/* ============================================
   CSS Variables & Reset
   ============================================ */
:root {
    /* Colors */
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-secondary: #64748b;
    --color-danger: #dc2626;
    --color-danger-hover: #b91c1c;
    --color-success: #16a34a;
    --color-warning: #ea580c;
    
    /* Neutrals */
    --color-bg: #ffffff;
    --color-bg-alt: #f8fafc;
    --color-border: #e2e8f0;
    --color-text: #0f172a;
    --color-text-muted: #64748b;
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    
    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Courier New', monospace;
    
    /* Layout */
    --header-height: 60px;
    --sidebar-width: 200px;
    --border-radius: 6px;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: var(--font-sans);
    font-size: 14px;
    line-height: 1.5;
    color: var(--color-text);
    background-color: var(--color-bg-alt);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

/* ============================================
   Header
   ============================================ */
.app-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 var(--space-lg);
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.header-left {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.app-header h1 {
    font-size: 18px;
    font-weight: 600;
    color: var(--color-text);
    margin: 0;
}

.privacy-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-xs) var(--space-sm);
    background-color: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    font-size: 12px;
    color: var(--color-text-muted);
    cursor: help;
}

.header-actions {
    display: flex;
    gap: var(--space-sm);
}

/* ============================================
   Buttons
   ============================================ */
button {
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--border-radius);
    font-weight: 500;
    transition: all 0.15s ease;
    white-space: nowrap;
}

.btn-primary {
    background-color: var(--color-primary);
    color: white;
}

.btn-primary:hover:not(:disabled) {
    background-color: var(--color-primary-hover);
}

.btn-secondary {
    background-color: var(--color-bg);
    color: var(--color-text);
    border: 1px solid var(--color-border);
}

.btn-secondary:hover:not(:disabled) {
    background-color: var(--color-bg-alt);
    border-color: var(--color-secondary);
}

.btn-danger {
    background-color: var(--color-danger);
    color: white;
}

.btn-danger:hover:not(:disabled) {
    background-color: var(--color-danger-hover);
}

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

button:active:not(:disabled) {
    transform: translateY(1px);
}

/* ============================================
   Layout
   ============================================ */
.app-container {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    overflow: hidden;
}

.module-rail {
    width: var(--sidebar-width);
    background-color: var(--color-bg);
    border-right: 1px solid var(--color-border);
    padding: var(--space-lg);
    overflow-y: auto;
    flex-shrink: 0;
}

.module-rail h2 {
    font-size: 14px;
    font-weight: 600;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--space-md);
}

.module-nav {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
}

.module-nav button {
    width: 100%;
    text-align: left;
    padding: var(--space-sm) var(--space-md);
    background-color: transparent;
    color: var(--color-text);
    border: 1px solid transparent;
    border-radius: var(--border-radius);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.module-nav button:before {
    content: '○';
    font-size: 16px;
    color: var(--color-text-muted);
}

.module-nav button.active:before {
    content: '●';
    color: var(--color-primary);
}

.module-nav button:hover {
    background-color: var(--color-bg-alt);
}

.module-nav button.active {
    background-color: var(--color-bg-alt);
    border-color: var(--color-primary);
    color: var(--color-primary);
    font-weight: 500;
}

.module-info {
    margin-top: var(--space-lg);
    padding: var(--space-md);
    background-color: var(--color-bg-alt);
    border-radius: var(--border-radius);
    font-size: 12px;
    color: var(--color-text-muted);
    line-height: 1.6;
}

.content-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* ============================================
   Panels
   ============================================ */
.data-panel,
.results-panel {
    display: flex;
    flex-direction: column;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
}

.data-panel {
    flex: 1;
    min-height: 0;
}

.results-panel {
    flex: 1;
    min-height: 0;
}

.panel-header {
    padding: var(--space-md) var(--space-lg);
    border-bottom: 1px solid var(--color-border);
    background-color: var(--color-bg-alt);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-md);
    flex-wrap: wrap;
}

.panel-header h2 {
    font-size: 16px;
    font-weight: 600;
    color: var(--color-text);
}

/* ============================================
   Sheet Tabs
   ============================================ */
.sheet-tabs {
    display: flex;
    gap: var(--space-xs);
}

.sheet-tabs .tab {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
    padding: var(--space-sm) var(--space-md);
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    color: var(--color-text);
}

.sheet-tabs .tab.active {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
    color: white;
}

.tab-label {
    font-weight: 500;
    font-size: 13px;
}

.tab-badge {
    font-size: 11px;
    opacity: 0.8;
}

/* ============================================
   Controls
   ============================================ */
.sheet-controls,
.results-actions {
    display: flex;
    gap: var(--space-sm);
    align-items: center;
}

.control-label {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-size: 13px;
    color: var(--color-text-muted);
    font-weight: 500;
}

.select-input {
    padding: var(--space-xs) var(--space-sm);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    background-color: var(--color-bg);
    color: var(--color-text);
    min-width: 150px;
}

.search-input {
    padding: var(--space-xs) var(--space-sm);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    width: 200px;
}

/* ============================================
   Empty States
   ============================================ */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    padding: var(--space-xl);
    text-align: center;
    color: var(--color-text-muted);
}

.empty-icon {
    font-size: 48px;
    margin-bottom: var(--space-md);
    opacity: 0.5;
}

.empty-state h3 {
    font-size: 16px;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--space-sm);
}

.empty-state p {
    font-size: 14px;
    margin-bottom: var(--space-lg);
}

/* ============================================
   Metrics Strip
   ============================================ */
.metrics-strip {
    display: flex;
    gap: var(--space-lg);
    padding: var(--space-md) var(--space-lg);
    background-color: var(--color-bg-alt);
    border-bottom: 1px solid var(--color-border);
    flex-wrap: wrap;
}

.metric {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.metric-label {
    font-size: 11px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-text-muted);
}

.metric-value {
    font-size: 20px;
    font-weight: 700;
    color: var(--color-text);
}

.metric-value.success {
    color: var(--color-success);
}

.metric-value.warning {
    color: var(--color-warning);
}

.metric-value.danger {
    color: var(--color-danger);
}

/* ============================================
   Modal
   ============================================ */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal.hidden {
    display: none;
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
}

.modal-content {
    position: relative;
    background-color: var(--color-bg);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-lg);
    width: 90%;
    max-width: 600px;
    max-height: 80vh;
    display: flex;
    flex-direction: column;
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-lg);
    border-bottom: 1px solid var(--color-border);
}

.modal-header h3 {
    font-size: 18px;
    font-weight: 600;
    color: var(--color-text);
}

.modal-close {
    padding: var(--space-xs) var(--space-sm);
    font-size: 24px;
    line-height: 1;
    color: var(--color-text-muted);
    background: none;
    border: none;
}

.modal-close:hover {
    color: var(--color-text);
}

.modal-body {
    padding: var(--space-lg);
    overflow-y: auto;
    flex: 1;
}

.modal-footer {
    padding: var(--space-lg);
    border-top: 1px solid var(--color-border);
    display: flex;
    justify-content: flex-end;
    gap: var(--space-sm);
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 768px) {
    .module-rail {
        position: fixed;
        left: -100%;
        top: var(--header-height);
        bottom: 0;
        z-index: 50;
        transition: left 0.3s ease;
    }
    
    .module-rail.open {
        left: 0;
    }
    
    .header-actions {
        flex-wrap: wrap;
    }
    
    .search-input {
        width: 100%;
    }
}