/* ===== CSS Variables ===== */
:root {
    /* Colors - Light Theme */
    --primary: #4f7cff;
    --primary-dark: #3d5fcc;
    --primary-light: #7d9eff;
    --secondary: #00c896;
    --secondary-dark: #00a67d;
    --accent-purple: #a855f7;
    --accent-orange: #ff6b35;
    --accent-pink: #ec4899;

    --background: #f5f7fa;
    --background-light: #ffffff;
    --surface: #ffffff;
    --surface-hover: #f8f9fb;

    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-muted: #9ca3af;

    --border: #e5e7eb;
    --border-light: #f3f4f6;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;

    /* Transitions */
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--background);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

/* ===== App Container ===== */
.app-container {
    display: grid;
    grid-template-columns: 1fr 340px;
    grid-template-rows: auto auto 1fr;
    gap: var(--spacing-lg);
    padding: var(--spacing-lg);
    max-width: 1920px;
    margin: 0 auto;
    min-height: 100vh;
}

/* ===== Header ===== */
.header {
    grid-column: 1 / -1;
    background: linear-gradient(135deg, #4f7cff 0%, #a855f7 100%);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-xl) var(--spacing-2xl);
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1) 0%, rgba(255, 255, 255, 0) 100%);
    pointer-events: none;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-lg);
    position: relative;
    z-index: 1;
}

.app-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: white;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.stats {
    display: flex;
    gap: var(--spacing-lg);
}

.stat-item {
    display: flex;
    flex-direction: column;
    padding: var(--spacing-md) var(--spacing-lg);
    background: rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-lg);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    min-width: 100px;
}

.stat-label {
    font-size: 0.75rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: var(--spacing-xs);
    font-weight: 500;
}

.stat-value {
    font-size: 1.75rem;
    font-weight: 700;
    color: white;
}

/* ===== Control Panel ===== */
.control-panel {
    grid-column: 1 / -1;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

.control-section {
    background: var(--surface);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border);
}

.control-section h3 {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

/* File Upload */
.file-upload-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.file-upload-item {
    display: grid;
    grid-template-columns: 130px 1fr;
    gap: var(--spacing-md);
    align-items: center;
}

.file-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
}

.file-input {
    display: none;
}

.file-name {
    padding: var(--spacing-md);
    background: var(--background);
    border: 2px dashed var(--border);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    color: var(--text-muted);
    cursor: pointer;
    transition: var(--transition);
}

.file-name:hover {
    border-color: var(--primary);
    background: var(--surface-hover);
    color: var(--text-secondary);
}

.file-name.has-file {
    border-style: solid;
    border-color: var(--secondary);
    color: var(--text-primary);
    background: rgba(0, 200, 150, 0.05);
    font-weight: 500;
}

/* Auto Assign Controls */
.auto-assign-controls {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.assign-scope {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.assign-scope label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    min-width: 70px;
}

.select-input {
    flex: 1;
    padding: var(--spacing-md);
    background: white;
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.875rem;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%234f7cff' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 36px;
}

.select-input:hover {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(79, 124, 255, 0.1);
}

.select-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(79, 124, 255, 0.2);
}

/* Dropdown options styling */
.select-input option {
    padding: var(--spacing-md);
    background: white;
    color: var(--text-primary);
    font-weight: 500;
}

/* Buttons */
.btn {
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--accent-purple) 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

.btn-secondary:hover {
    background: var(--surface-hover);
    border-color: var(--text-secondary);
}

.btn-success {
    background: linear-gradient(135deg, var(--secondary) 0%, #00daa0 100%);
    color: white;
}

.btn-success:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

.btn:active:not(:disabled) {
    transform: translateY(0);
}

/* ===== Main Content ===== */
.main-content {
    background: var(--surface);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    height: calc(100vh - 180px);
}

/* Dormitory Tabs */
.dormitory-tabs {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    border-bottom: 2px solid var(--border-light);
    padding-bottom: 2px;
}

.tab-btn {
    padding: var(--spacing-md) var(--spacing-xl);
    background: transparent;
    border: none;
    border-bottom: 3px solid transparent;
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
}

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

.tab-btn.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
}

/* Floor Selection */
.floor-selection {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    flex-wrap: wrap;
}

.floor-btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    background: var(--background);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.floor-btn:hover {
    background: var(--surface-hover);
    border-color: var(--primary);
    color: var(--primary);
}

.floor-btn.active {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
    box-shadow: var(--shadow);
}

/* Room Grid */
.room-grid-container {
    overflow-x: auto;
    overflow-y: auto;
    flex: 1;
    padding-right: 4px;
}

.room-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: var(--spacing-md);
    padding: var(--spacing-sm);
}

.room-card {
    background: var(--surface);
    border: 2px solid var(--border-light);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    min-height: 180px;
    transition: var(--transition);
    cursor: pointer;
}

.room-card:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.room-card.drop-target {
    border-color: var(--secondary);
    background: rgba(0, 200, 150, 0.05);
    border-style: dashed;
}

.room-card.full {
    border-color: var(--accent-orange);
    background: rgba(255, 107, 53, 0.03);
}

/* Room Gender Indicators */
.room-card.gender-male {
    border-left: 4px solid #3b82f6;
}

.room-card.gender-female {
    border-left: 4px solid #ec4899;
}

.room-card.gender-mixed {
    border-left: 4px solid var(--text-muted);
}

.room-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 1px solid var(--border-light);
}

.room-number {
    font-weight: 700;
    color: var(--primary);
    font-size: 1.125rem;
    display: flex;
    align-items: center;
}

.room-gender-badge {
    font-size: 0.7rem;
    padding: 2px 6px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    margin-left: var(--spacing-xs);
}

.room-gender-badge.male {
    background: rgba(59, 130, 246, 0.1);
    color: #3b82f6;
}

.room-gender-badge.female {
    background: rgba(236, 72, 153, 0.1);
    color: #ec4899;
}

.room-capacity {
    font-size: 0.75rem;
    color: var(--text-muted);
    background: var(--background);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-weight: 600;
}

.room-students {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.student-card {
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--background);
    border: 1px solid var(--border-light);
    border-left: 3px solid var(--primary);
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    cursor: grab;
    transition: var(--transition);
}

.student-card:hover {
    background: var(--surface);
    border-left-color: var(--accent-purple);
    box-shadow: var(--shadow-sm);
    transform: translateY(-2px);
}

.student-info {
    color: var(--text-muted);
    font-size: 0.7rem;
}

/* ===== Sidebar ===== */
.sidebar {
    background: var(--surface);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border);
    height: calc(100vh - 180px);
    display: flex;
    flex-direction: column;
}

.sidebar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--border-light);
}

.sidebar-header h3 {
    font-size: 1.125rem;
    color: var(--text-primary);
    font-weight: 700;
}

.unassigned-count {
    background: linear-gradient(135deg, var(--primary) 0%, var(--accent-purple) 100%);
    color: white;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.75rem;
    font-weight: 700;
}

.select-input-small {
    flex: 1;
    padding: var(--spacing-sm) var(--spacing-md);
    background: white;
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.875rem;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%234f7cff' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 36px;
}

.select-input-small:hover {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(79, 124, 255, 0.1);
}

.select-input-small:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(79, 124, 255, 0.2);
}

.select-input-small option {
    padding: var(--spacing-md);
    background: white;
    color: var(--text-primary);
    font-weight: 500;
}

.sidebar-content {
    flex: 1;
    overflow-y: auto;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(115px, 1fr));
    gap: var(--spacing-sm);
    align-content: start;
}

.sidebar-content::-webkit-scrollbar {
    width: 6px;
}

.sidebar-content::-webkit-scrollbar-track {
    background: var(--background);
    border-radius: var(--radius-sm);
}

.sidebar-content::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: var(--radius-sm);
}

.sidebar-content::-webkit-scrollbar-thumb:hover {
    background: var(--primary);
}

.empty-state {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
    padding: var(--spacing-2xl);
}

/* ===== Loading Overlay ===== */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(4px);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.loading-spinner {
    width: 60px;
    height: 60px;
    border: 4px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.loading-overlay p {
    margin-top: var(--spacing-lg);
    font-size: 1.125rem;
    color: var(--text-secondary);
    font-weight: 600;
}

/* ===== Toast Notifications ===== */
.toast-container {
    position: fixed;
    top: var(--spacing-lg);
    right: var(--spacing-lg);
    z-index: 1001;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.toast {
    padding: var(--spacing-md) var(--spacing-lg);
    background: white;
    border-left: 4px solid var(--primary);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    min-width: 300px;
    animation: slideIn 0.3s ease-out;
    border: 1px solid var(--border);
}

@keyframes slideIn {
    from {
        transform: translateX(400px);
        opacity: 0;
    }

    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.toast.success {
    border-left-color: var(--secondary);
}

.toast.error {
    border-left-color: var(--accent-pink);
}

.toast.warning {
    border-left-color: var(--accent-orange);
}

.toast-message {
    color: var(--text-primary);
    font-size: 0.875rem;
    font-weight: 500;
}

/* ===== Responsive Design ===== */
@media (max-width: 1024px) {
    .app-container {
        grid-template-columns: 1fr;
        grid-template-rows: auto auto auto 1fr;
    }

    .sidebar {
        grid-column: 1;
        grid-row: 4;
        max-height: 400px;
    }

    .control-panel {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .app-title {
        font-size: 1.5rem;
    }

    .stats {
        width: 100%;
        justify-content: space-between;
    }

    .room-grid {
        grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    }

    .header {
        padding: var(--spacing-lg);
    }

    .control-section {
        padding: var(--spacing-lg);
    }
}

/* Female Student Card Style */
.student-card.female {
    background-color: #fff0f7;
    border-left-color: #ec4899;
}

.student-card.female:hover {
    background-color: #ffe4f2;
    border-left-color: #db2777;
}

/* ===== Floor Configuration Controls ===== */
.floor-config-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
    flex-wrap: wrap;
    gap: var(--spacing-md);
    background: var(--background);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-light);
}

.floor-selection-container {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.floor-label {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--text-secondary);
}

.floor-controls-container {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

.floor-gender-config {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.floor-control-label {
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--text-secondary);
}

.floor-gender-btns {
    display: flex;
    gap: 4px;
}

.floor-gender-btn {
    padding: var(--spacing-xs) var(--spacing-md);
    background: white;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 0.8rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.floor-gender-btn:hover {
    background: var(--surface-hover);
    border-color: var(--primary);
    color: var(--primary);
}

.floor-gender-btn.active[data-gender="mixed"] {
    background: var(--text-secondary);
    border-color: var(--text-secondary);
    color: white;
    box-shadow: var(--shadow-sm);
}

.floor-gender-btn.active.male {
    background: #3b82f6;
    border-color: #3b82f6;
    color: white;
    box-shadow: var(--shadow-sm);
}

.floor-gender-btn.active.female {
    background: #ec4899;
    border-color: #ec4899;
    color: white;
    box-shadow: var(--shadow-sm);
}

.btn-sm {
    padding: var(--spacing-xs) var(--spacing-md) !important;
    font-size: 0.8rem !important;
}

/* ===== Room Layout Badge & Buttons ===== */
.room-layout-btn {
    background: transparent;
    border: none;
    cursor: pointer;
    font-size: 0.85rem;
    padding: 0 4px;
    color: var(--text-muted);
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.room-layout-btn:hover {
    color: var(--primary);
    transform: scale(1.15);
}

.room-layout-badge {
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--text-secondary);
    background: var(--background);
    padding: 3px var(--spacing-sm);
    border-radius: var(--radius-sm);
    margin-bottom: var(--spacing-sm);
    border: 1px solid var(--border-light);
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

/* ===== Layout Modal Design ===== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(4px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1005;
    animation: fadeIn 0.2s ease-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

.modal-container {
    background: var(--surface);
    border-radius: var(--radius-xl);
    width: 90%;
    max-width: 480px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border);
    overflow: hidden;
    animation: slideUp 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes slideUp {
    from {
        transform: translateY(30px);
        opacity: 0;
    }

    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-xl);
    border-bottom: 1px solid var(--border-light);
    background: var(--background-light);
}

.modal-header h3 {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
}

.close-modal-btn {
    background: transparent;
    border: none;
    font-size: 1.25rem;
    color: var(--text-muted);
    cursor: pointer;
    transition: var(--transition);
}

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

.modal-body {
    padding: var(--spacing-xl);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.modal-section h4 {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.section-desc {
    font-size: 0.78rem;
    color: var(--text-muted);
    margin-bottom: var(--spacing-sm);
}

.preset-buttons {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.preset-btn {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--background);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    cursor: pointer;
    text-align: left;
    transition: var(--transition);
}

.preset-btn:hover {
    background: rgba(79, 124, 255, 0.05);
    border-color: var(--primary);
    color: var(--primary);
}

.builder-sources {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.grade-source-block {
    flex: 1;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--background);
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    text-align: center;
    font-size: 0.85rem;
    font-weight: 700;
    color: var(--text-primary);
    cursor: grab;
    transition: var(--transition);
    user-select: none;
}

.grade-source-block:hover {
    border-color: var(--primary);
    background: var(--surface-hover);
    transform: translateY(-1px);
}

.builder-slots-container {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-sm);
    min-height: 80px;
    padding: var(--spacing-sm);
    background: var(--background);
    border: 2px dashed var(--border);
    border-radius: var(--radius-lg);
    align-items: center;
}

.builder-slots-container.drag-over {
    border-color: var(--secondary);
    background: rgba(0, 200, 150, 0.05);
}

.builder-slot {
    aspect-ratio: 1.2;
    background: white;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    position: relative;
    box-shadow: var(--shadow-sm);
    font-size: 0.85rem;
    font-weight: 700;
    transition: var(--transition);
}

.builder-slot.grade-1 {
    background: rgba(79, 124, 255, 0.08);
    border-color: var(--primary-light);
    color: var(--primary-dark);
}

.builder-slot.grade-2 {
    background: rgba(168, 85, 247, 0.08);
    border-color: #c084fc;
    color: var(--accent-purple);
}

.builder-slot.grade-3 {
    background: rgba(255, 107, 53, 0.08);
    border-color: #ff9e7d;
    color: var(--accent-orange);
}

.builder-slot.empty {
    border-style: dashed;
    color: var(--text-muted);
    font-size: 0.72rem;
    font-weight: 500;
    background: transparent;
}

.builder-slot .remove-slot {
    position: absolute;
    top: 2px;
    right: 2px;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: rgba(0, 0, 0, 0.1);
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.6rem;
    cursor: pointer;
    border: none;
}

.builder-slot .remove-slot:hover {
    background: var(--accent-pink);
    color: white;
}

.modal-footer {
    display: flex;
    justify-content: space-between;
    padding: var(--spacing-md) var(--spacing-xl);
    border-top: 1px solid var(--border-light);
    background: var(--background-light);
}