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

:root {
  --safe-area-top: 0px;
  --safe-area-right: 0px;
  --safe-area-bottom: 0px;
  --safe-area-left: 0px;
  --viewport-block: 100vh;
  --corner-spacing: 1rem;
  --corner-top-offset: calc(var(--corner-spacing) + var(--safe-area-top));
  --corner-left-offset: calc(var(--corner-spacing) + var(--safe-area-left));
  --corner-right-offset: calc(var(--corner-spacing) + var(--safe-area-right));
  --corner-button-gap: 0.5rem;
  --top-bar-background: #ffffff;
  --top-bar-control-background: #f1f1f1;
  --top-bar-control-border: #cfcfcf;
  --top-bar-control-border-hover: #b8b8b8;
  --button-outline-color: #d0d0d0;
  --toolbar-padding-block: 0.25rem;
  --search-form-gap: 0.75rem;
  --search-control-size: calc(24px + 1.5rem);
  --search-control-radius: 0.75rem;
}

@supports (padding-top: env(safe-area-inset-top)) {
  :root {
    --safe-area-top: env(safe-area-inset-top);
    --safe-area-right: env(safe-area-inset-right);
    --safe-area-bottom: env(safe-area-inset-bottom);
    --safe-area-left: env(safe-area-inset-left);
  }
}

@supports (height: 100svh) {
  :root {
    --viewport-block: 100svh;
  }
}

@supports (height: 100dvh) {
  :root {
    --viewport-block: 100dvh;
  }
}

html,
body {
  height: var(--viewport-block);
  min-height: var(--viewport-block);
  margin: 0;
  overflow-x: hidden;
  background-color: #ffffff;
}

button {
  border: 1px solid var(--button-outline-color);
}

body {
  font-family: sans-serif;
  max-width: 1000px;
  margin: 0 auto;
  width: 100%;
  padding-bottom: 0;
}

body.reading-active {
  max-width: none;
}

.screen {
  display: none;
  height: var(--viewport-block);
  min-height: var(--viewport-block);
  box-sizing: border-box;
}

.screen.active {
  display: flex;
  flex-direction: column;
}

#home-screen,
#settings-screen {
  --screen-padding-top: var(--corner-top-offset);
  --screen-padding-bottom: calc(2rem + var(--safe-area-bottom));
  align-items: center;
  justify-content: center;
  padding: var(--screen-padding-top) var(--corner-right-offset)
    var(--screen-padding-bottom) var(--corner-left-offset);
  gap: 1.5rem;
  min-height: max(
    0px,
    calc(var(--viewport-block) - var(--screen-padding-top) - var(--screen-padding-bottom))
  );
}
#settings-screen {
  justify-content: flex-start;
}


#reading-screen {
  align-items: stretch;
}

#home-screen {
  position: relative;
  height: var(--viewport-block);
}

.reading-tip {
  max-width: 24rem;
  text-align: center;
  line-height: 1.5;
  color: #555555;
}

.install-message {
  max-width: 24rem;
  text-align: center;
  line-height: 1.5;
  color: #333333;
}

#settings-screen {
  position: relative;
}

#home-screen button:not(.icon-button),
#settings-screen button:not(.icon-button),
.top-bar button:not(.icon-button) {
  margin: 0.5rem;
  padding: 0.5rem 1rem;
  font-size: 1rem;
}
#settings-screen button:not(.icon-button) {
  margin: 0.25rem;
  padding: 0.25rem 0.5rem;
}

#open-book-button {
  position: absolute;
  top: var(--corner-top-offset);
  left: var(--corner-left-offset);
}

#open-settings-button,
#settings-back {
  position: absolute;
  top: var(--corner-top-offset);
  right: var(--corner-right-offset);
}

#open-book-button,
#open-settings-button,
#settings-back,
#open-book-top-button,
#settings-toggle {
  margin: 0;
}

#reader {
  --reader-padding-top: 0px;
  --reader-padding-bottom: 0px;
  --reader-padding-left: 0px;
  --reader-padding-right: 0px;
  flex: 1;
  min-height: 0;
  max-width: 800px;
  margin: 0 auto;
  overflow-y: auto;
  overflow-x: hidden;
  padding-top: calc(var(--reader-padding-top) + var(--safe-area-top));
  padding-bottom: calc(var(--reader-padding-bottom) + var(--safe-area-bottom));
  padding-left: calc(var(--reader-padding-left) + var(--safe-area-left));
  padding-right: calc(var(--reader-padding-right) + var(--safe-area-right));
  background: #ffffff;
  color: #000000;
  display: flex;
  flex-direction: column;
  position: relative;
}

#reader-content {
  flex: 1 0 auto;
  width: 100%;
  min-height: 100%;
  background: inherit;
  color: inherit;
  white-space: inherit;
  word-wrap: break-word;
}

.reader-margin-overlay {
  display: block;
  width: 100%;
  flex: 0 0 auto;
  background: inherit;
  pointer-events: none;
  z-index: 1;
}

#reader-top-margin {
  position: sticky;
  top: 0;
  height: calc(var(--reader-padding-top) + var(--safe-area-top));
}

#reader-bottom-margin {
  position: sticky;
  bottom: 0;
  height: calc(var(--reader-padding-bottom) + var(--safe-area-bottom));
}

@media (max-width: 1023px) {
  #reader {
    width: 100%;
  }
}

@media (min-width: 1024px) {
  #reader {
    width: 60%;
  }
}

.top-bar {
  position: relative;
  display: none;
  justify-content: space-between;
  align-items: center;
  padding: 0;
  gap: var(--corner-button-gap);
}

.top-bar.visible {
  display: flex;
  position: absolute;      /* existing overlay behavior */
  top: 0;
  left: 0;
  right: 0;
  background-color: var(--top-bar-background);
  color: inherit;          /* keep theme colors */
  padding: calc(var(--toolbar-padding-block) + var(--safe-area-top))
    var(--corner-right-offset) var(--toolbar-padding-block)
    var(--corner-left-offset);
  z-index: 1;
}

.top-bar .icon-button#search-toggle[aria-expanded="true"] {
  background-color: rgba(0, 0, 0, 0.08);
}

.top-bar .icon-button#search-toggle[aria-expanded="true"] {
  background-color: color-mix(in srgb, currentColor 16%, transparent);
}

.top-bar .book-info {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.5rem;
  min-width: 0;
}

.top-bar .book-title {
  flex: 1 1 auto;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

  .top-bar .reading-progress {
    flex: 0 0 auto;
    width: var(--search-control-size);
    height: var(--search-control-size);
    padding: 0;
    font-size: 0.875rem;
    font-variant-numeric: tabular-nums;
    font-weight: 600;
  }


.controls {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  width: 100%;
  max-width: 600px;
}

.search-panel {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  margin-top: 0;
  padding: var(--toolbar-padding-block) var(--corner-right-offset)
    var(--toolbar-padding-block) var(--corner-left-offset);
  background-color: var(--top-bar-background);
  color: inherit;
  border-bottom: 1px solid var(--top-bar-control-border);
  z-index: 1;
}

.search-panel.open {
  display: block;
}

.search-form {
  display: grid;
  align-items: center;
  grid-template-columns: minmax(0, 1fr) auto auto;
  grid-template-areas: 'input counter navigation';
  column-gap: var(--search-form-gap);
  padding: 0;
  width: 100%;
}

.search-input {
  flex: 1 1 auto;
  width: 100%;
  padding: 0.375rem 0.75rem;
  border-radius: 0.5rem;
  border: 1px solid var(--button-outline-color);
  background-color: var(--top-bar-control-background);
  color: inherit;
  font-size: 1rem;
  min-width: 0;
  grid-area: input;
}

.search-nav-controls {
  display: inline-flex;
  gap: var(--corner-button-gap);
  flex: 0 0 auto;
  grid-area: navigation;
  justify-self: end;
  align-self: center;
}


.search-counter {
  display: flex;
  align-items: center;
  justify-content: center;
  height: var(--search-control-size);
  font-size: 0.875rem;
  min-width: 3.5rem;
  text-align: center;
  font-variant-numeric: tabular-nums;
  flex: 0 0 auto;
  grid-area: counter;
  justify-self: start;
  padding: 0 0.75rem;
  white-space: nowrap;
  align-self: center;
}

.visually-hidden {
  position: absolute !important;
  height: 1px;
  width: 1px;
  overflow: hidden;
  clip: rect(1px, 1px, 1px, 1px);
  white-space: nowrap;
  border: 0;
  padding: 0;
  margin: -1px;
}

.search-highlight {
  background-color: rgba(255, 235, 59, 0.4);
  color: inherit;
}

.search-highlight {
  background-color: color-mix(in srgb, currentColor 24%, transparent);
}

.search-active-match {
  background-color: rgba(255, 215, 0, 0.6);
  color: inherit;
  outline: 2px solid rgba(0, 0, 0, 0.35);
  outline-offset: 2px;
}

.search-active-match {
  background-color: color-mix(in srgb, currentColor 45%, transparent);
  outline-color: color-mix(in srgb, currentColor 55%, transparent);
}

@media (max-width: 640px) {
  .search-panel {
    left: 0;
    right: 0;
    width: 100%;
  }
}

.toc-highlight {
  outline: 2px solid #ffa500;
}

.settings-section label {
  display: inline-block;
  margin: 0;
}

.settings-section + .settings-section {
  margin-top: 1.5rem;
}

.settings-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 0.5rem;
}

.settings-table th,
.settings-table td {
  padding: 0.25rem 0.5rem;
  text-align: left;
  vertical-align: middle;
}

.settings-table th {
  width: 40%;
  font-weight: 600;
}

.settings-action-row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.settings-status {
  font-size: 0.875rem;
  color: #555555;
}

.settings-status.error {
  color: #b00020;
}

.font-size-controls,
.margin-controls {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.font-size-controls span,
.margin-controls span {
  min-width: 2ch;
  text-align: center;
}

.font-preview-wrapper {
  border: 1px solid #ccc;
  border-radius: 0.25rem;
  padding: 0.5rem;
  background: #f8f8f8;
}

.font-preview-content {
  display: block;
  width: 100%;
  min-height: 0;
  line-height: 1.5;
  border-radius: 0.25rem;
  box-sizing: border-box;
  background: #ffffff;
  color: inherit;
  transition: padding 0.2s ease;
  padding-top: var(--preview-padding-top, 0px);
  padding-bottom: var(--preview-padding-bottom, 0px);
  padding-left: var(--preview-padding-left, 0px);
  padding-right: var(--preview-padding-right, 0px);
}

.settings-title {
  margin: 0;
  text-align: center;
  width: 100%;
}

.settings-subsection {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  width: 100%;
  margin-top: 1rem;
}

.settings-subsection:first-of-type {
  margin-top: 0.5rem;
}

.settings-subheading {
  margin: 0;
  font-size: 1rem;
  font-weight: 600;
}

button.icon-button {
  appearance: none;
  border: 1px solid var(--button-outline-color);
  background-color: transparent;
  color: inherit;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem;
  margin: 0;
  line-height: 1;
  border-radius: 0.5rem;
  cursor: pointer;
  transition: background-color 0.2s ease, opacity 0.2s ease;
}

button.icon-button:hover {
  background-color: rgba(0, 0, 0, 0.08);
}

button.icon-button:hover {
  background-color: color-mix(in srgb, currentColor 16%, transparent);
}

button.icon-button:disabled {
  background-color: transparent;
  opacity: 0.4;
  cursor: not-allowed;
}

button.icon-button .icon {
  width: 24px;
  height: 24px;
}

button.icon-button.active {
  background-color: rgba(0, 0, 0, 0.12);
}

button.icon-button.active {
  background-color: color-mix(in srgb, currentColor 24%, transparent);
}

#reader h1,
#reader h2,
#reader h3,
#reader h4,
#reader h5,
#reader h6 {
  font-weight: bold;
  margin: 1em 0 0.5em;
}

#reader em {
  font-style: italic;
}

#reader strong {
  font-weight: bold;
}

#reader img {
  max-width: 100%;
  height: auto;
}

#reader .cover-image {
  display: block;
  margin: 0 auto 1em;
}

#reader .note-ref {
  cursor: pointer;
  font-size: 0.75em;
  vertical-align: super;
}

#reader .note .note-back-link {
  display: inline-block;
  margin-bottom: 0.25em;
  margin-right: 0.5em;
  text-decoration: none;
}

#reader .note .note-back-link p {
  display: inline;
  margin: 0;
  font-weight: 600;
  text-decoration: underline;
}

#reader .note .note-back-link:focus-visible {
  outline: 2px solid currentColor;
  outline-offset: 2px;
}

#reader .note {
  display: none;
  font-size: 0.875em;
  border-top: 1px solid #ccc;
  margin-top: 0.5em;
  padding-top: 0.5em;
}

#reader .note.visible {
  display: block;
}

#reader .note-ref.note-ref-highlight {
  background-color: rgba(255, 236, 179, 0.8);
  border-radius: 4px;
  transition: background-color 0.6s ease;
}