/* ======================================== */
/* STUDYNEST MEASURES & MENSURATION LESSONS                  */
/* ======================================== */

:root {
    --navy: #0f438c;
    --navy-dark: #0a326b;
    --blue: #637f99;
    --blue-light: #e8eff4;
    --page: #f0f4f7;
    --card: #ffffff;
    --border: #d6e0e7;
    --text: #1e2c43;
    --muted: #4f5d70;
    --yellow: #fff2bf;
    --yellow-border: #f5ad00;
    --green: #e4f5e8;
    --green-dark: #2f7444;
    --pink: #f8e8ef;
    --pink-dark: #8b4664;
    --purple: #eee8f8;
    --purple-dark: #654d91;
    --shadow: 0 12px 30px rgba(51, 75, 96, 0.08);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
    margin: 0;
    color: var(--text);
    background: var(--page);
    font-family: Arial, Helvetica, sans-serif;
    line-height: 1.65;
}

a { color: inherit; text-decoration: none; }

.announcement-bar {
    padding: 8px 18px;
    color: #111;
    background: #f7b500;
    font-size: .82rem;
    font-weight: 700;
    text-align: center;
}

.site-header {
    display: flex;
    min-height: 76px;
    padding: 0 38px;
    align-items: center;
    justify-content: space-between;
    gap: 30px;
    border-bottom: 1px solid var(--border);
    background: white;
}

.logo {
    color: var(--navy);
    font-size: 1.45rem;
    font-weight: 800;
}

.main-navigation {
    display: flex;
    flex-wrap: wrap;
    gap: 24px;
}

.main-navigation a {
    font-size: .88rem;
    font-weight: 700;
}

.lesson-hero {
    display: grid;
    min-height: 400px;
    padding: 60px clamp(22px, 7vw, 95px);
    align-items: center;
    grid-template-columns: minmax(0, 1.1fr) minmax(310px, .9fr);
    gap: 45px;
    background:
        radial-gradient(circle at 85% 15%, rgba(255,255,255,.95), transparent 26%),
        linear-gradient(135deg, #f8fbff, #eaf2fb);
}

.lesson-label,
.eyebrow {
    margin: 0 0 10px;
    color: var(--navy);
    font-size: .78rem;
    font-weight: 900;
    letter-spacing: .12em;
    text-transform: uppercase;
}

.lesson-hero h1 {
    margin: 0;
    color: var(--navy);
    font-size: clamp(2.9rem, 6vw, 4.8rem);
    line-height: 1.04;
    letter-spacing: -.04em;
}

.lesson-subtitle {
    max-width: 680px;
    margin: 20px 0 0;
    color: var(--muted);
    font-size: 1.08rem;
}

.lesson-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 24px;
}

.meta-pill {
    padding: 8px 13px;
    border: 1px solid var(--border);
    border-radius: 999px;
    color: var(--navy);
    background: white;
    font-size: .78rem;
    font-weight: 800;
}

.hero-visual {
    display: grid;
    min-height: 270px;
    place-items: center;
}

.mini-coordinate-plane {
    position: relative;
    width: 290px;
    height: 245px;
    border: 1px solid var(--border);
    border-radius: 25px;
    background:
        linear-gradient(#dfe8f2 1px, transparent 1px),
        linear-gradient(90deg, #dfe8f2 1px, transparent 1px),
        white;
    background-size: 32px 32px;
    box-shadow: var(--shadow);
}

.mini-coordinate-plane::before,
.mini-coordinate-plane::after {
    content: "";
    position: absolute;
    background: var(--navy);
}

.mini-coordinate-plane::before {
    top: 20px;
    bottom: 20px;
    left: 50%;
    width: 3px;
}

.mini-coordinate-plane::after {
    right: 20px;
    bottom: 50%;
    left: 20px;
    height: 3px;
}

.plot-dot {
    position: absolute;
    z-index: 2;
    width: 15px;
    height: 15px;
    border: 3px solid white;
    border-radius: 50%;
    background: var(--blue);
    box-shadow: 0 3px 9px rgba(15,67,140,.25);
}

.dot-a { left: 205px; top: 55px; }
.dot-b { left: 75px; top: 155px; }
.dot-c { left: 180px; top: 180px; }

.graph-line-demo {
    position: absolute;
    z-index: 1;
    left: 55px;
    bottom: 65px;
    width: 205px;
    height: 5px;
    border-radius: 999px;
    background: var(--blue);
    transform: rotate(-36deg);
    transform-origin: left center;
}

.lesson-main {
    width: min(1180px, calc(100% - 28px));
    margin: 36px auto 70px;
}

.lesson-section {
    margin-bottom: 28px;
    padding: 38px 52px;
    border: 1px solid var(--border);
    border-radius: 27px;
    background: white;
    box-shadow: var(--shadow);
}

.lesson-section h2 {
    margin: 0 0 18px;
    color: var(--navy);
    font-size: clamp(1.65rem, 3vw, 2.25rem);
}

.lesson-section h3 {
    margin: 25px 0 10px;
    color: var(--navy);
}

.lesson-section p { color: var(--muted); }

.objective-list,
.summary-list,
.practice-list {
    margin: 14px 0 0;
    padding-left: 24px;
}

.objective-list li,
.summary-list li,
.practice-list li {
    margin: 8px 0;
}

.think-box,
.key-idea,
.tip-box,
.warning-box,
.did-you-know,
.challenge-box {
    margin: 22px 0;
    padding: 20px 23px;
    border-radius: 0 17px 17px 0;
}

.think-box {
    border-left: 5px solid var(--yellow-border);
    background: var(--yellow);
}

.key-idea {
    border-left: 5px solid var(--blue);
    background: #eaf3ff;
}

.tip-box {
    border-left: 5px solid #54a46a;
    background: var(--green);
}

.warning-box {
    border-left: 5px solid #d5648f;
    background: var(--pink);
}

.did-you-know {
    border-left: 5px solid #8367b2;
    background: var(--purple);
}

.challenge-box {
    border-left: 5px solid #815a20;
    background: #f9eddc;
}

.math-display {
    margin: 20px 0;
    padding: 17px;
    border: 1px solid var(--border);
    border-radius: 15px;
    color: var(--navy);
    background: #f8fbff;
    font-size: 1.18rem;
    font-weight: 800;
    text-align: center;
}

.visual-grid-two {
    display: grid;
    grid-template-columns: repeat(2, minmax(0,1fr));
    gap: 20px;
    margin-top: 22px;
}

.visual-card {
    padding: 24px;
    border: 1px solid var(--border);
    border-radius: 21px;
    background: #f9fbfd;
}

.visual-card h3 { margin-top: 0; }

.coordinate-diagram,
.travel-diagram,
.line-diagram {
    position: relative;
    width: min(100%, 480px);
    height: 310px;
    margin: 24px auto;
    border: 1px solid var(--border);
    border-radius: 22px;
    background:
        linear-gradient(#dde7f1 1px, transparent 1px),
        linear-gradient(90deg, #dde7f1 1px, transparent 1px),
        white;
    background-size: 35px 35px;
    overflow: hidden;
}

.axis-x,
.axis-y {
    position: absolute;
    z-index: 2;
    background: var(--navy);
}

.axis-x {
    left: 25px;
    right: 25px;
    top: 50%;
    height: 3px;
}

.axis-y {
    top: 25px;
    bottom: 25px;
    left: 50%;
    width: 3px;
}

.axis-label {
    position: absolute;
    z-index: 3;
    color: var(--navy);
    font-weight: 900;
}

.x-label { right: 12px; top: calc(50% - 24px); }
.y-label { left: calc(50% + 10px); top: 8px; }

.quadrant {
    position: absolute;
    color: #7c8b9d;
    font-size: .75rem;
    font-weight: 800;
}

.q1 { right: 52px; top: 42px; }
.q2 { left: 52px; top: 42px; }
.q3 { left: 52px; bottom: 42px; }
.q4 { right: 52px; bottom: 42px; }

.example-table {
    width: 100%;
    margin: 22px 0;
    border-collapse: collapse;
    overflow: hidden;
    border-radius: 14px;
}

.example-table th,
.example-table td {
    padding: 13px;
    border: 1px solid var(--border);
    text-align: center;
}

.example-table th {
    color: white;
    background: var(--navy);
}

.example-table tr:nth-child(even) td {
    background: #f5f8fc;
}

.worked-example {
    margin: 22px 0;
    padding: 24px;
    border: 1px solid var(--border);
    border-radius: 20px;
    background: #fbfcfe;
}

.worked-example h3 { margin-top: 0; }

.step {
    display: grid;
    grid-template-columns: 42px minmax(0,1fr);
    gap: 14px;
    margin-top: 16px;
    align-items: start;
}

.step-number {
    display: grid;
    width: 38px;
    height: 38px;
    place-items: center;
    border-radius: 50%;
    color: white;
    background: var(--navy);
    font-weight: 900;
}

.quick-check {
    display: grid;
    grid-template-columns: repeat(3, minmax(0,1fr));
    gap: 15px;
    margin-top: 20px;
}

.quick-card {
    padding: 20px;
    border: 1px solid var(--border);
    border-radius: 18px;
    background: #f9fbfd;
}

.level-heading {
    display: inline-flex;
    margin: 22px 0 8px;
    padding: 7px 12px;
    border-radius: 999px;
    color: var(--navy);
    background: var(--blue-light);
    font-size: .75rem;
    font-weight: 900;
}

.lesson-navigation {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 15px;
    margin-top: 34px;
}

.nav-button {
    display: flex;
    min-height: 52px;
    padding: 12px 18px;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--border);
    border-radius: 999px;
    color: var(--navy);
    background: white;
    font-weight: 800;
    text-align: center;
}

.nav-button.primary {
    color: white;
    background: var(--navy);
}

.site-footer {
    padding: 34px 20px 24px;
    color: white;
    background: var(--navy);
    text-align: center;
}

.site-footer p { margin: 8px 0; font-size: .82rem; }

@media (max-width: 900px) {
    .lesson-hero { grid-template-columns: 1fr; }
    .visual-grid-two { grid-template-columns: 1fr; }
    .quick-check { grid-template-columns: 1fr; }
}

@media (max-width: 700px) {
    .site-header {
        padding: 18px 20px;
        align-items: flex-start;
        flex-direction: column;
    }

    .lesson-hero {
        padding: 45px 23px;
        text-align: center;
    }

    .lesson-meta { justify-content: center; }
    .lesson-section { padding: 28px 23px; }
    .lesson-navigation { grid-template-columns: 1fr; }
}
/* ======================================== */
/* VARIATION-SPECIFIC COMPONENTS            */
/* ======================================== */

.relationship-flow {
    display: grid;
    grid-template-columns: minmax(120px, 1fr) auto minmax(120px, 1fr);
    align-items: center;
    gap: 18px;
    margin: 24px 0;
}

.relationship-box {
    padding: 22px;
    border: 1px solid var(--border);
    border-radius: 19px;
    color: var(--navy);
    background: #f8fbff;
    font-size: 1.05rem;
    font-weight: 800;
    text-align: center;
}

.relationship-arrow {
    color: var(--blue);
    font-size: 2rem;
    font-weight: 900;
}

.ratio-strip {
    display: grid;
    grid-template-columns: repeat(4, minmax(80px, 1fr));
    gap: 12px;
    margin: 22px 0;
}

.ratio-strip div {
    padding: 17px 12px;
    border: 1px solid var(--border);
    border-radius: 16px;
    background: #f9fbfd;
    text-align: center;
}

.ratio-strip strong {
    display: block;
    color: var(--navy);
    font-size: 1.1rem;
}

.recognition-box {
    margin: 22px 0;
    padding: 21px 24px;
    border-left: 5px solid #7b68b0;
    border-radius: 0 17px 17px 0;
    background: #eee8f8;
}

.recognition-box h3 {
    margin-top: 0;
    color: #5c4788;
}

.answers-section details {
    margin-top: 18px;
    overflow: hidden;
    border: 1px solid var(--border);
    border-radius: 18px;
    background: #f9fbfd;
}

.answers-section summary {
    padding: 18px 22px;
    color: var(--navy);
    font-weight: 800;
    cursor: pointer;
    list-style-position: inside;
}

.answers-section summary:hover {
    background: #f1f6fc;
}

.answers-content {
    padding: 5px 24px 24px;
    border-top: 1px solid var(--border);
}

.answers-content h3 {
    margin-top: 22px;
}

.answers-content ol {
    padding-left: 24px;
}

.answers-content li {
    margin: 10px 0;
    color: var(--muted);
}

.answer-working {
    margin-top: 7px;
    padding: 10px 13px;
    border-radius: 12px;
    color: var(--text);
    background: white;
}

@media (max-width: 700px) {
    .relationship-flow {
        grid-template-columns: 1fr;
    }

    .relationship-arrow {
        transform: rotate(90deg);
        text-align: center;
    }

    .ratio-strip {
        grid-template-columns: repeat(2, minmax(80px, 1fr));
    }
}
/* ======================================== */
/* MEASURES & MENSURATION COMPONENTS        */
/* ======================================== */

.diagram-card {
    margin: 24px 0;
    padding: 22px;
    border: 1px solid var(--border);
    border-radius: 22px;
    background: #fbfdff;
}

.diagram-card svg {
    display: block;
    width: min(100%, 680px);
    height: auto;
    margin: 0 auto;
    color: var(--navy);
}

.diagram-card figcaption {
    margin-top: 14px;
    color: var(--muted);
    text-align: center;
}

.unit-ladder {
    display: grid;
    grid-template-columns: repeat(7, minmax(70px,1fr));
    gap: 8px;
    margin: 24px 0;
}

.unit-step {
    padding: 15px 8px;
    border: 1px solid var(--border);
    border-radius: 14px;
    background: #f8fbfd;
    text-align: center;
    font-weight: 800;
}

.unit-arrow {
    color: var(--blue);
    text-align: center;
    font-weight: 900;
}

.shape-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0,1fr));
    gap: 18px;
    margin: 22px 0;
}

.shape-card {
    padding: 22px;
    border: 1px solid var(--border);
    border-radius: 20px;
    background: #f9fbfd;
}

.shape-card h3 {
    margin-top: 0;
}

.measure-tip {
    margin: 22px 0;
    padding: 22px 24px;
    border-left: 5px solid #527aa3;
    border-radius: 0 17px 17px 0;
    background: #eaf3fa;
}

.answers-section details {
    margin-top: 18px;
    overflow: hidden;
    border: 1px solid var(--border);
    border-radius: 18px;
    background: #f9fbfd;
}

.answers-section summary {
    padding: 18px 22px;
    color: var(--navy);
    font-weight: 800;
    cursor: pointer;
    list-style-position: inside;
}

.answers-content {
    padding: 5px 24px 24px;
    border-top: 1px solid var(--border);
}

.answer-working {
    margin-top: 7px;
    padding: 10px 13px;
    border-radius: 12px;
    color: var(--text);
    background: white;
}

@media (max-width: 820px) {
    .unit-ladder {
        grid-template-columns: repeat(2, minmax(0,1fr));
    }

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

/* ======================================== */
/* MEASURES & MENSURATION HERO              */
/* Muted slate-blue topic theme.            */
/* ======================================== */

.measures-hero-art {
    position: relative;
    width: 310px;
    height: 245px;
    border: 1px solid var(--border);
    border-radius: 25px;
    background:
        radial-gradient(circle at 18% 15%, rgba(255,255,255,.98), transparent 31%),
        linear-gradient(145deg, #f8fbfd, #e8eff4);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.measure-ruler {
    position: absolute;
    z-index: 4;
    top: 36px;
    left: 34px;
    display: flex;
    align-items: flex-start;
    gap: 12px;
    width: 235px;
    height: 49px;
    padding: 8px 14px;
    border: 2px solid var(--navy);
    border-radius: 12px;
    background: white;
    box-shadow: var(--shadow);
    transform: rotate(-5deg);
    animation: rulerFloat 5.5s ease-in-out infinite;
}

.measure-ruler span {
    width: 2px;
    height: 18px;
    background: var(--navy);
}

.measure-ruler span:nth-child(odd) {
    height: 28px;
}

.measure-triangle {
    position: absolute;
    z-index: 2;
    bottom: 29px;
    left: 35px;
    width: 0;
    height: 0;
    border-right: 63px solid transparent;
    border-bottom: 108px solid var(--blue);
    border-left: 63px solid transparent;
    filter: drop-shadow(0 10px 15px rgba(51,75,96,.12));
    opacity: .86;
    animation: shapeFloat 5.2s ease-in-out infinite;
}

.measure-triangle::after {
    content: "";
    position: absolute;
    top: 26px;
    left: -38px;
    width: 0;
    height: 0;
    border-right: 38px solid transparent;
    border-bottom: 65px solid #f0f4f7;
    border-left: 38px solid transparent;
}

.measure-circle {
    position: absolute;
    z-index: 4;
    right: 35px;
    bottom: 35px;
    display: grid;
    width: 88px;
    height: 88px;
    place-items: center;
    border: 4px solid var(--navy);
    border-radius: 50%;
    color: var(--navy);
    background: rgba(255,255,255,.82);
    font-weight: 900;
    animation: shapeFloat 4.8s ease-in-out infinite reverse;
}

.measure-circle::before {
    content: "";
    position: absolute;
    width: 40px;
    height: 3px;
    border-radius: 5px;
    background: var(--navy);
    transform: rotate(-34deg);
    transform-origin: right center;
}

.measure-circle span {
    position: absolute;
    top: 17px;
    right: 22px;
    font-size: .78rem;
}

.measure-cube {
    position: absolute;
    z-index: 3;
    top: 93px;
    left: 126px;
    width: 74px;
    height: 74px;
    animation: cubeFloat 5.7s ease-in-out infinite;
}

.cube-front,
.cube-back {
    position: absolute;
    width: 48px;
    height: 48px;
    border: 3px solid var(--navy);
    border-radius: 5px;
    background: rgba(255,255,255,.68);
}

.cube-front {
    left: 0;
    bottom: 0;
}

.cube-back {
    top: 0;
    right: 0;
}

.cube-edge {
    position: absolute;
    width: 29px;
    height: 3px;
    border-radius: 4px;
    background: var(--navy);
    transform: rotate(-43deg);
}

.edge-one { top: 11px; left: 13px; }
.edge-two { top: 11px; right: 8px; }
.edge-three { bottom: 11px; left: 13px; }
.edge-four { right: 8px; bottom: 11px; }

.measure-chip {
    position: absolute;
    z-index: 6;
    top: 98px;
    right: 21px;
    display: grid;
    min-width: 54px;
    height: 43px;
    padding: 8px;
    place-items: center;
    border: 1px solid var(--border);
    border-radius: 14px;
    color: var(--navy);
    background: white;
    box-shadow: var(--shadow);
    font-weight: 900;
    animation: shapeFloat 4.5s ease-in-out infinite;
}

@keyframes rulerFloat {
    0%, 100% { transform: translateY(0) rotate(-5deg); }
    50% { transform: translateY(-6px) rotate(-3deg); }
}

@keyframes shapeFloat {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-7px); }
}

@keyframes cubeFloat {
    0%, 100% { transform: translateY(0) rotate(0); }
    50% { transform: translateY(-6px) rotate(2deg); }
}

@media (prefers-reduced-motion: reduce) {
    .measure-ruler,
    .measure-triangle,
    .measure-circle,
    .measure-cube,
    .measure-chip {
        animation: none;
    }
}

/* Interactive Measures & Mensuration labs */
.mm-interactive-lab{overflow:hidden}.mm-lab-grid{display:grid;grid-template-columns:minmax(220px,.75fr) minmax(320px,1.25fr);gap:24px;align-items:stretch}.mm-controls,.mm-visual{border:1px solid var(--border);border-radius:20px;background:#fff;padding:22px}.mm-controls{display:grid;gap:18px;align-content:center}.mm-controls label{display:grid;gap:8px;color:var(--navy);font-weight:800}.mm-controls input[type=range]{width:100%;accent-color:var(--blue)}.mm-controls input[type=number],.mm-controls select{width:100%;padding:11px 12px;border:1px solid var(--border);border-radius:12px;background:#fff;color:var(--text);font:inherit}.mm-visual{background:linear-gradient(180deg,#fbfdff,#f4f8ff)}#mm-svg{width:100%;min-height:250px}.mm-result{margin-top:12px;padding:14px 16px;border-radius:14px;background:var(--yellow-soft,#fff6cf);color:var(--navy);font-weight:900;text-align:center}.mm-button{border:0;border-radius:12px;padding:12px 16px;background:var(--navy);color:#fff;font-weight:850;cursor:pointer}.mm-button.secondary{background:#eaf1ff;color:var(--navy)}.mm-shape,.mm-face{fill:#dce9ff;stroke:#183b66;stroke-width:4}.mm-shape.light,.mm-face.light{fill:#f7dd87}.mm-face.dark{fill:#a9c7ff}.mm-guide{stroke:#e16b5b;stroke-width:3;stroke-dasharray:8 7}.mm-outline{fill:#fff;stroke:#183b66;stroke-width:4}.mm-fill{fill:#f7dd87;stroke:none}.mm-cut{fill:#fff;stroke:#e16b5b;stroke-width:3;stroke-dasharray:7 6}#mm-svg text{fill:#183b66;font-size:18px;font-weight:800}.mm-question{font-size:16px!important}.mm-result:not(.revealed){transition:filter .2s}.mm-interactive-lab:has(#mm-show) .mm-result:not(.revealed){filter:blur(7px);user-select:none}@media(max-width:780px){.mm-lab-grid{grid-template-columns:1fr}.mm-controls,.mm-visual{padding:16px}#mm-svg{min-height:220px}}