/* ============================================================
   Lazy Eye Reader — Styles
   A dichoptic reading practice tool
   ============================================================ */

/* ---------- CSS Custom Properties ---------- */

:root {
    /* Light theme (default) */
    --color-bg: #f1f5f9;
    --color-surface: #ffffff;
    --color-surface-raised: #ffffff;
    --color-border: #e2e8f0;
    --color-border-hover: #cbd5e1;
    --color-text: #0f172a;
    --color-text-secondary: #475569;
    --color-text-tertiary: #94a3b8;
    --color-accent: #374151;
    --color-accent-hover: #111827;
    --color-accent-subtle: #f3f4f6;
    --color-accent-ring: rgba(55, 65, 81, 0.2);
    --color-success: #10b981;
    --color-danger: #ef4444;
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --sidebar-width: 340px;
    --header-height: 60px;
    --transition-fast: 0.15s ease;
    --transition-normal: 0.2s ease;
    --transition-slow: 0.3s ease;
}

/* ---------- Dark Theme: Neutral Charcoal / Graphite ---------- */

[data-theme="dark"] {
    --color-bg: #161616;
    --color-surface: #212121;
    --color-surface-raised: #2b2b2b;
    --color-border: #363636;
    --color-border-hover: #484848;
    --color-text: #ededed;
    --color-text-secondary: #9e9e9e;
    --color-text-tertiary: #686868;
    --color-accent: #ededed;
    --color-accent-hover: #f0f0f0;
    --color-accent-subtle: #232323;
    --color-accent-ring: rgba(237, 237, 237, 0.18);
    --color-success: #4ade80;
    --color-danger: #f87171;
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.35), 0 1px 2px rgba(0, 0, 0, 0.25);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.45), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5), 0 4px 6px -4px rgba(0, 0, 0, 0.3);
}

/* ---------- Reset & Base ---------- */

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

html {
    -webkit-text-size-adjust: 100%;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    font-size: 14px;
    line-height: 1.5;
    color: var(--color-text);
    background-color: var(--color-bg);
    min-height: 100vh;
    overflow-x: hidden;
    transition: background-color var(--transition-slow), color var(--transition-slow);
}

fieldset {
    border: none;
    margin: 0;
    padding: 0;
}

legend {
    padding: 0;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
    font-size: inherit;
    color: inherit;
}

input, textarea, select {
    font-family: inherit;
    font-size: inherit;
    color: inherit;
}

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

a:hover {
    text-decoration: underline;
}

/* ---------- Typography ---------- */

h1, h2, h3, h4 {
    font-weight: 600;
    line-height: 1.3;
}

/* ---------- Header ---------- */

.app-header {
    position: sticky;
    top: 0;
    z-index: 100;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
    padding: 0 1.25rem;
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-xs);
    gap: 0.75rem;
    transition: background-color var(--transition-slow), border-color var(--transition-slow);
}

/* ---------- Header Brand ---------- */

.header-brand {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0;
    min-width: 0;
    overflow: hidden;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.brand-family, .brand-name {
    text-transform: inherit;
    letter-spacing: inherit;
}

.brand-family {
    font-size: 1.1875rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    white-space: nowrap;
    color: var(--color-text);
    text-decoration: none;
    flex-shrink: 0;
    transition: color var(--transition-fast);
}

.brand-family:hover {
    color: var(--color-accent);
    text-decoration: none;
}

.brand-family:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 3px;
    border-radius: 4px;
}

.brand-divider {
    font-size: 1.125rem;
    font-weight: 300;
    color: var(--color-text-tertiary);
    padding: 0 0.5rem;
    user-select: none;
    flex-shrink: 0;
}

.brand-name {
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    white-space: nowrap;
    color: var(--color-text);
    text-decoration: none;
    overflow: hidden;
    text-overflow: ellipsis;
    transition: color var(--transition-fast);
}

.brand-name:hover {
    color: var(--color-accent);
    text-decoration: none;
}

.brand-name:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 3px;
    border-radius: 4px;
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 0.375rem;
    flex-shrink: 0;
}

/* ---------- Icon Buttons ---------- */

.btn-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: var(--radius-md);
    color: var(--color-text-secondary);
    transition: background-color var(--transition-fast), color var(--transition-fast);
}

.btn-icon:hover {
    background-color: var(--color-accent-subtle);
    color: var(--color-accent);
}

.btn-icon:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.btn-icon svg {
    flex-shrink: 0;
}

.btn-icon-sm {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    border-radius: var(--radius-sm);
    color: var(--color-text-tertiary);
    transition: background-color var(--transition-fast), color var(--transition-fast);
}

.btn-icon-sm:hover {
    background-color: var(--color-accent-subtle);
    color: var(--color-accent);
}

.btn-icon-sm:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Theme toggle icon visibility */
[data-theme="light"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: inline; }
[data-theme="dark"] .icon-sun { display: inline; }
[data-theme="dark"] .icon-moon { display: none; }

/* Fullscreen toggle icon visibility */
.icon-minimize { display: none; }
body[data-fullscreen="true"] .icon-expand { display: none; }
body[data-fullscreen="true"] .icon-minimize { display: inline; }

/* ---------- App Layout ---------- */

.app-body {
    display: flex;
    min-height: calc(100vh - var(--header-height));
    position: relative;
}

/* ---------- Sidebar ---------- */

.sidebar {
    position: sticky;
    top: var(--header-height);
    width: var(--sidebar-width);
    height: calc(100vh - var(--header-height));
    flex-shrink: 0;
    background-color: var(--color-surface);
    border-right: 1px solid var(--color-border);
    overflow-y: auto;
    overflow-x: hidden;
    overscroll-behavior: contain;
    transition:
        width var(--transition-slow),
        background-color var(--transition-slow),
        border-color var(--transition-slow);
}

.sidebar-inner {
    width: var(--sidebar-width);
    padding: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    min-height: 100%;
}

/* Sidebar header — always visible on desktop */
.sidebar-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-bottom: 0.75rem;
    margin-bottom: 0.25rem;
    border-bottom: 1px solid var(--color-border);
}

.sidebar-title {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.sidebar-header-actions {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

/* Mobile close button: hidden on desktop */
#sidebar-close {
    display: none;
}

/* Desktop collapse button: visible on desktop */
#sidebar-collapse {
    display: inline-flex;
}

/* Scrollbar styling */
.sidebar::-webkit-scrollbar {
    width: 6px;
}
.sidebar::-webkit-scrollbar-track {
    background: transparent;
}
.sidebar::-webkit-scrollbar-thumb {
    background-color: var(--color-border);
    border-radius: 3px;
}
.sidebar::-webkit-scrollbar-thumb:hover {
    background-color: var(--color-border-hover);
}

/* Sidebar overlay (mobile) */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    z-index: 199;
    background-color: rgba(0, 0, 0, 0.4);
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.sidebar-overlay.visible {
    display: block;
    opacity: 1;
}

/* ---------- Sidebar Collapse (desktop) ---------- */

/* When sidebar is collapsed on desktop */
@media (min-width: 1024px) {
    body[data-sidebar-collapsed="true"] .sidebar {
        width: 0;
        border-right-color: transparent;
    }

    body[data-sidebar-collapsed="true"] .sidebar-inner {
        pointer-events: none;
        opacity: 0;
    }
}

/* Sidebar expand tab — appears when sidebar is collapsed on desktop */
.sidebar-expand-tab {
    display: none;
    position: fixed;
    top: calc(var(--header-height) + 2rem);
    left: 0;
    z-index: 101;
    align-items: center;
    gap: 0.375rem;
    padding: 0.625rem 0.75rem 0.625rem 0.5rem;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-left: none;
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    color: var(--color-text-secondary);
    font-size: 0.75rem;
    font-weight: 500;
    box-shadow: var(--shadow-md);
    cursor: pointer;
    transition:
        background-color var(--transition-fast),
        color var(--transition-fast),
        transform var(--transition-fast),
        box-shadow var(--transition-fast);
}

.sidebar-expand-tab:hover {
    background-color: var(--color-accent-subtle);
    color: var(--color-accent);
    transform: translateX(3px);
    box-shadow: var(--shadow-lg);
}

.sidebar-expand-tab:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

@media (min-width: 1024px) {
    body[data-sidebar-collapsed="true"] .sidebar-expand-tab {
        display: flex;
    }
}

/* ---------- Settings Groups ---------- */

.settings-group {
    padding: 1rem 0;
    border-bottom: 1px solid var(--color-border);
}

.settings-group:last-of-type {
    border-bottom: none;
}

.settings-group-title {
    font-size: 0.6875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-tertiary);
    margin-bottom: 0.875rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: default;
}

/* Quick start guide (<details>) */
.guide-section .settings-group-title {
    cursor: pointer;
    user-select: none;
}

.guide-section .settings-group-title:hover {
    color: var(--color-accent);
}

.guide-section summary {
    list-style: none;
}

.guide-section summary::-webkit-details-marker {
    display: none;
}

.guide-section summary::after {
    content: '';
    width: 16px;
    height: 16px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2394a3b8' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'/%3E%3C/svg%3E");
    transition: transform var(--transition-fast);
    margin-left: auto;
}

.guide-section[open] summary::after {
    transform: rotate(180deg);
}

.guide-steps {
    margin: 0.75rem 0 0.5rem 0;
    padding-left: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.guide-steps li {
    font-size: 0.8125rem;
    color: var(--color-text-secondary);
    line-height: 1.5;
}

.guide-steps strong {
    color: var(--color-text);
    font-weight: 600;
}

.guide-tip {
    font-size: 0.75rem;
    color: var(--color-text-tertiary);
    font-style: italic;
    margin-top: 0.5rem;
    padding-top: 0.5rem;
    border-top: 1px solid var(--color-border);
}

/* ---------- Form Fields ---------- */

.field-label {
    display: block;
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--color-text);
    margin-bottom: 0.375rem;
}

.field-label-sm {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-text-secondary);
}

.field-hint {
    font-size: 0.6875rem;
    color: var(--color-text-tertiary);
    margin-top: 0.25rem;
    line-height: 1.4;
}

/* ---------- Color Controls ---------- */

.color-field {
    margin-bottom: 1rem;
}

.color-field:last-child {
    margin-bottom: 0;
}

.color-input-row {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.color-swatch {
    -webkit-appearance: none;
    appearance: none;
    width: 40px;
    height: 40px;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 3px;
    cursor: pointer;
    background: transparent;
    flex-shrink: 0;
    transition: border-color var(--transition-fast);
}

.color-swatch:hover {
    border-color: var(--color-border-hover);
}

.color-swatch:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.color-swatch::-webkit-color-swatch-wrapper {
    padding: 0;
}

.color-swatch::-webkit-color-swatch {
    border: none;
    border-radius: 4px;
}

.color-swatch::-moz-color-swatch {
    border: none;
    border-radius: 4px;
}

.color-hex {
    width: 80px;
    padding: 0.4375rem 0.5rem;
    font-size: 0.8125rem;
    font-family: 'SF Mono', 'Cascadia Code', 'Consolas', monospace;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    text-transform: uppercase;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.color-hex:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px var(--color-accent-ring);
}

/* ---------- Range Sliders ---------- */

.range-field {
    margin-bottom: 0.875rem;
}

.range-field:last-child {
    margin-bottom: 0;
}

.range-field.compact {
    margin-top: 0.375rem;
    margin-bottom: 0;
}

.range-row {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 6px;
    background: var(--color-border);
    border-radius: 3px;
    outline: none;
    cursor: pointer;
    flex: 1;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--color-accent);
    cursor: pointer;
    border: 2px solid var(--color-surface);
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.15);
    box-shadow: var(--shadow-md);
}

input[type="range"]::-moz-range-thumb {
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--color-accent);
    cursor: pointer;
    border: 2px solid var(--color-surface);
    box-shadow: var(--shadow-sm);
}

input[type="range"]::-moz-range-track {
    height: 6px;
    background: var(--color-border);
    border-radius: 3px;
    border: none;
}

input[type="range"]:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 4px;
    border-radius: 3px;
}

.range-value {
    min-width: 3rem;
    text-align: right;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    font-variant-numeric: tabular-nums;
    white-space: nowrap;
    flex-shrink: 0;
}

/* ---------- Stepper Control ---------- */

.stepper-field {
    margin-bottom: 0.875rem;
}

.stepper {
    display: flex;
    align-items: center;
    gap: 0;
    width: fit-content;
}

.stepper-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    color: var(--color-text-secondary);
    font-size: 1.125rem;
    font-weight: 500;
    line-height: 1;
    transition: background-color var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
}

.stepper-btn:first-child {
    border-radius: var(--radius-md) 0 0 var(--radius-md);
    border-right: none;
}

.stepper-btn:last-child {
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    border-left: none;
}

.stepper-btn:hover {
    background-color: var(--color-accent-subtle);
    color: var(--color-accent);
    border-color: var(--color-accent);
}

.stepper-btn:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: -2px;
    z-index: 1;
}

.stepper-input {
    width: 52px;
    height: 36px;
    text-align: center;
    font-size: 0.875rem;
    font-weight: 600;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: 0;
    -moz-appearance: textfield;
    color: var(--color-text);
    transition: border-color var(--transition-fast);
}

.stepper-input::-webkit-inner-spin-button,
.stepper-input::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.stepper-input:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px var(--color-accent-ring);
    z-index: 1;
    position: relative;
}

/* ---------- Buttons ---------- */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.375rem;
    padding: 0.5rem 1rem;
    font-size: 0.8125rem;
    font-weight: 500;
    border-radius: var(--radius-md);
    transition: background-color var(--transition-fast), color var(--transition-fast), box-shadow var(--transition-fast), opacity var(--transition-fast);
    white-space: nowrap;
}

.btn:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-primary {
    background: var(--color-accent);
    color: var(--color-bg);
    border-radius: var(--radius-md);
    font-weight: 600;
    border: none;
    box-shadow: var(--shadow-xs);
    transition: background var(--transition-fast), color var(--transition-fast);
}

.btn-primary:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.btn-primary:hover:not(:disabled), .btn-primary:focus-visible:not(:disabled) {
    background: var(--color-accent-hover);
    color: var(--color-bg);
}

.btn-ghost {
    color: var(--color-text-secondary);
    background: transparent;
}

.btn-ghost:hover:not(:disabled) {
    background-color: var(--color-accent-subtle);
    color: var(--color-accent);
}

.btn-text {
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--color-accent);
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
    transition: background-color var(--transition-fast), color var(--transition-fast);
}

.btn-text:hover {
    background-color: var(--color-accent-subtle);
}

.btn-text:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* ---------- Presets ---------- */

.preset-slots {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.375rem;
    margin-bottom: 0.75rem;
}

.preset-btn {
    padding: 0.4375rem 0.25rem;
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: var(--radius-md);
    border: 1.5px solid var(--color-border);
    color: var(--color-text-secondary);
    background: var(--color-bg);
    transition: all var(--transition-fast);
    text-align: center;
    line-height: 1.3;
}

.preset-btn:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
    background: var(--color-accent-subtle);
}

.preset-btn:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.preset-btn.active {
    border-color: var(--color-accent);
    background-color: var(--color-accent);
    color: var(--color-bg);
}

.preset-btn.empty {
    border-style: dashed;
    opacity: 0.65;
}

.preset-btn.empty:hover {
    opacity: 1;
}

.preset-btn.occupied {
    border-style: solid;
    opacity: 1;
}

.preset-actions {
    display: flex;
    gap: 0.5rem;
}

.preset-actions .btn {
    flex: 1;
}

/* ---------- Main Content ---------- */

.main-content {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    gap: 1.25rem;
}

/* ---------- Section Headers ---------- */

.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 0.75rem;
    gap: 0.75rem;
}

.section-title {
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.section-actions {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

/* ---------- Input Section ---------- */

.input-section {
    flex-shrink: 0;
}

.input-section.collapsed textarea {
    display: none;
}

.input-section.collapsed .collapse-chevron {
    transform: rotate(180deg);
}

#text-input {
    display: block;
    width: 100%;
    resize: vertical;
    min-height: 80px;
    max-height: 400px;
    padding: 0.875rem 1rem;
    font-family: 'Georgia', 'Times New Roman', 'Noto Serif', serif;
    font-size: 0.9375rem;
    line-height: 1.6;
    color: var(--color-text);
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    outline: none;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

#text-input:focus {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px var(--color-accent-ring);
}

#text-input::placeholder {
    color: var(--color-text-tertiary);
}

/* ---------- Reader Section ---------- */

.reader-section {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-height: 0;
}

.active-preset-badge {
    font-size: 0.6875rem;
    font-weight: 600;
    padding: 0.1875rem 0.5rem;
    border-radius: 999px;
    background-color: var(--color-accent-subtle);
    color: var(--color-accent);
    letter-spacing: 0.02em;
}

.reader-canvas {
    flex: 1;
    background-color: var(--reader-bg, #000000);
    font-family: 'Georgia', 'Times New Roman', 'Noto Serif', serif;
    font-weight: 700;
    font-size: var(--reader-font-size, 20px);
    line-height: var(--reader-line-height, 1.8);
    letter-spacing: var(--reader-letter-spacing, 1px);
    padding: 2rem;
    min-height: 300px;
    border-radius: var(--radius-xl);
    overflow-y: auto;
    overflow-wrap: break-word;
    word-wrap: break-word;
    user-select: text;
    white-space: normal;
    box-shadow: var(--shadow-md);
    transition: border-radius var(--transition-normal), padding var(--transition-normal);
}

.reader-canvas-wrapper {
    max-width: var(--reader-content-width, 800px);
    margin: 0 auto;
}

.reader-placeholder {
    color: var(--color-text-tertiary);
    font-weight: 400;
    font-style: italic;
    font-size: 1rem;
    text-align: center;
    padding: 3rem 1rem;
}

.reader-truncated {
    margin-top: 1.5rem;
    padding: 0.75rem 1rem;
    font-size: 0.8125rem;
    font-weight: 400;
    color: var(--color-text-tertiary);
    background: rgba(255, 255, 255, 0.08);
    border-radius: var(--radius-md);
    text-align: center;
}

/* ---------- Fullscreen Reading Mode ---------- */

body[data-fullscreen="true"] .app-header,
body[data-fullscreen="true"] .sidebar,
body[data-fullscreen="true"] .sidebar-overlay,
body[data-fullscreen="true"] .input-section,
body[data-fullscreen="true"] .fab,
body[data-fullscreen="true"] .sidebar-expand-tab,
body[data-fullscreen="true"] .section-header {
    display: none !important;
}

body[data-fullscreen="true"] .app-body {
    min-height: 100vh;
}

body[data-fullscreen="true"] .main-content {
    padding: 0;
    gap: 0;
}

body[data-fullscreen="true"] .reader-section {
    flex: 1;
    min-height: 100vh;
}

body[data-fullscreen="true"] .reader-canvas {
    min-height: 100vh;
    border-radius: 0;
    padding: 3rem 4rem;
    box-shadow: none;
}

/* ---------- Fullscreen Exit Button ---------- */

.fullscreen-exit-btn {
    position: fixed;
    top: 1rem;
    right: 1rem;
    z-index: 600;
    width: 42px;
    height: 42px;
    border-radius: var(--radius-md);
    background: rgba(20, 20, 20, 0.65);
    color: rgba(255, 255, 255, 0.7);
    display: none;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    transition:
        background var(--transition-fast),
        color var(--transition-fast),
        opacity var(--transition-fast),
        transform var(--transition-fast);
    opacity: 0.55;
}

body[data-fullscreen="true"] .fullscreen-exit-btn {
    display: flex;
}

.fullscreen-exit-btn:hover {
    background: rgba(30, 30, 30, 0.95);
    color: #ffffff;
    opacity: 1;
    transform: scale(1.05);
}

.fullscreen-exit-btn:focus-visible {
    outline: 2px solid rgba(139, 140, 248, 0.9);
    outline-offset: 3px;
    opacity: 1;
}

/* ---------- Fullscreen Hint Banner ---------- */

.fullscreen-hint {
    position: fixed;
    top: 1.25rem;
    left: 50%;
    transform: translateX(-50%) translateY(-1.5rem);
    z-index: 601;
    padding: 0.5rem 1.125rem;
    font-size: 0.8125rem;
    font-weight: 500;
    color: rgba(255, 255, 255, 0.9);
    background: rgba(15, 15, 15, 0.82);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 999px;
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
    pointer-events: none;
    opacity: 0;
    white-space: nowrap;
    transition: opacity 0.35s ease, transform 0.35s ease;
}

.fullscreen-hint kbd {
    font-family: inherit;
    font-size: 0.75rem;
    padding: 0.1rem 0.35rem;
    border-radius: 4px;
    background: rgba(255, 255, 255, 0.15);
    border: 1px solid rgba(255, 255, 255, 0.25);
}

body[data-fullscreen="true"] .fullscreen-hint.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

/* ---------- Mobile FAB ---------- */

.fab {
    display: none;
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    z-index: 500;
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--color-surface-raised);
    box-shadow: var(--shadow-lg);
    align-items: center;
    justify-content: center;
    border: none;
    cursor: pointer;
    transition: background var(--transition-fast), box-shadow var(--transition-fast);
}

.fab svg {
    color: var(--color-text);
    width: 28px;
    height: 28px;
    display: block;
}

[data-theme="dark"] .fab svg {
    color: #ededed;
}

.fab:active {
    box-shadow: var(--shadow-md);
}

/* ---------- Toast Notification ---------- */

/* Uses explicit dark background so it reads clearly on any theme */
.toast {
    position: fixed;
    bottom: 1.5rem;
    left: 50%;
    transform: translateX(-50%) translateY(1rem);
    z-index: 700;
    padding: 0.625rem 1.25rem;
    font-size: 0.8125rem;
    font-weight: 500;
    color: #f0f0f0;
    background-color: #1a1a1a;
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 999px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.45), 0 1px 3px rgba(0, 0, 0, 0.3);
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition-normal), transform var(--transition-normal);
    white-space: nowrap;
    max-width: 90vw;
    text-align: center;
}

.toast.visible {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
    pointer-events: auto;
}

/* ---------- Sidebar Footer ---------- */

.sidebar-footer {
    margin-top: 0.5rem;
    padding-top: 1rem;
}

.disclaimer {
    font-size: 0.6875rem;
    line-height: 1.5;
    color: var(--color-text-tertiary);
}

/* ---------- Responsive: Tablet / Mobile (<1024px) ---------- */

@media (max-width: 1023px) {
    /* On mobile, sidebar is a fixed overlay drawer */
    .sidebar {
        position: fixed;
        top: 0;
        left: 0;
        z-index: 200;
        height: 100vh;
        width: min(var(--sidebar-width), 85vw) !important; /* override collapse */
        transform: translateX(-100%);
        transition: transform var(--transition-slow), background-color var(--transition-slow);
        border-right: 1px solid var(--color-border) !important;
        border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
        box-shadow: none;
    }

    .sidebar.open {
        transform: translateX(0);
        box-shadow: var(--shadow-lg);
    }

    /* Show mobile close button, hide desktop collapse */
    #sidebar-close {
        display: inline-flex;
    }

    #sidebar-collapse {
        display: none;
    }

    /* Desktop-only elements hidden on mobile */
    .sidebar-expand-tab {
        display: none !important;
    }

    body[data-sidebar-collapsed="true"] .sidebar {
        width: min(var(--sidebar-width), 85vw) !important;
        border-right-color: var(--color-border) !important;
    }

    body[data-sidebar-collapsed="true"] .sidebar-inner {
        pointer-events: auto !important;
        opacity: 1 !important;
    }


    .main-content {
        padding: 1.25rem;
    }

        .fab {
            display: flex;
        }
}


/* ---------- Responsive: Mobile ---------- */

@media (max-width: 639px) {

    .app-header {
        padding: 0 0.875rem;
    }

    .brand-divider,
    .brand-name {
        display: none;
    }

    .main-content {
        padding: 1rem;
        gap: 1rem;
    }

    .reader-canvas {
        padding: 1.25rem;
        min-height: 250px;
        border-radius: var(--radius-lg);
    }

    .section-header {
        flex-wrap: wrap;
    }

    .preset-slots {
        grid-template-columns: repeat(2, 1fr);
    }

    .preset-actions {
        flex-direction: column;
    }

    #text-input {
        font-size: 0.875rem;
        min-height: 60px;
    }

    .toast {
        bottom: 5rem;
    }

    body[data-fullscreen="true"] .reader-canvas {
        padding: 1.5rem 1.25rem;
    }
}

/* ---------- Reduced Motion ---------- */

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        transition-duration: 0.01ms !important;
        animation-duration: 0.01ms !important;
    }

    html {
        scroll-behavior: auto;
    }
}

/* ---------- Print ---------- */

@media print {
    .app-header,
    .sidebar,
    .sidebar-overlay,
    .fab,
    .toast,
    .input-section,
    .section-header,
    .fullscreen-exit-btn,
    .fullscreen-hint,
    .sidebar-expand-tab {
        display: none !important;
    }

    .app-body {
        display: block;
    }

    .main-content {
        padding: 0;
    }

    .reader-canvas {
        box-shadow: none;
        border-radius: 0;
        min-height: auto;
        page-break-inside: auto;
    }
}