/* CSS Variables for theming */
:root {
    --bg-primary: #f5f5f5;
    --bg-secondary: white;
    --bg-header: #f8f9fa;
    --bg-hint: #fafafa;
    --bg-cell-focus: #e8f4fc;
    --text-primary: #333;
    --text-secondary: #666;
    --text-muted: #888;
    --border-color: #e0e0e0;
    --border-hover: #999;
    --accent-color: #4a90d9;
    --accent-hover: #3a7bc8;
    --cell-focus-shadow: rgba(74, 144, 217, 0.3);
    --selection-bg: rgba(74, 144, 217, 0.15);
    --selection-border: #4a90d9;
    --selection-grid: rgba(0, 0, 0, 0.12);
}

/* Dark mode colors */
.dark-mode {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-header: #363636;
    --bg-hint: #252525;
    --bg-cell-focus: #1e3a5f;
    --text-primary: #e0e0e0;
    --text-secondary: #b0b0b0;
    --text-muted: #808080;
    --border-color: #404040;
    --border-hover: #606060;
    --accent-color: #5a9fe9;
    --accent-hover: #4a8fd9;
    --cell-focus-shadow: rgba(90, 159, 233, 0.3);
    --selection-bg: rgba(90, 159, 233, 0.2);
    --selection-border: #5a9fe9;
    --selection-grid: rgba(255, 255, 255, 0.12);
}

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

html, body {
    height: 100%;
    overflow: hidden;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    transition: background-color 0.3s, color 0.3s;
}

.container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    width: 100vw;
}

/* Header bar */
.header {
    display: flex;
    align-items: center;
    padding: 12px 16px;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    gap: 16px;
    flex-shrink: 0;
    transition: background-color 0.3s, border-color 0.3s;
}

.header h1 {
    color: var(--text-primary);
    font-weight: 500;
    font-size: 1.25rem;
    margin: 0;
    display: flex;
    align-items: center;
    gap: 8px;
}

.header h1 i {
    color: var(--accent-color);
}

.toolbar {
    display: flex;
    gap: 8px;
    align-items: center;
    flex: 1;
}

/* Format buttons group */
.format-buttons {
    display: flex;
    gap: 2px;
    background: var(--bg-header);
    border-radius: 4px;
    padding: 2px;
}

.format-btn {
    width: 32px;
    height: 32px;
    padding: 0 !important;
    background: transparent !important;
    border: none !important;
    border-radius: 3px;
    color: var(--text-secondary) !important;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s, color 0.2s;
}

.format-btn:hover {
    background: var(--bg-secondary) !important;
    color: var(--text-primary) !important;
}

.format-btn.active {
    background: var(--accent-color) !important;
    color: white !important;
}

.format-btn i {
    font-size: 0.875rem !important;
}

/* Toolbar divider */
.toolbar-divider {
    width: 1px;
    height: 24px;
    background: var(--border-color);
    margin: 0 4px;
}

.color-control {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 2px 6px;
    border-radius: 4px;
    border: 1px solid var(--border-color);
    background: var(--bg-header);
}

.color-control i {
    font-size: 0.8125rem;
    color: var(--text-secondary);
}

.color-control input[type="color"] {
    width: 28px;
    height: 28px;
    padding: 0;
    border: none;
    background: transparent;
    cursor: pointer;
}

.color-control input[type="color"]::-webkit-color-swatch-wrapper {
    padding: 0;
}

.color-control input[type="color"]::-webkit-color-swatch {
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.color-control input[type="color"]::-moz-color-swatch {
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.toolbar button {
    padding: 6px 12px;
    font-size: 0.8125rem;
    font-family: inherit;
    background-color: var(--accent-color);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.2s;
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.toolbar button i {
    font-size: 0.75rem;
}

.toolbar button:hover:not(:disabled) {
    background-color: var(--accent-hover);
}

.toolbar button:disabled {
    background-color: #ccc;
    cursor: not-allowed;
}

.dark-mode .toolbar button:disabled {
    background-color: #555;
    color: #888;
}

/* Theme toggle button */
.theme-toggle {
    background: transparent !important;
    border: 1px solid var(--border-color) !important;
    padding: 8px 10px !important;
    font-size: 0.875rem !important;
    color: var(--text-secondary) !important;
}

.theme-toggle:hover:not(:disabled) {
    background: var(--bg-header) !important;
    color: var(--text-primary) !important;
}

.theme-toggle i {
    font-size: 0.875rem !important;
}

.icon-dark {
    display: none;
}

.dark-mode .icon-light {
    display: none;
}

.dark-mode .icon-dark {
    display: inline;
}

/* Copy URL button */
.copy-btn {
    background: transparent !important;
    border: 1px solid var(--border-color) !important;
    padding: 8px 10px !important;
    font-size: 0.875rem !important;
    color: var(--text-secondary) !important;
}

.copy-btn:hover:not(:disabled) {
    background: var(--bg-header) !important;
    color: var(--text-primary) !important;
}

.copy-btn.copied {
    color: #22c55e !important;
    border-color: #22c55e !important;
}

.copy-btn.copied i::before {
    content: "\f00c"; /* fa-check */
}

/* GitHub link */
.github-link {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    padding: 8px 10px;
    border-radius: 4px;
    border: 1px solid var(--border-color);
    transition: color 0.2s, background-color 0.2s;
    text-decoration: none;
    font-size: 1rem;
}

.github-link:hover {
    color: var(--text-primary);
    background-color: var(--bg-header);
}

.grid-size {
    color: var(--text-muted);
    font-size: 0.8125rem;
    margin-left: auto;
    display: flex;
    align-items: center;
    gap: 6px;
}

.grid-size i {
    opacity: 0.7;
}

/* Main grid area - fills remaining space */
.grid-wrapper {
    flex: 1;
    overflow: auto;
    background: var(--bg-secondary);
    transition: background-color 0.3s;
}

.spreadsheet {
    display: grid;
    /* grid-template-columns set dynamically via JS */
    gap: 0;
    min-width: fit-content;
}

/* Header cells (A-Z and row numbers) */
.header-cell {
    background-color: var(--bg-header);
    border: 1px solid var(--border-color);
    padding: 8px;
    text-align: center;
    font-weight: 500;
    color: var(--text-secondary);
    font-size: 0.8125rem;
    user-select: none;
    position: sticky;
    z-index: 2;
    transition: background-color 0.3s, border-color 0.3s, color 0.3s;
}

.header-cell.header-active {
    background-color: var(--bg-cell-focus);
    border-color: var(--accent-color);
    color: var(--text-primary);
}

/* Column headers stick to top */
.header-cell.col-header {
    top: 0;
    z-index: 3;
}

/* Row headers stick to left */
.header-cell.row-header {
    left: 0;
    z-index: 2;
}

/* Corner cell (top-left) */
.corner-cell {
    background-color: var(--bg-header);
    border: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    left: 0;
    z-index: 4;
    transition: background-color 0.3s, border-color 0.3s;
}

/* Data cells */
.cell {
    border: 1px solid var(--border-color);
    margin: -1px 0 0 -1px;
    transition: border-color 0.3s;
    background-color: var(--cell-bg, transparent);
}

.cell:hover {
    border-color: var(--border-hover);
    z-index: 1;
    position: relative;
}

.cell-content {
    width: 100%;
    height: 100%;
    min-height: 32px;
    padding: 6px 8px;
    border: none;
    outline: none;
    font-size: 0.8125rem;
    font-family: inherit;
    background: transparent;
    color: var(--text-primary);
    transition: background-color 0.3s, color 0.3s;
    overflow: hidden;
    word-wrap: break-word;
}

.cell-content:focus {
    background-color: var(--bg-cell-focus);
}

.cell:has(.cell-content:focus) {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 2px var(--cell-focus-shadow);
    z-index: 2;
    position: relative;
}

/* Formula suggestions dropdown */
.formula-dropdown {
    position: fixed;
    min-width: 220px;
    max-width: 320px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
    padding: 4px;
    z-index: 10;
    display: none;
}

.formula-dropdown.open {
    display: block;
}

.formula-item {
    padding: 6px 8px;
    border-radius: 4px;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.formula-item:hover,
.formula-item.active {
    background: var(--bg-cell-focus);
}

.formula-name {
    color: var(--text-primary);
    font-weight: 600;
    font-size: 0.8125rem;
}

.formula-hint {
    color: var(--text-muted);
    font-size: 0.75rem;
}

/* Multi-cell selection styles */
.cell.cell-selected {
    background-color: var(--cell-bg, transparent);
    box-shadow: inset 0 0 0 9999px var(--selection-bg);
    border-color: var(--selection-grid);
    position: relative;
    z-index: 1;
}

.cell.cell-selected .cell-content {
    background-color: transparent;
}

/* Selection border outline (Google Sheets style) */
.cell.cell-selected.selection-top {
    border-top: 2px solid var(--selection-border);
}

.cell.cell-selected.selection-bottom {
    border-bottom: 2px solid var(--selection-border);
}

.cell.cell-selected.selection-left {
    border-left: 2px solid var(--selection-border);
}

.cell.cell-selected.selection-right {
    border-right: 2px solid var(--selection-border);
}

/* Prevent text selection during drag */
.spreadsheet.selecting {
    user-select: none;
    cursor: cell;
}

.spreadsheet.selecting .cell-content {
    user-select: none;
    pointer-events: none;
}

/* Footer hint */
.hint {
    padding: 8px 16px;
    color: var(--text-muted);
    font-size: 0.75rem;
    background: var(--bg-hint);
    border-top: 1px solid var(--border-color);
    flex-shrink: 0;
    transition: background-color 0.3s, border-color 0.3s, color 0.3s;
    display: flex;
    align-items: center;
    gap: 8px;
}

.hint i {
    opacity: 0.7;
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .header {
        padding: 8px 12px;
        flex-wrap: wrap;
        gap: 8px;
    }

    .header h1 {
        font-size: 1rem;
    }

    .toolbar {
        order: 1;
        width: 100%;
    }

    .toolbar button {
        padding: 6px 10px;
        font-size: 0.75rem;
    }

    .header-cell {
        padding: 6px;
        font-size: 0.75rem;
    }

    .cell-content {
        min-height: 44px;
        padding: 6px;
        font-size: 16px; /* Prevents zoom on iOS */
    }

    .hint {
        font-size: 0.7rem;
        padding: 6px 12px;
    }
}