/* =============================================
   DONOR AREA ESTIMATOR - STYLES
   haircostcalculator.com
   ============================================= */

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

body {
    font-family: 'Inter', sans-serif;
    background-color: #F2F1ED;
    color: #111;
}

/* =============================================
   HEADER
   ============================================= */
.dk-site-header {
    background: rgba(247, 245, 240, 0.92);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    position: sticky;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid #e2ddd5;
}

.dk-header-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    padding: 18px 40px;
}

.dk-logo-link {
    text-decoration: none;
    color: #1a1814;
    display: flex;
    align-items: center;
    gap: 10px;
}

.dk-logo-text {
    font-family: 'Inter', sans-serif;
    font-size: 16px;
    font-weight: 600;
    letter-spacing: -0.5px;
}

/* =============================================
   BREADCRUMB
   ============================================= */
.breadcrumb {
    max-width: 960px;
    margin: 0 auto;
    padding: 1rem 20px 0;
    font-family: 'Inter', sans-serif;
    font-size: 12px;
    color: #a09990;
    display: flex;
    gap: 0.5rem;
    align-items: center;
    flex-wrap: wrap;
}
.breadcrumb a { color: #6b6560; text-decoration: none; }
.breadcrumb a:hover { color: #1a4d3a; }
.breadcrumb-sep { color: #a09990; }

/* =============================================
   HERO SECTION
   ============================================= */
.hero {
    max-width: 960px;
    margin: 0 auto;
    padding: 3rem 20px 2.5rem;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
}
.hero-eyebrow {
    font-family: 'Inter', sans-serif;
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: #2d7a5a;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}
.hero-eyebrow::before {
    content: '';
    display: inline-block;
    width: 24px;
    height: 1px;
    background: #2d7a5a;
}
.hero h1 {
    font-family: 'Inter', sans-serif;
    font-size: clamp(34px, 5vw, 56px);
    font-weight: 800;
    line-height: 1.1;
    color: #111;
    margin-bottom: 20px;
    letter-spacing: -2px;
}
.hero-lead {
    font-family: 'Inter', sans-serif;
    font-size: 1.0625rem;
    color: #6b6560;
    max-width: 680px;
    line-height: 1.75;
    margin: 0 auto;
}

/* =============================================
   FOOTER
   ============================================= */
.dk-footer {
    background: #F8F9FF;
    padding: 60px 20px;
    border-top: 1px solid #E2E8F0;
    text-align: center;
    font-family: 'Inter', sans-serif;
}
.dk-footer a { color: #64748B; text-decoration: none; transition: color 0.2s; font-size: 13px; margin: 0 10px; }
.dk-footer a:hover { color: #4F46E5; }
.dk-footer-copy { font-size: 13px; color: #94A3B8; margin-bottom: 12px; }

/* =============================================
   CONTAINER
   ============================================= */
.donor-container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 20px;
}

/* =============================================
   TOOL SECTION & CARD
   ============================================= */
.donor-tool-section {
    padding: 0 20px 80px;
}

.donor-card {
    background: #FFF;
    border-radius: 28px;
    padding: 60px 70px;
    box-shadow: 0 24px 80px rgba(0,0,0,0.07), 0 4px 16px rgba(0,0,0,0.04);
    border: 1px solid #EBEBEB;
    margin-top: -20px;
    min-height: 380px;
}

/* =============================================
   STEP TYPOGRAPHY & LAYOUT
   ============================================= */
.serif-title {
    font-family: 'DM Serif Display', serif;
    font-size: 38px;
    letter-spacing: -1px;
    line-height: 1.15;
    color: #111;
}

.step-label {
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 2px;
    text-transform: uppercase;
    color: #AAA;
    margin-bottom: 16px;
    display: block;
}

.step-sub {
    font-size: 16px;
    color: #888;
    margin-top: 10px;
    line-height: 1.6;
}

/* =============================================
   RANGE SLIDER
   ============================================= */
.age-display {
    font-size: 88px;
    font-weight: 900;
    color: #111;
    line-height: 1;
    letter-spacing: -4px;
    margin: 12px 0 8px;
}

.age-label {
    font-size: 13px;
    color: #AAA;
    font-weight: 600;
    letter-spacing: 1px;
    text-transform: uppercase;
    margin-bottom: 28px;
}

input[type="range"] {
    -webkit-appearance: none;
    width: 100%;
    height: 4px;
    background: #E5E1D3;
    border-radius: 4px;
    outline: none;
    cursor: pointer;
    accent-color: #111;
    margin-bottom: 8px;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 22px;
    height: 22px;
    background: #111;
    border-radius: 50%;
    cursor: pointer;
    transition: transform 0.15s ease, box-shadow 0.15s ease;
    box-shadow: 0 2px 8px rgba(0,0,0,0.2);
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.15);
    box-shadow: 0 4px 16px rgba(0,0,0,0.25);
}

.range-labels {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    color: #BBB;
    font-weight: 600;
    margin-bottom: 36px;
}

/* =============================================
   BUTTONS
   ============================================= */
.dk-btn-black {
    display: block;
    width: 100%;
    padding: 18px 32px;
    background: #111;
    color: #FFF;
    border: none;
    border-radius: 14px;
    font-family: 'Inter', sans-serif;
    font-size: 14px;
    font-weight: 700;
    letter-spacing: 1px;
    text-transform: uppercase;
    cursor: pointer;
    transition: background 0.2s ease, transform 0.15s ease, box-shadow 0.2s ease;
    box-shadow: 0 4px 16px rgba(0,0,0,0.12);
    margin-top: 32px;
}

.dk-btn-black:hover:not(:disabled) {
    background: #4F46E5;
    transform: translateY(-3px);
    box-shadow: 0 10px 24px rgba(79, 70, 229, 0.25);
}

.dk-btn-black:active:not(:disabled) {
    transform: translateY(0);
}

.dk-btn-black:disabled {
    background: #CCC;
    color: #FFF;
    cursor: not-allowed;
    box-shadow: none;
}

/* =============================================
   CHOICE CARDS (Step 2)
   ============================================= */
.choice-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin: 36px 0 0;
}

.dk-calc-card {
    background: #FAFAF8;
    border-radius: 18px;
    padding: 36px 24px;
    text-align: center;
    cursor: pointer;
    border: 2px solid #EBEBEB;
    font-size: 13px;
    font-weight: 700;
    letter-spacing: 1.5px;
    text-transform: uppercase;
    color: #555;
    transition: all 0.2s ease;
    line-height: 1.4;
}

.dk-calc-card:hover {
    border-color: #111;
    background: #F7F6F2;
    color: #111;
    transform: translateY(-2px);
    box-shadow: 0 8px 28px rgba(0,0,0,0.08);
}

.dk-calc-card.selected {
    border-color: #111;
    background: #111;
    color: #FFF;
}

.choice-icon {
    font-size: 32px;
    display: block;
    margin-bottom: 12px;
}

/* =============================================
   UPLOAD ZONE (Step 3)
   ============================================= */
.upload-zone {
    border: 2px dashed #D5D0C8;
    padding: 56px 32px;
    border-radius: 20px;
    margin: 28px 0;
    background: #FDFDFA;
    cursor: pointer;
    transition: all 0.25s ease;
    text-align: center;
}

.upload-zone:hover {
    border-color: #111;
    background: #F7F6F2;
}

.upload-zone.has-file {
    border-style: solid;
    border-color: #111;
    background: #F7F6F2;
}

.upload-icon {
    font-size: 40px;
    display: block;
    margin-bottom: 14px;
}

.upload-title {
    font-size: 14px;
    font-weight: 700;
    color: #333;
    letter-spacing: 0.5px;
    margin-bottom: 6px;
}

.upload-hint {
    font-size: 12px;
    color: #AAA;
    font-weight: 500;
}

.upload-success {
    font-size: 14px;
    font-weight: 700;
    color: #2C7A3A;
    margin-top: 10px;
}

/* =============================================
   PROGRESS BAR
   ============================================= */
.progress-bar-wrap {
    display: flex;
    gap: 8px;
    margin-bottom: 48px;
}

.progress-segment {
    flex: 1;
    height: 3px;
    background: #E5E1D3;
    border-radius: 4px;
    overflow: hidden;
}

.progress-segment.active {
    background: #111;
}

.progress-segment.done {
    background: #111;
    opacity: 0.35;
}

/* =============================================
   FEATURES SECTION
   ============================================= */
.donor-features {
    padding: 0 20px;
}

.feature-grid {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 48px;
    padding: 100px 0;
    border-bottom: 1px solid #E5E1D3;
}

.feature-item {
    position: relative;
    padding-top: 28px;
}

.feature-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 32px;
    height: 3px;
    background: #111;
    border-radius: 2px;
}

.feature-item h3 {
    font-family: 'DM Serif Display', serif;
    font-size: 22px;
    margin-bottom: 14px;
    color: #111;
}

.feature-item p {
    color: #777;
    font-size: 14px;
    line-height: 1.75;
    font-weight: 400;
}

/* =============================================
   FOOTER
   ============================================= */
.donor-footer {
    background: #111;
    color: #888;
    text-align: center;
    padding: 36px 20px;
    font-size: 13px;
}

/* =============================================
   RESULT PANEL
   ============================================= */
.result-panel {
    text-align: center;
}

.result-score {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 140px;
    height: 140px;
    background: #111;
    border-radius: 50%;
    margin: 24px auto;
    position: relative;
}

.result-score-num {
    font-size: 42px;
    font-weight: 900;
    color: #FFF;
    letter-spacing: -2px;
}

.result-score-unit {
    font-size: 13px;
    color: rgba(255,255,255,0.5);
    position: absolute;
    bottom: 32px;
    left: 50%;
    transform: translateX(-50%);
    white-space: nowrap;
    font-weight: 600;
}

.result-meta-grid {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 16px;
    margin: 32px 0;
    text-align: left;
}

.result-meta-item {
    background: #F7F6F2;
    border-radius: 14px;
    padding: 20px;
    border: 1px solid #EBEBEB;
}

.result-meta-label {
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 1.5px;
    text-transform: uppercase;
    color: #AAA;
    margin-bottom: 8px;
}

.result-meta-value {
    font-size: 22px;
    font-weight: 900;
    color: #111;
    letter-spacing: -0.5px;
}

.result-disclaimer {
    font-size: 12px;
    color: #BBB;
    margin-top: 24px;
    line-height: 1.6;
    padding: 16px;
    background: #F9F9F7;
    border-radius: 10px;
    border: 1px solid #EBEBEB;
}

/* =============================================
   LOADING STATE
   ============================================= */
.loading-spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255,255,255,0.3);
    border-radius: 50%;
    border-top-color: #FFF;
    animation: spin 0.8s linear infinite;
    vertical-align: middle;
    margin-right: 10px;
}

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

/* =============================================
   METHODOLOGY GRID
   ============================================= */
.donor-methodology-section {
    padding: 80px 20px;
    background: #FAFAFA;
    border-top: 1px solid #EBEBEB;
}

.donor-methodology-section .serif-title {
    text-align: center;
    margin-bottom: 24px;
}

.donor-methodology-section .methodology-intro {
    text-align: center;
    max-width: 680px;
    margin: 0 auto 60px;
    color: #666;
    font-size: 16px;
    line-height: 1.7;
}

.methodology-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
}

.method-card {
    background: #FFF;
    border: 1px solid #EBEBEB;
    border-radius: 20px;
    padding: 40px;
    position: relative;
    overflow: hidden;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.method-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 16px 40px rgba(0,0,0,0.06);
}

.method-num {
    position: absolute;
    top: -16px;
    right: -12px;
    font-family: 'DM Serif Display', serif;
    font-size: 120px;
    color: #F4F4F4;
    line-height: 1;
    z-index: 0;
    pointer-events: none;
    letter-spacing: -6px;
}

.method-content {
    position: relative;
    z-index: 1;
}

.method-content h3 {
    font-size: 18px;
    font-weight: 700;
    color: #111;
    margin-bottom: 14px;
}

.method-content p {
    font-size: 14.5px;
    color: #666;
    line-height: 1.6;
}

@media (max-width: 768px) {
    .methodology-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    .method-card {
        padding: 32px 24px;
    }
    .method-num {
        font-size: 100px;
        top: -10px;
        right: -8px;
    }
}

/* =============================================
   RESPONSIVE
   ============================================= */
@media (max-width: 768px) {
    .donor-card {
        padding: 36px 28px;
    }

    .feature-grid {
        grid-template-columns: 1fr;
        gap: 40px;
        padding: 60px 0;
    }

    .comp-row {
        padding: 18px 20px;
        font-size: 12px;
    }

    .choice-grid {
        grid-template-columns: 1fr;
    }

    .result-meta-grid {
        grid-template-columns: 1fr;
    }

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

    .age-display {
        font-size: 64px;
    }

    .dk-site-header {
        padding: 16px 20px;
    }
}

/* =============================================
   METHODOLOGY & CLINICAL REFERENCES
   ============================================= */
.dk-methodology-section {
    padding: 80px 20px;
    background-color: #F8FAFF;
    border-top: 1px solid #E5EAF5;
    font-family: 'Inter', sans-serif;
}
.dk-methodology-container { max-width: 1000px; margin: 0 auto; text-align: center; }

.dk-methodology-title { font-size: 28px; font-weight: 800; color: #0F172A; margin-bottom: 15px; letter-spacing: -0.5px; }
.dk-methodology-desc { font-size: 15px; color: #475569; max-width: 800px; margin: 0 auto 40px; line-height: 1.6; }

.dk-source-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 12px; text-align: left; }
.dk-source-item { background: #FFFFFF; padding: 15px 20px; border-radius: 12px; text-decoration: none; border: 1px solid #E2E8F0; transition: 0.3s; }
.dk-source-item:hover { border-color: #4F46E5; transform: translateY(-3px); box-shadow: 0 10px 20px rgba(79, 70, 229, 0.05); }
.dk-source-tag { display: inline-block; font-size: 10px; font-weight: 800; background: #EEF2FF; padding: 2px 8px; border-radius: 4px; margin-bottom: 8px; color: #4F46E5; }
.dk-source-item p { margin: 0; font-size: 13px; color: #334155; line-height: 1.4; font-weight: 500; }

.dk-disclaimer { margin-top: 50px; font-size: 12px; color: #94A3B8; line-height: 1.5; border-top: 1px solid #E2E8F0; padding-top: 20px; }

@media (max-width: 768px) {
    .dk-source-grid { grid-template-columns: 1fr; }
}