/* CSS Custom Properties */
:root {
    --color-primary: #6B4423;
    --color-secondary: #8B5A2B;
    --color-accent: #D4A574;
    --color-warning: #E8A849;
    --color-success: #4A9D5B;
    --color-white: #FFFFFF;
    --color-light: #FAF7F4;
    --color-dark: #2C2417;
    --color-error: #C94B4B;
    --color-gray: #7A7067;
    --color-gray-light: #B8AFA6;
    --color-border: #E5DDD5;
    
    --font-family: 'Segoe UI', -apple-system, BlinkMacSystemFont, Roboto, sans-serif;
    --font-size-base: 16px;
    --font-size-small: 14px;
    --font-size-xs: 12px;
    --font-size-large: 18px;
    --font-size-xl: 22px;
    --font-size-xxl: 28px;
    
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    
    --border-radius: 12px;
    --border-radius-lg: 16px;
    --border-radius-sm: 8px;
    --box-shadow: 0 2px 12px rgba(107, 68, 35, 0.08);
    --box-shadow-lg: 0 8px 24px rgba(107, 68, 35, 0.12);
    --box-shadow-sm: 0 1px 4px rgba(107, 68, 35, 0.06);
    
    --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-fast: all 0.15s ease;
    --animation-duration: 0.4s;
    
    --header-height: 110px;
    --bottom-nav-height: 70px;
    --safe-area-bottom: env(safe-area-inset-bottom, 0px);
}

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

html {
    font-size: var(--font-size-base);
    scroll-behavior: smooth;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--color-dark);
    background-color: var(--color-light);
    min-height: 100vh;
    min-height: 100dvh;
    display: flex;
    flex-direction: column;
    padding-top: var(--header-height);
    padding-bottom: calc(var(--bottom-nav-height) + var(--safe-area-bottom));
    overflow-x: hidden;
}

/* Container */
.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    width: 100%;
}

/* Header - Fixed */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
    color: var(--color-white);
    padding: var(--spacing-md) 0;
    box-shadow: var(--box-shadow-lg);
}

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

.header__logo {
    width: 90px;
    height: 90px;
    object-fit: contain;
}

.header__text {
    text-align: left;
}

.header__title {
    font-size: var(--font-size-xl);
    font-weight: 700;
    margin-bottom: 2px;
    letter-spacing: -0.5px;
    line-height: 1.2;
}
.black-bar {
position: fixed;
bottom: 0;
left: 0;
right: 0;
height: 30px;
background-color: #000000;
z-index: 1001;
}
.header__subtitle {
    font-size: var(--font-size-small);
    opacity: 0.9;
    font-weight: 400;
}

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

/* Page transitions */
.page {
    animation: pageIn var(--animation-duration) ease;
}

.page.hidden {
    display: none !important;
}

@keyframes pageIn {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Section Titles */
.section-title {
    font-size: var(--font-size-xl);
    color: var(--color-primary);
    margin-bottom: var(--spacing-lg);
    text-align: center;
    font-weight: 600;
}

/* Loading State */
.loading {
    text-align: center;
    padding: var(--spacing-xxl);
}

.loading__spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto var(--spacing-md);
}

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

/* Messages */
.error-message,
.success-message {
    display: flex;
    align-items: center;
    padding: var(--spacing-md);
    border-radius: var(--border-radius-sm);
    margin-bottom: var(--spacing-lg);
    animation: slideDown var(--animation-duration) ease;
}

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

.error-message {
    background-color: #FEF2F2;
    border: 1px solid var(--color-error);
    color: var(--color-error);
}

.success-message {
    background-color: #F0FDF4;
    border: 1px solid var(--color-success);
    color: var(--color-success);
}

.error-message__icon,
.success-message__icon {
    margin-right: var(--spacing-sm);
    font-size: var(--font-size-large);
    flex-shrink: 0;
}

.error-message__text,
.success-message__text {
    flex: 1;
    font-size: var(--font-size-small);
}

.error-message__close,
.success-message__close {
    background: none;
    border: none;
    font-size: var(--font-size-xl);
    cursor: pointer;
    padding: var(--spacing-xs);
    margin-left: var(--spacing-sm);
    border-radius: var(--border-radius-sm);
    transition: var(--transition-fast);
    opacity: 0.6;
    line-height: 1;
}

.error-message__close:hover,
.success-message__close:hover {
    opacity: 1;
    background-color: rgba(0, 0, 0, 0.05);
}

/* Species Selection */
.species-selection {
    margin-bottom: var(--spacing-xxl);
}

.species-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.species-card {
    background: var(--color-white);
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--box-shadow-sm);
    -webkit-tap-highlight-color: transparent;
}

.species-card:hover {
    border-color: var(--color-accent);
    transform: translateY(-2px);
    box-shadow: var(--box-shadow);
}

.species-card:active {
    transform: scale(0.98);
}

.species-card:focus {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

.species-card.selected {
    border-color: var(--color-primary);
    background-color: #FBF7F4;
    box-shadow: var(--box-shadow);
}

.species-card__icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-sm);
    display: block;
}

.species-card__title {
    font-size: var(--font-size-base);
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
}

.species-card__description {
    color: var(--color-gray);
    font-size: var(--font-size-xs);
    line-height: 1.4;
}

/* Age Input */
.age-input {
    background: var(--color-white);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--box-shadow);
    margin-bottom: var(--spacing-xxl);
}

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

.input-label {
    display: block;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-size-base);
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.age-input__field {
    width: 100%;
    padding: var(--spacing-md);
    border: 2px solid var(--color-border);
    border-radius: var(--border-radius);
    font-size: var(--font-size-large);
    font-family: inherit;
    transition: var(--transition);
    padding-right: 60px;
    background: var(--color-white);
    color: var(--color-dark);
}

.age-input__field:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(107, 68, 35, 0.1);
}

.age-input__field::placeholder {
    color: var(--color-gray-light);
}

.age-input__field.invalid {
    border-color: var(--color-error);
}

.age-input__field.valid {
    border-color: var(--color-success);
}

.input-unit {
    position: absolute;
    right: var(--spacing-md);
    color: var(--color-gray);
    font-weight: 500;
    pointer-events: none;
}

.input-help {
    display: block;
    margin-top: var(--spacing-sm);
    color: var(--color-gray);
    font-size: var(--font-size-xs);
}

/* Buttons */
.button-group {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--border-radius);
    font-size: var(--font-size-base);
    font-weight: 600;
    font-family: inherit;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    min-width: 120px;
    -webkit-tap-highlight-color: transparent;
}

.btn-icon {
    flex-shrink: 0;
}

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

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

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

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

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

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

.btn--tertiary:hover {
    background-color: var(--color-warning);
}

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

.btn--danger:hover {
    background-color: #B43B3B;
}

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

/* Results */
.results {
    animation: pageIn var(--animation-duration) ease;
}

.result-card {
    background: linear-gradient(135deg, var(--color-white) 0%, #FBF7F4 100%);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--box-shadow-lg);
    text-align: center;
    border: 2px solid var(--color-accent);
}

.result-card__header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.result-card__species-icon {
    font-size: 2rem;
}

.result-card__title {
    font-size: var(--font-size-large);
    color: var(--color-primary);
    font-weight: 600;
}

.result-card__age {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--color-secondary);
    margin-bottom: var(--spacing-md);
    animation: pulse 2s infinite;
}

.result-card__phase {
    font-size: var(--font-size-base);
    color: var(--color-white);
    background-color: var(--color-success);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: 50px;
    display: inline-block;
    font-weight: 600;
}

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

/* Life Stage Information */
.life-stage-info {
    background: var(--color-white);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--box-shadow-sm);
    border-left: 4px solid var(--color-accent);
}

.life-stage-info__title {
    font-size: var(--font-size-base);
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
    font-weight: 600;
}

.life-stage-info__content {
    color: var(--color-dark);
    font-size: var(--font-size-small);
    line-height: 1.7;
}

.life-stage-info__content p {
    margin-bottom: var(--spacing-sm);
}

.life-stage-info__content p:last-child {
    margin-bottom: 0;
}

/* Milestones */
.milestones {
    background: var(--color-white);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--box-shadow-sm);
}

.milestones__title {
    font-size: var(--font-size-base);
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
    font-weight: 600;
}

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

.milestone-item {
    display: flex;
    align-items: flex-start;
    padding: var(--spacing-md);
    background-color: var(--color-light);
    border-radius: var(--border-radius-sm);
    border-left: 3px solid var(--color-warning);
}

.milestone-item__icon {
    font-size: var(--font-size-large);
    margin-right: var(--spacing-md);
    flex-shrink: 0;
}

.milestone-item__content {
    flex: 1;
}

.milestone-item__title {
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
    font-size: var(--font-size-small);
}

.milestone-item__description {
    color: var(--color-gray);
    font-size: var(--font-size-xs);
    line-height: 1.4;
}

/* Saved Calculations */
.saved-calculations {
    margin-bottom: var(--spacing-xl);
}

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

/* Empty State */
.empty-state {
    text-align: center;
    padding: var(--spacing-xxl) var(--spacing-lg);
    color: var(--color-gray);
}

.empty-state__icon {
    color: var(--color-gray-light);
    margin-bottom: var(--spacing-md);
}

.empty-state__text {
    font-size: var(--font-size-base);
    font-weight: 500;
    color: var(--color-gray);
    margin-bottom: var(--spacing-xs);
}

.empty-state__subtext {
    font-size: var(--font-size-small);
    color: var(--color-gray-light);
}

.saved-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-md);
    background: var(--color-white);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius-sm);
    margin-bottom: var(--spacing-sm);
    transition: var(--transition-fast);
    box-shadow: var(--box-shadow-sm);
}

.saved-item:hover {
    background-color: #FBF7F4;
    border-color: var(--color-accent);
}

.saved-item__info {
    flex: 1;
    min-width: 0;
}

.saved-item__species {
    font-weight: 600;
    color: var(--color-primary);
    font-size: var(--font-size-small);
}

.saved-item__age {
    color: var(--color-gray);
    font-size: var(--font-size-xs);
    margin-top: 2px;
}

.saved-item__result {
    font-weight: 600;
    color: var(--color-secondary);
    font-size: var(--font-size-small);
    margin: 0 var(--spacing-md);
    white-space: nowrap;
}

.saved-item__delete {
    background: none;
    border: none;
    color: var(--color-gray-light);
    cursor: pointer;
    padding: var(--spacing-sm);
    border-radius: var(--border-radius-sm);
    transition: var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.saved-item__delete:hover {
    background-color: var(--color-error);
    color: var(--color-white);
}

/* Info Page */
.info-page {
    padding-bottom: var(--spacing-xl);
}

.info-card {
    background: var(--color-white);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
    box-shadow: var(--box-shadow-sm);
}

.info-card__title {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-base);
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
    font-weight: 600;
}

.info-card__title svg {
    color: var(--color-accent);
    flex-shrink: 0;
}

.info-card p {
    color: var(--color-gray);
    font-size: var(--font-size-small);
    line-height: 1.6;
}

.info-list {
    list-style: none;
    padding: 0;
}

.info-list li {
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid var(--color-border);
    font-size: var(--font-size-small);
    color: var(--color-gray);
}

.info-list li:last-child {
    border-bottom: none;
}

.info-list strong {
    color: var(--color-primary);
}

/* Footer */
.footer {
    background-color: var(--color-primary);
    color: var(--color-white);
    padding: var(--spacing-md) 0;
    text-align: center;
    margin-bottom: calc(var(--bottom-nav-height) + var(--safe-area-bottom));
}

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

.footer__text a {
    color: var(--color-accent);
    text-decoration: none;
    transition: var(--transition-fast);
}

.footer__text a:hover {
    text-decoration: underline;
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: var(--color-white);
    display: flex;
    justify-content: space-around;
    align-items: stretch;
    height: var(--bottom-nav-height);
    padding-bottom: var(--safe-area-bottom);
    box-shadow: 0 -2px 16px rgba(107, 68, 35, 0.1);
    border-top: 1px solid var(--color-border);
    margin-bottom: 60px;
}

.bottom-nav__item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--color-gray);
    padding: var(--spacing-sm);
    transition: var(--transition-fast);
    -webkit-tap-highlight-color: transparent;
    position: relative;
}

.bottom-nav__item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%) scaleX(0);
    width: 50%;
    height: 3px;
    background: var(--color-primary);
    border-radius: 0 0 3px 3px;
    transition: var(--transition);
}

.bottom-nav__item.active::before {
    transform: translateX(-50%) scaleX(1);
}

.bottom-nav__item:hover,
.bottom-nav__item.active {
    color: var(--color-primary);
}

.bottom-nav__item.active {
    color: var(--color-primary);
}

.bottom-nav__icon {
    width: 24px;
    height: 24px;
    transition: var(--transition-fast);
}

.bottom-nav__item.active .bottom-nav__icon {
    transform: scale(1.1);
}

.bottom-nav__label {
    font-size: 11px;
    font-weight: 500;
    letter-spacing: 0.2px;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Responsive Design */
@media (max-width: 480px) {
    :root {
        --header-height: 95px;
        --bottom-nav-height: 60px;
    }
    
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .header {
        padding: var(--spacing-sm) 0;
    }
    
    .header__logo {
        width: 72px;
        height: 72px;
    }
    
    .header__title {
        font-size: var(--font-size-large);
    }
    
    .header__subtitle {
        font-size: var(--font-size-xs);
    }
    
    .section-title {
        font-size: var(--font-size-large);
    }
    
    .species-grid {
        gap: var(--spacing-sm);
    }
    
    .species-card {
        padding: var(--spacing-md);
    }
    
    .species-card__icon {
        font-size: 2rem;
    }
    
    .species-card__title {
        font-size: var(--font-size-small);
    }
    
    .age-input {
        padding: var(--spacing-lg);
    }
    
    .button-group {
        flex-direction: column;
        align-items: stretch;
    }
    
    .btn {
        width: 100%;
    }
    
    .result-card {
        padding: var(--spacing-lg);
    }
    
    .result-card__age {
        font-size: 2rem;
    }
    
    .saved-item {
        flex-wrap: wrap;
        gap: var(--spacing-sm);
    }
    
    .saved-item__result {
        margin: 0;
        order: 3;
        flex-basis: 100%;
    }
    
    .saved-item__delete {
        order: 2;
    }
    
    .bottom-nav__label {
        font-size: 10px;
    }
    
    .bottom-nav__icon {
        width: 22px;
        height: 22px;
    }
}

@media (min-width: 481px) and (max-width: 768px) {
    .species-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 769px) {
    .species-grid {
        grid-template-columns: repeat(4, 1fr);
    }
    
    .container {
        max-width: 800px;
    }
}

/* Landscape orientation adjustments */
@media (max-height: 500px) and (orientation: landscape) {
    :root {
        --header-height: 70px;
        --bottom-nav-height: 50px;
    }
    
    .header {
        padding: var(--spacing-xs) 0;
    }
    
    .header__logo {
        width: 60px;
        height: 60px;
    }
    
    .header__title {
        font-size: var(--font-size-base);
        margin-bottom: 0;
    }
    
    .header__subtitle {
        display: none;
    }
    
    .main {
        padding: var(--spacing-md) 0;
    }
    
    .bottom-nav__label {
        display: none;
    }
    
    .bottom-nav__icon {
        width: 28px;
        height: 28px;
    }
}

/* Print Styles */
@media print {
    .header,
    .footer,
    .btn,
    .saved-calculations,
    .bottom-nav {
        display: none !important;
    }
    
    body {
        padding: 0;
    }
    
    .results {
        page-break-inside: avoid;
    }
    
    body {
        background: white;
        color: black;
    }
    
    .result-card,
    .life-stage-info,
    .milestones {
        box-shadow: none;
        border: 1px solid #ccc;
    }
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    html {
        scroll-behavior: auto;
    }
}

/* Dark mode support (optional enhancement) */
@media (prefers-color-scheme: dark) {
    :root {
        --color-light: #1A1510;
        --color-white: #252019;
        --color-dark: #F5F0EB;
        --color-gray: #A39889;
        --color-gray-light: #6B6157;
        --color-border: #3D352B;
    }
    
    .header {
        background: linear-gradient(135deg, #4A3018 0%, #5C4028 100%);
    }
    
    .bottom-nav {
        background: #252019;
        border-top-color: #3D352B;
    }
    
    .age-input__field {
        background: #1A1510;
        color: var(--color-dark);
    }
}