/* =========================================================
   SYSTEMS OF LINEAR EQUATIONS PRACTICE PAGE
   ========================================================= */

:root
{
    --sle-navy: #102a43;
    --sle-navy-dark: #081c2f;
    --sle-blue: #1f6f8b;
    --sle-teal: #159a9c;
    --sle-teal-dark: #117b7d;
    --sle-green: #198754;
    --sle-red: #c0392b;
    --sle-orange: #d97706;
    --sle-purple: #6f42c1;
    --sle-light: #f5f8fb;
    --sle-lighter: #fbfcfe;
    --sle-border: #dbe5ee;
    --sle-text: #243b53;
    --sle-muted: #627d98;
    --sle-white: #ffffff;
    --sle-shadow: 0 18px 45px rgba(16, 42, 67, 0.12);
    --sle-shadow-small: 0 8px 24px rgba(16, 42, 67, 0.09);
}


/* =========================================================
   GENERAL PAGE STYLING
   ========================================================= */

.systems-linear-equations-page
{
    background: var(--sle-white);
    color: var(--sle-text);
    font-family: "Inter", sans-serif;
}

.systems-linear-equations-page *,
.systems-linear-equations-page *::before,
.systems-linear-equations-page *::after
{
    box-sizing: border-box;
}

.systems-linear-equations-page button,
.systems-linear-equations-page input,
.systems-linear-equations-page select
{
    font-family: inherit;
}

.systems-linear-equations-page button
{
    cursor: pointer;
}


/* =========================================================
   PRACTICE SECTION
   ========================================================= */

.sle-section
{
    position: relative;
    padding: 5rem 1.5rem;
    background:
        radial-gradient(
            circle at top left,
            rgba(21, 154, 156, 0.08),
            transparent 32rem
        ),
        linear-gradient(
            180deg,
            #ffffff 0%,
            #f5f8fb 100%
        );
}

.sle-app
{
    width: min(100%, 1040px);
    margin: 0 auto;
}


/* =========================================================
   TOOLBAR
   ========================================================= */

.sle-toolbar
{
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 2rem;
    margin-bottom: 2rem;
}

.sle-toolbar-heading
{
    max-width: 680px;
}

.sle-toolbar-heading h2
{
    margin: 0 0 0.75rem;
    color: var(--sle-navy);
    font-size: clamp(1.8rem, 4vw, 2.55rem);
    font-weight: 800;
    line-height: 1.15;
}

.sle-toolbar-heading p:last-child
{
    max-width: 640px;
    margin: 0;
    color: var(--sle-muted);
    font-size: 1rem;
    line-height: 1.7;
}

.sle-eyebrow
{
    margin: 0 0 0.5rem;
    color: var(--sle-teal-dark);
    font-size: 0.78rem;
    font-weight: 800;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.sle-controls
{
    flex: 0 0 auto;
}

.sle-control-group
{
    min-width: 190px;
}

.sle-control-group label
{
    display: block;
    margin-bottom: 0.45rem;
    color: var(--sle-navy);
    font-size: 0.85rem;
    font-weight: 700;
}

.sle-select
{
    width: 100%;
    min-height: 48px;
    padding: 0.7rem 2.5rem 0.7rem 0.95rem;
    border: 1px solid var(--sle-border);
    border-radius: 0.75rem;
    background-color: var(--sle-white);
    color: var(--sle-navy);
    font-size: 0.95rem;
    font-weight: 700;
    outline: none;
    box-shadow: var(--sle-shadow-small);
    transition:
        border-color 0.2s ease,
        box-shadow 0.2s ease,
        transform 0.2s ease;
}

.sle-select:hover
{
    border-color: rgba(21, 154, 156, 0.6);
}

.sle-select:focus
{
    border-color: var(--sle-teal);
    box-shadow:
        0 0 0 4px rgba(21, 154, 156, 0.14),
        var(--sle-shadow-small);
}


/* =========================================================
   METHOD SELECTOR
   ========================================================= */

.sle-method-selector
{
    margin-bottom: 1.7rem;
    padding: 1.25rem;
    border: 1px solid var(--sle-border);
    border-radius: 1rem;
    background: var(--sle-white);
    box-shadow: var(--sle-shadow-small);
}

.sle-method-heading
{
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 0.9rem;
}

.sle-method-label
{
    color: var(--sle-navy);
    font-size: 0.9rem;
    font-weight: 800;
}

.sle-method-help
{
    color: var(--sle-muted);
    font-size: 0.8rem;
}

.sle-method-tabs
{
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 0.75rem;
}

.sle-method-button
{
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.6rem;
    min-height: 54px;
    padding: 0.8rem 1rem;
    border: 2px solid var(--sle-border);
    border-radius: 0.85rem;
    background: var(--sle-lighter);
    color: var(--sle-navy);
    font-size: 0.88rem;
    font-weight: 800;
    transition:
        transform 0.2s ease,
        border-color 0.2s ease,
        background-color 0.2s ease,
        color 0.2s ease,
        box-shadow 0.2s ease;
}

.sle-method-button svg
{
    width: 18px;
    height: 18px;
}

.sle-method-button:hover
{
    transform: translateY(-1px);
    border-color: rgba(21, 154, 156, 0.5);
    background: rgba(21, 154, 156, 0.055);
    color: var(--sle-teal-dark);
}

.sle-method-button.is-active
{
    border-color: var(--sle-teal);
    background:
        linear-gradient(
            135deg,
            rgba(21, 154, 156, 0.13),
            rgba(31, 111, 139, 0.07)
        );
    color: var(--sle-teal-dark);
    box-shadow: 0 6px 18px rgba(21, 154, 156, 0.14);
}


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

.sle-progress-area
{
    margin-bottom: 1.25rem;
}

.sle-progress-text
{
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 0.6rem;
    color: var(--sle-navy);
    font-size: 0.88rem;
    font-weight: 700;
}

.sle-progress-track
{
    width: 100%;
    height: 12px;
    overflow: hidden;
    border-radius: 999px;
    background: #dfe9f1;
}

.sle-progress-bar
{
    width: 10%;
    height: 100%;
    border-radius: inherit;
    background:
        linear-gradient(
            90deg,
            var(--sle-teal),
            var(--sle-blue)
        );
    transition: width 0.35s ease;
}


/* =========================================================
   MAIN PRACTICE CARD
   ========================================================= */

.sle-card
{
    padding: clamp(1.4rem, 4vw, 2.5rem);
    border: 1px solid rgba(219, 229, 238, 0.9);
    border-radius: 1.35rem;
    background: var(--sle-white);
    box-shadow: var(--sle-shadow);
}

.sle-card-top
{
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.sle-card-label
{
    margin: 0 0 0.3rem;
    color: var(--sle-navy);
    font-size: 0.95rem;
    font-weight: 800;
}

.sle-step-instruction
{
    margin: 0;
    color: var(--sle-muted);
    font-size: 0.92rem;
    line-height: 1.5;
}

.sle-card-badges
{
    display: flex;
    align-items: center;
    justify-content: flex-end;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.sle-method-badge,
.sle-difficulty-badge
{
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 34px;
    padding: 0.45rem 0.8rem;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 800;
    letter-spacing: 0.03em;
    white-space: nowrap;
}

.sle-method-badge
{
    background: rgba(31, 111, 139, 0.11);
    color: var(--sle-blue);
}

.sle-difficulty-badge
{
    background: rgba(21, 154, 156, 0.11);
    color: var(--sle-teal-dark);
}


/* =========================================================
   ORIGINAL SYSTEM
   ========================================================= */

.sle-original-system-area
{
    margin-bottom: 1.5rem;
    padding: 1.35rem;
    border: 1px solid var(--sle-border);
    border-radius: 1rem;
    background: var(--sle-lighter);
}

.sle-system-label
{
    display: block;
    margin-bottom: 0.8rem;
    color: var(--sle-muted);
    font-size: 0.78rem;
    font-weight: 800;
    letter-spacing: 0.06em;
    text-transform: uppercase;
}

.sle-system-display
{
    position: relative;
    display: grid;
    gap: 0.45rem;
    padding-left: 1.4rem;
}

.sle-system-display::before
{
    content: "{";
    position: absolute;
    left: 0;
    top: 50%;
    color: var(--sle-teal-dark);
    font-family: Georgia, "Times New Roman", serif;
    font-size: 3.7rem;
    font-weight: 400;
    line-height: 1;
    transform: translateY(-52%) scaleY(1.25);
    transform-origin: center;
}

.sle-system-equation
{
    color: var(--sle-navy-dark);
    font-size: clamp(1.25rem, 4vw, 1.75rem);
    font-weight: 750;
    line-height: 1.4;
    overflow-wrap: anywhere;
}


/* =========================================================
   FIVE-STEP PROGRESS
   ========================================================= */

.sle-step-progress
{
    display: grid;
    grid-template-columns:
        auto minmax(18px, 1fr)
        auto minmax(18px, 1fr)
        auto minmax(18px, 1fr)
        auto minmax(18px, 1fr)
        auto;
    align-items: center;
    gap: 0.45rem;
    margin: 1.8rem 0;
}

.sle-step-marker
{
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.35rem;
    min-width: 64px;
    text-align: center;
}

.sle-step-marker span
{
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border: 2px solid var(--sle-border);
    border-radius: 50%;
    background: var(--sle-white);
    color: var(--sle-muted);
    font-size: 0.82rem;
    font-weight: 800;
    transition:
        border-color 0.25s ease,
        background-color 0.25s ease,
        color 0.25s ease,
        transform 0.25s ease;
}

.sle-step-marker small
{
    color: var(--sle-muted);
    font-size: 0.66rem;
    font-weight: 700;
    line-height: 1.2;
}

.sle-step-marker.is-active span
{
    border-color: var(--sle-teal);
    background: var(--sle-teal);
    color: var(--sle-white);
    transform: scale(1.05);
}

.sle-step-marker.is-active small
{
    color: var(--sle-teal-dark);
    font-weight: 800;
}

.sle-step-marker.is-complete span
{
    border-color: var(--sle-green);
    background: var(--sle-green);
    color: var(--sle-white);
}

.sle-step-marker.is-complete small
{
    color: var(--sle-green);
}

.sle-step-connector
{
    height: 3px;
    border-radius: 999px;
    background: var(--sle-border);
    transition: background-color 0.25s ease;
}

.sle-step-connector.is-complete
{
    background: var(--sle-green);
}


/* =========================================================
   ACTIVE WORK AREA
   ========================================================= */

.sle-work-area
{
    margin-top: 1rem;
    padding: clamp(1.25rem, 3vw, 1.8rem);
    border: 2px solid rgba(21, 154, 156, 0.2);
    border-radius: 1rem;
    background:
        linear-gradient(
            135deg,
            rgba(21, 154, 156, 0.065),
            rgba(31, 111, 139, 0.035)
        );
}

.sle-work-step[hidden]
{
    display: none !important;
}

.sle-work-step-number
{
    margin: 0 0 0.35rem;
    color: var(--sle-teal-dark);
    font-size: 0.76rem;
    font-weight: 800;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.sle-work-step h3
{
    margin: 0 0 0.55rem;
    color: var(--sle-navy);
    font-size: clamp(1.2rem, 3vw, 1.55rem);
    font-weight: 800;
    line-height: 1.3;
}

.sle-work-description
{
    margin: 0 0 1.3rem;
    color: var(--sle-muted);
    font-size: 0.9rem;
    line-height: 1.65;
}


/* =========================================================
   EQUATION CHOICES
   ========================================================= */

.sle-equation-choice-grid
{
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.9rem;
}

.sle-equation-choice
{
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.45rem;
    width: 100%;
    min-height: 110px;
    padding: 1rem 1.15rem;
    border: 2px solid var(--sle-border);
    border-radius: 0.9rem;
    background: var(--sle-white);
    color: var(--sle-navy);
    text-align: left;
    box-shadow: var(--sle-shadow-small);
    transition:
        transform 0.2s ease,
        border-color 0.2s ease,
        background-color 0.2s ease,
        box-shadow 0.2s ease;
}

.sle-equation-choice:hover
{
    transform: translateY(-2px);
    border-color: rgba(21, 154, 156, 0.55);
    box-shadow: 0 10px 24px rgba(16, 42, 67, 0.11);
}

.sle-choice-number
{
    color: var(--sle-muted);
    font-size: 0.72rem;
    font-weight: 800;
    letter-spacing: 0.06em;
    text-transform: uppercase;
}

.sle-equation-choice strong
{
    color: var(--sle-navy-dark);
    font-size: clamp(1.1rem, 3vw, 1.4rem);
    font-weight: 800;
}

.sle-equation-choice.is-correct
{
    border-color: var(--sle-green);
    background: rgba(25, 135, 84, 0.06);
}

.sle-equation-choice.is-incorrect
{
    border-color: var(--sle-red);
    background: rgba(192, 57, 43, 0.055);
}


/* =========================================================
   ACTIVE EQUATION DISPLAY
   ========================================================= */

.sle-active-equation
{
    margin: 1rem 0 1.35rem;
    padding: 1.15rem 1.2rem;
    border: 1px solid rgba(21, 154, 156, 0.22);
    border-radius: 0.85rem;
    background: var(--sle-white);
    color: var(--sle-navy-dark);
    font-size: clamp(1.5rem, 5vw, 2.15rem);
    font-weight: 800;
    line-height: 1.4;
    text-align: center;
    box-shadow: var(--sle-shadow-small);
    overflow-wrap: anywhere;
}

.sle-input-slot
{
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 74px;
    min-height: 44px;
    margin: 0 0.15rem;
    padding: 0.1rem 0.5rem;
    border: 2px dashed rgba(21, 154, 156, 0.55);
    border-radius: 0.55rem;
    background: rgba(21, 154, 156, 0.07);
    color: var(--sle-teal-dark);
}


/* =========================================================
   ANSWER FORMS
   ========================================================= */

.sle-answer-form
{
    margin-top: 1.25rem;
}

.sle-input-label
{
    display: block;
    margin-bottom: 0.6rem;
    color: var(--sle-navy);
    font-size: 0.9rem;
    font-weight: 800;
}

.sle-input-row
{
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 0.8rem;
}

.sle-step-input
{
    width: 100%;
    min-height: 56px;
    padding: 0.85rem 1rem;
    border: 2px solid var(--sle-border);
    border-radius: 0.85rem;
    background: var(--sle-white);
    color: var(--sle-navy-dark);
    font-size: 1.05rem;
    font-weight: 650;
    outline: none;
    transition:
        border-color 0.2s ease,
        box-shadow 0.2s ease,
        background-color 0.2s ease;
}

.sle-step-input::placeholder
{
    color: #9aabba;
    font-weight: 500;
}

.sle-step-input:hover
{
    border-color: #b9cad8;
}

.sle-step-input:focus
{
    border-color: var(--sle-teal);
    box-shadow: 0 0 0 4px rgba(21, 154, 156, 0.13);
}

.sle-step-input.is-correct
{
    border-color: var(--sle-green);
    background: rgba(25, 135, 84, 0.045);
}

.sle-step-input.is-incorrect
{
    border-color: var(--sle-red);
    background: rgba(192, 57, 43, 0.045);
}

.sle-input-help
{
    margin: 0.6rem 0 0;
    color: var(--sle-muted);
    font-size: 0.78rem;
    line-height: 1.5;
}


/* =========================================================
   SOLVE HISTORY
   ========================================================= */

.sle-solve-history-area
{
    margin-top: 1.25rem;
    padding: 1.15rem;
    border: 1px solid var(--sle-border);
    border-radius: 0.9rem;
    background: var(--sle-white);
}

.sle-solve-history-heading
{
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--sle-border);
    color: var(--sle-navy);
    font-size: 0.82rem;
    font-weight: 800;
}

.sle-solve-history-heading span:last-child
{
    color: var(--sle-muted);
    font-weight: 600;
}

.sle-solve-history
{
    display: grid;
    gap: 0.7rem;
    margin: 1rem 0 0;
    padding: 0;
    list-style: none;
}

.sle-history-item
{
    display: grid;
    grid-template-columns: 70px minmax(0, 1fr);
    align-items: center;
    gap: 0.9rem;
    padding: 0.8rem 0.9rem;
    border-radius: 0.75rem;
    background: var(--sle-light);
}

.sle-history-number
{
    color: var(--sle-teal-dark);
    font-size: 0.76rem;
    font-weight: 800;
    text-transform: uppercase;
}

.sle-history-equation
{
    color: var(--sle-navy);
    font-size: 1rem;
    font-weight: 700;
    overflow-wrap: anywhere;
}

.sle-history-correct
{
    border-left: 4px solid var(--sle-green);
    background: rgba(25, 135, 84, 0.07);
}


/* =========================================================
   ORDERED PAIR ENTRY
   ========================================================= */

.sle-ordered-pair-form
{
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.sle-ordered-pair-entry
{
    display: flex;
    align-items: flex-end;
    gap: 0.45rem;
}

.sle-parenthesis
{
    color: var(--sle-navy);
    font-size: 3rem;
    font-weight: 400;
    line-height: 1.05;
}

.sle-coordinate-comma
{
    padding-bottom: 0.55rem;
    color: var(--sle-navy);
    font-size: 1.8rem;
    font-weight: 800;
}

.sle-coordinate-input-group
{
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.sle-coordinate-input-group label
{
    color: var(--sle-muted);
    font-size: 0.72rem;
    font-weight: 800;
    text-align: center;
    text-transform: uppercase;
}

.sle-coordinate-input
{
    width: 90px;
    min-height: 56px;
    padding: 0.65rem;
    border: 2px solid var(--sle-border);
    border-radius: 0.8rem;
    background: var(--sle-white);
    color: var(--sle-navy-dark);
    font-size: 1.2rem;
    font-weight: 800;
    text-align: center;
    outline: none;
    transition:
        border-color 0.2s ease,
        box-shadow 0.2s ease,
        background-color 0.2s ease;
}

.sle-coordinate-input:focus
{
    border-color: var(--sle-teal);
    box-shadow: 0 0 0 4px rgba(21, 154, 156, 0.13);
}

.sle-coordinate-input.is-correct
{
    border-color: var(--sle-green);
    background: rgba(25, 135, 84, 0.045);
}

.sle-coordinate-input.is-incorrect
{
    border-color: var(--sle-red);
    background: rgba(192, 57, 43, 0.045);
}


/* =========================================================
   BUTTONS
   ========================================================= */

.sle-submit-button,
.sle-next-button
{
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.45rem;
    min-height: 56px;
    padding: 0.85rem 1.4rem;
    border: 0;
    border-radius: 0.85rem;
    color: var(--sle-white);
    font-size: 0.92rem;
    font-weight: 800;
    white-space: nowrap;
    transition:
        transform 0.2s ease,
        box-shadow 0.2s ease,
        filter 0.2s ease;
}

.sle-submit-button
{
    background:
        linear-gradient(
            135deg,
            var(--sle-teal),
            var(--sle-blue)
        );
    box-shadow: 0 8px 20px rgba(21, 154, 156, 0.22);
}

.sle-next-button
{
    background:
        linear-gradient(
            135deg,
            var(--sle-green),
            #157347
        );
    box-shadow: 0 8px 20px rgba(25, 135, 84, 0.22);
}

.sle-submit-button:hover,
.sle-next-button:hover
{
    transform: translateY(-2px);
    filter: brightness(1.04);
}

.sle-submit-button:hover
{
    box-shadow: 0 12px 24px rgba(21, 154, 156, 0.28);
}

.sle-next-button:hover
{
    box-shadow: 0 12px 24px rgba(25, 135, 84, 0.28);
}

.sle-submit-button:active,
.sle-next-button:active
{
    transform: translateY(0);
}

.sle-submit-button:disabled
{
    cursor: not-allowed;
    opacity: 0.58;
    transform: none;
    box-shadow: none;
}

.sle-action-row
{
    display: flex;
    flex-wrap: wrap;
    gap: 0.7rem;
    margin-top: 1.25rem;
}

.sle-secondary-button
{
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.45rem;
    min-height: 42px;
    padding: 0.6rem 0.9rem;
    border: 1px solid var(--sle-border);
    border-radius: 0.7rem;
    background: var(--sle-white);
    color: var(--sle-navy);
    font-size: 0.82rem;
    font-weight: 750;
    transition:
        border-color 0.2s ease,
        background-color 0.2s ease,
        color 0.2s ease,
        transform 0.2s ease;
}

.sle-secondary-button svg
{
    width: 17px;
    height: 17px;
}

.sle-secondary-button:hover
{
    transform: translateY(-1px);
    border-color: rgba(21, 154, 156, 0.55);
    background: rgba(21, 154, 156, 0.06);
    color: var(--sle-teal-dark);
}

.sle-close-button
{
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    padding: 0;
    border: 0;
    border-radius: 50%;
    background: rgba(16, 42, 67, 0.07);
    color: var(--sle-navy);
}

.sle-close-button:hover
{
    background: rgba(16, 42, 67, 0.13);
}

.sle-close-button svg
{
    width: 18px;
    height: 18px;
}

.sle-submit-button:focus-visible,
.sle-next-button:focus-visible,
.sle-secondary-button:focus-visible,
.sle-close-button:focus-visible,
.sle-method-button:focus-visible,
.sle-equation-choice:focus-visible
{
    outline: 3px solid rgba(21, 154, 156, 0.25);
    outline-offset: 3px;
}


/* =========================================================
   FEEDBACK
   ========================================================= */

.sle-feedback
{
    margin-top: 1rem;
    padding: 0.9rem 1rem;
    border: 1px solid transparent;
    border-radius: 0.8rem;
    font-size: 0.88rem;
    font-weight: 650;
    line-height: 1.55;
}

.sle-feedback-neutral
{
    border-color: var(--sle-border);
    background: var(--sle-light);
    color: var(--sle-muted);
}

.sle-feedback-correct
{
    border-color: rgba(25, 135, 84, 0.26);
    background: rgba(25, 135, 84, 0.08);
    color: #12633e;
}

.sle-feedback-incorrect
{
    border-color: rgba(192, 57, 43, 0.25);
    background: rgba(192, 57, 43, 0.07);
    color: #922b21;
}

.sle-feedback-warning
{
    border-color: rgba(217, 119, 6, 0.28);
    background: rgba(217, 119, 6, 0.08);
    color: #9a5204;
}


/* =========================================================
   HINT PANEL
   ========================================================= */

.sle-help-panel
{
    display: flex;
    align-items: flex-start;
    gap: 0.9rem;
    margin-top: 1rem;
    padding: 1rem;
    border: 1px solid rgba(217, 119, 6, 0.22);
    border-radius: 0.9rem;
    background: rgba(217, 119, 6, 0.07);
}

.sle-help-panel[hidden],
.sle-reference-panel[hidden],
.sle-problem-complete[hidden],
.sle-results[hidden]
{
    display: none !important;
}

.sle-help-panel-icon
{
    display: flex;
    align-items: center;
    justify-content: center;
    flex: 0 0 auto;
    width: 38px;
    height: 38px;
    border-radius: 50%;
    background: rgba(217, 119, 6, 0.14);
    color: var(--sle-orange);
}

.sle-help-panel-icon svg
{
    width: 19px;
    height: 19px;
}

.sle-help-panel strong
{
    display: block;
    margin-bottom: 0.2rem;
    color: #804000;
    font-size: 0.86rem;
}

.sle-help-panel p
{
    margin: 0;
    color: #855008;
    font-size: 0.85rem;
    line-height: 1.55;
}


/* =========================================================
   REFERENCE PANEL
   ========================================================= */

.sle-reference-panel
{
    margin-top: 1rem;
    padding: 1.15rem;
    border: 1px solid rgba(111, 66, 193, 0.2);
    border-radius: 0.9rem;
    background: rgba(111, 66, 193, 0.055);
}

.sle-reference-panel-heading
{
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.sle-reference-panel-heading h3
{
    margin: 0;
    color: var(--sle-navy);
    font-size: 1rem;
    font-weight: 800;
}

.sle-reference-grid
{
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.85rem;
    margin-top: 1rem;
}

.sle-reference-item
{
    padding: 1rem;
    border: 1px solid rgba(111, 66, 193, 0.13);
    border-radius: 0.8rem;
    background: rgba(255, 255, 255, 0.7);
}

.sle-reference-item strong
{
    display: block;
    margin-bottom: 0.5rem;
    color: var(--sle-purple);
    font-size: 0.85rem;
}

.sle-reference-equation
{
    display: block;
    margin-bottom: 0.45rem;
    color: var(--sle-navy);
    font-size: 1rem;
    font-weight: 800;
}

.sle-reference-item p
{
    margin: 0;
    color: var(--sle-muted);
    font-size: 0.8rem;
    line-height: 1.55;
}


/* =========================================================
   PROBLEM COMPLETE PANEL
   ========================================================= */

.sle-problem-complete
{
    display: grid;
    grid-template-columns: auto minmax(0, 1fr) auto;
    align-items: center;
    gap: 1.1rem;
    margin-top: 1.25rem;
    padding: 1.2rem;
    border: 1px solid rgba(25, 135, 84, 0.25);
    border-radius: 0.95rem;
    background: rgba(25, 135, 84, 0.07);
}

.sle-problem-complete-icon
{
    display: flex;
    align-items: center;
    justify-content: center;
    width: 46px;
    height: 46px;
    border-radius: 50%;
    background: var(--sle-green);
    color: var(--sle-white);
}

.sle-problem-complete-icon svg
{
    width: 24px;
    height: 24px;
}

.sle-problem-complete-label
{
    margin: 0 0 0.2rem;
    color: var(--sle-green);
    font-size: 0.72rem;
    font-weight: 800;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.sle-problem-complete h3
{
    margin: 0 0 0.2rem;
    color: var(--sle-navy);
    font-size: 1.15rem;
    font-weight: 800;
}

.sle-problem-complete p:last-child
{
    margin: 0;
    color: var(--sle-muted);
    font-size: 0.82rem;
}


/* =========================================================
   STATISTICS
   ========================================================= */

.sle-stats
{
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 1rem;
    margin-top: 1.25rem;
}

.sle-stat
{
    padding: 1.1rem;
    border: 1px solid var(--sle-border);
    border-radius: 0.95rem;
    background: var(--sle-white);
    text-align: center;
    box-shadow: var(--sle-shadow-small);
}

.sle-stat span
{
    display: block;
    min-height: 2.5em;
    margin-bottom: 0.45rem;
    color: var(--sle-muted);
    font-size: 0.76rem;
    font-weight: 700;
    line-height: 1.35;
}

.sle-stat strong
{
    display: block;
    color: var(--sle-navy);
    font-size: 1.65rem;
    font-weight: 800;
}


/* =========================================================
   RESULTS SCREEN
   ========================================================= */

.sle-results
{
    margin-top: 1.5rem;
    padding: clamp(1.5rem, 4vw, 2.5rem);
    border: 1px solid rgba(21, 154, 156, 0.22);
    border-radius: 1.2rem;
    background:
        radial-gradient(
            circle at top right,
            rgba(21, 154, 156, 0.12),
            transparent 22rem
        ),
        var(--sle-white);
    text-align: center;
    box-shadow: var(--sle-shadow);
}

.sle-results-label
{
    margin: 0 0 0.5rem;
    color: var(--sle-teal-dark);
    font-size: 0.78rem;
    font-weight: 800;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.sle-results h2
{
    margin: 0 0 0.65rem;
    color: var(--sle-navy);
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 800;
}

.sle-results > p:not(.sle-results-label)
{
    max-width: 600px;
    margin: 0 auto;
    color: var(--sle-muted);
    line-height: 1.65;
}

.sle-results-grid
{
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 1rem;
    margin: 1.75rem 0;
}

.sle-result-item
{
    padding: 1.1rem;
    border: 1px solid var(--sle-border);
    border-radius: 0.85rem;
    background: var(--sle-light);
}

.sle-result-item span
{
    display: block;
    min-height: 2.5em;
    margin-bottom: 0.4rem;
    color: var(--sle-muted);
    font-size: 0.75rem;
    font-weight: 700;
}

.sle-result-item strong
{
    color: var(--sle-navy);
    font-size: 1.55rem;
    font-weight: 800;
}

.sle-result-accuracy
{
    border-color: rgba(21, 154, 156, 0.3);
    background: rgba(21, 154, 156, 0.08);
}


/* =========================================================
   INFORMATION CARDS
   ========================================================= */

.sle-info
{
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.5rem;
    padding-top: 4.5rem;
    padding-bottom: 4.5rem;
}

.sle-info article
{
    padding: 1.7rem;
    border: 1px solid var(--sle-border);
    border-radius: 1rem;
    background: var(--sle-white);
    box-shadow: var(--sle-shadow-small);
    transition:
        transform 0.2s ease,
        box-shadow 0.2s ease,
        border-color 0.2s ease;
}

.sle-info article:hover
{
    transform: translateY(-4px);
    border-color: rgba(21, 154, 156, 0.35);
    box-shadow: var(--sle-shadow);
}

.sle-info-icon
{
    display: flex;
    align-items: center;
    justify-content: center;
    width: 46px;
    height: 46px;
    margin-bottom: 1rem;
    border-radius: 0.8rem;
    background: rgba(21, 154, 156, 0.1);
    color: var(--sle-teal-dark);
}

.sle-info-icon svg
{
    width: 21px;
    height: 21px;
}

.sle-info h2
{
    margin: 0 0 0.75rem;
    color: var(--sle-navy);
    font-size: 1.12rem;
    font-weight: 800;
}

.sle-info p
{
    margin: 0;
    color: var(--sle-muted);
    font-size: 0.91rem;
    line-height: 1.7;
}


/* =========================================================
   EXAMPLE SECTION
   ========================================================= */

.sle-example-section
{
    padding: 5rem 0;
    background: var(--sle-navy);
    color: var(--sle-white);
}

.sle-example-content
{
    width: min(100%, 840px);
    margin: 0 auto;
}

.sle-example-heading
{
    text-align: center;
}

.sle-example-heading .sle-eyebrow
{
    color: #6dd8d9;
}

.sle-example-heading h2
{
    margin: 0 0 0.85rem;
    color: var(--sle-white);
    font-size: clamp(1.8rem, 4vw, 2.45rem);
    font-weight: 800;
}

.sle-example-heading p
{
    margin: 0;
    color: #c8d8e5;
}

.sle-example-system
{
    position: relative;
    display: grid;
    gap: 0.35rem;
    width: fit-content;
    margin: 2rem auto;
    padding: 1.2rem 1.6rem 1.2rem 2.7rem;
    border: 1px solid rgba(255, 255, 255, 0.13);
    border-radius: 1rem;
    background: rgba(255, 255, 255, 0.07);
    color: var(--sle-white);
    font-size: clamp(1.35rem, 4vw, 1.85rem);
    font-weight: 800;
}

.sle-example-system::before
{
    content: "{";
    position: absolute;
    left: 1rem;
    top: 50%;
    color: #6dd8d9;
    font-family: Georgia, "Times New Roman", serif;
    font-size: 3.6rem;
    font-weight: 400;
    line-height: 1;
    transform: translateY(-52%) scaleY(1.2);
}

.sle-example-steps
{
    display: grid;
    gap: 0.9rem;
}

.sle-example-step
{
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.15rem;
    border: 1px solid rgba(255, 255, 255, 0.11);
    border-radius: 0.9rem;
    background: rgba(255, 255, 255, 0.055);
}

.sle-example-step-number
{
    display: flex;
    align-items: center;
    justify-content: center;
    flex: 0 0 auto;
    width: 42px;
    height: 42px;
    border-radius: 50%;
    background: var(--sle-teal);
    color: var(--sle-white);
    font-weight: 800;
}

.sle-example-step > div
{
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
}

.sle-example-step-label
{
    color: #a9bfd0;
    font-size: 0.76rem;
    font-weight: 700;
    text-transform: uppercase;
}

.sle-example-step strong
{
    color: var(--sle-white);
    font-size: 1.1rem;
}

.sle-example-note
{
    margin: 1.5rem 0 0;
    color: #c8d8e5;
    font-size: 0.9rem;
    line-height: 1.7;
    text-align: center;
}


/* =========================================================
   SEO SECTION
   ========================================================= */

.sle-seo-section
{
    padding: 5rem 0;
    background: var(--sle-white);
}

.sle-seo-content
{
    width: min(100%, 860px);
    margin: 0 auto;
}

.sle-seo-content h2
{
    margin: 0 0 1rem;
    color: var(--sle-navy);
    font-size: clamp(1.8rem, 4vw, 2.45rem);
    font-weight: 800;
    line-height: 1.2;
}

.sle-seo-content h3
{
    margin: 2.2rem 0 0.75rem;
    color: var(--sle-navy);
    font-size: 1.3rem;
    font-weight: 800;
}

.sle-seo-content p
{
    margin: 0 0 1rem;
    color: var(--sle-muted);
    font-size: 0.96rem;
    line-height: 1.8;
}

.sle-seo-links
{
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 1.2rem;
    margin-top: 2rem;
}

.sle-resource-link
{
    color: var(--sle-teal-dark);
    font-size: 0.9rem;
    font-weight: 700;
    text-decoration: none;
}

.sle-resource-link:hover
{
    color: var(--sle-navy);
    text-decoration: underline;
}


/* =========================================================
   ANIMATIONS
   ========================================================= */

@keyframes sleShake
{
    0%,
    100%
    {
        transform: translateX(0);
    }

    25%
    {
        transform: translateX(-5px);
    }

    50%
    {
        transform: translateX(5px);
    }

    75%
    {
        transform: translateX(-3px);
    }
}

@keyframes slePop
{
    0%
    {
        transform: scale(0.97);
        opacity: 0.5;
    }

    100%
    {
        transform: scale(1);
        opacity: 1;
    }
}

.sle-shake
{
    animation: sleShake 0.3s ease;
}

.sle-pop
{
    animation: slePop 0.25s ease;
}


/* =========================================================
   TABLET
   ========================================================= */

@media (max-width: 900px)
{
    .sle-toolbar
    {
        align-items: stretch;
        flex-direction: column;
        gap: 1.25rem;
    }

    .sle-control-group
    {
        width: 100%;
        max-width: 320px;
    }

    .sle-stats,
    .sle-results-grid
    {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .sle-info
    {
        grid-template-columns: 1fr;
    }

    .sle-step-progress
    {
        gap: 0.25rem;
    }

    .sle-step-marker
    {
        min-width: 50px;
    }

    .sle-step-marker small
    {
        font-size: 0.6rem;
    }

    .sle-reference-grid
    {
        grid-template-columns: 1fr;
    }
}


/* =========================================================
   MOBILE
   ========================================================= */

@media (max-width: 650px)
{
    .sle-section
    {
        padding: 3.5rem 1rem;
    }

    .sle-card
    {
        padding: 1.15rem;
        border-radius: 1rem;
    }

    .sle-card-top
    {
        flex-direction: column;
    }

    .sle-card-badges
    {
        justify-content: flex-start;
    }

    .sle-method-heading
    {
        align-items: flex-start;
        flex-direction: column;
        gap: 0.25rem;
    }

    .sle-method-tabs
    {
        grid-template-columns: 1fr;
    }

    .sle-method-button
    {
        justify-content: flex-start;
    }

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

    .sle-input-row
    {
        grid-template-columns: 1fr;
    }

    .sle-submit-button
    {
        width: 100%;
    }

    .sle-ordered-pair-form
    {
        align-items: stretch;
        flex-direction: column;
    }

    .sle-ordered-pair-entry
    {
        justify-content: center;
    }

    .sle-ordered-pair-form .sle-submit-button
    {
        width: 100%;
    }

    .sle-problem-complete
    {
        grid-template-columns: auto minmax(0, 1fr);
    }

    .sle-problem-complete .sle-next-button
    {
        grid-column: 1 / -1;
        width: 100%;
    }

    .sle-step-progress
    {
        display: flex;
        align-items: flex-start;
        justify-content: space-between;
        gap: 0.2rem;
        overflow-x: auto;
        padding-bottom: 0.4rem;
    }

    .sle-step-marker
    {
        flex: 0 0 58px;
    }

    .sle-step-connector
    {
        flex: 1 0 16px;
        min-width: 16px;
        margin-top: 17px;
    }

    .sle-original-system-area
    {
        padding: 1.1rem;
    }

    .sle-system-display
    {
        padding-left: 1.2rem;
    }

    .sle-system-display::before
    {
        font-size: 3.15rem;
    }

    .sle-system-equation
    {
        font-size: 1.15rem;
    }

    .sle-active-equation
    {
        padding: 1rem 0.75rem;
        font-size: 1.35rem;
    }

    .sle-history-item
    {
        grid-template-columns: 1fr;
        gap: 0.3rem;
    }

    .sle-solve-history-heading
    {
        align-items: flex-start;
        flex-direction: column;
        gap: 0.2rem;
    }

    .sle-stats,
    .sle-results-grid
    {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .sle-action-row
    {
        display: grid;
        grid-template-columns: 1fr;
    }

    .sle-secondary-button
    {
        width: 100%;
    }

    .sle-example-system
    {
        width: 100%;
    }

    .sle-example-step
    {
        align-items: flex-start;
    }
}


/* =========================================================
   SMALL MOBILE
   ========================================================= */

@media (max-width: 420px)
{
    .sle-stats,
    .sle-results-grid
    {
        grid-template-columns: 1fr;
    }

    .sle-coordinate-input
    {
        width: 72px;
    }

    .sle-parenthesis
    {
        font-size: 2.6rem;
    }

    .sle-coordinate-comma
    {
        font-size: 1.5rem;
    }

    .sle-method-selector
    {
        padding: 1rem;
    }

    .sle-work-area
    {
        padding: 1rem;
    }
}

/* =========================================================
   ELIMINATION WORKFLOW
   ========================================================= */

.sle-elimination-multiplier-area
{
    margin-bottom: 1.35rem;
    padding: 1.15rem;
    border: 1px solid var(--sle-border);
    border-radius: 0.9rem;
    background: var(--sle-white);
    box-shadow: var(--sle-shadow-small);
}

.sle-elimination-multiplier-area[hidden]
{
    display: none !important;
}

.sle-elimination-multiplier-grid
{
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
    margin-bottom: 1rem;
}

.sle-elimination-multiplier-item
{
    display: grid;
    gap: 0.55rem;
    padding: 1rem;
    border: 1px solid var(--sle-border);
    border-radius: 0.8rem;
    background: var(--sle-lighter);
}

.sle-elimination-multiplier-item label
{
    color: var(--sle-navy);
    font-size: 0.78rem;
    font-weight: 800;
}

.sle-elimination-small-equation
{
    color: var(--sle-navy-dark);
    font-size: 1.1rem;
    font-weight: 800;
    line-height: 1.45;
}


/* =========================================================
   STACKED EQUATIONS
   ========================================================= */

.sle-elimination-ready-area
{
    margin-top: 1rem;
}

.sle-elimination-stack
{
    width: min(100%, 560px);
    margin: 1rem auto 1.5rem;
    padding: 1rem 1.25rem;
    border: 1px solid var(--sle-border);
    border-radius: 0.9rem;
    background: var(--sle-white);
    box-shadow: var(--sle-shadow-small);
}

.sle-elimination-stack-equation
{
    padding: 0.25rem 0;
    color: var(--sle-navy-dark);
    font-size: clamp(1.3rem, 4vw, 1.8rem);
    font-weight: 800;
    line-height: 1.4;
    text-align: center;
}

.sle-elimination-stack-line
{
    height: 3px;
    margin-top: 0.55rem;
    border-radius: 999px;
    background: var(--sle-navy);
}


/* =========================================================
   ELIMINATION CHOICE STATES
   ========================================================= */

.sle-equation-choice.is-selected
{
    border-color: var(--sle-blue);
    background: rgba(31, 111, 139, 0.07);
    box-shadow: 0 8px 20px rgba(31, 111, 139, 0.11);
}

.sle-equation-choice.is-selected .sle-choice-number
{
    color: var(--sle-blue);
}


/* =========================================================
   ELIMINATION RESULT FORM
   ========================================================= */

#eliminationResultForm
{
    margin-top: 1.25rem;
}

#eliminationResultForm[hidden]
{
    display: none !important;
}


/* =========================================================
   ELIMINATION WORK HISTORY
   ========================================================= */

#eliminationSolveHistory
{
    margin-top: 1rem;
}


/* =========================================================
   TABLET
   ========================================================= */

@media (max-width: 900px)
{
    .sle-elimination-multiplier-grid
    {
        grid-template-columns: 1fr;
    }
}


/* =========================================================
   MOBILE
   ========================================================= */

@media (max-width: 650px)
{
    .sle-elimination-stack
    {
        padding: 0.9rem;
    }

    .sle-elimination-stack-equation
    {
        font-size: 1.2rem;
    }

    .sle-elimination-multiplier-item
    {
        padding: 0.85rem;
    }
}

/* =========================================================
   TEMPORARY GRAPH ENGINE TEST
   ========================================================= */

.sle-systems-graph-board
{
    width: 100%;
    height: 520px;
    border: 1px solid var(--sle-border);
    border-radius: 0.9rem;
    background: var(--sle-white);
    overflow: hidden;
}

@media (max-width: 650px)
{
    .sle-systems-graph-board
    {
        height: 400px;
    }

        .sle-seo-links
    {
        align-items: stretch;
        flex-direction: column;
    }

    .sle-seo-links .btn,
    .sle-seo-links .sle-resource-link
    {
        width: 100%;
    }
}

.sle-resource-link
{
    display: inline-flex;
    align-items: center;
    justify-content: center;

    min-height: 48px;

    padding: 0.75rem 1.05rem;

    border: 1px solid rgba(21, 154, 156, 0.55);
    border-radius: 0.7rem;

    background: var(--sle-white);
    color: var(--sle-teal-dark);

    font-size: 0.9rem;
    font-weight: 700;
    line-height: 1.2;
    text-align: center;
    text-decoration: none;

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

.sle-resource-link:hover
{
    transform: translateY(-1px);

    border-color: var(--sle-teal);

    background: rgba(21, 154, 156, 0.06);
    color: var(--sle-teal-dark);

    text-decoration: none;

    box-shadow: var(--sle-shadow-small);
}