/* ==============================================
   CSS Custom Properties (Variables)
   ============================================== */
:root {
    /* Color Palette */
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #21262d;
    --border-color: #30363d;
    --text-primary: #c9d1d9;
    --text-secondary: #8b949e;
    --text-tertiary: #6e7681;
    --accent-blue: #58a6ff;
    --accent-green: #3fb950;
    --accent-orange: #f85149;

    /* Component-specific Variables */
    --node-bg: var(--bg-secondary);
    --node-border: var(--border-color);

    /* Shadow Effects */
    --shadow-light: rgba(0, 0, 0, 0.1);
    --shadow-medium: rgba(0, 0, 0, 0.25);
    --shadow-heavy: rgba(0, 0, 0, 0.4);

    /* Animation */
    --transition-speed: 0.2s;
}

/* ==============================================
   Global Styles & Reset
   ============================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    overflow: hidden;
    user-select: none;
    /* Prevent text selection while dragging */
}

/* ==============================================
   Application Layout
   ============================================== */
.app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

/* Header Section */
.app-header {
    background-color: var(--bg-secondary);
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
}

.app-header h1 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.header-controls {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

/* Main Content Area */
.app-main {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* Control Panel */
.control-panel {
    width: 320px;
    background-color: var(--bg-secondary);
    padding: 1.5rem;
    overflow-y: auto;
    border-right: 1px solid var(--border-color);
    flex-shrink: 0;
}

.panel-section {
    margin-bottom: 2rem;
}

.panel-section h2 {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* ==============================================
   Form Controls
   ============================================== */
.control-group {
    margin-bottom: 1.25rem;
    position: relative;
}

.control-group label {
    display: flex;
    align-items: center;
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

/* Search Input */
.search-wrapper {
    position: relative;
}

.search-wrapper i {
    position: absolute;
    left: 0.75rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-tertiary);
}

#item-selector-search {
    width: 100%;
    padding: 0.75rem 0.75rem 0.75rem 2.5rem;
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 0.9rem;
    transition: border-color var(--transition-speed), background-color var(--transition-speed);
}

#item-selector-search:focus {
    outline: none;
    border-color: var(--accent-blue);
    background-color: var(--bg-primary);
}

/* Dropdown Component */
.item-dropdown {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    max-height: 250px;
    overflow-y: auto;
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-top: 0.25rem;
    z-index: 1000;
    display: none;
    /* Controlled by JS */
}

.item-dropdown.is-active {
    display: block;
}

.dropdown-item {
    padding: 0.75rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    transition: background-color var(--transition-speed);
}

.dropdown-item:hover,
.dropdown-item.is-selected {
    background-color: var(--accent-blue);
}

.dropdown-item img {
    width: 24px;
    height: 24px;
    border-radius: 4px;
}

.dropdown-item.no-results {
    justify-content: center;
    color: #888;
    cursor: default;
}

.dropdown-item.no-results:hover {
    background-color: transparent;
}

/* Input Field Wrapper */
.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-wrapper input {
    width: 100%;
    padding: 0.75rem;
    background-color: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-primary);
    font-size: 0.9rem;
    transition: border-color var(--transition-speed), background-color var(--transition-speed);
    /* Remove arrows from number inputs */
    -webkit-appearance: none;
    -moz-appearance: textfield;
}

.input-wrapper input::-webkit-outer-spin-button,
.input-wrapper input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.input-wrapper input:focus {
    outline: none;
    border-color: var(--accent-blue);
    background-color: var(--bg-primary);
}

.input-suffix {
    position: absolute;
    right: 0.75rem;
    color: var(--text-tertiary);
    font-size: 0.875rem;
    pointer-events: none;
}