/**
 * Date Calculator Styles
 * Professional, modern, and fully responsive design
 */

/* ============================================
   VARIABLES
   ============================================ */
:root {
    --primary-color: #4CAF50;
    --primary-dark: #388E3C;
    --primary-light: #81C784;
    --secondary-color: #2196F3;
    --accent-color: #FF9800;
    --danger-color: #FF6B6B;
    --warning-color: #FFA726;
    --success-color: #4CAF50;
    --info-color: #29B6F6;
    --text-primary: #2c3e50;
    --text-secondary: #7f8c8d;
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --border-color: #e0e0e0;
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.12);
    --border-radius: 12px;
    --transition: all 0.3s ease;
}

/* Dark mode */
[data-theme="dark"] {
    --text-primary: #ecf0f1;
    --text-secondary: #bdc3c7;
    --bg-light: #1a1a1a;
    --bg-white: #2c2c2c;
    --border-color: #404040;
}

/* ============================================
   BREADCRUMB
   ============================================ */
.breadcrumb-nav {
    background: var(--bg-light);
    padding: 1rem 0;
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.breadcrumb {
    background: transparent;
    margin-bottom: 0;
    padding: 0;
}

.breadcrumb-item + .breadcrumb-item::before {
    content: "›";
    color: var(--text-secondary);
}

.breadcrumb-item a {
    color: var(--secondary-color);
    text-decoration: none;
    transition: var(--transition);
}

.breadcrumb-item a:hover {
    color: var(--primary-color);
    text-decoration: underline;
}

.breadcrumb-item.active {
    color: var(--text-primary);
}

/* ============================================
   PAGE HEADER
   ============================================ */
.date-calculator-container {
    padding: 2rem 0 4rem;
}

.page-header {
    margin-bottom: 3rem;
}

.page-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1rem;
    line-height: 1.2;
}

.page-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.6;
}

/* ============================================
   CALCULATOR TABS
   ============================================ */
.calculator-tabs-wrapper {
    margin-bottom: 2rem;
}

.calculator-tabs {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.tab-button {
    background: var(--bg-white);
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.tab-button:hover {
    border-color: var(--primary-color);
    background: rgba(76, 175, 80, 0.05);
}

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

.tab-button i {
    font-size: 1.25rem;
}

/* ============================================
   TAB CONTENT
   ============================================ */
.calculator-content {
    margin-bottom: 3rem;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
    animation: fadeIn 0.3s ease-in;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ============================================
   CALCULATOR CARDS
   ============================================ */
.calculator-card {
    background: var(--bg-white);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    margin-bottom: 1.5rem;
    transition: var(--transition);
}

.calculator-card:hover {
    box-shadow: var(--shadow-lg);
}

.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.section-title i {
    color: var(--primary-color);
}

/* ============================================
   FORM ELEMENTS
   ============================================ */
.date-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95rem;
    margin-bottom: 0;
}

.required {
    color: var(--danger-color);
}

.form-hint {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

.date-input-wrapper {
    position: relative;
}

.date-input {
    padding-right: 3rem;
}

.input-icon {
    position: absolute;
    right: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
    pointer-events: none;
}

.form-control {
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: var(--transition);
    background: var(--bg-white);
    color: var(--text-primary);
    width: 100%;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.1);
}

.form-control:hover {
    border-color: var(--primary-color);
}

.form-select {
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    background: var(--bg-white);
    color: var(--text-primary);
    cursor: pointer;
    transition: var(--transition);
}

.form-select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.1);
}

/* Checkbox */
.form-check-wrapper {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.5rem 0;
}

.form-check-input {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.form-check-label {
    font-size: 0.95rem;
    color: var(--text-primary);
    cursor: pointer;
    margin: 0;
}

/* Operation Toggle */
.operation-toggle {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.75rem;
}

.operation-toggle input[type="radio"] {
    display: none;
}

.toggle-option {
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    background: var(--bg-white);
    color: var(--text-primary);
}

.toggle-option:hover {
    border-color: var(--primary-color);
    background: rgba(76, 175, 80, 0.05);
}

.operation-toggle input[type="radio"]:checked + .toggle-option {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* Unit Tabs */
.unit-tabs {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.unit-tab {
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-white);
    color: var(--text-primary);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
}

.unit-tab:hover {
    border-color: var(--primary-color);
    background: rgba(76, 175, 80, 0.05);
}

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

/* Range Slider */
.form-range {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 8px;
    background: var(--border-color);
    border-radius: 10px;
    outline: none;
    padding: 0;
    margin: 10px 0;
}

.form-range::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 24px;
    height: 24px;
    background: var(--primary-color);
    border: 4px solid white;
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 6px rgba(0,0,0,0.2);
    transition: var(--transition);
}

.form-range::-webkit-slider-thumb:hover {
    transform: scale(1.15);
    box-shadow: 0 3px 8px rgba(76, 175, 80, 0.4);
}

.form-range::-moz-range-thumb {
    width: 24px;
    height: 24px;
    background: var(--primary-color);
    border: 4px solid white;
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 6px rgba(0,0,0,0.2);
    transition: var(--transition);
}

.form-range::-moz-range-thumb:hover {
    transform: scale(1.15);
    box-shadow: 0 3px 8px rgba(76, 175, 80, 0.4);
}

.range-labels {
    display: flex;
    justify-content: space-between;
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: -5px;
}

/* Buttons */
.btn {
    padding: 0.875rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    text-decoration: none;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    border: 2px solid var(--primary-color);
}

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

.btn-calculate {
    width: 100%;
    padding: 1rem;
    font-size: 1.1rem;
}

.btn-outline-secondary {
    background: white;
    border: 2px solid var(--border-color);
    color: var(--text-primary);
}

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

.btn-outline-success {
    background: white;
    border: 2px solid var(--success-color);
    color: var(--success-color);
}

.btn-outline-success:hover {
    background: var(--success-color);
    color: white;
}

.btn-outline-primary {
    background: white;
    border: 2px solid var(--secondary-color);
    color: var(--secondary-color);
}

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

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

/* Quick Actions */
.quick-actions {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 0.5rem;
}

/* ============================================
   SETTINGS CARD
   ============================================ */
.settings-card {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.settings-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: white;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.settings-card .form-label {
    color: white;
}

.settings-card .form-select {
    background: rgba(255, 255, 255, 0.9);
}

/* ============================================
   PRESETS CARD
   ============================================ */
.presets-card {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
}

.preset-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: white;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.preset-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.75rem;
}

.btn-preset {
    background: rgba(255, 255, 255, 0.2);
    border: 2px solid rgba(255, 255, 255, 0.3);
    color: white;
    padding: 0.875rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.25rem;
    backdrop-filter: blur(10px);
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 600;
}

.btn-preset:hover {
    background: rgba(255, 255, 255, 0.3);
    border-color: rgba(255, 255, 255, 0.5);
    transform: translateY(-2px);
}

.btn-preset.active {
    background: rgba(255, 255, 255, 0.4);
    border-color: white;
}

/* ============================================
   RESULTS SECTION
   ============================================ */
.results-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* Main Result Card */
.main-result-card {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    border-radius: var(--border-radius);
    padding: 2.5rem;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: 1.5rem;
    color: white;
}

.result-icon-large {
    width: 80px;
    height: 80px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    flex-shrink: 0;
}

.result-content-large {
    flex: 1;
}

.result-label-large {
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    opacity: 0.95;
}

.result-value-large {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    line-height: 1.2;
}

.result-description {
    font-size: 1rem;
    opacity: 0.9;
}

/* Age Card Variant */
.age-card {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
}

/* Result Date Card Variant */
.result-date-card {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

.result-date {
    font-size: 2rem;
}

/* Results Grid */
.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.25rem;
}

.result-card {
    background: var(--bg-white);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: var(--transition);
}

.result-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.result-icon {
    width: 50px;
    height: 50px;
    background: var(--bg-light);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: var(--primary-color);
    flex-shrink: 0;
}

.result-content {
    flex: 1;
}

.result-label {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.35rem;
}

.result-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.2;
}

/* Detailed Breakdown */
.detailed-breakdown {
    background: var(--bg-white);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
}

.breakdown-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.25rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.breakdown-title i {
    color: var(--primary-color);
}

.breakdown-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.breakdown-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem;
    background: var(--bg-light);
    border-radius: 8px;
}

.breakdown-label {
    font-weight: 500;
    color: var(--text-secondary);
}

.breakdown-value {
    font-weight: 600;
    color: var(--text-primary);
}

/* Timeline */
.timeline-card {
    background: var(--bg-white);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
}

.timeline-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.timeline-title i {
    color: var(--primary-color);
}

.timeline-wrapper {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.timeline-point {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.timeline-marker {
    width: 16px;
    height: 16px;
    background: var(--primary-color);
    border: 3px solid white;
    border-radius: 50%;
    box-shadow: 0 0 0 2px var(--primary-color);
}

.timeline-label {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-primary);
    text-align: center;
}

.timeline-line {
    flex: 1;
    height: 4px;
    background: var(--border-color);
    border-radius: 2px;
    position: relative;
}

.timeline-progress {
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 100%;
    background: var(--primary-color);
    border-radius: 2px;
}

.timeline-info {
    text-align: center;
    padding: 0.75rem;
    background: var(--bg-light);
    border-radius: 8px;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.timeline-info i {
    color: var(--primary-color);
}

/* Birthday Card */
.birthday-card {
    background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.birthday-icon {
    width: 70px;
    height: 70px;
    background: rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: #ff6b6b;
    flex-shrink: 0;
}

.birthday-content {
    flex: 1;
}

.birthday-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: #333;
    margin-bottom: 0.5rem;
}

.birthday-date {
    font-size: 1.5rem;
    font-weight: 700;
    color: #333;
    margin-bottom: 0.25rem;
}

.birthday-countdown {
    font-size: 1rem;
    color: #666;
    margin-bottom: 0.5rem;
}

.birthday-day {
    display: inline-block;
    padding: 0.35rem 0.75rem;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    color: #333;
}

/* Milestones */
.milestones-card {
    background: var(--bg-white);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
}

.milestones-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.25rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.milestones-title i {
    color: var(--accent-color);
}

.milestones-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.milestone-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    background: var(--bg-light);
    border-radius: 8px;
    transition: var(--transition);
}

.milestone-item:hover {
    background: rgba(76, 175, 80, 0.05);
    transform: translateX(5px);
}

.milestone-item i {
    font-size: 1.5rem;
    color: var(--accent-color);
}

.milestone-content {
    flex: 1;
}

.milestone-title {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.milestone-countdown {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Fun Facts */
.fun-facts-card {
    background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    color: #333;
}

.fun-facts-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: #333;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.fun-fact {
    padding: 1rem;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 8px;
    backdrop-filter: blur(10px);
}

.fun-fact p {
    margin: 0;
    font-size: 0.95rem;
    line-height: 1.6;
    color: #333;
}

.fun-fact i {
    color: var(--accent-color);
    margin-right: 0.5rem;
}

/* Export Actions */
.export-actions {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

/* ============================================
   FEATURES SECTION
   ============================================ */
.features-section {
    margin: 4rem 0;
    padding: 3rem 2rem;
    background: var(--bg-light);
    border-radius: var(--border-radius);
}

.section-heading {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 2.5rem;
}

.feature-card {
    background: var(--bg-white);
    border-radius: var(--border-radius);
    padding: 2rem;
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    height: 100%;
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    width: 70px;
    height: 70px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    font-size: 2rem;
    color: white;
}

.feature-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.75rem;
}

.feature-description {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ============================================
   HOW TO SECTION
   ============================================ */
.how-to-section {
    margin: 4rem 0;
}

.how-to-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2.5rem;
}

.how-to-card {
    background: var(--bg-white);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    position: relative;
    padding-top: 4rem;
}

.how-to-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.how-to-number {
    position: absolute;
    top: -20px;
    left: 50%;
    transform: translateX(-50%);
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
    box-shadow: var(--shadow-md);
}

.how-to-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    text-align: center;
}

.how-to-description {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.7;
    text-align: center;
}

/* ============================================
   FAQ SECTION
   ============================================ */
.faq-section {
    margin: 4rem 0;
    padding: 3rem 2rem;
    background: var(--bg-light);
    border-radius: var(--border-radius);
}

.faq-container {
    max-width: 900px;
    margin: 2.5rem auto 0;
}

.faq-item {
    background: var(--bg-white);
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    transition: var(--transition);
}

.faq-item:hover {
    box-shadow: var(--shadow-md);
}

.faq-question {
    width: 100%;
    background: transparent;
    border: none;
    padding: 1.5rem;
    text-align: left;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    transition: var(--transition);
}

.faq-question:hover {
    color: var(--primary-color);
}

.faq-question i {
    transition: transform 0.3s ease;
    color: var(--primary-color);
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.faq-item.active .faq-answer {
    max-height: 500px;
}

.faq-answer div {
    padding: 0 1.5rem 1.5rem;
}

.faq-answer p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin: 0;
}

/* ============================================
   USE CASES SECTION
   ============================================ */
.use-cases-section {
    margin: 4rem 0;
}

.use-case-card {
    background: var(--bg-white);
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    height: 100%;
}

.use-case-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.use-case-card h3 i {
    color: var(--primary-color);
}

.use-case-card ul {
    list-style: none;
    padding: 0;
}

.use-case-card li {
    padding: 0.75rem 0;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-secondary);
    line-height: 1.6;
}

.use-case-card li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

/* ============================================
   TOAST NOTIFICATIONS
   ============================================ */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 9999;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.toast {
    background: white;
    border-radius: 8px;
    padding: 1rem 1.5rem;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    min-width: 300px;
    opacity: 0;
    transform: translateX(400px);
    transition: all 0.3s ease;
}

.toast.show {
    opacity: 1;
    transform: translateX(0);
}

.toast-icon {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    flex-shrink: 0;
}

.toast-success .toast-icon {
    background: var(--success-color);
    color: white;
}

.toast-error .toast-icon {
    background: var(--danger-color);
    color: white;
}

.toast-info .toast-icon {
    background: var(--info-color);
    color: white;
}

.toast-warning .toast-icon {
    background: var(--warning-color);
    color: white;
}

.toast-message {
    flex: 1;
    color: var(--text-primary);
    font-size: 0.95rem;
}

/* ============================================
   ANIMATIONS
   ============================================ */
@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.02); }
}

.pulse-animation {
    animation: pulse 0.6s ease-in-out;
}

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

.slide-in {
    animation: slideIn 0.5s ease-out;
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */
@media (max-width: 1200px) {
    .results-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 992px) {
    .page-title {
        font-size: 2rem;
    }
    
    .calculator-tabs {
        flex-direction: column;
    }
    
    .tab-button {
        width: 100%;
    }
}

@media (max-width: 768px) {
    .date-calculator-container {
        padding: 1rem 0 2rem;
    }
    
    .page-title {
        font-size: 1.75rem;
    }
    
    .page-subtitle {
        font-size: 1rem;
    }
    
    .calculator-card {
        padding: 1.5rem;
    }
    
    .main-result-card {
        flex-direction: column;
        text-align: center;
        padding: 2rem;
    }
    
    .result-value-large {
        font-size: 2rem;
    }
    
    .results-grid {
        grid-template-columns: 1fr;
    }
    
    .unit-tabs {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .preset-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .birthday-card {
        flex-direction: column;
        text-align: center;
    }
    
    .timeline-wrapper {
        flex-direction: column;
    }
    
    .timeline-line {
        width: 4px;
        height: 60px;
    }
    
    .how-to-grid {
        grid-template-columns: 1fr;
    }
    
    .toast-container {
        left: 10px;
        right: 10px;
    }
    
    .toast {
        min-width: auto;
    }
}

@media (max-width: 576px) {
    .page-title {
        font-size: 1.5rem;
    }
    
    .section-heading {
        font-size: 1.5rem;
    }
    
    .calculator-card {
        padding: 1rem;
    }
    
    .tab-button {
        padding: 0.75rem 1rem;
        font-size: 0.9rem;
    }
    
    .tab-button span {
        display: none;
    }
    
    .tab-button i {
        margin: 0;
    }
    
    .result-card {
        flex-direction: column;
        text-align: center;
    }
    
    .result-icon {
        width: 45px;
        height: 45px;
        font-size: 1.25rem;
    }
    
    .result-value {
        font-size: 1.25rem;
    }
    
    .breakdown-item {
        flex-direction: column;
        gap: 0.5rem;
        text-align: center;
    }
    
    .quick-actions {
        flex-direction: column;
    }
    
    .quick-actions .btn {
        width: 100%;
    }
    
    .export-actions {
        flex-direction: column;
    }
    
    .export-actions .btn {
        width: 100%;
    }
    
    .unit-tabs {
        grid-template-columns: 1fr;
    }
    
    .preset-grid {
        grid-template-columns: 1fr;
    }
}

/* ============================================
   PRINT STYLES
   ============================================ */
@media print {
    .breadcrumb-nav,
    .calculator-tabs-wrapper,
    .calculator-card,
    .quick-actions,
    .export-actions,
    .features-section,
    .how-to-section,
    .faq-section,
    .use-cases-section {
        display: none !important;
    }
    
    .results-section {
        page-break-inside: avoid;
    }
}

/* ============================================
   ACCESSIBILITY
   ============================================ */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

/* Focus styles for keyboard navigation */
*:focus-visible {
    outline: 3px solid var(--primary-color);
    outline-offset: 2px;
}

button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible {
    outline: 3px solid var(--primary-color);
    outline-offset: 2px;
}

/* ============================================
   UTILITY CLASSES
   ============================================ */
.text-center {
    text-align: center;
}

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

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

.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 1rem; }
.mt-4 { margin-top: 1.5rem; }
.mt-5 { margin-top: 3rem; }

.mb-1 { margin-bottom: 0.25rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 1rem; }
.mb-4 { margin-bottom: 1.5rem; }
.mb-5 { margin-bottom: 3rem; }

.p-1 { padding: 0.25rem; }
.p-2 { padding: 0.5rem; }
.p-3 { padding: 1rem; }
.p-4 { padding: 1.5rem; }
.p-5 { padding: 3rem; }

.d-none { display: none; }
.d-block { display: block; }
.d-flex { display: flex; }
.d-grid { display: grid; }

.gap-1 { gap: 0.25rem; }
.gap-2 { gap: 0.5rem; }
.gap-3 { gap: 1rem; }
.gap-4 { gap: 1.5rem; }
.gap-5 { gap: 3rem; }

/* ============================================
   CUSTOM SCROLLBAR
   ============================================ */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 5px;
}

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