/**
 * Simulador Físico - Estilos
 * Desenvolvido por B20 Conteúdo Digital
 * https://www.b20.com.br
 */

/* ============================================
   CSS VARIABLES
   ============================================ */
:root {
    --primary-color: #00A82D;
    --primary-dark: #008024;
    --primary-light: #2DBE60;
    --bg-primary: #FFFFFF;
    --bg-secondary: #F8F8F8;
    --text-primary: #4A4A4A;
    --text-secondary: #757575;
    --border-color: #E0E0E0;
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.15);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --spacing-unit: 8px;
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --max-width: 1200px;
    --header-height: 64px;
    --bottom-nav-height: 64px;
}

/* ============================================
   RESET & BASE
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    padding-top: var(--header-height);
    padding-bottom: var(--bottom-nav-height);
    min-height: 100vh;
}

/* ============================================
   TYPOGRAPHY
   ============================================ */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    color: var(--text-primary);
}

h1 { font-size: 1.75rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }

p {
    margin-bottom: calc(var(--spacing-unit) * 2);
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover {
    color: var(--primary-dark);
}

/* ============================================
   HEADER
   ============================================ */
.app-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: var(--bg-primary);
    box-shadow: var(--shadow-sm);
    z-index: 100;
    display: flex;
    align-items: center;
    padding: 0 calc(var(--spacing-unit) * 2);
}

.header-content {
    max-width: var(--max-width);
    width: 100%;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.app-header h1 {
    font-size: 1.25rem;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
    margin: 0;
}

.header-logo {
    height: 32px;
    width: auto;
    object-fit: contain;
}

.btn-settings {
    background: transparent;
    border: none;
    font-size: 1.5rem;
    color: var(--text-secondary);
    cursor: pointer;
    padding: calc(var(--spacing-unit) * 1);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.btn-settings:hover,
.btn-settings:focus {
    color: var(--primary-color);
    background: var(--bg-secondary);
    outline: none;
}

/* ============================================
   MAIN CONTENT
   ============================================ */
.app-main {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: calc(var(--spacing-unit) * 3) calc(var(--spacing-unit) * 2);
    min-height: calc(100vh - var(--header-height) - var(--bottom-nav-height));
}

.section {
    display: none;
    animation: fadeIn var(--transition-normal);
}

.section.active {
    display: block;
}

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

/* ============================================
   HERO
   ============================================ */
.hero {
    text-align: center;
    padding: calc(var(--spacing-unit) * 4) 0;
    margin-bottom: calc(var(--spacing-unit) * 4);
}

.hero-logo {
    height: 80px;
    width: auto;
    object-fit: contain;
    margin-bottom: calc(var(--spacing-unit) * 2);
    filter: drop-shadow(0 4px 8px rgba(0, 0, 0, 0.1));
}

.hero h2 {
    color: var(--primary-color);
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.hero p {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.hero-features {
    display: flex;
    justify-content: center;
    gap: calc(var(--spacing-unit) * 3);
    margin-top: calc(var(--spacing-unit) * 2);
    flex-wrap: wrap;
}

.feature-item {
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.feature-item i {
    color: var(--primary-color);
    font-size: 1.2rem;
}

/* ============================================
   MODULES GRID
   ============================================ */
.modules-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: calc(var(--spacing-unit) * 3);
    margin-bottom: calc(var(--spacing-unit) * 4);
}

.module-card {
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    padding: calc(var(--spacing-unit) * 3);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
    text-align: center;
    cursor: pointer;
}

.module-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.module-icon {
    font-size: 3rem;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.module-card h3 {
    margin-bottom: calc(var(--spacing-unit) * 1);
}

.module-formula {
    color: var(--text-secondary);
    font-family: 'Courier New', monospace;
    font-size: 1.1rem;
    margin-bottom: calc(var(--spacing-unit) * 1);
}

.module-description {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.4;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

/* Learn Section Styles */
.learn-header {
    text-align: center;
    margin-bottom: calc(var(--spacing-unit) * 4);
}

.learn-logo {
    height: 60px;
    width: auto;
    object-fit: contain;
    margin-bottom: calc(var(--spacing-unit) * 2);
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.1));
}

.learn-content {
    display: flex;
    flex-direction: column;
    gap: calc(var(--spacing-unit) * 4);
}

.learn-article {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: calc(var(--spacing-unit) * 2);
    box-shadow: var(--shadow-md);
    border-left: 4px solid var(--primary-color);
}

.learn-article h3 {
    color: var(--primary-color);
    margin-bottom: calc(var(--spacing-unit) * 2);
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
}

.learn-article h4 {
    color: var(--primary-dark);
    margin: calc(var(--spacing-unit) * 3) 0 calc(var(--spacing-unit) * 1.5) 0;
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
}

.learn-article h5 {
    color: var(--text-primary);
    margin: calc(var(--spacing-unit) * 2) 0 calc(var(--spacing-unit) * 1) 0;
    font-size: 1.1rem;
}

.highlight-box, .law-box, .energy-box, .momentum-box, .impulse-box, .conservation-box {
    background: rgba(0, 168, 45, 0.05);
    border: 1px solid rgba(0, 168, 45, 0.2);
    border-radius: var(--radius-md);
    padding: calc(var(--spacing-unit) * 2);
    margin: calc(var(--spacing-unit) * 2) 0;
}

.concept-box {
    display: grid;
    gap: calc(var(--spacing-unit) * 3);
    margin: calc(var(--spacing-unit) * 2) 0;
}

.concept-item {
    background: var(--bg-secondary);
    padding: calc(var(--spacing-unit) * 2);
    border-radius: var(--radius-md);
    border-left: 3px solid var(--primary-color);
}

.concept-item h5 {
    color: var(--primary-color);
    margin-bottom: calc(var(--spacing-unit) * 1);
}

.example-box {
    background: rgba(255, 193, 7, 0.1);
    border-left: 4px solid #ffc107;
    padding: calc(var(--spacing-unit) * 1.5);
    margin: calc(var(--spacing-unit) * 1.5) 0;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.example-box strong {
    color: #856404;
}

.applications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: calc(var(--spacing-unit) * 3);
    margin: calc(var(--spacing-unit) * 3) 0;
}

.application-item {
    background: var(--bg-secondary);
    padding: calc(var(--spacing-unit) * 3);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--primary-color);
}

.application-item h4 {
    color: var(--primary-color);
    margin-bottom: calc(var(--spacing-unit) * 2);
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
}

.application-item ul {
    margin: 0;
    padding-left: calc(var(--spacing-unit) * 2);
}

.application-item li {
    margin-bottom: calc(var(--spacing-unit) * 0.5);
    line-height: 1.5;
}

.final-message {
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--primary-color) 100%);
    color: white;
    padding: calc(var(--spacing-unit) * 3);
    border-radius: var(--radius-lg);
    text-align: center;
    margin-top: calc(var(--spacing-unit) * 3);
}

.final-message h4 {
    color: white;
    margin-bottom: calc(var(--spacing-unit) * 2);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: calc(var(--spacing-unit) * 1);
}

.final-message p {
    margin-bottom: calc(var(--spacing-unit) * 1.5);
    line-height: 1.6;
}

.final-message strong {
    color: var(--primary-light);
}

.units-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: calc(var(--spacing-unit) * 2);
    margin-bottom: calc(var(--spacing-unit) * 2);
}


/* ============================================
   BUTTONS
   ============================================ */
.btn-primary,
.btn-secondary,
.btn-calculate {
    padding: calc(var(--spacing-unit) * 1.5) calc(var(--spacing-unit) * 3);
    border: none;
    border-radius: var(--radius-sm);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
    justify-content: center;
    min-height: 44px;
    min-width: 44px;
}

.btn-primary,
.btn-calculate {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover,
.btn-calculate:hover {
    background: var(--primary-dark);
    transform: scale(1.02);
}

.btn-primary:active,
.btn-calculate:active {
    transform: scale(0.98);
}

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

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

.btn-back {
    background: transparent;
    border: none;
    color: var(--primary-color);
    font-size: 1rem;
    cursor: pointer;
    padding: calc(var(--spacing-unit) * 1);
    margin-bottom: calc(var(--spacing-unit) * 3);
    display: inline-flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
    transition: all var(--transition-fast);
}

.btn-back:hover {
    transform: translateX(-4px);
}

/* ============================================
   CALCULATOR
   ============================================ */
.calculator-container {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: calc(var(--spacing-unit) * 4);
    box-shadow: var(--shadow-md);
    max-width: 600px;
    margin: 0 auto;
}

.calculator-header {
    text-align: center;
    margin-bottom: calc(var(--spacing-unit) * 4);
}

.calculator-icon {
    font-size: 4rem;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.theory-box {
    background: var(--bg-secondary);
    border-left: 4px solid var(--primary-color);
    padding: calc(var(--spacing-unit) * 2);
    border-radius: var(--radius-sm);
    margin-bottom: calc(var(--spacing-unit) * 4);
}

.theory-box h3 {
    margin-bottom: calc(var(--spacing-unit) * 1);
}

.theory-box p {
    margin-bottom: 0;
    line-height: 1.8;
}

.theory-box b {
    color: var(--primary-dark);
    font-weight: 600;
}

.theory-box p:not(:last-child) {
    margin-bottom: calc(var(--spacing-unit) * 1.5);
}

/* ============================================
   FORMS
   ============================================ */
.calculator-form {
    display: flex;
    flex-direction: column;
    gap: calc(var(--spacing-unit) * 3);
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: calc(var(--spacing-unit) * 1);
}

.form-group label {
    font-weight: 600;
    color: var(--text-primary);
}

.form-group input {
    padding: calc(var(--spacing-unit) * 1.5);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    transition: border-color var(--transition-fast);
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-group input:invalid:not(:placeholder-shown) {
    border-color: #e74c3c;
}

/* Tooltips e Dicas */
.input-tooltip {
    position: relative;
    display: inline-block;
    margin-left: calc(var(--spacing-unit) * 1);
    cursor: help;
}

.tooltip-icon {
    color: var(--text-secondary);
    font-size: 0.8rem;
    transition: color var(--transition-fast);
}

.tooltip-icon:hover {
    color: var(--primary-color);
}

.tooltip-text {
    visibility: hidden;
    width: 200px;
    background-color: var(--text-primary);
    color: white;
    text-align: center;
    border-radius: var(--radius-sm);
    padding: calc(var(--spacing-unit) * 1);
    position: absolute;
    z-index: 100;
    bottom: 125%;
    left: 50%;
    margin-left: -100px;
    opacity: 0;
    transition: opacity var(--transition-fast);
    font-size: 0.8rem;
    line-height: 1.4;
}

.tooltip-text::after {
    content: "";
    position: absolute;
    top: 100%;
    left: 50%;
    margin-left: -5px;
    border-width: 5px;
    border-style: solid;
    border-color: var(--text-primary) transparent transparent transparent;
}

.input-tooltip:hover .tooltip-text {
    visibility: visible;
    opacity: 1;
}

.help-text {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: calc(var(--spacing-unit) * 0.5);
    font-style: italic;
}

.form-group small {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.btn-calculate {
    margin-top: calc(var(--spacing-unit) * 2);
    width: 100%;
}

/* ============================================
   RESULT BOX
   ============================================ */
.result-box {
    margin-top: calc(var(--spacing-unit) * 4);
    padding: calc(var(--spacing-unit) * 3);
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--primary-color) 100%);
    color: white;
    border-radius: var(--radius-md);
    animation: slideUp var(--transition-normal);
}

.result-box.hidden {
    display: none;
}

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

.result-box h3 {
    color: white;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.result-value {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.result-steps {
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-sm);
    padding: calc(var(--spacing-unit) * 2);
    margin: calc(var(--spacing-unit) * 2) 0;
    font-family: 'Courier New', monospace;
    font-size: 0.95rem;
    line-height: 1.6;
}

.result-steps ol {
    margin: 0;
    padding-left: calc(var(--spacing-unit) * 2);
}

.result-steps li {
    margin-bottom: calc(var(--spacing-unit) * 0.5);
    color: white;
}

.result-steps li:last-child {
    font-weight: 600;
    color: var(--primary-light);
}

.result-formula {
    font-family: 'Courier New', monospace;
    font-size: 1.1rem;
    margin-bottom: calc(var(--spacing-unit) * 3);
    opacity: 0.9;
}

.result-box .btn-secondary {
    background: white;
    color: var(--primary-color);
    width: 100%;
}

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

/* ============================================
   HISTORY
   ============================================ */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: calc(var(--spacing-unit) * 3);
    flex-wrap: wrap;
    gap: calc(var(--spacing-unit) * 2);
}

.history-list {
    display: flex;
    flex-direction: column;
    gap: calc(var(--spacing-unit) * 2);
}

.history-item {
    background: var(--bg-primary);
    padding: calc(var(--spacing-unit) * 3);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    animation: slideIn var(--transition-normal);
}

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

.history-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: calc(var(--spacing-unit) * 2);
}

.history-title {
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
    font-weight: 600;
}

.history-icon {
    font-size: 1.5rem;
}

.history-date {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.history-content {
    color: var(--text-secondary);
    margin-bottom: calc(var(--spacing-unit) * 1);
}

.history-result {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
}

.btn-delete-history {
    background: transparent;
    border: none;
    color: #e74c3c;
    cursor: pointer;
    padding: calc(var(--spacing-unit) * 1);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.btn-delete-history:hover {
    background: rgba(231, 76, 60, 0.1);
}

.empty-state {
    text-align: center;
    padding: calc(var(--spacing-unit) * 6) calc(var(--spacing-unit) * 2);
    color: var(--text-secondary);
}

.empty-state i {
    font-size: 4rem;
    margin-bottom: calc(var(--spacing-unit) * 2);
    opacity: 0.5;
}

.empty-hint {
    font-size: 0.875rem;
    margin-top: calc(var(--spacing-unit) * 1);
}

/* ============================================
   FAQ
   ============================================ */
.faq-container {
    display: flex;
    flex-direction: column;
    gap: calc(var(--spacing-unit) * 2);
}

.faq-item {
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.faq-question {
    width: 100%;
    padding: calc(var(--spacing-unit) * 2.5);
    background: transparent;
    border: none;
    text-align: left;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-primary);
    transition: background var(--transition-fast);
}

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

.faq-icon {
    font-size: 1.5rem;
    color: var(--primary-color);
    transition: transform var(--transition-fast);
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
}

.faq-answer {
    padding: 0 calc(var(--spacing-unit) * 2.5) calc(var(--spacing-unit) * 2.5);
    color: var(--text-secondary);
    line-height: 1.8;
    animation: expandAnswer var(--transition-normal);
}

.faq-answer[hidden] {
    display: none;
}

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

/* ============================================
   BOTTOM NAVIGATION
   ============================================ */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: var(--bottom-nav-height);
    background: var(--bg-primary);
    box-shadow: 0 -2px 8px rgba(0, 0, 0, 0.1);
    display: flex;
    justify-content: space-around;
    align-items: center;
    z-index: 100;
    padding: 0 calc(var(--spacing-unit) * 2);
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    font-size: 0.75rem;
    padding: calc(var(--spacing-unit) * 1);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    flex: 1;
    max-width: 120px;
    text-decoration: none;
}

.nav-item i {
    font-size: 1.5rem;
    margin-bottom: calc(var(--spacing-unit) * 0.5);
}

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

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

/* ============================================
   MODAL
   ============================================ */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 200;
    padding: calc(var(--spacing-unit) * 2);
    animation: fadeIn var(--transition-normal);
}

.modal[hidden] {
    display: none;
}

.modal-content {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    max-width: 500px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    animation: slideUp var(--transition-normal);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: calc(var(--spacing-unit) * 3);
    border-bottom: 1px solid var(--border-color);
}

.btn-close-modal {
    background: transparent;
    border: none;
    font-size: 1.5rem;
    color: var(--text-secondary);
    cursor: pointer;
    padding: calc(var(--spacing-unit) * 1);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

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

.modal-body {
    padding: calc(var(--spacing-unit) * 3);
}

/* Delete Modal Styles */
.delete-modal-content {
    max-width: 450px;
    animation: slideInFromBottom var(--transition-normal);
}

.delete-modal-header {
    background: linear-gradient(135deg, #ffebee 0%, #ffcdd2 100%);
    border-bottom: 2px solid #e57373;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: calc(var(--spacing-unit) * 2) calc(var(--spacing-unit) * 3);
}

.delete-modal-header .delete-icon {
    width: 48px;
    height: 48px;
    background: #f44336;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.5rem;
    box-shadow: 0 4px 8px rgba(244, 67, 54, 0.3);
    flex-shrink: 0;
    margin-right: calc(var(--spacing-unit) * 2);
}

.delete-modal-header h2 {
    color: #c62828;
    margin: 0;
    flex: 1;
    text-align: center;
    font-size: 1.2rem;
}

.btn-close-modal {
    background: transparent;
    border: none;
    color: #c62828;
    font-size: 1.5rem;
    cursor: pointer;
    padding: calc(var(--spacing-unit) * 1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    flex-shrink: 0;
    margin-left: calc(var(--spacing-unit) * 2);
}

.btn-close-modal:hover {
    background: rgba(198, 40, 40, 0.1);
    transform: scale(1.1);
}

.delete-modal-body {
    padding: calc(var(--spacing-unit) * 3);
    text-align: center;
}

.delete-message {
    margin-bottom: calc(var(--spacing-unit) * 3);
}

.delete-message p {
    margin-bottom: calc(var(--spacing-unit) * 2);
    font-size: 1.1rem;
    color: var(--text-primary);
}

.calculation-preview {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: calc(var(--spacing-unit) * 2);
    margin: calc(var(--spacing-unit) * 2) 0;
    border-left: 4px solid var(--primary-color);
    text-align: left;
}

.calculation-preview .preview-title {
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: calc(var(--spacing-unit) * 1);
    display: flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
}

.calculation-preview .preview-formula {
    font-family: 'Courier New', monospace;
    background: rgba(0, 168, 45, 0.05);
    padding: calc(var(--spacing-unit) * 1);
    border-radius: var(--radius-sm);
    margin-bottom: calc(var(--spacing-unit) * 1);
    color: var(--text-primary);
}

.calculation-preview .preview-result {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 1.1rem;
}

.warning-text {
    color: #f57c00;
    font-size: 0.9rem;
    background: rgba(245, 124, 0, 0.1);
    padding: calc(var(--spacing-unit) * 1.5);
    border-radius: var(--radius-sm);
    border-left: 4px solid #f57c00;
    display: flex;
    align-items: flex-start;
    gap: calc(var(--spacing-unit) * 1);
    margin-top: calc(var(--spacing-unit) * 2);
}

.warning-text i {
    margin-top: 2px;
    flex-shrink: 0;
}

.delete-actions {
    display: flex;
    gap: calc(var(--spacing-unit) * 2);
    justify-content: center;
    flex-wrap: wrap;
}

.btn-danger {
    background: #f44336;
    color: white;
    border: 2px solid #f44336;
    padding: calc(var(--spacing-unit) * 1.5) calc(var(--spacing-unit) * 3);
    border-radius: var(--radius-md);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    gap: calc(var(--spacing-unit) * 1);
    min-height: 44px;
}

.btn-danger:hover {
    background: #d32f2f;
    border-color: #d32f2f;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(244, 67, 54, 0.3);
}

.btn-danger:active {
    transform: translateY(0);
}

.btn-secondary:hover {
    background: var(--border-color);
    transform: translateY(-1px);
}

@keyframes slideInFromBottom {
    from {
        opacity: 0;
        transform: translateY(50px) scale(0.9);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

/* ============================================
   TOAST
   ============================================ */
.toast {
    position: fixed;
    bottom: calc(var(--bottom-nav-height) + var(--spacing-unit) * 2);
    left: 50%;
    transform: translateX(-50%);
    background: var(--text-primary);
    color: white;
    padding: calc(var(--spacing-unit) * 2) calc(var(--spacing-unit) * 3);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    z-index: 300;
    animation: toastSlideUp var(--transition-normal);
    max-width: 90%;
    text-align: center;
}

.toast[hidden] {
    display: none;
}

@keyframes toastSlideUp {
    from {
        opacity: 0;
        transform: translate(-50%, 20px);
    }
    to {
        opacity: 1;
        transform: translate(-50%, 0);
    }
}

/* ============================================
   FOOTER
   ============================================ */
.app-footer {
    background: var(--bg-primary);
    padding: calc(var(--spacing-unit) * 4) calc(var(--spacing-unit) * 2) 8rem;
    border-top: 1px solid var(--border-color);
    margin-top: calc(var(--spacing-unit) * 6);
}

.footer-content {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: calc(var(--spacing-unit) * 2);
    flex-wrap: wrap;
}

.footer-logo {
    height: 40px;
    width: auto;
    object-fit: contain;
}

.page-logo {
    height: 60px;
    width: auto;
    object-fit: contain;
    margin-bottom: calc(var(--spacing-unit) * 2);
    display: block;
    margin-left: auto;
    margin-right: auto;
}

.page-header {
    text-align: center;
    margin-bottom: calc(var(--spacing-unit) * 4);
}

.footer-text {
    text-align: center;
}

.footer-text p {
    margin-bottom: calc(var(--spacing-unit) * 1);
    color: var(--text-secondary);
}

.b20-link {
    color: var(--primary-color);
    font-weight: 600;
    transition: all var(--transition-fast);
}

.b20-link:hover {
    text-decoration: underline;
    transform: scale(1.05);
    display: inline-block;
}

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 768px) {
    .modules-grid {
        grid-template-columns: 1fr;
    }
    
    .calculator-container {
        padding: calc(var(--spacing-unit) * 2);
    }
    
    .section-header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .section-header .btn-secondary {
        width: 100%;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 14px;
    }
    
    .hero {
        padding: calc(var(--spacing-unit) * 2) 0;
    }
    
    .nav-item span {
        font-size: 0.7rem;
    }
}

/* ============================================
   ACCESSIBILITY
   ============================================ */
.sr-only {
    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-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* ============================================
   SAFE AREAS (iPhone notch)
   ============================================ */
@supports (padding: env(safe-area-inset-top)) {
    .app-header {
        padding-top: env(safe-area-inset-top);
        height: calc(var(--header-height) + env(safe-area-inset-top));
    }
    
    .bottom-nav {
        padding-bottom: env(safe-area-inset-bottom);
        height: calc(var(--bottom-nav-height) + env(safe-area-inset-bottom));
    }
    
    body {
        padding-top: calc(var(--header-height) + env(safe-area-inset-top));
        padding-bottom: calc(var(--bottom-nav-height) + env(safe-area-inset-bottom));
    }
}