:root {
    --bg: #FFFFFF;
    --surface: #FFFFFF;
    --text-primary: #222222;
    --text-secondary: #858480;
    --accent: #FF5722;
    --disabled: #e6e7eb;
    --disabled-hover: #d2d5db;
    --border: #E0E0E0;
    --border-dark: #222222;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scrollbar-gutter: stable;
}

body {
    font-family: 'Inter Tight', -apple-system, BlinkMacSystemFont, sans-serif;
    font-weight: 400;
    background: var(--bg);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 160px 24px 32px 24px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

#page-scroll {
    position: fixed;
    top: 80px;
    bottom: 0;
    left: 0;
    right: 0;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
}

#page-scroll .container {
    padding-top: 48px;
    padding-bottom: 80px;
    min-height: 100%;
}

header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 80px;
    padding: 0 24px;
    display: flex;
    align-items: stretch;
    background: var(--bg);
    z-index: 100;
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    border-bottom: 1px solid var(--border-dark);
    padding-top:6px;
}

.site-name {
    font-family: 'Zalando Sans Expanded', sans-serif;    
    font-size: 16px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: -0.025em;
}

.site-name a {
    color: inherit;
    text-decoration: none;
}

.header-info {
    font-family: 'Inter Tight', sans-serif;
    font-size: 16px;
    color: var(--text-primary);
    text-decoration: none;
    cursor: pointer;
}

.header-info, .site-name a {
    transition: color 0.15s ease;
}

.header-info:hover, .site-name a:hover {
    color: var(--text-secondary);
}


.step-indicator {
    font-family: 'Inter Tight', sans-serif;
    font-size: 12px;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}


.step {
    display: none;
    flex-direction: column;
    flex: 1;
}

.step.active {
    display: flex;
}

.step.active .step-content {
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.step-content {
    flex: 1;
}

.step-title {
    font-family: 'Zalando Sans Expanded', sans-serif;
    font-size: 32px;
    line-height: 1.2;
    font-weight: 600;
    margin-bottom: 4px;
    letter-spacing: -0.3px;
    text-transform:uppercase;
}

.step-description {
    font-family: 'Inter Tight', sans-serif;
    color: var(--text-primary);
    font-size: 16px;
    line-height: 1.6;
    margin-bottom: 32px;
    text-wrap:pretty;
}

/* Input field */
.input-group {
    margin-bottom: 24px;
}

.input-group input[type="number"] {
    font-family: 'Zalando Sans Expanded', sans-serif;
    width: 100%;
    padding: 20px;
    font-size: 32px;
    font-weight: 400;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--surface);
    text-align: center;
    transition: border-color 0.2s ease;
}

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

.input-group input::placeholder {
    color: var(--disabled);
    font-weight: 400;
}

.input-suffix {
    font-family: 'Inter Tight', sans-serif;
    text-align: center;
    color: var(--text-secondary);
    text-transform: uppercase;
    font-size: 12px;
    font-weight: 400;
    margin-top: 12px;
    letter-spacing: 1px;
}

.suggested-ranges {
    margin-top: 48px;
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 24px;
}

.suggested-ranges-title {
    font-family: 'Inter Tight', sans-serif;
    font-size: 12px;
    font-weight: 400;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 12px;
}

.range-item {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    padding: 16px 0;
    border-bottom: 1px solid var(--border);
}

.range-item:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.range-item:first-of-type {
    padding-top: 8px;
}

.range-value {
    font-family: 'Inter Tight', sans-serif;
    font-size: 16px;
    font-weight: 500;
    color: var(--text-primary);
    text-align: left;
}

.range-label {
    font-size: 16px;
    font-weight: 400;
    color: var(--text-primary);
}

/* Selection cards */
.card-grid {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px 20px;
    cursor: pointer;
    transition: all 0.15s ease;
    min-height: 44px;
}

.card:hover {
    border-color: var(--text-primary);
}

.card.selected {
    border-color: var(--text-primary);
    background: #f5f5f0;
    
}

.card.selected .card-subtitle {
    color: var(--text-secondary);
}

.card-title {
    font-size: 16px;
    font-weight: 500;
}

.card-subtitle {
    font-family: 'Inter Tight', sans-serif;
    color: var(--text-secondary);
    font-size: 14px;
    margin-top: 2px;
}


/* Navigation buttons */
.nav-buttons {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    display: none;
    gap: 12px;
    max-width: 600px;
    margin: 0 auto;
    padding: 12px 24px calc(12px + env(safe-area-inset-bottom, 0px)) 24px;
    backdrop-filter: blur(6px);
}

.nav-buttons.active {
    display: flex;
}

.btn {
    font-family: 'Inter Tight', sans-serif;
    flex: 1;
    padding: 16px 24px;
    font-size: 14px;
    font-weight: 400;
    border: none;
    border-radius: 9999px;
    cursor: pointer;
    transition: all 0.15s ease;
    min-height: 48px;
    text-transform: none;
    letter-spacing: 0;
}

.btn-primary {
    background: rgb(240, 255, 102);
    color: var(--text-primary);
}

.btn-primary:hover {
    background: rgb(220, 235, 80);
}

.btn-primary:disabled {
    background: var(--disabled);
    color: var(--text-secondary);
    cursor: not-allowed;
}

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

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

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

/* Info link */
.info-link {
    font-family: 'Inter Tight', sans-serif;
    display: block;
    text-align: center;
    margin-top: 12px;
    padding: 12px;
    color: var(--text-secondary);
    font-size: 14px;
    cursor: pointer;
    transition: color 0.15s ease;
    text-decoration: none;
}

.info-link:hover {
    color: var(--text-primary);
}

/* Overlay */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg);
    z-index: 200;
    opacity: 0;
    visibility: hidden;
    transition: opacity 300ms ease-in-out, visibility 300ms ease-in-out;
    overflow-y: auto;
}

.overlay.active {
    opacity: 1;
    visibility: visible;
}

.overlay-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 80px;
    padding: 0 24px;
    display: flex;
    align-items: stretch;
    background: var(--bg);
    z-index: 201;
}

.overlay-header-inner {
    display: flex;
    align-items: center;
    justify-content: flex-end;
    width: 100%;
    padding-top: 4px;
}

.overlay-close {
    font-family: 'Inter Tight', sans-serif;
    font-size: 16px;
    color: var(--text-primary);
    background: none;
    border: none;
    cursor: pointer;
    padding: 0;
}

.overlay-close:hover {
    color: var(--text-secondary);
}

.overlay-content {
    max-width: 680px;
    margin: 0 auto;
    padding: 120px 24px calc(100px + env(safe-area-inset-bottom, 0px)) 24px;
}

.overlay-block {
    margin-bottom: 40px;
}

.overlay-block:last-child {
    margin-bottom: 0;
}

.overlay-title {
    font-size: 21px;
    font-weight: 600;
    margin-bottom: 8px;
    letter-spacing: -0.025em;
}

.overlay-text a:not(.cite-ref) {
    color: var(--text-primary);
    text-decoration: underline;
    text-decoration-skip-ink: auto;
    transition: color 0.15s ease;
}

.overlay-text a:not(.cite-ref):hover {
    color: var(--text-secondary);
}

.overlay-text {
    font-family: 'Inter Tight', sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
}

/* Results */
.results-section {
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 12px;
}

.results-title {
    font-family: 'Inter Tight', sans-serif;
    font-size: 12px;
    font-weight: 400;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 12px;
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 0;
    border-bottom: 1px solid var(--border);
}

.result-item:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.result-item:first-child {
    padding-top: 0;
}

.result-label {
    font-family: 'Inter Tight', sans-serif;
    font-size: 16px;
    font-weight: 500;
}

.result-value {
    font-family: 'Inter Tight', sans-serif;
    font-size: 16px;
    font-weight: 400;
}

/* Summary row */
.summary-row {
    display: flex;
    gap: 12px;
    margin-bottom: 24px;
}

.summary-item {
    flex: 1;
    text-align: center;
    padding: 20px 16px;
    border: 1px solid var(--border);
    border-radius: 8px;
}

.summary-value {
    font-family: 'Zalando Sans Expanded', sans-serif;
    font-size: 32px;
    font-weight: 400;
}

.summary-value.accent {
    color: var(--text-primary);
}

.summary-label {
    font-family: 'Inter Tight', sans-serif;
    font-size: 12px;
    color: var(--text-secondary);
    margin-top: 4px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Concentration result display */
.concentration-result {
    margin-top: 32px;
    padding: 20px;
    border: 1px solid var(--border);
    border-radius: 8px;
    display: none;
}

.concentration-result.visible {
    display: block;
}

.concentration-result .result-item {
    border-bottom: none;
    padding: 0;
}

.concentration-description {
    font-family: 'Inter Tight', sans-serif;
    font-size: 14px;
    line-height: 1.5;
    color: var(--text-secondary);
    margin-top: 4px;
}

/* Citation footnote */
.cite-ref {
    font-size: 0.65em;
    color: var(--text-primary);
    text-decoration: none;
    vertical-align: super;
    padding:2px;
    line-height: 0;
}

.cite-ref:hover {
    color: var(--text-secondary);
}

/* Sources section */
.sources-list {
    list-style: decimal;
    padding:12px 0 0 15px;
}

.source-item {
    font-family: 'Inter Tight', sans-serif;
    font-size: 14px;
    color: var(--text-primary);
    margin-bottom: 16px;
}

.source-item a {
    color: var(--text-primary);
    text-decoration: none;
}

.source-item a:hover {
    color: var(--text-secondary);
}

.source-item a::after {
    content: '';
    display: inline-block;
    width: 11px;
    height: 11px;
    background-image: url('img/external-link.svg');
    background-size: contain;
    background-repeat: no-repeat;
    background-position: center;
    vertical-align: middle;
    margin: 0 0 2px 4px;
    opacity: 1;
    transition: opacity 0.15s ease;
}

.source-item a:hover::after {
    opacity: 0.5;
}

.info-section,
.introduction-section {
    opacity: 0;
    transform: translateY(10px);
    transition: opacity 0.4s ease, transform 0.4s ease;
}

.info-section.visible,
.introduction-section.visible {
    opacity: 1;
    transform: translateY(0);
}

.info-section {
    padding-top: 48px;
}

.sources-section {
    padding-top:12px;
    margin-top: 56px;
}

/* Info photo collage */
.info-photos {
    position: relative;
    left: 50%;
    width: min(1000px, 100vw);
    padding: 0 24px;
    margin: 60px 0 36px 0;
    display: grid;
    grid-template-columns: 55fr 45fr;
    gap: 36px;
    align-items: end;
    opacity: 0;
    transform: translateX(-50%) translateY(10px);
    transition: opacity 0.4s ease, transform 0.4s ease;
}

.info-photos.visible {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

.info-photo {
    display: block;
    width: 100%;
    height: auto;
    background: #f5f5f0;
}

.info-photo:nth-child(1) {
    aspect-ratio: 4 / 3;
}

.info-photo:nth-child(2) {
    aspect-ratio: 3 / 4;
}

/* Concentration image */
.concentration-image-wrapper {
    max-width: 300px;
    width: 100%;
    margin-left: auto;
    margin-right: auto;
    margin-bottom: 24px;
    background-color: #ffffff;
    aspect-ratio: 1024 / 714;
    display: none;
}

.concentration-image-wrapper img {
    width: 100%;
    height: auto;
    display: block;
}

.concentration-image-wrapper.visible {
    display: block;
}

@media (max-width: 600px) {
    .concentration-image-wrapper {
        max-width: 200px;
    }
}

/* Responsive */
@media (max-width: 700px) {
    .info-photos {
        gap: 24px;
    }
}

@media (max-width: 600px) {
    header,
    .overlay-header {
        height: 60px;
    }

    .info-photos {
        margin: 42px 0 24px 0;
    }

    #page-scroll {
        top: 60px;
        /*bottom: calc(60px + env(safe-area-inset-bottom, 0px));*/
    }

    #page-scroll .container {
        padding-top: 36px;
        padding-bottom: calc(80px + env(safe-area-inset-bottom, 0px));
    }

    .container {
        padding: 96px 24px calc(120px + env(safe-area-inset-bottom, 0px)) 24px;
    }

    .overlay-content {
        padding-top: 96px;
    }

    .step-title {
        font-size: 28px;
    }

    .input-group input[type="number"] {
        font-size: 28px;
    }

    .summary-value {
        font-size: 28px;
    }
}

@media (max-width: 374px) {
    .container {
        padding: 96px 16px calc(84px + env(safe-area-inset-bottom, 0px)) 16px;
    }

    .step-title {
        font-size: 16px;
    }

    .card-title {
        font-size: 16px;
    }

    .input-group input[type="number"] {
        font-size: 28px;
        padding: 16px;
    }

    .summary-value {
        font-size: 20px;
    }
}