/* Modern CSS Reset */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

/* CSS Variables */
:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --secondary: #8b5cf6;
    --accent: #06b6d4;
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    
    --radius-sm: 0.375rem;
    --radius: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Base Styles */
body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--gray-800);
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    overflow-x: hidden;
}

/* App Layout */
.app {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Header */
.header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--gray-200);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    max-width: 1400px;
    margin: 0 auto;
}

.logo {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.logo i {
    font-size: 2.5rem;
    color: var(--primary);
}

.logo-text h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--gray-800);
    margin: 0;
}

.logo-text p {
    font-size: 0.875rem;
    color: var(--gray-600);
    margin: 0;
}

.header-actions {
    display: flex;
    gap: 0.75rem;
}

/* Main Content */
.main-content {
    display: flex;
    flex: 1;
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
    padding: 2rem;
    gap: 2rem;
}

/* Sidebar */
.sidebar {
    width: 280px;
    flex-shrink: 0;
}

.nav-tabs {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(20px);
    border-radius: var(--radius-xl);
    padding: 1rem;
    box-shadow: var(--shadow-lg);
}

.nav-tab {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 1rem 1.25rem;
    border: none;
    background: transparent;
    border-radius: var(--radius-lg);
    font-weight: 500;
    color: var(--gray-600);
    cursor: pointer;
    transition: var(--transition);
    text-align: left;
    width: 100%;
}

.nav-tab:hover {
    background: var(--gray-100);
    color: var(--gray-800);
}

.nav-tab.active {
    background: var(--primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.nav-tab i {
    font-size: 1.25rem;
    width: 20px;
}

/* Content Area */
.content {
    flex: 1;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    overflow: hidden;
}

.tab-content {
    display: none;
    height: 100%;
}

.tab-content.active {
    display: block;
}

/* Calculator Grid */
.calculator-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0;
    height: 100%;
}

.input-section, .result-section {
    padding: 2rem;
}

.input-section {
    border-right: 1px solid var(--gray-200);
    background: var(--gray-50);
}

.result-section {
    background: white;
}

/* Section Headers */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--gray-200);
}

.section-header h2 {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--gray-800);
}

.section-actions {
    display: flex;
    gap: 0.5rem;
}

/* Form Grid */
.form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group.full-width {
    grid-column: 1 / -1;
}

.form-group label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 500;
    color: var(--gray-700);
    margin-bottom: 0.5rem;
    font-size: 0.875rem;
}

.form-group label i {
    color: var(--primary);
    width: 16px;
}

/* Form Inputs */
.form-input, .form-select {
    padding: 0.875rem 1rem;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    transition: var(--transition);
    background: white;
    color: var(--gray-800);
}

.form-input:focus, .form-select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-input::placeholder {
    color: var(--gray-400);
}

.form-hint {
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-top: 0.25rem;
}

/* Input with Actions */
.input-with-actions {
    display: flex;
    gap: 0.5rem;
}

.input-with-actions .form-input {
    flex: 1;
}

/* Size Inputs */
.size-inputs {
    display: flex;
    align-items: end;
    gap: 1rem;
}

.size-input {
    flex: 1;
}

.size-input label {
    font-size: 0.75rem;
    color: var(--gray-500);
    margin-bottom: 0.25rem;
}

.size-separator {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--gray-400);
    margin-bottom: 0.5rem;
}

/* Area Display */
.area-display {
    background: var(--gray-50);
    border-radius: var(--radius-lg);
    padding: 1rem;
    margin-top: 1rem;
    border: 1px solid var(--gray-200);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.area-info, .fill-info {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
}

.area-label, .fill-label {
    font-size: 0.75rem;
    color: var(--gray-500);
    font-weight: 500;
}

.area-value, .fill-value {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--primary);
}

.area-value {
    color: var(--primary);
}

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

/* Options Grid */
.options-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

/* Buttons */
.btn-primary, .btn-secondary, .btn-icon, .btn-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-lg);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    font-size: 0.875rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

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

.btn-secondary {
    background: var(--gray-100);
    color: var(--gray-700);
    border: 1px solid var(--gray-200);
}

.btn-secondary:hover {
    background: var(--gray-200);
    color: var(--gray-800);
}

.btn-icon {
    padding: 0.75rem;
    background: var(--gray-100);
    color: var(--gray-600);
    border-radius: var(--radius);
}

.btn-icon:hover {
    background: var(--gray-200);
    color: var(--gray-800);
}

.btn-link {
    background: transparent;
    color: var(--primary);
    padding: 0.5rem 0;
}

.btn-link:hover {
    color: var(--primary-dark);
}

/* Checkbox */
.checkbox-label {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
    font-weight: 400;
    color: var(--gray-700);
}

.checkbox-label input[type="checkbox"] {
    display: none;
}

.checkmark {
    width: 20px;
    height: 20px;
    border: 2px solid var(--gray-300);
    border-radius: var(--radius-sm);
    position: relative;
    transition: var(--transition);
    flex-shrink: 0;
}

.checkbox-label input[type="checkbox"]:checked + .checkmark {
    background: var(--primary);
    border-color: var(--primary);
}

.checkbox-label input[type="checkbox"]:checked + .checkmark::after {
    content: '✓';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-size: 12px;
    font-weight: bold;
}

/* Price Card */
.price-card {
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
    border-radius: var(--radius-xl);
    padding: 2rem;
    border: 1px solid var(--gray-200);
}

.price-breakdown {
    margin-bottom: 2rem;
}

.price-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    border-bottom: 1px solid var(--gray-200);
    font-size: 0.95rem;
}

.price-item:last-child {
    border-bottom: none;
}

.price-item.total {
    font-weight: 600;
    font-size: 1.25rem;
    color: white;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    margin-top: 1rem;
    border: none;
}

.price-summary {
    background: white;
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    margin-bottom: 2rem;
    border: 1px solid var(--gray-200);
}

.summary-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 0;
    font-weight: 500;
}

.summary-item:first-child {
    border-bottom: 1px solid var(--gray-200);
    margin-bottom: 0.75rem;
    padding-bottom: 0.75rem;
}

/* Calculation Details */
.calculation-details {
    background: var(--gray-50);
    border-radius: var(--radius-lg);
    padding: 1rem;
    margin-top: 1rem;
    border: 1px solid var(--gray-200);
}

.detail-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.5rem 0;
    font-size: 0.875rem;
    color: var(--gray-600);
}

.detail-item:not(:last-child) {
    border-bottom: 1px solid var(--gray-200);
}

/* Design Workspace */
.design-workspace, .history-workspace, .settings-workspace {
    padding: 2rem;
}

.design-tools {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.tool-group h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: 1rem;
}

.tool-options {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.tool-btn {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    background: white;
    color: var(--gray-600);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

.tool-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

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

.color-picker {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.color-palette {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.color-item {
    width: 40px;
    height: 40px;
    border-radius: var(--radius);
    cursor: pointer;
    border: 2px solid var(--gray-200);
    transition: var(--transition);
    position: relative;
}

.color-item:hover {
    transform: scale(1.1);
    border-color: var(--primary);
}

.color-item.active {
    border-color: var(--primary);
    border-width: 3px;
    transform: scale(1.1);
    box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.2);
}

.color-item.active::after {
    content: '✓';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-weight: bold;
    font-size: 16px;
    text-shadow: 0 0 3px rgba(0, 0, 0, 0.8);
}

/* History */
.history-controls {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
}

.history-list {
    margin-top: 2rem;
}

.history-empty {
    text-align: center;
    padding: 3rem;
    color: var(--gray-500);
}

.history-empty i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

/* Settings */
.settings-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.setting-group h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: 1.5rem;
}

.setting-item {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.setting-item label {
    font-weight: 500;
    color: var(--gray-700);
    font-size: 0.875rem;
}

.setting-item input {
    padding: 0.75rem 1rem;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    transition: var(--transition);
}

.setting-item input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

/* Footer */
.footer {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-top: 1px solid var(--gray-200);
    margin-top: auto;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2rem;
    max-width: 1400px;
    margin: 0 auto;
}

.footer-info {
    display: flex;
    gap: 2rem;
    color: var(--gray-600);
}

.footer-info p {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin: 0;
}

.footer-actions {
    display: flex;
    gap: 1rem;
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.loading-overlay.show {
    display: flex;
}

.loading-spinner {
    background: white;
    padding: 2rem;
    border-radius: var(--radius-xl);
    text-align: center;
    box-shadow: var(--shadow-xl);
}

.loading-spinner i {
    font-size: 2rem;
    color: var(--primary);
    margin-bottom: 1rem;
}

.loading-spinner p {
    margin: 0;
    color: var(--gray-600);
}

/* Toast Notifications */
.toast-container {
    position: fixed;
    top: 2rem;
    right: 2rem;
    z-index: 1001;
}

.toast {
    background: white;
    border-radius: var(--radius-lg);
    padding: 1rem 1.5rem;
    margin-bottom: 1rem;
    box-shadow: var(--shadow-lg);
    border-left: 4px solid var(--primary);
    animation: slideInRight 0.3s ease-out;
}

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

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

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

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(100%);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* Responsive Design */
@media (max-width: 1024px) {
    .main-content {
        flex-direction: column;
        padding: 1rem;
    }
    
    .sidebar {
        width: 100%;
    }
    
    .nav-tabs {
        flex-direction: row;
        overflow-x: auto;
        padding: 0.75rem;
    }
    
    .nav-tab {
        white-space: nowrap;
        min-width: fit-content;
    }
    
    .calculator-grid {
        grid-template-columns: 1fr;
    }
    
    .input-section {
        border-right: none;
        border-bottom: 1px solid var(--gray-200);
    }
}

@media (max-width: 768px) {
    .header-content {
        padding: 1rem;
        flex-direction: column;
        gap: 1rem;
    }
    
    .form-grid {
        grid-template-columns: 1fr;
    }
    
    .size-inputs {
        flex-direction: column;
        gap: 1rem;
    }
    
    .size-separator {
        display: none;
    }
    
    .options-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .footer-info {
        flex-direction: column;
        gap: 0.5rem;
    }
}

@media (max-width: 480px) {
    .main-content {
        padding: 0.5rem;
    }
    
    .input-section, .result-section {
        padding: 1rem;
    }
    
    .design-workspace, .history-workspace, .settings-workspace {
        padding: 1rem;
    }
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.tab-content.active {
    animation: fadeInUp 0.3s ease-out;
}

.price-card {
    animation: fadeInUp 0.3s ease-out;
}

/* Hover Effects */
.form-group input:hover,
.form-group select:hover {
    border-color: var(--gray-300);
}

.price-item:hover {
    background: rgba(102, 126, 234, 0.05);
    border-radius: 5px;
    padding-left: 10px;
    padding-right: 10px;
}

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

::-webkit-scrollbar-track {
    background: var(--gray-100);
    border-radius: var(--radius);
}

::-webkit-scrollbar-thumb {
    background: var(--gray-300);
    border-radius: var(--radius);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--gray-400);
}