/* ============================================
   AUTOMATON DESIGNER - PROFESSIONAL UI
   LeetCode-inspired professional design
   ============================================ */

/* CSS Variables */
:root {
    /* Professional Color Palette (LeetCode-inspired) */
    --bg-primary: #ffffff;
    --bg-secondary: #fafafa;
    --bg-tertiary: #f7f8fa;
    --bg-hover: #f0f0f1;
    --surface: #ffffff;
    
    --text-primary: #262626;
    --text-secondary: #595959;
    --text-muted: #8c8c8c;
    
    --accent-primary: #ffa116;
    --accent-secondary: #2db55d;
    --accent-danger: #ef4743;
    --accent-success: #00b8a3;
    --accent-info: #0a84ff;
    
    --border-color: #e5e5e5;
    --border-hover: #d4d4d4;
    
    /* State colors */
    --state-fill: #ffffff;
    --state-stroke: #262626;
    --state-hover: #f7f8fa;
    --state-active: #e5e5e5;
    
    /* Typography */
    --font-display: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
    --font-body: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', 'Monaco', 'Inconsolata', 'Fira Code', 'Courier New', monospace;
    
    /* Spacing */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    
    /* Sizes */
    --sidebar-width: 320px;
    --state-radius: 32px;
}

/* Dark theme variant (optional - can be toggled) */
.dark-theme {
    --bg-primary: #1a1a1a;
    --bg-secondary: #262626;
    --bg-tertiary: #2a2a2a;
    --bg-hover: #333333;
    --surface: #262626;
    
    --text-primary: #eff1f6;
    --text-secondary: #a3a3a3;
    --text-muted: #737373;
    
    --border-color: #3a3a3a;
    --border-hover: #4a4a4a;
    
    --state-fill: #2a2a2a;
    --state-stroke: #eff1f6;
    --state-hover: #333333;
}

/* ============================================
   RESET & BASE
   ============================================ */

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

body {
    font-family: var(--font-body);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--border-hover);
}

/* ============================================
   LAYOUT
   ============================================ */

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

/* ============================================
   SIDEBAR
   ============================================ */

.sidebar {
    width: var(--sidebar-width);
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    flex-shrink: 0;
}

.sidebar-header {
    padding: var(--space-lg) var(--space-xl);
    border-bottom: 1px solid var(--border-color);
    background: var(--bg-primary);
}

.logo {
    display: flex;
    flex-direction: column;
    gap: var(--space-xs);
    font-family: var(--font-display);
    font-weight: 600;
    line-height: 1.2;
}

.logo-text {
    font-size: 20px;
    color: var(--text-primary);
    letter-spacing: -0.5px;
}

.subtitle {
    font-size: 13px;
    color: var(--text-secondary);
    font-weight: 400;
}

/* ============================================
   PANELS
   ============================================ */

.panel {
    padding: var(--space-lg);
    border-bottom: 1px solid var(--border-color);
}

.panel-title {
    font-size: 13px;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--space-md);
}

.panel-expandable .panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    user-select: none;
    margin-bottom: var(--space-md);
}

.panel-expandable .panel-header:hover .panel-title {
    color: var(--accent-primary);
}

.toggle-btn {
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 12px;
    cursor: pointer;
    transition: transform 0.2s ease, color 0.2s;
    padding: var(--space-xs);
}

.toggle-btn:hover {
    color: var(--accent-primary);
}

.toggle-btn.collapsed {
    transform: rotate(-90deg);
}

.panel-content {
    max-height: 800px;
    overflow-y: auto;
    transition: max-height 0.3s ease, opacity 0.3s ease;
}

.panel-content.hidden {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
}

/* ============================================
   INSTRUCTIONS
   ============================================ */

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

.instruction {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-sm) var(--space-md);
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 13px;
    transition: background 0.2s, border-color 0.2s;
}

.instruction:hover {
    background: var(--bg-hover);
    border-color: var(--border-hover);
}

.key {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 12px;
    font-family: var(--font-mono);
}

.desc {
    color: var(--text-secondary);
}

.info-note {
    margin-top: var(--space-md);
    padding: var(--space-sm) var(--space-md);
    background: var(--bg-tertiary);
    border-left: 3px solid var(--accent-primary);
    font-size: 11px;
    color: var(--text-secondary);
    border-radius: 4px;
}

/* ============================================
   BUTTONS
   ============================================ */

.button-group {
    display: flex;
    gap: var(--space-sm);
    margin-bottom: var(--space-sm);
}

.button-group:last-child {
    margin-bottom: 0;
}

.btn {
    flex: 1;
    font-family: var(--font-body);
    font-size: 13px;
    font-weight: 500;
    padding: var(--space-sm) var(--space-md);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s ease;
    background: var(--bg-primary);
    color: var(--text-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-xs);
}

.btn:hover {
    background: var(--bg-hover);
    border-color: var(--border-hover);
}

.btn:active {
    transform: scale(0.98);
}

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

.btn-primary:hover {
    background: #ff9500;
    border-color: #ff9500;
}

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

.btn-secondary:hover {
    background: var(--bg-hover);
}

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

.btn-danger:hover {
    background: #e63946;
    border-color: #e63946;
}

.btn-sm {
    padding: 6px 12px;
    font-size: 12px;
}

.btn-block {
    width: 100%;
}

.btn-icon {
    font-size: 14px;
}

.btn-icon-sm {
    background: var(--accent-primary);
    color: white;
    border: none;
    border-radius: 50%;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-weight: 700;
    font-size: 14px;
    transition: all 0.2s;
}

.btn-icon-sm:hover {
    background: #ff9500;
    transform: scale(1.05);
}

/* ============================================
   TEST PANEL
   ============================================ */

.test-section {
    margin-bottom: var(--space-lg);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--space-sm);
}

.input-label {
    display: block;
    font-size: 12px;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: var(--space-sm);
}

.input-field {
    width: 100%;
    padding: var(--space-sm) var(--space-md);
    font-family: var(--font-mono);
    font-size: 13px;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    transition: border-color 0.2s, box-shadow 0.2s;
}

.input-field:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(255, 161, 22, 0.1);
}

.button-row {
    display: flex;
    gap: var(--space-sm);
    margin-top: var(--space-sm);
}

.result-box {
    padding: var(--space-md);
    border-radius: 6px;
    font-size: 13px;
    font-family: var(--font-mono);
    margin-bottom: var(--space-md);
    min-height: 40px;
    border: 1px solid var(--border-color);
    background: var(--bg-primary);
    color: var(--text-secondary);
}

.result-box.accept {
    background: #f0fdf4;
    border-color: var(--accent-secondary);
    color: #166534;
}

.result-box.reject {
    background: #fef2f2;
    border-color: var(--accent-danger);
    color: #991b1b;
}

.result-box.empty {
    background: var(--bg-tertiary);
    border-style: dashed;
}

.step-viz {
    font-size: 12px;
    font-family: var(--font-mono);
    line-height: 1.8;
    color: var(--text-secondary);
    padding: var(--space-sm);
    background: var(--bg-tertiary);
    border-radius: 6px;
    margin-bottom: var(--space-md);
}

.step-viz .state-indicator {
    display: inline-block;
    padding: 2px 8px;
    background: var(--accent-primary);
    color: white;
    border-radius: 4px;
    margin: 0 4px;
    font-weight: 600;
}

.testcases-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    margin-bottom: var(--space-md);
    max-height: 200px;
    overflow-y: auto;
}

.testcase-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-sm) var(--space-md);
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 12px;
    transition: background 0.2s;
}

.testcase-item:hover {
    background: var(--bg-hover);
}

.testcase-input {
    font-weight: 600;
    color: var(--text-primary);
    font-family: var(--font-mono);
}

.testcase-expected {
    color: var(--text-muted);
    font-size: 11px;
    margin-left: var(--space-sm);
}

.testcase-result {
    margin-left: auto;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 11px;
    font-weight: 600;
}

.testcase-result.pass {
    background: #dcfce7;
    color: #166534;
}

.testcase-result.fail {
    background: #fee2e2;
    color: #991b1b;
}

.testcase-actions {
    display: flex;
    gap: var(--space-xs);
    margin-left: var(--space-sm);
}

.btn-delete {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 4px;
    font-size: 16px;
    opacity: 0.6;
    transition: opacity 0.2s, color 0.2s;
}

.btn-delete:hover {
    opacity: 1;
    color: var(--accent-danger);
}

/* ============================================
   CANVAS AREA
   ============================================ */

.canvas-area {
    flex: 1;
    position: relative;
    background: var(--bg-primary);
    overflow: hidden;
    /* Subtle dot pattern */
    background-image: radial-gradient(circle, var(--border-color) 1px, transparent 1px);
    background-size: 20px 20px;
}

#canvas {
    width: 100%;
    height: 100%;
    display: block;
    /* Professional crosshair cursor */
    cursor: crosshair;
}

#canvas:active {
    cursor: grabbing;
}

/* Trash Zone */
.trash-zone {
    position: absolute;
    bottom: 24px;
    right: 24px;
    width: 120px;
    height: 120px;
    background: var(--bg-secondary);
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    opacity: 0.6;
    transition: all 0.3s ease;
    pointer-events: none;
    z-index: 100;
}

.trash-zone.active {
    opacity: 1;
    background: #fef2f2;
    border-color: var(--accent-danger);
    border-width: 3px;
    border-style: solid;
    transform: scale(1.1);
}

.trash-icon {
    font-size: 48px;
    opacity: 0.5;
    transition: opacity 0.3s;
}

.trash-zone.active .trash-icon {
    opacity: 1;
    animation: shake 0.5s ease-in-out infinite;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-4px); }
    75% { transform: translateX(4px); }
}

.trash-text {
    font-size: 11px;
    font-weight: 600;
    color: var(--text-muted);
    text-align: center;
}

.trash-zone.active .trash-text {
    color: var(--accent-danger);
}

.state {
    cursor: move;
    transition: filter 0.2s;
}

.state:hover {
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.1));
}

.state:active {
    cursor: grabbing;
}

.state.dragging-to-trash {
    opacity: 0.5;
}

/* ============================================
   SVG ELEMENTS
   ============================================ */

.state-circle {
    fill: var(--state-fill);
    stroke: var(--state-stroke);
    stroke-width: 2px;
    transition: all 0.2s;
}

.state:hover .state-circle {
    fill: var(--state-hover);
    stroke-width: 2.5px;
}

.state-final-inner {
    fill: none;
    stroke: var(--state-stroke);
    stroke-width: 2px;
}

.state-label {
    font-family: var(--font-mono);
    font-size: 14px;
    font-weight: 600;
    fill: var(--text-primary);
    text-anchor: middle;
    dominant-baseline: middle;
    pointer-events: none;
    user-select: none;
}

.start-indicator {
    stroke: var(--accent-danger);
    stroke-width: 2.5px;
    fill: none;
}

.transition {
    cursor: pointer;
}

.transition-path {
    fill: none;
    stroke: var(--text-primary);
    stroke-width: 1.5px;
    marker-end: url(#arrowhead);
    transition: all 0.2s;
}

.transition:hover .transition-path {
    stroke: var(--accent-primary);
    stroke-width: 2px;
}

.transition-label {
    font-family: var(--font-mono);
    font-size: 13px;
    font-weight: 600;
    fill: var(--text-primary);
    text-anchor: middle;
    dominant-baseline: middle;
    pointer-events: none;
    user-select: none;
}

.transition-label-bg {
    fill: var(--bg-primary);
    stroke: var(--bg-primary);
    stroke-width: 6;
}

/* ============================================
   MODALS
   ============================================ */

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.modal-backdrop {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(4px);
}

.modal-content {
    position: relative;
    background: var(--bg-primary);
    padding: var(--space-xl);
    border-radius: 8px;
    border: 1px solid var(--border-color);
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    min-width: 320px;
    animation: slideUp 0.3s ease;
}

@keyframes slideUp {
    from { 
        transform: translateY(20px);
        opacity: 0;
    }
    to { 
        transform: translateY(0);
        opacity: 1;
    }
}

.modal-title {
    font-family: var(--font-display);
    font-size: 16px;
    font-weight: 600;
    margin-bottom: var(--space-lg);
    color: var(--text-primary);
}

.form-group {
    margin-bottom: var(--space-md);
}

.modal-buttons {
    display: flex;
    gap: var(--space-sm);
    justify-content: flex-end;
    margin-top: var(--space-lg);
}

/* ============================================
   RESPONSIVE
   ============================================ */

@media (max-width: 768px) {
    .app-container {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        max-height: 50vh;
        border-right: none;
        border-bottom: 1px solid var(--border-color);
    }
    
    .canvas-area {
        flex: 1;
    }
}

/* ============================================
   UTILITIES
   ============================================ */

.hidden {
    display: none !important;
}

.no-select {
    user-select: none;
    -webkit-user-select: none;
    -moz-user-select: none;
}