/* ==========================================================
   Page
   ========================================================== */

.divisibility-rules-page {
    background: #f4f7fb;
}


/* ==========================================================
   Section Layout
   ========================================================== */

.divisibility-rules-overview,
.divisibility-rules-tool-section,
.divisibility-rules-strategies,
.divisibility-rules-applications,
.divisibility-rules-reference,
.divisibility-rules-cta {
    padding: 5rem 0;
}

.divisibility-rules-tool-section {
    background: #ffffff;
}

.divisibility-rules-section-heading {
    max-width: 760px;
    margin: 0 auto 3rem;
    text-align: center;
}

.divisibility-rules-eyebrow {
    margin-bottom: .75rem;
    color: #0d9488;
    font-size: .8rem;
    font-weight: 800;
    letter-spacing: .14em;
    text-transform: uppercase;
}

.divisibility-rules-section-heading h2 {
    margin-bottom: 1rem;
    font-weight: 800;
    font-size: clamp(2rem,4vw,2.8rem);
}

.divisibility-rules-section-heading p {
    color: #64748b;
    font-size: 1.05rem;
    line-height: 1.8;
}


/* ==========================================================
   Overview Cards
   ========================================================== */

.divisibility-rules-overview-grid {
    display: grid;
    grid-template-columns: repeat(4,minmax(0,1fr));
    gap: 1.5rem;
}

.divisibility-rules-overview-card {
    background: #fff;
    border: 1px solid #dbe4ef;
    border-radius: 18px;
    padding: 2rem;
    text-align: center;
    transition: .2s ease;
}

.divisibility-rules-overview-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 18px 35px rgba(15,23,42,.08);
}

.divisibility-rules-step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 52px;
    height: 52px;
    margin-bottom: 1rem;
    border-radius: 50%;
    background: #0d9488;
    color: #fff;
    font-size: 1.25rem;
    font-weight: 800;
}

.divisibility-rules-overview-card h3 {
    margin-bottom: .75rem;
    font-size: 1.2rem;
    font-weight: 700;
}

.divisibility-rules-overview-card p {
    margin: 0;
    color: #64748b;
    line-height: 1.7;
}


/* ==========================================================
   Tool Container
   ========================================================== */

.divisibility-rules-tool {
    background: #fff;
    border: 1px solid #dbe4ef;
    border-radius: 22px;
    padding: 2.5rem;
    box-shadow: 0 18px 45px rgba(15,23,42,.06);
}

.divisibility-rules-tool-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 2rem;
    margin-bottom: 2rem;
}

.divisibility-rules-tool-header h2 {
    margin: 0;
    font-size: 2rem;
    font-weight: 800;
}


/* ==========================================================
   Scoreboard
   ========================================================== */

.divisibility-rules-scoreboard {
    display: flex;
    gap: 1rem;
}

.divisibility-rules-score-item {
    min-width: 110px;
    padding: 1rem;
    border: 1px solid #dbe4ef;
    border-radius: 14px;
    background: #f8fafc;
    text-align: center;
}

.divisibility-rules-score-label {
    display: block;
    margin-bottom: .35rem;
    color: #64748b;
    font-size: .72rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: .08em;
}

.divisibility-rules-score-item strong {
    color: #0f172a;
    font-size: 1.8rem;
    font-weight: 800;
}

/* ==========================================================
   Settings
   ========================================================== */

.divisibility-rules-settings {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr)) auto;
    gap: 1rem;
    align-items: end;
    margin-bottom: 2rem;
    border: 1px solid #dbe4ef;
    border-radius: 16px;
    background: #f8fafc;
    padding: 1.5rem;
}

.divisibility-rules-setting-group label {
    display: block;
    margin-bottom: .5rem;
    color: #334155;
    font-size: .9rem;
    font-weight: 700;
}

.divisibility-rules-setting-group .form-select {
    min-height: 3.15rem;
    border: 1px solid #cbd5e1;
    border-radius: 12px;
    background-color: #ffffff;
}

.divisibility-rules-setting-group .form-select:focus {
    border-color: #0d9488;
    box-shadow: 0 0 0 .2rem rgba(13, 148, 136, .14);
}

#newProblemButton {
    min-height: 3.15rem;
    white-space: nowrap;
}


/* ==========================================================
   Buttons
   ========================================================== */

.divisibility-rules-page .btn-teal {
    border-color: #0d9488;
    background: #0d9488;
    color: #ffffff;
}

.divisibility-rules-page .btn-teal:hover,
.divisibility-rules-page .btn-teal:focus {
    border-color: #0f766e;
    background: #0f766e;
    color: #ffffff;
}

.divisibility-rules-page .btn-outline-teal {
    border-color: #0d9488;
    color: #0d9488;
}

.divisibility-rules-page .btn-outline-teal:hover,
.divisibility-rules-page .btn-outline-teal:focus {
    border-color: #0d9488;
    background: #0d9488;
    color: #ffffff;
}


/* ==========================================================
   Problem Display
   ========================================================== */

.divisibility-rules-problem-area {
    margin-bottom: 2rem;
    border: 1px solid #dbe4ef;
    border-radius: 18px;
    background: #f8fafc;
    padding: 2.25rem;
    text-align: center;
}

.divisibility-rules-problem-label {
    margin-bottom: 1rem;
    color: #64748b;
    font-size: .8rem;
    font-weight: 800;
    letter-spacing: .1em;
    text-transform: uppercase;
}

.divisibility-rules-target-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 220px;
    min-height: 115px;
    margin-bottom: 1rem;
    border: 2px solid #dbe4ef;
    border-radius: 18px;
    background: #ffffff;
    color: #0f172a;
    padding: 1rem 1.75rem;
    font-size: clamp(3rem, 8vw, 5rem);
    font-weight: 800;
    line-height: 1;
    letter-spacing: .03em;
}

.divisibility-rules-problem-instruction {
    max-width: 720px;
    margin: 0 auto;
    color: #64748b;
    line-height: 1.75;
}


/* ==========================================================
   Progress Tracker
   ========================================================== */

.divisibility-rules-progress {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 2rem;
}

.divisibility-rules-progress-step {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: .6rem;
    min-width: 120px;
    color: #94a3b8;
}

.divisibility-rules-progress-step p {
    margin: 0;
    font-size: .82rem;
    font-weight: 700;
    text-align: center;
}

.divisibility-rules-progress-circle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 46px;
    height: 46px;
    border: 2px solid #cbd5e1;
    border-radius: 50%;
    background: #ffffff;
    font-weight: 800;
    transition: .2s ease;
}

.divisibility-rules-progress-line {
    width: 90px;
    height: 2px;
    background: #dbe4ef;
    transition: .2s ease;
}

.divisibility-rules-progress-step.active {
    color: #0d9488;
}

.divisibility-rules-progress-step.active
.divisibility-rules-progress-circle {
    border-color: #0d9488;
    background: #0d9488;
    color: #ffffff;
}

.divisibility-rules-progress-step.complete {
    color: #15803d;
}

.divisibility-rules-progress-step.complete
.divisibility-rules-progress-circle {
    border-color: #15803d;
    background: #15803d;
    color: #ffffff;
}

.divisibility-rules-progress-line.complete {
    background: #15803d;
}


/* ==========================================================
   Workspace
   ========================================================== */

.divisibility-rules-workspace {
    border-top: 1px solid #e2e8f0;
    padding-top: 2rem;
}

.divisibility-rules-work-step {
    max-width: 980px;
    margin: 0 auto;
}

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

.divisibility-rules-work-label {
    margin-bottom: .5rem;
    color: #0d9488;
    font-size: .8rem;
    font-weight: 800;
    letter-spacing: .1em;
    text-transform: uppercase;
}

.divisibility-rules-work-step h3 {
    margin-bottom: 1rem;
    color: #0f172a;
    font-size: 1.65rem;
    font-weight: 800;
}

.divisibility-rules-step-instruction {
    margin-bottom: 1.75rem;
    color: #64748b;
    line-height: 1.75;
}


/* ==========================================================
   Rule Selection Grid
   ========================================================== */

.divisibility-rules-rule-grid {
    display: grid;
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.divisibility-rules-rule-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 180px;
    border: 2px solid #dbe4ef;
    border-radius: 16px;
    background: #ffffff;
    color: #334155;
    padding: 1.25rem;
    cursor: pointer;
    text-align: center;
    transition:
        border-color .2s ease,
        background .2s ease,
        color .2s ease,
        transform .2s ease,
        box-shadow .2s ease;
}

.divisibility-rules-rule-card:hover,
.divisibility-rules-rule-card:focus {
    border-color: #5eead4;
    background: #f0fdfa;
    outline: none;
    transform: translateY(-3px);
    box-shadow: 0 12px 24px rgba(15, 23, 42, .07);
}

.divisibility-rules-rule-card.selected,
.divisibility-rules-rule-card[aria-pressed="true"] {
    border-color: #0d9488;
    background: #ccfbf1;
    color: #115e59;
}

.divisibility-rules-rule-card.correct {
    border-color: #15803d;
    background: #dcfce7;
    color: #166534;
}

.divisibility-rules-rule-card.incorrect {
    border-color: #dc2626;
    background: #fef2f2;
    color: #991b1b;
}

.divisibility-rules-rule-card:disabled {
    cursor: not-allowed;
    opacity: .7;
    transform: none;
}

.divisibility-rules-rule-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 54px;
    height: 54px;
    margin-bottom: 1rem;
    border-radius: 50%;
    background: #0d9488;
    color: #ffffff;
    font-size: 1.35rem;
    font-weight: 800;
}

.divisibility-rules-rule-card.selected
.divisibility-rules-rule-number,
.divisibility-rules-rule-card[aria-pressed="true"]
.divisibility-rules-rule-number {
    background: #115e59;
}

.divisibility-rules-rule-name {
    margin-bottom: .45rem;
    color: inherit;
    font-size: .98rem;
    font-weight: 800;
}

.divisibility-rules-rule-summary {
    color: #64748b;
    font-size: .85rem;
    line-height: 1.5;
}

.divisibility-rules-rule-card.selected
.divisibility-rules-rule-summary,
.divisibility-rules-rule-card[aria-pressed="true"]
.divisibility-rules-rule-summary {
    color: #356b67;
}

.divisibility-rules-selection-actions {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: .75rem;
}

/* ==========================================================
   Explanation List
   ========================================================== */

.divisibility-rules-explanation-list {
    display: grid;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.divisibility-rules-explanation-card {
    border: 1px solid #dbe4ef;
    border-radius: 16px;
    background: #ffffff;
    padding: 1.5rem;
}

.divisibility-rules-explanation-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 1rem;
}

.divisibility-rules-explanation-divisor {
    color: #334155;
    font-size: .95rem;
    font-weight: 700;
}

.divisibility-rules-explanation-divisor strong {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 2.5rem;
    min-height: 2.5rem;
    margin-left: .35rem;
    border-radius: 50%;
    background: #0d9488;
    color: #ffffff;
    font-size: 1rem;
    font-weight: 800;
}

.divisibility-rules-explanation-status {
    min-height: 1.4rem;
    font-size: .85rem;
    font-weight: 800;
}

.divisibility-rules-explanation-status.correct {
    color: #15803d;
}

.divisibility-rules-explanation-status.incorrect {
    color: #dc2626;
}

.divisibility-rules-explanation-prompt {
    margin-bottom: 1.25rem;
    color: #64748b;
    line-height: 1.7;
}


/* ==========================================================
   Digit Displays
   ========================================================== */

.divisibility-rules-digit-display {
    display: flex;
    align-items: stretch;
    justify-content: center;
    gap: .35rem;
    margin-bottom: 1.25rem;
    overflow-wrap: anywhere;
}

.divisibility-rules-digit-group {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 4rem;
    border: 2px solid #dbe4ef;
    border-radius: 14px;
    background: #f8fafc;
    color: #0f172a;
    padding: .75rem 1rem;
    font-size: clamp(1.6rem, 5vw, 2.5rem);
    font-weight: 800;
    letter-spacing: .08em;
}

.divisibility-rules-digit-group.highlighted {
    border-color: #0d9488;
    background: #ccfbf1;
    color: #115e59;
}

.divisibility-rules-digit-expression {
    margin-bottom: 1.25rem;
    border: 1px solid #dbe4ef;
    border-radius: 14px;
    background: #f8fafc;
    padding: 1rem;
    color: #0f172a;
    text-align: center;
    font-size: clamp(1.25rem, 4vw, 1.8rem);
    font-weight: 800;
    line-height: 1.5;
}


/* ==========================================================
   Explanation Inputs
   ========================================================== */

.divisibility-rules-field-label {
    display: block;
    margin-bottom: .5rem;
    color: #334155;
    font-size: .9rem;
    font-weight: 700;
}

.divisibility-rules-number-input {
    min-height: 3.2rem;
    max-width: 260px;
    border: 2px solid #dbe4ef;
    border-radius: 12px;
    background: #ffffff;
    text-align: center;
    font-size: 1.05rem;
    font-weight: 800;
    transition:
        border-color .2s ease,
        background .2s ease,
        box-shadow .2s ease;
}

.divisibility-rules-number-input:focus {
    border-color: #0d9488;
    box-shadow: 0 0 0 .2rem rgba(13, 148, 136, .14);
}

.divisibility-rules-number-input.correct,
.divisibility-rules-input-correct {
    border-color: #15803d !important;
    background: #f0fdf4;
}

.divisibility-rules-number-input.incorrect,
.divisibility-rules-input-incorrect {
    border-color: #dc2626 !important;
    background: #fef2f2;
}


/* ==========================================================
   Combined Rule Choices
   ========================================================== */

.divisibility-rules-combined-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
}

.divisibility-rules-binary-choice {
    min-height: 4rem;
    border: 2px solid #dbe4ef;
    border-radius: 14px;
    background: #f8fafc;
    color: #334155;
    padding: 1rem;
    cursor: pointer;
    font-weight: 800;
    line-height: 1.5;
    transition:
        border-color .2s ease,
        background .2s ease,
        color .2s ease,
        transform .2s ease;
}

.divisibility-rules-binary-choice:hover,
.divisibility-rules-binary-choice:focus {
    border-color: #5eead4;
    background: #f0fdfa;
    outline: none;
    transform: translateY(-2px);
}

.divisibility-rules-binary-choice.selected,
.divisibility-rules-binary-choice[aria-pressed="true"] {
    border-color: #0d9488;
    background: #ccfbf1;
    color: #115e59;
}

.divisibility-rules-binary-choice.correct {
    border-color: #15803d;
    background: #dcfce7;
    color: #166534;
}

.divisibility-rules-binary-choice.incorrect {
    border-color: #dc2626;
    background: #fef2f2;
    color: #991b1b;
}

.divisibility-rules-binary-choice:disabled {
    cursor: not-allowed;
    opacity: .7;
    transform: none;
}


/* ==========================================================
   Alternating Sum Rule
   ========================================================== */

.divisibility-rules-alternating-groups {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
    margin-bottom: 1.25rem;
}

.divisibility-rules-alternating-group {
    border: 1px solid #dbe4ef;
    border-radius: 14px;
    background: #f8fafc;
    padding: 1.2rem;
}

.divisibility-rules-group-label {
    margin-bottom: .75rem;
    color: #0d9488;
    font-size: .78rem;
    font-weight: 800;
    letter-spacing: .1em;
    text-transform: uppercase;
}

.divisibility-rules-alternating-group
.divisibility-rules-digit-expression {
    margin-bottom: 1rem;
    background: #ffffff;
}


/* ==========================================================
   Explanation Actions
   ========================================================== */

.divisibility-rules-explanation-actions {
    display: flex;
    justify-content: center;
}

.divisibility-rules-explanation-actions .btn {
    min-width: 190px;
}

/* ==========================================================
   Division Confirmation List
   ========================================================== */

.divisibility-rules-confirmation-list {
    display: grid;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.divisibility-rules-division-card {
    border: 1px solid #dbe4ef;
    border-radius: 16px;
    background: #ffffff;
    padding: 1.5rem;
}

.divisibility-rules-division-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    margin-bottom: 1rem;
}

.divisibility-rules-division-title {
    color: #334155;
    font-size: .95rem;
    font-weight: 700;
}

.divisibility-rules-division-title strong {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 2.5rem;
    min-height: 2.5rem;
    margin-left: .35rem;
    border-radius: 50%;
    background: #0d9488;
    color: #ffffff;
    font-size: 1rem;
    font-weight: 800;
}

.divisibility-rules-division-status {
    min-height: 1.4rem;
    font-size: .85rem;
    font-weight: 800;
}

.divisibility-rules-division-status.correct {
    color: #15803d;
}

.divisibility-rules-division-status.incorrect {
    color: #dc2626;
}

.divisibility-rules-division-equation {
    margin-bottom: 1rem;
    border: 1px solid #dbe4ef;
    border-radius: 14px;
    background: #f8fafc;
    padding: 1rem;
    color: #0f172a;
    text-align: center;
    font-size: clamp(1.25rem, 4vw, 1.8rem);
    font-weight: 800;
}

.divisibility-rules-division-input-row {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: .75rem;
}

.divisibility-rules-division-input-row
.divisibility-rules-number-input {
    width: 180px;
    max-width: 100%;
}

.divisibility-rules-division-text {
    color: #64748b;
    font-weight: 700;
}

.divisibility-rules-remainder-input {
    width: 120px !important;
}


/* ==========================================================
   Confirmation Actions
   ========================================================== */

.divisibility-rules-confirmation-actions {
    display: flex;
    justify-content: center;
}

.divisibility-rules-confirmation-actions .btn {
    min-width: 190px;
}


/* ==========================================================
   Feedback
   ========================================================== */

.divisibility-rules-feedback {
    max-width: 980px;
    margin: 1.5rem auto 0;
    border: 1px solid #cbd5e1;
    border-radius: 14px;
    background: #f8fafc;
    padding: 1rem 1.2rem;
    color: #334155;
    font-weight: 700;
    line-height: 1.65;
}

.divisibility-rules-feedback.success {
    border-color: #86cda9;
    background: #f0fdf4;
    color: #166534;
}

.divisibility-rules-feedback.error {
    border-color: #f0a7a7;
    background: #fef2f2;
    color: #991b1b;
}

.divisibility-rules-feedback.info {
    border-color: #93c5fd;
    background: #eff6ff;
    color: #1e40af;
}

.divisibility-rules-feedback[hidden] {
    display: none !important;
}


/* ==========================================================
   Hint
   ========================================================== */

.divisibility-rules-hint-button {
    display: block;
    margin: 1.5rem auto 0;
    border: 0;
    background: transparent;
    color: #0d9488;
    padding: .35rem;
    font-weight: 800;
    text-decoration: underline;
    text-underline-offset: .2rem;
}

.divisibility-rules-hint-button:hover,
.divisibility-rules-hint-button:focus {
    color: #0f766e;
}

.divisibility-rules-hint {
    max-width: 980px;
    margin: 1rem auto 0;
    border-left: 4px solid #0d9488;
    border-radius: 6px 14px 14px 6px;
    background: #f0fdfa;
    padding: 1rem 1.2rem;
    color: #355d59;
    line-height: 1.65;
}

.divisibility-rules-hint[hidden] {
    display: none !important;
}


/* ==========================================================
   Completion
   ========================================================== */

.divisibility-rules-completion {
    max-width: 980px;
    margin: 2rem auto 0;
    border: 1px solid #86cda9;
    border-radius: 18px;
    background: #f0fdf4;
    padding: 2rem;
    text-align: center;
}

.divisibility-rules-completion[hidden] {
    display: none !important;
}

.divisibility-rules-completion-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 58px;
    height: 58px;
    margin-bottom: 1rem;
    border-radius: 50%;
    background: #15803d;
    color: #ffffff;
    font-size: 1.55rem;
    font-weight: 800;
}

.divisibility-rules-completion h3 {
    margin-bottom: .75rem;
    color: #14532d;
    font-size: 1.7rem;
    font-weight: 800;
}

.divisibility-rules-completion > p {
    color: #3f624b;
    line-height: 1.7;
}

.divisibility-rules-final-summary {
    margin: 1.5rem 0;
    border: 1px solid #bbf7d0;
    border-radius: 14px;
    background: #ffffff;
    padding: 1.15rem;
    color: #0f172a;
    font-size: clamp(1.2rem, 4vw, 1.65rem);
    font-weight: 700;
}

.divisibility-rules-final-summary strong {
    color: #15803d;
}

.divisibility-rules-completion-explanation {
    max-width: 720px;
    margin: 0 auto 1.5rem;
}


/* ==========================================================
   Disabled States
   ========================================================== */

.divisibility-rules-page button:disabled,
.divisibility-rules-page input:disabled,
.divisibility-rules-page select:disabled {
    cursor: not-allowed;
    opacity: .68;
}

.divisibility-rules-page input:disabled {
    background: #f1f5f9;
}

/* ==========================================================
   Strategy Cards
   ========================================================== */

.divisibility-rules-strategy-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 1rem;
}

.divisibility-rules-strategy-card {
    min-height: 100%;
    border: 1px solid #dbe4ef;
    border-radius: 16px;
    background: #ffffff;
    padding: 1.5rem;
    box-shadow: 0 12px 28px rgba(15, 23, 42, .05);
}

.divisibility-rules-strategy-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 3rem;
    height: 3rem;
    margin-bottom: 1rem;
    border-radius: 50%;
    background: #0d9488;
    color: #ffffff;
}

.divisibility-rules-strategy-icon svg {
    width: 1.3rem;
    height: 1.3rem;
}

.divisibility-rules-strategy-card h3 {
    margin-bottom: .75rem;
    color: #0f172a;
    font-size: 1.1rem;
    font-weight: 800;
}

.divisibility-rules-strategy-card p {
    margin-bottom: 0;
    color: #64748b;
    line-height: 1.65;
}


/* ==========================================================
   Application Cards
   ========================================================== */

.divisibility-rules-applications {
    background: #ffffff;
}

.divisibility-rules-application-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1rem;
}

.divisibility-rules-application-card {
    min-height: 100%;
    border: 1px solid #dbe4ef;
    border-radius: 16px;
    background: #ffffff;
    padding: 1.5rem;
    box-shadow: 0 12px 28px rgba(15, 23, 42, .05);
}

.divisibility-rules-application-card h3 {
    margin-bottom: .75rem;
    color: #0f172a;
    font-size: 1.1rem;
    font-weight: 800;
}

.divisibility-rules-application-card p {
    margin-bottom: 0;
    color: #64748b;
    line-height: 1.65;
}


/* ==========================================================
   Reference Section
   ========================================================== */

.divisibility-rules-reference {
    background: #f7f9fc;
}

.divisibility-rules-reference-grid {
    display: grid;
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 1rem;
}

.divisibility-rules-reference-card {
    min-height: 100%;
    border: 1px solid #dbe4ef;
    border-radius: 16px;
    background: #ffffff;
    padding: 1.3rem;
    text-align: center;
}

.divisibility-rules-reference-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 3rem;
    height: 3rem;
    margin-bottom: 1rem;
    border-radius: 50%;
    background: #0d9488;
    color: #ffffff;
    font-size: 1.15rem;
    font-weight: 800;
}

.divisibility-rules-reference-card p {
    margin-bottom: 0;
    color: #64748b;
    font-size: .92rem;
    line-height: 1.6;
}


/* ==========================================================
   Bottom CTA
   ========================================================== */

.divisibility-rules-cta {
    background: #ffffff;
}

.divisibility-rules-cta-card {
    max-width: 900px;
    margin: 0 auto;
    border-radius: 20px;
    background: #0f172a;
    color: #ffffff;
    padding: 3rem;
    text-align: center;
}

.divisibility-rules-cta-card h2 {
    margin-bottom: 1rem;
    color: #ffffff;
    font-weight: 800;
}

.divisibility-rules-cta-card p {
    max-width: 700px;
    margin: 0 auto 2rem;
    color: rgba(255, 255, 255, .8);
    line-height: 1.75;
}


/* ==========================================================
   Responsive
   ========================================================== */

@media (max-width: 1100px) {

    .divisibility-rules-rule-grid,
    .divisibility-rules-reference-grid {
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

}

@media (max-width: 992px) {

    .divisibility-rules-overview-grid,
    .divisibility-rules-strategy-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .divisibility-rules-application-grid {
        grid-template-columns: 1fr;
    }

    .divisibility-rules-settings {
        grid-template-columns: 1fr;
    }

    .divisibility-rules-tool-header {
        flex-direction: column;
        align-items: stretch;
    }

    .divisibility-rules-scoreboard {
        display: grid;
        grid-template-columns: repeat(3, minmax(0, 1fr));
    }

    .divisibility-rules-progress-step {
        min-width: 100px;
    }

    .divisibility-rules-progress-line {
        width: 55px;
    }

}

@media (max-width: 768px) {

    .divisibility-rules-overview,
    .divisibility-rules-tool-section,
    .divisibility-rules-strategies,
    .divisibility-rules-applications,
    .divisibility-rules-reference,
    .divisibility-rules-cta {
        padding: 3.5rem 0;
    }

    .divisibility-rules-overview-grid,
    .divisibility-rules-strategy-grid {
        grid-template-columns: 1fr;
    }

    .divisibility-rules-tool {
        padding: 1.25rem;
    }

    .divisibility-rules-problem-area {
        padding: 1.5rem 1rem;
    }

    .divisibility-rules-target-number {
        min-width: 0;
        width: 100%;
        max-width: 320px;
    }

    .divisibility-rules-progress {
        justify-content: flex-start;
        overflow-x: auto;
        padding-bottom: .5rem;
    }

    .divisibility-rules-progress-step {
        flex: 0 0 auto;
        min-width: 90px;
    }

    .divisibility-rules-progress-line {
        flex: 0 0 42px;
    }

    .divisibility-rules-rule-grid,
    .divisibility-rules-reference-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .divisibility-rules-combined-grid,
    .divisibility-rules-alternating-groups {
        grid-template-columns: 1fr;
    }

    .divisibility-rules-selection-actions {
        flex-direction: column;
    }

    .divisibility-rules-selection-actions .btn {
        width: 100%;
    }

    .divisibility-rules-explanation-header,
    .divisibility-rules-division-header {
        align-items: flex-start;
        flex-direction: column;
    }

    .divisibility-rules-number-input {
        max-width: 100%;
    }

    .divisibility-rules-division-input-row {
        flex-direction: column;
        align-items: stretch;
    }

    .divisibility-rules-division-input-row
    .divisibility-rules-number-input,
    .divisibility-rules-remainder-input {
        width: 100% !important;
    }

    .divisibility-rules-division-text {
        text-align: center;
    }

    .divisibility-rules-cta-card {
        padding: 2rem 1.5rem;
    }

}

@media (max-width: 480px) {

    .divisibility-rules-tool-header {
        gap: 1.25rem;
    }

    .divisibility-rules-score-item {
        min-width: 0;
        padding: .75rem .45rem;
    }

    .divisibility-rules-score-label {
        font-size: .63rem;
    }

    .divisibility-rules-score-item strong {
        font-size: 1.35rem;
    }

    .divisibility-rules-rule-grid,
    .divisibility-rules-reference-grid {
        grid-template-columns: 1fr;
    }

    .divisibility-rules-rule-card {
        min-height: 0;
    }

    .divisibility-rules-digit-display {
        flex-direction: column;
    }

    .divisibility-rules-digit-group {
        width: 100%;
    }

}