/* =======================================================
   RESET AND VARIABLES
======================================================= */

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

:root {
    --flash-green: #1e7e34;
    --flash-green-dark: #17672a;
    --flash-green-light: #eaf7ee;

    --flash-background: #f3f6f4;
    --flash-surface: #ffffff;

    --flash-text: #171917;
    --flash-muted: #68706b;

    --flash-border: #dce5de;
    --flash-border-dark: #cad6cd;

    --flash-shadow:
        0 16px 42px rgba(24, 72, 37, 0.12);
}

body {
    min-height: 100vh;

    background: var(--flash-background);
    color: var(--flash-text);

    font-family:
        system-ui,
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        sans-serif;
}

/* =======================================================
   PAGE
======================================================= */

.flashcard-page {
    width: 100%;
    min-height: 100vh;

    padding: 28px;
}

.flashcard-shell {
    width: 100%;
    max-width: 1180px;

    margin: 0 auto;
}


/* =======================================================
   ACTIVITY PAGE HEADER
======================================================= */

.flashcard-page-header {
    margin-bottom: 28px;
}


/* =======================================================
   TOP NAVIGATION
======================================================= */

.flashcard-topbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 24px;

    margin-bottom: 28px;
}

.flashcard-back-link {
    display: inline-flex;
    align-items: center;

    padding: 10px 16px;

    background: var(--flash-surface);
    color: var(--flash-green);

    border: 1px solid var(--flash-border);
    border-radius: 999px;

    font-size: 14px;
    font-weight: 800;

    text-decoration: none;

    transition:
        background-color 0.18s ease,
        border-color 0.18s ease,
        transform 0.18s ease;
}

.flashcard-back-link:hover {
    background: var(--flash-green-light);
    border-color: rgba(30, 126, 52, 0.28);

    transform: translateY(-1px);
}


/* =======================================================
   BIOLOGY BRAIN BRAND
======================================================= */
.flashcard-brand {
    display: inline-flex;
    align-items: center;
    justify-content: center;

    text-decoration: none;
}

.flashcard-brand-logo {
    width: 105px;
    height: 105px;

    display: block;

    object-fit: contain;

    transition:
        transform 0.18s ease;
}

.flashcard-brand:hover .flashcard-brand-logo {
    transform: scale(1.05);
}


/* =======================================================
   ACTIVITY TITLE
======================================================= */

.flashcard-heading-row {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    gap: 36px;
}

.flashcard-heading-copy {
    min-width: 0;
}

.flashcard-eyebrow {
    margin: 0 0 10px;

    color: var(--flash-green);

    font-size: 13px;
    font-weight: 850;

    text-transform: uppercase;
    letter-spacing: 0.1em;
}

.flashcard-heading-row h1 {
    margin: 0;

    color: var(--flash-text);

    font-size: clamp(38px, 5vw, 56px);
    font-weight: 800;
    line-height: 1.04;

    letter-spacing: -0.035em;
}

.flashcard-description {
    max-width: 720px;

    margin: 14px 0 0;

    color: var(--flash-muted);

    font-size: 17px;
    line-height: 1.55;
}


/* =======================================================
   CARD COUNT
======================================================= */

.flashcard-header-stat {
    flex: 0 0 auto;

    min-width: 118px;

    padding: 16px 20px;

    background: var(--flash-surface);

    border: 1px solid var(--flash-border);
    border-radius: 16px;

    box-shadow:
        0 8px 22px rgba(24, 72, 37, 0.08);

    text-align: center;
}

.flashcard-header-stat strong {
    display: block;

    color: var(--flash-green);

    font-size: 25px;
    line-height: 1;
}

.flashcard-header-stat span {
    display: block;

    margin-top: 7px;

    color: var(--flash-muted);

    font-size: 12px;
    font-weight: 750;
}

/* =======================================================
   STUDY AREA
======================================================= */

.flashcard-study-area {

    padding: 30px 32px;

    background: white;

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

    border-radius: 22px;

    box-shadow:  0 12px 34px rgba(24, 72, 37, 0.08);

}

.flashcard-toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 22px;

    margin-bottom: 17px;
}

.flashcard-unit-label {
    margin: 0 0 5px;

    color: var(--flash-green);

    font-size: 12px;
    font-weight: 850;

    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.flashcard-toolbar h2 {
    margin: 0;

    font-size: 25px;
}

.flashcard-shuffle-button {
    flex: 0 0 auto;

    padding: 10px 16px;

    background: white;
    color: var(--flash-green);

    border: 1px solid var(--flash-green);
    border-radius: 10px;

    font: inherit;
    font-size: 14px;
    font-weight: 800;

    cursor: pointer;

    transition:
        background-color 0.2s ease,
        color 0.2s ease,
        transform 0.2s ease;
}

.flashcard-shuffle-button:hover {
    background: var(--flash-green);
    color: white;

    transform: translateY(-1px);
}

/* =======================================================
   PROGRESS
======================================================= */

.flashcard-progress-track {
    width: 100%;
    height: 9px;

    overflow: hidden;

    margin-bottom: 28px;

    background: #e8ede9;

    border-radius: 999px;
}

.flashcard-progress-fill {
    width: 20%;
    height: 100%;

    background:
        linear-gradient(
            90deg,
            #1e7e34,
            #48b96d
        );

    border-radius: inherit;

    transition: width 0.3s ease;
}

/* =======================================================
   CARD STAGE
======================================================= */

.flashcard-stage {
    width: 100%;

    display: flex;
    justify-content: center;

    perspective: 1600px;
}

.flashcard {
    width: min(100%, 860px);
    aspect-ratio: 16 / 8.6;

    padding: 0;

    background: transparent;

    border: none;
    border-radius: 18px;

    cursor: pointer;

    perspective: 1600px;

    -webkit-tap-highlight-color: transparent;
}

.flashcard:focus-visible {
    outline: 4px solid rgba(30, 126, 52, 0.23);
    outline-offset: 5px;
}

.flashcard-inner {
    position: relative;

    width: 100%;
    height: 100%;

    display: block;

    transform-style: preserve-3d;

    transition:
        transform 0.62s
        cubic-bezier(0.2, 0.72, 0.28, 1);
}

.flashcard.is-flipped .flashcard-inner {
    transform: rotateY(180deg);
}

/* =======================================================
   CARD FACES
======================================================= */

.flashcard-face {
    position: absolute;
    inset: 0;

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

    padding: 54px 70px;

    overflow: hidden;

    background: #ffffff;
    color: var(--flash-text);

    border: 1px solid #d9e2db;
    border-radius: 18px;

    box-shadow:
        0 13px 34px rgba(21, 60, 31, 0.12);

    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
}

.flashcard-face::before {
    content: "";

    position: absolute;
    inset: 0;

    pointer-events: none;

    background:
        radial-gradient(
            circle at 15% 15%,
            rgba(30, 126, 52, 0.05),
            transparent 25%
        );
}

.flashcard-front {
    transform: rotateY(0deg);
}

.flashcard-back {
    transform: rotateY(180deg);

    background:
        linear-gradient(
            145deg,
            #ffffff 0%,
            #f7fbf8 100%
        );
}

.flashcard-side-label {
    position: absolute;
    top: 22px;
    left: 25px;

    color: var(--flash-green);

    font-size: 12px;
    font-weight: 850;

    text-transform: uppercase;
    letter-spacing: 0.09em;
}

.flashcard-main-text {
    position: relative;
    z-index: 1;

    max-width: 90%;

    color: #171917;

    font-size: clamp(38px, 6vw, 66px);
    font-weight: 750;
    line-height: 1.15;

    text-align: center;
}

.flashcard-definition-text {
    position: relative;
    z-index: 1;

    max-width: 760px;

    color: #252a26;

    font-size: clamp(22px, 3.2vw, 36px);
    font-weight: 600;
    line-height: 1.45;

    text-align: center;
}

.flashcard-flip-hint {
    position: absolute;
    right: 25px;
    bottom: 21px;

    color: #7a827d;

    font-size: 12px;
    font-weight: 650;
}

/* =======================================================
   NAVIGATION
======================================================= */

.flashcard-navigation {
    display: grid;
    grid-template-columns:
        minmax(135px, auto)
        1fr
        minmax(135px, auto);
    align-items: center;
    gap: 18px;

    max-width: 860px;

    margin: 26px auto 0;
}

.flashcard-nav-button {
    min-height: 48px;

    padding: 12px 20px;

    border-radius: 11px;

    font: inherit;
    font-size: 14px;
    font-weight: 800;

    cursor: pointer;

    transition:
        transform 0.18s ease,
        background-color 0.18s ease,
        box-shadow 0.18s ease;
}

.flashcard-nav-button.primary {
    background: var(--flash-green);
    color: white;

    border: 2px solid var(--flash-green);
}

.flashcard-nav-button.primary:hover {
    background: var(--flash-green-dark);

    transform: translateY(-2px);

    box-shadow:
        0 8px 18px rgba(30, 126, 52, 0.2);
}

.flashcard-nav-button.secondary {
    background: white;
    color: #505752;

    border: 2px solid var(--flash-border-dark);
}

.flashcard-nav-button.secondary:hover {
    background: #f4f7f5;

    transform: translateY(-2px);
}

.flashcard-nav-button:disabled {
    opacity: 0.45;
    cursor: not-allowed;
    transform: none;
}

.flashcard-position {
    color: var(--flash-muted);

    font-size: 14px;
    font-weight: 800;

    text-align: center;
}

/* =======================================================
   KEYBOARD HELP AND EXIT
======================================================= */

.flashcard-keyboard-help {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 18px;

    margin-top: 22px;

    color: #737b76;

    font-size: 12px;
}

.flashcard-keyboard-help span {
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.flashcard-keyboard-help kbd {
    min-width: 29px;
    padding: 4px 7px;

    background: #f3f6f4;

    border: 1px solid #d8e0da;
    border-bottom-width: 2px;
    border-radius: 6px;

    color: #505752;

    font-family: inherit;
    font-size: 11px;
    font-weight: 800;

    text-align: center;
}

/* =======================================================
   CARD CHANGE ANIMATION
======================================================= */

.flashcard.card-changing {
    animation: cardChange 0.22s ease;
}

@keyframes cardChange {
    0% {
        opacity: 1;
        transform: translateX(0);
    }

    45% {
        opacity: 0.35;
        transform: translateX(8px);
    }

    100% {
        opacity: 1;
        transform: translateX(0);
    }
}

/* =======================================================
   REDUCED MOTION
======================================================= */

@media (prefers-reduced-motion: reduce) {
    .flashcard-inner,
    .flashcard,
    .flashcard-nav-button,
    .flashcard-shuffle-button,
    .flashcard-progress-fill {
        transition: none;
        animation: none;
    }
}

/* =======================================================
   RESPONSIVE
======================================================= */

@media (max-width: 800px) {
    .flashcard-page {
        padding: 16px;
    }

    .flashcard-topbar {
        margin-bottom: 24px;
    }
    
    .flashcard-heading-row {
        align-items: flex-start;
        flex-direction: column;
        gap: 20px;
    }
    
    .flashcard-header-stat {
        min-width: 110px;
    }
    
    .flashcard-heading-row h1 {
        font-size: clamp(36px, 8vw, 48px);
    }


    .flashcard-study-area {
        padding: 24px;
    }

    .flashcard-face {
        padding: 45px 35px;
    }
}

@media (max-width: 580px) {
    .flashcard-page {
        padding: 10px;
    }

    .flashcard-topbar {
        align-items: flex-start;
        flex-direction: column;
        gap: 14px;
    }
    
    .flashcard-brand {
        align-self: flex-end;
    }
    
    .flashcard-header-stat {
        width: 100%;
    }
    
    .flashcard-description {
        font-size: 15px;
    }

    .flashcard-toolbar {
        align-items: flex-start;
        flex-direction: column;
    }

    .flashcard {
        aspect-ratio: 1.3 / 1;
    }

    .flashcard-face {
        padding: 48px 22px;
    }

    .flashcard-navigation {
        grid-template-columns: 1fr 1fr;
    }

    .flashcard-position {
        grid-column: 1 / -1;
        grid-row: 1;
    }

    .flashcard-keyboard-help {
        display: none;
    }

    .flashcard-flip-hint {
        right: 16px;
        bottom: 15px;
    }
}

/* =======================================================
   VERY SMALL PHONE — FLASHCARD DEFINITION
======================================================= */

@media (max-width: 400px) {

    .flashcard-face {
        padding:
            58px
            20px
            46px;
    }

    .flashcard-side-label {
        top:
            18px;

        left:
            20px;
    }

    .flashcard-definition-text {
        max-width:
            94%;

        font-size:
            clamp(
                18px,
                6vw,
                24px
            );

        line-height:
            1.34;
    }

    .flashcard-main-text {
        max-width:
            94%;

        font-size:
            clamp(
                32px,
                10vw,
                46px
            );
    }

    .flashcard-flip-hint {
        right:
            16px;

        bottom:
            14px;

        font-size:
            10px;
    }

}

/* =======================================================
   CONDENSED RESULTS REVIEW
======================================================= */

.review-priority-section {
    margin-top: 8px;
}


.review-section-heading {
    margin-bottom: 12px;

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

    text-align: left;
}


.review-section-heading > div {
    display: flex;
    flex-direction: column;
    gap: 3px;
}


.review-section-heading strong {
    color: var(--text-main);

    font-size: 16px;
    font-weight: 850;
}


.review-section-eyebrow {
    color: var(--incorrect);

    font-size: 10px;
    font-weight: 900;

    letter-spacing: 0.1em;

    text-transform: uppercase;
}


.review-priority-list {
    display: flex;
    flex-direction: column;

    gap: 10px;
}


/* =======================================================
   PERFECT SUMMARY
======================================================= */

.review-perfect-summary {
    padding: 17px 18px;

    display: flex;
    align-items: center;

    gap: 12px;

    background: var(--correct-bg);

    border: 1px solid #cce5d3;
    border-radius: 13px;

    text-align: left;
}


.review-perfect-icon {
    width: 34px;
    height: 34px;

    flex: 0 0 auto;

    display: grid;
    place-items: center;

    background: var(--correct);

    border-radius: 50%;

    color: white;

    font-size: 17px;
    font-weight: 900;
}


.review-perfect-summary > div {
    display: flex;
    flex-direction: column;

    gap: 2px;
}


.review-perfect-summary strong {
    font-size: 14px;
}


.review-perfect-summary div span {
    color: var(--text-muted);

    font-size: 12px;
}


/* =======================================================
   COLLAPSED CORRECT ANSWERS
======================================================= */

.correct-review-details {
    margin-top: 16px;

    overflow: hidden;

    border: 1px solid #cfe3d4;
    border-radius: 13px;

    background: #f8fcf9;
}


.correct-review-details summary {
    min-height: 58px;

    padding: 14px 16px;

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

    gap: 12px;

    cursor: pointer;

    list-style: none;

    user-select: none;
}


.correct-review-details summary::-webkit-details-marker {
    display: none;
}


.correct-review-summary-main {
    display: inline-flex;
    align-items: center;

    gap: 10px;

    color: var(--correct);
}


.correct-review-check {
    width: 27px;
    height: 27px;

    display: inline-grid;
    place-items: center;

    flex: 0 0 auto;

    background: var(--correct);

    border-radius: 50%;

    color: white;

    font-size: 13px;
    font-weight: 900;
}


.correct-review-summary-main strong {
    color: var(--text-main);

    font-size: 14px;
}


.correct-review-toggle {
    color: var(--brand);

    font-size: 12px;
    font-weight: 850;
}


.correct-review-details[open]
.correct-review-toggle {
    font-size: 0;
}


.correct-review-details[open]
.correct-review-toggle::after {
    content: "Hide answers";

    font-size: 12px;
}


.correct-review-list {
    padding: 0 12px 12px;

    display: flex;
    flex-direction: column;

    gap: 8px;
}


.correct-review-list
.review-row {
    margin: 0;
}


/* =======================================================
   MOBILE CONDENSED RESULTS
======================================================= */

@media (max-width: 600px) {

    .correct-review-details summary {
        padding: 13px 14px;
    }


    .correct-review-summary-main strong {
        font-size: 13px;
    }


    .correct-review-toggle {
        font-size: 11px;
    }


    .correct-review-details[open]
    .correct-review-toggle::after {
        font-size: 11px;
    }

}

.results-logo {
    display: block;

    width: 100%;
    height: 100%;

    object-fit: contain;
}