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

:root {
    --bg: #ffffff;
    --header-bg: #f0f0f0;
    --border: #d0d0d0;
    --selected-bg: #d4e6f9;
    --selected-border: #2266cc;
    --text: #222;
    --row-num-bg: #f5f5f5;
    --row-num-width: 50px;
    --toolbar-height: 36px;
    --status-height: 24px;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    font-size: 13px;
}

html, body {
    height: 100%;
    overflow: hidden;
    background: var(--bg);
    color: var(--text);
}

#app {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

/* Toolbar / formula bar */
#toolbar {
    display: flex;
    align-items: center;
    height: var(--toolbar-height);
    border-bottom: 1px solid var(--border);
    background: var(--header-bg);
    padding: 0 4px;
    flex-shrink: 0;
}

#cell-ref {
    width: 80px;
    text-align: center;
    font-weight: 600;
    border-right: 1px solid var(--border);
    padding: 0 8px;
    line-height: var(--toolbar-height);
    flex-shrink: 0;
    font-size: 12px;
    color: #555;
}

#formula-bar {
    flex: 1;
    border: none;
    outline: none;
    padding: 4px 8px;
    font-size: 13px;
    font-family: inherit;
    background: var(--bg);
    height: 100%;
}

#formula-bar:focus {
    background: #fff;
    box-shadow: inset 0 0 0 1px var(--selected-border);
}

/* Table container */
#table-container {
    flex: 1;
    overflow: auto;
    position: relative;
}

#csv-table {
    border-collapse: collapse;
    table-layout: fixed;
    min-width: 100%;
}

/* Header row */
#table-head th {
    position: sticky;
    top: 0;
    z-index: 10;
    background: var(--header-bg);
    border: 1px solid var(--border);
    border-top: none;
    padding: 4px 6px;
    font-weight: 600;
    text-align: left;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    user-select: none;
    cursor: default;
    height: 26px;
    font-size: 12px;
    max-width: 150px;
}

#table-head th.row-number-header {
    width: var(--row-num-width);
    min-width: var(--row-num-width);
    max-width: var(--row-num-width);
    position: sticky;
    left: 0;
    z-index: 11;
    text-align: center;
    background: var(--header-bg);
}

/* Column resize handle */
.col-resize-handle {
    position: absolute;
    right: -3px;
    top: 0;
    bottom: 0;
    width: 6px;
    cursor: col-resize;
    z-index: 4;
}

.col-resize-handle:hover,
.col-resize-handle.active {
    background: var(--selected-border);
    opacity: 0.3;
}

th .header-content {
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
    text-overflow: ellipsis;
}

th .header-text {
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
}

th .header-edit-input {
    width: 100%;
    border: 1px solid var(--selected-border);
    outline: none;
    padding: 1px 4px;
    font-size: 12px;
    font-weight: 600;
    font-family: inherit;
}

/* Data cells */
#table-body td {
    border: 1px solid var(--border);
    padding: 2px 6px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    height: 24px;
    cursor: cell;
    font-size: 13px;
    max-width: 150px;
}

#table-body td.row-number {
    position: sticky;
    left: 0;
    z-index: 1;
    background: var(--row-num-bg);
    text-align: center;
    font-size: 11px;
    color: #888;
    width: var(--row-num-width);
    min-width: var(--row-num-width);
    max-width: var(--row-num-width);
    cursor: default;
    user-select: none;
}

/* Selection */
td.selected {
    background: var(--selected-bg) !important;
}

td.cursor-cell {
    outline: 2px solid var(--selected-border);
    outline-offset: -1px;
}

/* Status bar */
#status-bar {
    height: var(--status-height);
    line-height: var(--status-height);
    border-top: 1px solid var(--border);
    padding: 0 12px;
    background: var(--header-bg);
    font-size: 11px;
    color: #666;
    flex-shrink: 0;
}

/* Command Palette */
#overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.3);
    z-index: 99;
}

#overlay.hidden, #command-palette.hidden {
    display: none;
}

#command-palette {
    position: fixed;
    top: 80px;
    left: 50%;
    transform: translateX(-50%);
    width: 460px;
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 8px;
    box-shadow: 0 8px 32px rgba(0,0,0,0.2);
    z-index: 100;
    overflow: hidden;
}

#command-input {
    width: 100%;
    border: none;
    border-bottom: 1px solid var(--border);
    padding: 12px 16px;
    font-size: 15px;
    outline: none;
    font-family: inherit;
}

#command-list {
    max-height: 300px;
    overflow-y: auto;
}

.command-item {
    padding: 8px 16px;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.command-item:hover,
.command-item.active {
    background: var(--selected-bg);
}

.command-item .cmd-name {
    font-size: 14px;
}

.command-item .cmd-shortcut {
    font-size: 11px;
    color: #888;
    background: #eee;
    padding: 2px 6px;
    border-radius: 3px;
}

/* Drag over style */
#table-container.drag-over {
    background: var(--selected-bg);
}