:root {
    /* Color scheme */
    --sd-bg-primary: #1e1e1e;
    --sd-bg-secondary: #252526;
    --sd-bg-tertiary: #2d2d30;
    --sd-bg-hover: #37373d;
    --sd-border-color: #3e3e42;
    --sd-text-primary: #ffffff;
    --sd-text-secondary: #cccccc;
    --sd-text-muted: #6a6a6a;
    
    /* Accent colors */
    --sd-accent-primary: #1e88e5;
    --sd-accent-dark: #0e639c;
    --sd-accent-bg: rgba(14, 99, 156, 0.1);
    --sd-accent-bg-medium: rgba(14, 99, 156, 0.3);
    --sd-accent-bg-strong: rgba(14, 99, 156, 0.4);
    
    /* Spacing */
    --sd-padding-small: 8px;
    --sd-padding-medium: 16px;
    --sd-padding-large: 20px;
    
    /* Sizes */
    --sd-border-width: 1px;
    --sd-border-width-thick: 3px;
    --sd-handle-size: 4px;
    --sd-min-dock-size: 100px;
    --sd-scrollbar-size: 4px;
    
    /* Transitions */
    --sd-transition-fast: 0.2s;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    height: 100vh;
    overflow: hidden;
    background: var(--sd-bg-primary);
}

/* Root frame only */
#app.sd-frame {
    width: 100%;
    height: 100vh;
}

/* Frame - can contain multiple docks in split view */
.sd-frame {
    display: flex;
    flex-direction: row;
    flex: 1;
    min-width: 0;
    min-height: 0;
}

.sd-frame:last-child {
    border-right: none;
}

.sd-frame.horizontal {
    flex-direction: row;
}

.sd-frame.vertical {
    flex-direction: column;
}

.sd-dock {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--sd-bg-secondary);
    border: var(--sd-border-width) solid var(--sd-border-color);
    position: relative;
    min-width: var(--sd-min-dock-size);
    min-height: var(--sd-min-dock-size);
}

.sd-dock-navbar {
    display: flex;
    background: var(--sd-bg-tertiary);
    border-bottom: var(--sd-border-width) solid var(--sd-border-color);
    overflow-x: auto;
    overflow-y: hidden;
    flex-shrink: 0;
}

.sd-dock-navbar::-webkit-scrollbar {
    height: var(--sd-scrollbar-size);
}

.sd-dock-navbar::-webkit-scrollbar-thumb {
    background: #555;
    border-radius: 2px;
}

.sd-panel-title {
    padding: var(--sd-padding-small) var(--sd-padding-medium);
    background: var(--sd-bg-tertiary);
    color: var(--sd-text-secondary);
    border-right: var(--sd-border-width) solid var(--sd-border-color);
    cursor: pointer;
    user-select: none;
    white-space: nowrap;
    display: flex;
    align-items: center;
    gap: var(--sd-padding-small);
    transition: background var(--sd-transition-fast);
}

.sd-panel-title:hover {
    background: var(--sd-bg-hover);
}

.sd-panel-title.active {
    background: var(--sd-bg-primary);
    color: var(--sd-text-primary);
}

.sd-panel-title.dragging {
    opacity: 0.5;
}

.sd-panel-title.drop-before {
    border-left: var(--sd-border-width-thick) solid var(--sd-accent-primary);
}

.sd-panel-title.drop-after {
    border-right: var(--sd-border-width-thick) solid var(--sd-accent-primary);
}

.sd-panel-title-text {
    pointer-events: none;
}

.sd-panel-close {
    width: var(--sd-padding-medium);
    height: var(--sd-padding-medium);
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 3px;
    font-size: var(--sd-padding-medium);
    line-height: 1;
}

.sd-panel-close:hover {
    background: #555;
}

.sd-dock-content {
    flex: 1;
    overflow: auto;
    position: relative;
}

.sd-panel-content {
    display: none;
    padding: var(--sd-padding-large);
    color: var(--sd-text-secondary);
    height: 100%;
}

.sd-panel-content.active {
    display: block;
}

/* Drop zones - 5 zones per dock */
.sd-dock.drop-center {
    outline: var(--sd-border-width-thick) solid var(--sd-accent-dark);
    outline-offset: calc(-1 * var(--sd-border-width-thick));
    background: var(--sd-accent-bg);
}

.sd-dock.drop-navbar .sd-dock-navbar {
    background: var(--sd-accent-bg-medium);
    outline: 2px solid var(--sd-accent-primary);
    outline-offset: -2px;
}

.sd-dock.drop-top::before,
.sd-dock.drop-bottom::before,
.sd-dock.drop-left::before,
.sd-dock.drop-right::before {
    content: '';
    position: absolute;
    background: var(--sd-accent-bg-strong);
    border: 2px dashed var(--sd-accent-primary);
    pointer-events: none;
    z-index: 1000;
}

.sd-dock.drop-top::before {
    top: 0;
    left: 0;
    right: 0;
    height: 30%;
}

.sd-dock.drop-bottom::before {
    bottom: 0;
    left: 0;
    right: 0;
    height: 30%;
}

.sd-dock.drop-left::before {
    top: 0;
    left: 0;
    bottom: 0;
    width: 30%;
}

.sd-dock.drop-right::before {
    top: 0;
    right: 0;
    bottom: 0;
    width: 30%;
}

/* Drag ghost */
.drag-ghost {
    position: fixed;
    background: var(--sd-bg-tertiary);
    color: var(--sd-text-secondary);
    padding: var(--sd-padding-small) var(--sd-padding-medium);
    border: var(--sd-border-width) solid var(--sd-accent-dark);
    border-radius: 4px;
    pointer-events: none;
    z-index: 10000;
    opacity: 0.8;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.4);
}

/* Empty dock message */
.sd-dock-empty {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--sd-text-muted);
    font-size: 14px;
    height: 100%;
}

/* Resize handles */
.sd-resize-handle {
    position: relative;
    flex-shrink: 0;
    background: var(--sd-border-color);
    z-index: 10;
}

.sd-resize-handle:hover {
    background: var(--sd-accent-dark);
}

.sd-resize-handle:active {
    background: var(--sd-accent-primary);
}

.sd-resize-handle.horizontal {
    width: var(--sd-handle-size);
    cursor: col-resize;
}

.sd-resize-handle.vertical {
    height: var(--sd-handle-size);
    cursor: row-resize;
}