/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --color-primary: #1A535C;
    --color-secondary: #4ECDC4;
    --color-background: #F7FFF7;
    --color-accent: #FF6B6B;
    --color-warning: #FFE66D;
    --color-white: #FFFFFF;
    --color-gray-light: #E8F4F8;
    --color-gray-medium: #B8D4DA;
    --color-gray-dark: #2C3E50;
    --color-text: #2C3E50;
    --color-text-light: #7F8C8D;
    
    --font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-size-small: 0.875rem;
    --font-size-base: 1rem;
    --font-size-large: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-xxl: 2rem;
    
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    
    --border-radius: 8px;
    --border-radius-large: 16px;
    --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --box-shadow-large: 0 8px 25px rgba(0, 0, 0, 0.15);
    
    --transition: all 0.3s ease;
    --transition-fast: all 0.15s ease;
}

body {
    font-family: var(--font-family);
    background-color: var(--color-background);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Navigation */
.nav {
    background-color: var(--color-primary);
    color: var(--color-white);
    padding: var(--spacing-md) 0;
    box-shadow: var(--box-shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav__container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav__logo h1 {
    font-size: var(--font-size-xl);
    font-weight: bold;
}

.nav__menu {
    display: flex;
    gap: var(--spacing-sm);
}

.nav__button {
    background: transparent;
    border: 2px solid transparent;
    color: var(--color-white);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    font-size: var(--font-size-small);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.nav__button:hover,
.nav__button:focus {
    background-color: var(--color-secondary);
    border-color: var(--color-secondary);
    outline: none;
}

.nav__button.nav__button--active {
    background-color: var(--color-secondary);
    border-color: var(--color-secondary);
}

/* Main Content */
.main {
    flex: 1;
    padding: var(--spacing-xl) 0;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Screen Management */
.screen {
    display: none;
    animation: fadeIn 0.5s ease-in-out;
}

.screen--active {
    display: block;
}

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

/* Buttons */
.btn {
    background-color: var(--color-secondary);
    color: var(--color-white);
    border: none;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: var(--font-size-base);
    font-weight: 600;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    text-decoration: none;
    min-height: 48px;
}

.btn:hover:not(:disabled),
.btn:focus:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--box-shadow-large);
    outline: none;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

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

.btn--primary:hover:not(:disabled) {
    background-color: #0F3A42;
}

.btn--secondary {
    background-color: var(--color-gray-medium);
    color: var(--color-text);
}

.btn--secondary:hover:not(:disabled) {
    background-color: var(--color-gray-dark);
    color: var(--color-white);
}

.btn--success {
    background-color: #27AE60;
}

.btn--success:hover:not(:disabled) {
    background-color: #219A52;
}

.btn--danger {
    background-color: var(--color-accent);
}

.btn--danger:hover:not(:disabled) {
    background-color: #E74C3C;
}

.btn--small {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-small);
    min-height: 36px;
}

.btn--large {
    padding: var(--spacing-lg) var(--spacing-xl);
    font-size: var(--font-size-large);
    min-height: 56px;
}

/* Home Screen */
.home {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.home__header {
    margin-bottom: var(--spacing-xxl);
}

.home__title {
    font-size: var(--font-size-xxl);
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
}

.home__subtitle {
    font-size: var(--font-size-large);
    color: var(--color-text-light);
}

.category-selector {
    margin-bottom: var(--spacing-xxl);
}

.category-selector__label {
    display: block;
    margin-bottom: var(--spacing-md);
    font-weight: 600;
    color: var(--color-primary);
}

.category-selector__select {
    width: 100%;
    max-width: 300px;
    padding: var(--spacing-md);
    border: 2px solid var(--color-gray-medium);
    border-radius: var(--border-radius);
    font-size: var(--font-size-base);
    background-color: var(--color-white);
    color: var(--color-text);
    cursor: pointer;
    transition: var(--transition);
}

.category-selector__select:focus {
    outline: none;
    border-color: var(--color-secondary);
    box-shadow: 0 0 0 3px rgba(78, 205, 196, 0.2);
}

.stats {
    margin-top: var(--spacing-xxl);
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-lg);
}

.stats__item {
    background-color: var(--color-white);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    text-align: center;
}

.stats__number {
    display: block;
    font-size: var(--font-size-xxl);
    font-weight: bold;
    color: var(--color-secondary);
}

.stats__label {
    color: var(--color-text-light);
    font-size: var(--font-size-small);
}

/* Challenge Screen */
.challenge {
    max-width: 800px;
    margin: 0 auto;
}

.challenge__header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
}

.challenge__category {
    background-color: var(--color-secondary);
    color: var(--color-white);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius);
    font-weight: 600;
    font-size: var(--font-size-small);
}

.challenge__content {
    background-color: var(--color-white);
    padding: var(--spacing-xxl);
    border-radius: var(--border-radius-large);
    box-shadow: var(--box-shadow-large);
    margin-bottom: var(--spacing-xl);
    text-align: center;
}

.challenge__title {
    font-size: var(--font-size-xl);
    color: var(--color-primary);
    line-height: 1.4;
}

/* Timer */
.timer {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.timer__circle {
    position: relative;
    width: 200px;
    height: 200px;
    margin: 0 auto var(--spacing-lg);
}

.timer__svg {
    width: 100%;
    height: 100%;
    transform: rotate(-90deg);
}

.timer__track {
    fill: none;
    stroke: var(--color-gray-light);
    stroke-width: 8;
}

.timer__progress {
    fill: none;
    stroke: var(--color-secondary);
    stroke-width: 8;
    stroke-linecap: round;
    stroke-dasharray: 283;
    stroke-dashoffset: 0;
    transition: stroke-dashoffset 1s linear;
}

.timer__display {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
}

.timer__time {
    display: block;
    font-size: var(--font-size-xxl);
    font-weight: bold;
    color: var(--color-primary);
}

.timer__label {
    font-size: var(--font-size-small);
    color: var(--color-text-light);
}

.challenge__actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* History Screen */
.history__header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.history__title {
    font-size: var(--font-size-xxl);
    color: var(--color-primary);
}

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

.history__filter-select {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 2px solid var(--color-gray-medium);
    border-radius: var(--border-radius);
    background-color: var(--color-white);
    color: var(--color-text);
    cursor: pointer;
}

.history__empty {
    text-align: center;
    padding: var(--spacing-xxl);
    color: var(--color-text-light);
}

.history__item {
    background-color: var(--color-white);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    margin-bottom: var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-md);
}

.history__item-content {
    flex: 1;
}

.history__item-title {
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
}

.history__item-meta {
    font-size: var(--font-size-small);
    color: var(--color-text-light);
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.history__item-actions {
    display: flex;
    gap: var(--spacing-sm);
}

.history__item-favorite {
    background: none;
    border: none;
    font-size: var(--font-size-large);
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.history__item-favorite:hover {
    background-color: var(--color-gray-light);
}

.history__item-favorite--active {
    color: var(--color-accent);
}

/* Score Screen */
.score__header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.score__title {
    font-size: var(--font-size-xxl);
    color: var(--color-primary);
}

.score__current {
    background-color: var(--color-white);
    padding: var(--spacing-xxl);
    border-radius: var(--border-radius-large);
    box-shadow: var(--box-shadow-large);
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.score__points {
    margin-bottom: var(--spacing-lg);
}

.score__number {
    display: block;
    font-size: 3rem;
    font-weight: bold;
    color: var(--color-secondary);
}

.score__label {
    color: var(--color-text-light);
}

.score__level {
    max-width: 300px;
    margin: 0 auto;
}

.score__level-name {
    display: block;
    font-size: var(--font-size-large);
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
}

.score__progress-bar {
    background-color: var(--color-gray-light);
    height: 8px;
    border-radius: 4px;
    overflow: hidden;
}

.score__progress-fill {
    background-color: var(--color-secondary);
    height: 100%;
    border-radius: 4px;
    transition: width 0.5s ease;
}

.achievements {
    margin-bottom: var(--spacing-xl);
}

.achievements__title {
    font-size: var(--font-size-xl);
    color: var(--color-primary);
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.achievements__grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: var(--spacing-md);
}

.achievement {
    background-color: var(--color-white);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    text-align: center;
    transition: var(--transition);
}

.achievement:hover {
    transform: translateY(-2px);
    box-shadow: var(--box-shadow-large);
}

.achievement__icon {
    font-size: var(--font-size-xxl);
    margin-bottom: var(--spacing-md);
}

.achievement__title {
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
}

.achievement__description {
    font-size: var(--font-size-small);
    color: var(--color-text-light);
}

.achievement--locked {
    opacity: 0.5;
    filter: grayscale(1);
}

.score__stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-lg);
}

.score__stat {
    background-color: var(--color-white);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    text-align: center;
}

.score__stat-number {
    display: block;
    font-size: var(--font-size-xxl);
    font-weight: bold;
    color: var(--color-secondary);
}

.score__stat-label {
    color: var(--color-text-light);
    font-size: var(--font-size-small);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    animation: fadeIn 0.3s ease;
}

.modal--active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal__content {
    background-color: var(--color-white);
    border-radius: var(--border-radius-large);
    box-shadow: var(--box-shadow-large);
    max-width: 500px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from { transform: scale(0.8); opacity: 0; }
    to { transform: scale(1); opacity: 1; }
}

.modal__header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-gray-light);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal__title {
    font-size: var(--font-size-xl);
    color: var(--color-primary);
}

.modal__close {
    background: none;
    border: none;
    font-size: var(--font-size-xxl);
    cursor: pointer;
    color: var(--color-text-light);
    padding: var(--spacing-xs);
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.modal__close:hover {
    background-color: var(--color-gray-light);
    color: var(--color-text);
}

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

.modal__text {
    margin-bottom: var(--spacing-lg);
    color: var(--color-text);
}

.share-buttons {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: var(--spacing-md);
}

.share-btn {
    padding: var(--spacing-md);
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition);
    color: var(--color-white);
}

.share-btn--twitter {
    background-color: #1DA1F2;
}

.share-btn--facebook {
    background-color: #4267B2;
}

.share-btn--whatsapp {
    background-color: #25D366;
}

.share-btn--copy {
    background-color: var(--color-primary);
}

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

/* Toast Notifications */
.toast-container {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1100;
}

.toast {
    background-color: var(--color-white);
    color: var(--color-text);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow-large);
    margin-bottom: var(--spacing-md);
    border-left: 4px solid var(--color-secondary);
    animation: slideInRight 0.3s ease;
    max-width: 300px;
}

.toast--success {
    border-left-color: #27AE60;
}

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

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

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

/* Footer */
.footer {
    background-color: var(--color-primary);
    color: var(--color-white);
    padding: var(--spacing-lg) 0;
    text-align: center;
    margin-top: auto;
}

.footer__text {
    font-size: var(--font-size-small);
}

.footer__link {
    color: var(--color-secondary);
    text-decoration: none;
    transition: var(--transition);
}

.footer__link:hover {
    color: var(--color-white);
    text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 768px) {
    :root {
        --font-size-xxl: 1.75rem;
        --font-size-xl: 1.25rem;
        --spacing-xxl: 2rem;
    }
    
    .nav__container {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .nav__menu {
        width: 100%;
        justify-content: center;
    }
    
    .nav__button {
        flex: 1;
        justify-content: center;
    }
    
    .challenge__header {
        flex-direction: column;
        gap: var(--spacing-md);
        align-items: stretch;
    }
    
    .challenge__actions {
        flex-direction: column;
    }
    
    .history__header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .history__filters {
        justify-content: center;
    }
    
    .history__item {
        flex-direction: column;
        align-items: stretch;
        text-align: center;
    }
    
    .history__item-meta {
        justify-content: center;
    }
    
    .timer__circle {
        width: 150px;
        height: 150px;
    }
    
    .share-buttons {
        grid-template-columns: 1fr;
    }
    
    .stats {
        grid-template-columns: 1fr;
    }
    
    .score__stats {
        grid-template-columns: 1fr;
    }
    
    .achievements__grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .challenge__content {
        padding: var(--spacing-lg);
    }
    
    .score__current {
        padding: var(--spacing-lg);
    }
    
    .modal__content {
        width: 95%;
    }
    
    .toast-container {
        right: 10px;
        left: 10px;
    }
    
    .toast {
        max-width: none;
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus indicators */
button:focus,
select:focus,
input:focus {
    outline: 2px solid var(--color-secondary);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --box-shadow: 0 0 0 1px #000000;
        --box-shadow-large: 0 0 0 2px #000000;
    }
}