:root {

    --satva-cream: #f5e6d8;
    --satva-blush: #d6bebe;
    --satva-tan: #c9a27c;
    --satva-brown: #8a6f55;
    --satva-dark: #1f1f1f;
    --satva-white: #ffffff;

    --satva-muted: #5f554d;
    --satva-border: rgba(138, 111, 85, 0.15);
    --satva-error: #8a4f4f;

    --font-main:
        Inter,
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        sans-serif;

    --content-width: 900px;

    --radius-large: 24px;
    --radius-medium: 14px;

    --shadow-soft:
        0 18px 50px rgba(31, 31, 31, 0.08);

}


/* ------------------------------
   RESET
------------------------------ */

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


html {
    min-height: 100%;
    scroll-behavior: smooth;
}


body {
    min-height: 100vh;

    background:
        linear-gradient(
            135deg,
            var(--satva-cream) 0%,
            #f8efea 50%,
            var(--satva-blush) 100%
        );

    color: var(--satva-dark);

    font-family: var(--font-main);
    font-size: 16px;
    line-height: 1.6;

    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
}


/* ------------------------------
   ACCESSIBILITY
------------------------------ */

button,
input,
a {
    -webkit-tap-highlight-color: transparent;
}


button:focus-visible,
input:focus-visible,
a:focus-visible {
    outline: 3px solid var(--satva-brown);
    outline-offset: 4px;
}


/* ------------------------------
   APPLICATION
------------------------------ */

#app {
    min-height: 100vh;

    display: flex;
    align-items: center;
    justify-content: center;

    padding: 32px 20px;
}


.screen {
    width: 100%;
    max-width: var(--content-width);
}


/* ------------------------------
   SHARED ASSESSMENT CARD
------------------------------ */

.assessment-card {

    width: 100%;

    padding: 52px 50px;

    background:
        rgba(255, 255, 255, 0.78);

    border:
        1px solid var(--satva-border);

    border-radius:
        var(--radius-large);

    box-shadow:
        var(--shadow-soft);

    backdrop-filter:
        blur(12px);

}


.screen-intro {

    max-width: 680px;

    margin:
        18px auto 32px;

    color:
        var(--satva-muted);

    font-size:
        1.05rem;

    line-height:
        1.7;

}


/* ------------------------------
   WELCOME SCREEN
------------------------------ */

.welcome-content {

    width: 100%;

    padding: 64px 56px;

    background:
        rgba(255, 255, 255, 0.72);

    border:
        1px solid var(--satva-border);

    border-radius:
        var(--radius-large);

    box-shadow:
        var(--shadow-soft);

    text-align:
        center;

    backdrop-filter:
        blur(12px);

}


.eyebrow {

    margin-bottom:
        18px;

    color:
        var(--satva-brown);

    font-size:
        0.82rem;

    font-weight:
        700;

    letter-spacing:
        0.28em;

    text-transform:
        uppercase;

}


h1 {

    max-width:
        760px;

    margin:
        0 auto;

    color:
        var(--satva-dark);

    font-size:
        clamp(2rem, 5vw, 3.6rem);

    font-weight:
        600;

    line-height:
        1.12;

    letter-spacing:
        -0.035em;

}


.intro {

    max-width:
        650px;

    margin:
        28px auto 36px;

    color:
        var(--satva-muted);

    font-size:
        clamp(1rem, 2vw, 1.15rem);

    line-height:
        1.75;

}


/* ------------------------------
   BUTTONS
------------------------------ */

button {

    border:
        0;

    font:
        inherit;

    cursor:
        pointer;
}


/* Primary buttons */

#start-assessment,
.primary-button {

    min-height:
        52px;

    padding:
        14px 30px;

    background:
        var(--satva-dark);

    color:
        var(--satva-white);

    border-radius:
        999px;

    font-weight:
        600;

    transition:
        transform 160ms ease,
        opacity 160ms ease,
        box-shadow 160ms ease;

}


#start-assessment:hover,
.primary-button:hover {

    transform:
        translateY(-2px);

    box-shadow:
        0 10px 24px rgba(31, 31, 31, 0.16);

}


#start-assessment:active,
.primary-button:active {

    transform:
        translateY(0);

}


#start-assessment:disabled,
.primary-button:disabled {

    opacity:
        0.45;

    cursor:
        not-allowed;

    transform:
        none;

    box-shadow:
        none;

}


/* Secondary buttons */

.secondary-button {

    min-height:
        48px;

    margin-top:
        16px;

    padding:
        11px 22px;

    background:
        transparent;

    color:
        var(--satva-brown);

    border:
        1px solid
        rgba(138, 111, 85, 0.35);

    border-radius:
        999px;

    font-weight:
        600;

    transition:
        background 160ms ease,
        transform 160ms ease;

}


.secondary-button:hover {

    background:
        rgba(138, 111, 85, 0.08);

    transform:
        translateY(-1px);

}


/* ------------------------------
   PARTICIPANT SELECTION
------------------------------ */

#participant-selection-screen .assessment-card,
#student-age-screen .assessment-card,
#assessment-loading-screen .assessment-card,
#assessment-ready-screen .assessment-card,
#question-completion-screen .assessment-card {

    text-align:
        center;

}


.participant-options {

    display:
        grid;

    grid-template-columns:
        repeat(2, minmax(0, 1fr));

    gap:
        16px;

    margin:
        28px 0 24px;

}


.participant-option {

    width:
        100%;

    min-height:
        130px;

    padding:
        24px;

    background:
        rgba(255, 255, 255, 0.72);

    border:
        1px solid
        rgba(138, 111, 85, 0.18);

    border-radius:
        var(--radius-medium);

    color:
        var(--satva-dark);

    text-align:
        left;

    transition:
        transform 160ms ease,
        border-color 160ms ease,
        background 160ms ease,
        box-shadow 160ms ease;

}


.participant-option:hover {

    transform:
        translateY(-2px);

    border-color:
        rgba(138, 111, 85, 0.45);

    background:
        rgba(255, 255, 255, 0.95);

    box-shadow:
        0 10px 28px
        rgba(31, 31, 31, 0.07);

}


.participant-option-title {

    display:
        block;

    margin-bottom:
        8px;

    font-size:
        1.1rem;

    font-weight:
        650;

}


.participant-option-description {

    display:
        block;

    color:
        var(--satva-muted);

    font-size:
        0.94rem;

    line-height:
        1.55;

}


/* ------------------------------
   AGE FIELD
------------------------------ */

.age-field {

    max-width:
        360px;

    margin:
        0 auto 28px;

    text-align:
        left;

}


.age-field label {

    display:
        block;

    margin-bottom:
        8px;

    color:
        var(--satva-dark);

    font-weight:
        600;

}


.age-field input {

    width:
        100%;

    min-height:
        54px;

    padding:
        12px 16px;

    background:
        rgba(255, 255, 255, 0.92);

    border:
        1px solid
        rgba(138, 111, 85, 0.28);

    border-radius:
        var(--radius-medium);

    color:
        var(--satva-dark);

    font:
        inherit;

}


.age-field input:focus {

    border-color:
        var(--satva-brown);

    outline:
        none;

    box-shadow:
        0 0 0 4px
        rgba(138, 111, 85, 0.12);

}


/* ------------------------------
   QUESTION PROGRESS
------------------------------ */

.question-progress {

    display:
        flex;

    justify-content:
        space-between;

    margin-bottom:
        10px;

    color:
        var(--satva-brown);

    font-size:
        0.9rem;

    font-weight:
        600;

}


.progress-track {

    width:
        100%;

    height:
        6px;

    margin-bottom:
        38px;

    overflow:
        hidden;

    background:
        rgba(138, 111, 85, 0.12);

    border-radius:
        999px;

}


.progress-fill {

    height:
        100%;

    background:
        var(--satva-tan);

    border-radius:
        inherit;

    transition:
        width 220ms ease;

}


/* ------------------------------
   QUESTION
------------------------------ */

#question-screen .assessment-card {

    max-width:
        820px;

    margin:
        0 auto;

}


#question-screen h1 {

    max-width:
        720px;

    margin:
        0 auto 34px;

    font-size:
        clamp(1.65rem, 4vw, 2.55rem);

    line-height:
        1.25;

}


.answer-options {

    display:
        grid;

    gap:
        12px;

    max-width:
        700px;

    margin:
        0 auto 30px;

}


.answer-option {

    position:
        relative;

    display:
        flex;

    align-items:
        flex-start;

    gap:
        14px;

    width:
        100%;

    min-height:
        64px;

    padding:
        18px 20px;

    background:
        rgba(255, 255, 255, 0.76);

    border:
        1px solid
        rgba(138, 111, 85, 0.18);

    border-radius:
        var(--radius-medium);

    color:
        var(--satva-dark);

    cursor:
        pointer;

    text-align:
        left;

    transition:
        background 160ms ease,
        border-color 160ms ease,
        transform 160ms ease;

}


.answer-option:hover {

    background:
        rgba(255, 255, 255, 0.98);

    border-color:
        rgba(138, 111, 85, 0.38);

    transform:
        translateY(-1px);

}


.answer-option input {

    flex:
        0 0 auto;

    width:
        20px;

    height:
        20px;

    margin-top:
        2px;

    accent-color:
        var(--satva-brown);

}


.answer-option:has(input:checked) {

    background:
        rgba(214, 190, 190, 0.28);

    border-color:
        var(--satva-brown);

}


.answer-option-text {

    flex:
        1;

    line-height:
        1.55;

}


/* ------------------------------
   QUESTION NAVIGATION
------------------------------ */

.question-navigation {

    display:
        flex;

    align-items:
        center;

    justify-content:
        center;

    gap:
        12px;

    flex-wrap:
        wrap;

}


/* ------------------------------
   FORM / ERROR MESSAGES
------------------------------ */

.form-error {

    margin-top:
        10px;

    color:
        var(--satva-error);

    font-size:
        0.92rem;

    line-height:
        1.5;

}


#assessment-loading-screen .assessment-card,
#assessment-ready-screen .assessment-card,
#question-completion-screen .assessment-card {

    padding-top:
        70px;

    padding-bottom:
        70px;

}


/* ------------------------------
   MOBILE
------------------------------ */

@media (max-width: 640px) {

    #app {

        padding:
            18px 14px;

    }


    .welcome-content,
    .assessment-card {

        padding:
            40px 22px;

    }


    h1 {

        font-size:
            clamp(1.9rem, 10vw, 2.7rem);

    }


    .intro {

        margin-top:
            22px;

        margin-bottom:
            30px;

        font-size:
            1rem;

    }


    #start-assessment,
    .primary-button {

        width:
            100%;

    }


    .participant-options {

        grid-template-columns:
            1fr;

        gap:
            12px;

    }


    .participant-option {

        min-height:
            110px;

    }


    .question-progress {

        font-size:
            0.82rem;

    }


    .progress-track {

        margin-bottom:
            28px;

    }


    #question-screen h1 {

        margin-bottom:
            26px;

        font-size:
            1.55rem;

    }


    .answer-option {

        padding:
            16px;

    }


    .question-navigation {

        align-items:
            stretch;

        flex-direction:
            column-reverse;

    }


    .question-navigation button {

        width:
            100%;

    }

}


/* ------------------------------
   REDUCED MOTION
------------------------------ */

@media (prefers-reduced-motion: reduce) {

    html {

        scroll-behavior:
            auto;

    }


    #start-assessment,
    .primary-button,
    .secondary-button,
    .participant-option,
    .answer-option,
    .progress-fill {

        transition:
            none;

    }

}