-delay: 135ms; }
.tiles > *:nth-child(5), .deck-manage-list > *:nth-child(5), .home-col > .deck-row:nth-child(5), .stagger > *:nth-child(5), .grade-row > *:nth-child(5) { animation-delay: 180ms; }
.tiles > *:nth-child(6), .deck-manage-list > *:nth-child(6), .home-col > .deck-row:nth-child(6), .stagger > *:nth-child(6), .grade-row > *:nth-child(6) { animation-delay: 225ms; }
.tiles > *:nth-child(7), .deck-manage-list > *:nth-child(7), .home-col > .deck-row:nth-child(7), .stagger > *:nth-child(7), .grade-row > *:nth-child(7) { animation-delay: 270ms; }
.tiles > *:nth-child(8), .deck-manage-list > *:nth-child(8), .home-col > .deck-row:nth-child(8), .stagger > *:nth-child(8), .grade-row > *:nth-child(8) { animation-delay: 315ms; }
.tiles > *:nth-child(9), .deck-manage-list > *:nth-child(9), .home-col > .deck-row:nth-child(9), .stagger > *:nth-child(9), .grade-row > *:nth-child(9) { animation-delay: 360ms; }
.tiles > *:nth-child(10), .deck-manage-list > *:nth-child(10), .home-col > .deck-row:nth-child(10), .stagger > *:nth-child(10), .grade-row > *:nth-child(10) { animation-delay: 405ms; }
.tiles > *:nth-child(11), .deck-manage-list > *:nth-child(11), .home-col > .deck-row:nth-child(11), .stagger > *:nth-child(11), .grade-row > *:nth-child(11) { animation-delay: 450ms; }
.tiles > *:nth-child(12), .deck-manage-list > *:nth-child(12), .home-col > .deck-row:nth-child(12), .stagger > *:nth-child(12), .grade-row > *:nth-child(12) { animation-delay: 495ms; }

/* hover / press feedback */
.tile, .deck-row {
  transition: transform 220ms var(--ease-out), border-color var(--speed), box-shadow 220ms var(--ease-out);
}
.tile:hover, .deck-row:hover {
  transform: translateY(-2px); border-color: var(--border-strong);
  box-shadow: 0 12px 28px -14px var(--shadow);
}
.btn, .icon-btn, .grade-btn, .add-fab, .swatch {
  transition: filter var(--speed), background var(--speed), border-color var(--speed),
    color var(--speed), transform 140ms var(--ease-out), box-shadow var(--speed);
}
.btn:active, .icon-btn:active, .add-fab:active, .swatch:active { transform: scale(0.95); }
.grade-btn:hover { transform: translateY(-2px); }
.grade-btn:active { transform: scale(0.96); }
.side-item { transition: background var(--speed), color var(--speed), transform 180ms var(--ease-out); }
.side-item:hover { transform: translateX(2px); }
.side-item.active svg, .bn-item.active svg { animation: pop 340ms var(--ease-spring); }
.study-bar > div { transition: width 420ms var(--ease-out); }

/* modals + toasts */
.modal-overlay { animation: fade-in 180ms ease backwards; }
.modal { animation: modal-in 300ms var(--ease-spring) backwards; }
.modal-overlay.closing { animation: fade-out 170ms ease forwards; }
.modal-overlay.closing .modal { animation: modal-out 170ms ease-in forwards; }
.toast { transition: opacity 250ms ease, transform 250ms ease; }

/* study: 3D flip on reveal, cards slide through */
@keyframes card-in { from { opacity: 0; transform: translateX(56px) rotate(1.5deg); } }
@keyframes card-in-left { from { opacity: 0; transform: translateX(-56px) rotate(-1.5deg); } }
@keyframes card-out { to { opacity: 0; transform: translateX(-70px) rotate(-2.5deg); } }
@keyframes flip-lift { 50% { transform: scale(1.035); } }

.flip-scene { width: 100%; max-width: 720px; perspective: 1800px; }
.flip-scene.card-in { animation: card-in 340ms var(--ease-out) backwards; }
.flip-scene.card-in-left { animation: card-in-left 340ms var(--ease-out) backwards; }
.flip-scene.card-out { animation: card-out 220ms ease-in forwards; }
.flip-scene.flipping { animation: flip-lift 640ms var(--ease-out); }
.flip-card {
  display: grid; transform-style: preserve-3d;
  transition: transform 640ms cubic-bezier(0.3, 0.7, 0.2, 1.08);
}
.flip-card.flipped { transform: rotateY(180deg); }
.flip-card.instant { transition: none; }
.flip-card > .face {
  grid-area: 1 / 1; max-width: none;
  backface-visibility: hidden; -webkit-backface-visibility: hidden;
}
.flip-card > .face-back { transform: rotateY(180deg); }
.flip-card > .face-front { cursor: pointer; }
.flip-card > .face-front:hover { border-color: var(--border-strong); }
.flip-scene.card-out .face-back {
  transition: box-shadow 200ms ease, border-color 200ms ease;
  border-color: var(--grade, var(--accent));
  box-shadow: 0 0 46px -10px var(--grade, var(--accent));
}
.study-controls { display: flex; flex-direction: column; align-items: center; width: 100%; }
.study-controls > * { animation: rise-in 320ms var(--ease-out) backwards; }
.study-controls > .study-caption { animation-delay: 160ms; }