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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    overflow: hidden;
    height: 100vh;
}

#app {
    display: flex;
    height: 100vh;
}

#reader-container {
    flex: 1;
    position: relative;
    overflow: hidden;
    transition: margin-right 0.3s ease;
}

#sidebar {
    width: 320px;
    background: #1a1a1a;
    color: #e8e8e8;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    transition: width 0.3s ease;
    position: relative;
    flex-shrink: 0;
}

#sidebar.collapsed {
    width: 48px;
}

.sidebar-content {
    padding: 64px 24px 24px 24px;
    display: flex;
    flex-direction: column;
    gap: 24px;
    opacity: 1;
    transition: opacity 0.2s ease;
}

#sidebar.collapsed .sidebar-content {
    opacity: 0;
    pointer-events: none;
}

.sidebar-toggle {
    position: absolute;
    top: 16px;
    left: 12px;
    width: 32px;
    height: 32px;
    border-radius: 6px;
    background: transparent;
    color: #e8e8e8;
    border: none;
    cursor: pointer;
    font-size: 18px;
    z-index: 10;
    transition: background 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0;
}

.sidebar-toggle:hover {
    background: #2a2a2a;
}

#sidebar.collapsed .sidebar-toggle {
    left: 8px;
}

.sidebar-section {
    display: flex;
    flex-direction: column;
    gap: 12px;
    background: #242424;
    border: 1px solid #2a2a2a;
    border-radius: 8px;
    padding: 16px;
    transition: all 0.2s ease;
}

.sidebar-section:hover {
    border-color: #3a3a3a;
}

.sidebar-section.collapsible {
    padding: 0;
    overflow: hidden;
}

.section-header {
    font-size: 14px;
    font-weight: 600;
    color: #e8e8e8;
    text-transform: none;
    letter-spacing: 0;
    margin: 0;
    padding: 16px;
    cursor: pointer;
    user-select: none;
    display: flex;
    align-items: center;
    gap: 10px;
    transition: background 0.2s ease;
}

.section-header:hover {
    background: rgba(255, 255, 255, 0.03);
}

.section-icon {
    font-size: 18px;
    line-height: 1;
}

.collapse-arrow {
    margin-left: auto;
    font-size: 10px;
    transition: transform 0.3s ease;
    color: #a0a0a0;
}

.section-header.collapsed .collapse-arrow {
    transform: rotate(-90deg);
}

.section-content {
    display: flex;
    flex-direction: column;
    gap: 12px;
    padding: 0 16px 16px 16px;
    max-height: 1000px;
    opacity: 1;
    transition: max-height 0.3s ease, opacity 0.3s ease, padding 0.3s ease;
}

.section-content.collapsed {
    max-height: 0;
    opacity: 0;
    padding: 0 16px;
    overflow: hidden;
}

.sidebar-section h3 {
    font-size: 14px;
    font-weight: 600;
    color: #a0a0a0;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.control-group label {
    font-size: 13px;
    color: #a0a0a0;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.control-value {
    color: #60a5fa;
    font-weight: 500;
}

input[type="range"] {
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: #2a2a2a;
    outline: none;
    -webkit-appearance: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: #60a5fa;
    cursor: pointer;
}

input[type="range"]::-moz-range-thumb {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: #60a5fa;
    cursor: pointer;
    border: none;
}

.btn-group {
    display: flex;
    gap: 8px;
}

button {
    flex: 1;
    padding: 10px 16px;
    border: 1px solid #2a2a2a;
    background: #2a2a2a;
    color: #e8e8e8;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
    font-weight: 500;
    transition: all 0.2s;
}

button:hover {
    background: #3a3a3a;
    border-color: #3a3a3a;
}

button.active {
    background: #60a5fa;
    border-color: #60a5fa;
    color: #fff;
}

select {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid #2a2a2a;
    background: #2a2a2a;
    color: #e8e8e8;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
}

.margin-drag-zone {
    position: absolute;
    top: 0;
    height: 100%;
    cursor: ew-resize;
    z-index: 100;
    transition: background 0.2s, border-color 0.2s;
    border: 1px dashed transparent;
    pointer-events: auto;
}

.margin-drag-zone-left {
    left: 0;
}

.margin-drag-zone-right {
    right: 0;
}

.margin-drag-zone:hover {
    background: rgba(59, 130, 246, 0.08);
    border-color: rgba(59, 130, 246, 0.2);
}

.margin-drag-zone.dragging {
    background: rgba(59, 130, 246, 0.15);
    border-color: rgba(59, 130, 246, 0.4);
}

select {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid #2a2a2a;
    background: #2a2a2a;
    color: #e8e8e8;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
}

select:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

input[type="checkbox"] {
    width: 16px;
    height: 16px;
    cursor: pointer;
    accent-color: #60a5fa;
}

.ebook-text-content.flow-mode {
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
}