/* ========================================
   ROOT VARIABLES & RESET
   ======================================== */

:root {
    --color-dark-navy: #003F87;
    --color-educational-blue: #0052A3;
    --color-light-blue: #FFFFFF;
    --color-white: #FFFFFF;
    --color-gray-50: #FFFFFF;
    --color-gray-100: #FFFFFF;
    --color-gray-200: #F0F8FF;
    --color-gray-400: #003F87;
    --color-gray-600: #FFFFFF;
    --color-gray-700: #003F87;

    --font-primary: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    --font-size-base: 16px;
    --line-height-base: 1.6;

    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;

    --transition-base: all 0.3s ease;
    --transition-smooth: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);

    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);

    --border-radius-sm: 0.375rem;
    --border-radius-md: 0.5rem;
    --border-radius-lg: 1rem;
    --border-radius-xl: 1.5rem;
}

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

html {
    scroll-behavior: smooth;
    font-size: var(--font-size-base);
}

body {
    font-family: var(--font-primary);
    line-height: var(--line-height-base);
    color: #FFFFFF;
    background-color: #003F87;
    overflow-x: hidden;
}

/* ========================================
   TYPOGRAPHY
   ======================================== */

h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    color: #FFFFFF;
}

h1 {
    font-size: 2.25rem;
}

h2 {
    font-size: 2rem;
}

h3 {
    font-size: 1.5rem;
}

p {
    margin: 0;
}

a {
    color: #0052A3;
    text-decoration: none;
    transition: var(--transition-base);
}

a:hover {
    color: #003F87;
}

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

.btn {
    display: inline-block;
    padding: 0.875rem 1.75rem;
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: var(--border-radius-md);
    cursor: pointer;
    transition: var(--transition-smooth);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-family: var(--font-primary);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn:active {
    transform: translateY(0);
}

.btn--primary {
    background-color: #0052A3;
    color: var(--color-white);
}

.btn--primary:hover {
    background-color: #003F87;
}

.btn--secondary {
    background-color: transparent;
    color: #FFFFFF;
    border: 2px solid #FFFFFF;
}

.btn--secondary:hover {
    background-color: #FFFFFF;
    border-color: #FFFFFF;
    color: #003F87;
}

.btn--outline {
    background-color: transparent;
    color: #0052A3;
    border: 2px solid #0052A3;
    width: 100%;
    padding: 0.75rem 1.5rem;
}

.btn--outline:hover {
    background-color: #0052A3;
    color: var(--color-white);
}

/* ========================================
   CONTAINERS & LAYOUT
   ======================================== */

.header__container,
.hero__container,
.modules__container,
.features__container,
.about__container,
.footer__container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

section {
    padding: var(--spacing-2xl) 0;
}

.section__title {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    font-size: 2rem;
    position: relative;
    animation: fadeInUp 0.8s ease-out;
    color: #FFFFFF;
}

.section__title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: #5B9FD4;
    margin: var(--spacing-md) auto 0;
    border-radius: 2px;
}

/* ========================================
   HEADER
   ======================================== */

.header {
    background-color: #003F87;
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 100;
    animation: slideDown 0.5s ease-out;
}

@keyframes slideDown {
    from {
        transform: translateY(-100%);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.header__container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg) var(--spacing-lg);
}

.header__logo-section {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.header__logo {
    width: 72px;
    height: 72px;
    border-radius: var(--border-radius-md);
    object-fit: contain;
    background-color: #FFFFFF;
    padding: 8px;
}

.header__brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: #FFFFFF;
    letter-spacing: -0.02em;
}

.nav__list {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
    margin: 0;
}

.nav__link {
    position: relative;
    color: #FFFFFF;
    font-weight: 500;
    font-size: 0.95rem;
}

.nav__link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: #FFFFFF;
    transition: width 0.3s ease;
}

.nav__link:hover::after {
    width: 100%;
}

/* ========================================
   HERO SECTION
   ======================================== */

.hero {
    background: #003F87;
    padding: var(--spacing-2xl) 0 var(--spacing-xl);
}

.hero__container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    align-items: center;
}

.hero__content {
    animation: fadeInLeft 0.8s ease-out;
}

.hero__title {
    font-size: 3rem;
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: var(--spacing-md);
    color: #FFFFFF;
}

.hero__subtitle {
    font-size: 1.125rem;
    color: #FFFFFF;
    margin-bottom: var(--spacing-lg);
    line-height: 1.8;
}

.hero__buttons {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.hero__illustration {
    position: relative;
    height: 400px;
    animation: fadeInRight 0.8s ease-out;
}

.hero__shape {
    position: absolute;
    border-radius: 50%;
    animation: float 3s ease-in-out infinite;
}

.hero__shape--1 {
    width: 150px;
    height: 150px;
    background: var(--color-educational-blue);
    top: 50px;
    right: 100px;
    opacity: 0.22;
    animation-delay: 0s;
}

.hero__shape--2 {
    width: 100px;
    height: 100px;
    background: var(--color-light-blue);
    top: 200px;
    right: 20px;
    opacity: 0.28;
    animation-delay: 1s;
}

.hero__shape--3 {
    width: 80px;
    height: 80px;
    background: var(--color-educational-blue);
    top: 300px;
    right: 150px;
    opacity: 0.18;
    animation-delay: 2s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-20px);
    }
}

@keyframes fadeInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes fadeInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ========================================
   MODULES SECTION
   ======================================== */

.modules {
    background-color: #0052A3;
}

.modules__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.module-card {
    background: #0052A3;
    border: 2px solid #5B9FD4;
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    transition: var(--transition-smooth);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    animation: fadeInUp 0.8s ease-out;
    animation-fill-mode: both;
}

.module-card:nth-child(1) {
    animation-delay: 0.1s;
}

.module-card:nth-child(2) {
    animation-delay: 0.2s;
}

.module-card:nth-child(3) {
    animation-delay: 0.3s;
}

.module-card:nth-child(4) {
    animation-delay: 0.4s;
}

.module-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: #FFFFFF;
}

.module-card__header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.module-card__icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 60px;
    height: 60px;
    background: #0052A3;
    border-radius: var(--border-radius-lg);
    font-size: 1.75rem;
    color: var(--color-white);
    font-weight: 700;
}

.module-card__title {
    font-size: 1.5rem;
    color: #FFFFFF;
}

.module-card__content {
    list-style: none;
    flex-grow: 1;
    margin-bottom: var(--spacing-lg);
}

.module-card__item {
    padding: var(--spacing-sm) 0;
    color: #FFFFFF;
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    display: flex;
    align-items: center;
}

.module-card__item:last-child {
    border-bottom: none;
}

.module-card__item::before {
    content: '✓';
    display: inline-block;
    margin-right: var(--spacing-sm);
    color: #5B9FD4;
    font-weight: 700;
}

.module-card .btn {
    margin-top: auto;
}

/* ========================================
   FEATURES SECTION
   ======================================== */

.features {
    background: linear-gradient(135deg, #0052A3 0%, #003F87 100%);
}

.features__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-2xl);
}

.feature-block {
    text-align: center;
    padding: var(--spacing-lg);
    animation: fadeInUp 0.8s ease-out;
    animation-fill-mode: both;
}

.feature-block:nth-child(1) {
    animation-delay: 0.1s;
}

.feature-block:nth-child(2) {
    animation-delay: 0.2s;
}

.feature-block:nth-child(3) {
    animation-delay: 0.3s;
}

.feature-block__icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    display: inline-block;
    transition: var(--transition-smooth);
}

.feature-block:hover .feature-block__icon {
    transform: scale(1.1) rotate(5deg);
}

.feature-block__title {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-md);
    color: #FFFFFF;
}

.feature-block__description {
    color: #FFFFFF;
    line-height: 1.8;
}

/* ========================================
   ABOUT SECTION
   ======================================== */

.about {
    background-color: #0052A3;
    color: var(--color-white);
}

.about__container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    text-align: center;
}

.about .section__title {
    color: var(--color-white);
}

.about .section__title::after {
    background: #FFFFFF;
}

.about__text {
    font-size: 1.125rem;
    line-height: 1.9;
    color: var(--color-white);
    animation: fadeInUp 0.8s ease-out;
}

/* ========================================
   FOOTER
   ======================================== */

.footer {
    background-color: #003F87;
    color: var(--color-white);
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer__container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.footer__content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-xl);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer__section {
    animation: fadeInUp 0.8s ease-out;
}

.footer__title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    color: var(--color-white);
}

.footer__subtitle {
    color: #FFFFFF;
    font-size: 0.9rem;
}

.footer__text {
    color: #FFFFFF;
    font-size: 0.9rem;
}

.footer__bottom {
    text-align: center;
}

.footer__copyright {
    color: #FFFFFF;
    font-size: 0.85rem;
}

.footer__author {
    color: #FFFFFF;
    font-size: 0.8rem;
    margin-top: 0.5rem;
}

/* ========================================
   ALGEBRA MODULE STYLES
   ======================================== */

.module-hero {
    position: relative;
    background: linear-gradient(135deg, #0F172A 0%, #2563EB 52%, #7C3AED 100%);
    color: #FFFFFF;
    padding: var(--spacing-2xl) 0;
}

.module-hero__container,
.module-objectives .container,
.module-chapters .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.module-hero__container {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: var(--spacing-2xl);
    align-items: center;
}

.module-hero__content {
    max-width: 760px;
    animation: fadeInLeft 0.8s ease-out;
}

.module-hero__visual {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 320px;
    animation: fadeInRight 0.8s ease-out;
}

.module-hero__logo-panel {
    position: relative;
    z-index: 2;
    width: 320px;
    height: 320px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.12);
    border: 1px solid rgba(255, 255, 255, 0.28);
    box-shadow: 0 24px 50px rgba(15, 23, 42, 0.25);
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(4px);
}

.module-hero__logo {
    width: 220px;
    height: 220px;
    object-fit: contain;
    background: #FFFFFF;
    border-radius: 28px;
    padding: 22px;
}

.module-hero__orb {
    position: absolute;
    border-radius: 50%;
    display: block;
    animation: float 3.5s ease-in-out infinite;
}

.module-hero__orb--one {
    width: 150px;
    height: 150px;
    background: rgba(124, 58, 237, 0.28);
    top: 10px;
    right: 60px;
}

.module-hero__orb--two {
    width: 110px;
    height: 110px;
    background: rgba(255, 255, 255, 0.18);
    bottom: 24px;
    left: 30px;
    animation-delay: 0.8s;
}

.module-hero__orb--three {
    width: 75px;
    height: 75px;
    background: rgba(37, 99, 235, 0.24);
    bottom: 60px;
    right: 20px;
    animation-delay: 1.4s;
}

.eyebrow {
    display: inline-block;
    margin-bottom: var(--spacing-sm);
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: rgba(255, 255, 255, 0.8);
}

.module-hero h1 {
    font-size: clamp(2.3rem, 4vw, 3.5rem);
    line-height: 1.1;
    margin-bottom: var(--spacing-md);
    color: #FFFFFF;
}

.module-hero__subtitle {
    max-width: 680px;
    font-size: 1.125rem;
    line-height: 1.8;
    color: rgba(255, 255, 255, 0.92);
}

.module-objectives {
    background: #FFFFFF;
    color: #0F172A;
    padding: var(--spacing-2xl) 0;
}

.module-objectives h2,
.module-chapters h2 {
    color: #0F172A;
    margin-bottom: var(--spacing-xl);
    font-size: clamp(1.8rem, 2vw, 2.4rem);
    display: inline-block;
}

.module-objectives h2::after,
.module-chapters h2::after {
    content: '';
    display: block;
    width: 72px;
    height: 4px;
    border-radius: 999px;
    background: linear-gradient(90deg, #7C3AED 0%, #2563EB 100%);
    margin-top: var(--spacing-sm);
}

.objectives-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: var(--spacing-lg);
}

.objective-card {
    background: linear-gradient(180deg, #FFFFFF 0%, #F8FAFC 100%);
    border: 1px solid rgba(15, 23, 42, 0.08);
    border-left: 4px solid #7C3AED;
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    box-shadow: 0 8px 24px rgba(15, 23, 42, 0.06);
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    transition: var(--transition-smooth);
    min-height: 180px;
}

.objective-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 16px 32px rgba(124, 58, 237, 0.18);
}

.objective-card h3 {
    color: #0F172A;
    font-size: 1.2rem;
    line-height: 1.5;
}

.module-chapters {
    background: #F8FAFC;
    color: #0F172A;
    padding: var(--spacing-2xl) 0;
}

.chapters-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: var(--spacing-lg);
}

.chapter-card {
    background: #FFFFFF;
    border: 1px solid rgba(15, 23, 42, 0.08);
    border-radius: var(--border-radius-xl);
    box-shadow: 0 8px 24px rgba(15, 23, 42, 0.06);
    padding: var(--spacing-xl);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    min-height: 330px;
    transition: var(--transition-smooth);
}

.chapter-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #7C3AED 0%, #2563EB 100%);
}

.chapter-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 16px 32px rgba(124, 58, 237, 0.18);
    border-color: rgba(124, 58, 237, 0.2);
}

.chapter-card__icon {
    width: 68px;
    height: 68px;
    border-radius: 18px;
    background: linear-gradient(135deg, rgba(124, 58, 237, 0.14), rgba(37, 99, 235, 0.12));
    color: #7C3AED;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
}

.chapter-card h3 {
    color: #0F172A;
    margin-bottom: var(--spacing-sm);
    font-size: 1.5rem;
    line-height: 1.3;
}

.chapter-card p {
    color: #475569;
    line-height: 1.7;
    margin-bottom: var(--spacing-lg);
    flex-grow: 1;
}

.chapter-card .btn {
    width: fit-content;
    min-width: 140px;
    padding: 0.85rem 1.4rem;
}

.chapter-card .btn--primary {
    background: #7C3AED;
    color: #FFFFFF;
    border: 1px solid #7C3AED;
}

.chapter-card .btn--primary:hover {
    background: #6D28D9;
    border-color: #6D28D9;
    box-shadow: 0 12px 22px rgba(124, 58, 237, 0.22);
}

.site-header .btn--secondary {
    background: rgba(255, 255, 255, 0.12);
    border: 1px solid rgba(255, 255, 255, 0.28);
    color: #FFFFFF;
}

.site-header .btn--secondary:hover {
    background: #FFFFFF;
    border-color: #FFFFFF;
    color: #2563EB;
}

.site-header .btn--primary {
    background: #7C3AED;
    border-color: #7C3AED;
    color: #FFFFFF;
}

.site-header .btn--primary:hover {
    background: #6D28D9;
    border-color: #6D28D9;
    color: #FFFFFF;
}

/* ========================================
   TOP NAV STYLES
   ======================================== */

.top-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md) 0;
}

.top-nav__right {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

/* ========================================
   RESPONSIVE DESIGN (MOBILE FIRST)
   ======================================== */

@media (max-width: 640px) {
    .module-hero__container,
    .module-objectives .container,
    .module-chapters .container {
        padding: 0 var(--spacing-md);
    }

    .objectives-grid,
    .chapters-grid {
        grid-template-columns: 1fr;
    }

    .objective-card,
    .chapter-card {
        min-height: auto;
    }

    .top-nav {
        flex-direction: column;
        justify-content: center;
        padding: var(--spacing-md) 0;
        gap: var(--spacing-sm);
    }

    .top-nav .btn {
        width: 100%;
        text-align: center;
    }
}

@media (min-width: 641px) and (max-width: 1024px) {
    .objectives-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

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

/* ========================================
   LESSON PAGE STYLES
   ======================================== */

.lesson-hero {
    padding-top: var(--spacing-2xl);
}

.lesson-objectives,
.lesson-theory,
.lesson-guided,
.lesson-practice,
.lesson-quiz,
.lesson-summary,
.lesson-navigation {
    background: #FFFFFF;
    color: #0F172A;
    padding: var(--spacing-2xl) 0;
}

.lesson-objectives .container,
.lesson-theory .container,
.lesson-guided .container,
.lesson-practice .container,
.lesson-quiz .container,
.lesson-summary .container,
.lesson-navigation__container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.lesson-objectives h2,
.lesson-theory h2,
.lesson-guided h2,
.lesson-practice h2,
.lesson-quiz h2,
.lesson-summary h2,
.lesson-navigation h2 {
    color: #0F172A;
    margin-bottom: var(--spacing-xl);
    font-size: clamp(1.8rem, 2vw, 2.4rem);
    display: inline-block;
}

.lesson-objectives h2::after,
.lesson-theory h2::after,
.lesson-guided h2::after,
.lesson-practice h2::after,
.lesson-quiz h2::after,
.lesson-summary h2::after,
.lesson-navigation h2::after {
    content: '';
    display: block;
    width: 72px;
    height: 4px;
    border-radius: 999px;
    background: linear-gradient(90deg, #7C3AED 0%, #2563EB 100%);
    margin-top: var(--spacing-sm);
}

.lesson-panel,
.lesson-placeholder {
    background: #FFFFFF;
    border: 1px solid rgba(15, 23, 42, 0.08);
    border-radius: var(--border-radius-lg);
    box-shadow: 0 8px 24px rgba(15, 23, 42, 0.06);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
    transition: var(--transition-smooth);
}

.lesson-panel:hover,
.lesson-placeholder:hover {
    transform: translateY(-4px);
    box-shadow: 0 16px 32px rgba(124, 58, 237, 0.12);
}

.lesson-panel h3,
.lesson-placeholder p,
.lesson-panel p,
.lesson-list li {
    color: #0F172A;
}

.lesson-panel h3 {
    margin-bottom: var(--spacing-md);
    font-size: 1.35rem;
}

.lesson-panel p,
.lesson-list {
    color: #475569;
    line-height: 1.8;
}

.lesson-list {
    list-style: none;
    padding-left: 0;
}

.lesson-list li {
    position: relative;
    padding-left: 1.5rem;
    margin-bottom: var(--spacing-sm);
    color: #0F172A;
}

.lesson-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    top: 0;
    color: #7C3AED;
    font-weight: 700;
}

.lesson-list--ordered {
    list-style: decimal;
    padding-left: 1.5rem;
}

.lesson-list--ordered li {
    padding-left: 0;
}

.lesson-list--ordered li::before {
    display: none;
}

.lesson-placeholder {
    border: 1px dashed rgba(124, 58, 237, 0.35);
    background: linear-gradient(180deg, #F8FAFC 0%, #FFFFFF 100%);
}

.lesson-placeholder p {
    margin-bottom: var(--spacing-sm);
    color: #475569;
}

.lesson-placeholder p:last-child {
    margin-bottom: 0;
}

.lesson-navigation__buttons {
    display: flex;
    justify-content: space-between;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.lesson-navigation__buttons .btn {
    min-width: 220px;
}

.lesson-navigation__buttons .btn--secondary {
    background: transparent;
    border: 2px solid #2563EB;
    color: #2563EB;
}

.lesson-navigation__buttons .btn--secondary:hover {
    background: #2563EB;
    border-color: #2563EB;
    color: #FFFFFF;
}

.lesson-navigation__buttons .btn--primary {
    background: #7C3AED;
    border: 1px solid #7C3AED;
    color: #FFFFFF;
}

.lesson-navigation__buttons .btn--primary:hover {
    background: #6D28D9;
    border-color: #6D28D9;
    box-shadow: 0 12px 22px rgba(124, 58, 237, 0.22);
}

@media (max-width: 640px) {
    .lesson-objectives .container,
    .lesson-theory .container,
    .lesson-guided .container,
    .lesson-practice .container,
    .lesson-quiz .container,
    .lesson-summary .container,
    .lesson-navigation__container {
        padding: 0 var(--spacing-md);
    }

    .lesson-navigation__buttons {
        flex-direction: column;
    }

    .lesson-navigation__buttons .btn {
        width: 100%;
    }
}

/* Small devices: up to 640px */
@media (max-width: 640px) {
    h1 {
        font-size: 1.75rem;
    }

    h2 {
        font-size: 1.5rem;
    }

    h3 {
        font-size: 1.25rem;
    }

    .header__container {
        flex-direction: column;
        padding: var(--spacing-md);
    }

    .nav__list {
        flex-direction: column;
        gap: var(--spacing-md);
        width: 100%;
        text-align: center;
    }

    section {
        padding: var(--spacing-xl) 0;
    }

    .hero__container {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }

    .hero__title {
        font-size: 2rem;
    }

    .hero__subtitle {
        font-size: 1rem;
    }

    .hero__buttons {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        text-align: center;
    }

    .hero__illustration {
        height: 300px;
    }

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

    .features__grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }

    .section__title {
        font-size: 1.5rem;
        margin-bottom: var(--spacing-xl);
    }

    .footer__content {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }
}

/* Medium devices: 641px to 1024px */
@media (min-width: 641px) and (max-width: 1024px) {
    h1 {
        font-size: 2.5rem;
    }

    .header__container {
        padding: var(--spacing-md) var(--spacing-lg);
    }

    .nav__list {
        gap: var(--spacing-md);
    }

    .hero__title {
        font-size: 2.5rem;
    }

    .modules__grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .features__grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Large devices: 1025px and above */
@media (min-width: 1025px) {
    .nav__list {
        gap: var(--spacing-xl);
    }

    .modules__grid {
        grid-template-columns: repeat(4, 1fr);
    }

    .features__grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* ========================================
   ACCESSIBILITY
   ======================================== */

/* Focus visible for keyboard navigation */
.btn:focus-visible,
.nav__link:focus-visible {
    outline: 2px solid #FFFFFF;
    outline-offset: 2px;
}

/* Reduce motion for users who prefer it */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* High contrast mode support */
@media (prefers-contrast: more) {
    .btn--secondary,
    .btn--outline {
        border-width: 3px;
    }

    .module-card {
        border-width: 2px;
    }

    .nav__link::after {
        height: 3px;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --color-white: #FFFFFF;
        --color-gray-50: #F0F9FF;
        --color-gray-100: #E0F2FE;
        --color-gray-200: #BFDBFE;
        --color-gray-600: #FFFFFF;
        --color-gray-700: #FFFFFF;
    }

    body {
        background-color: #003F87;
        color: var(--color-white);
    }

    h1, h2, h3, h4, h5, h6 {
        color: var(--color-white);
    }

    .header {
        background-color: #003F87;
        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
    }

    .nav__link {
        color: var(--color-white);
    }

    .hero {
        background: #003F87;
    }

    .module-card {
        background: #0052A3;
        border-color: #5B9FD4;
    }

    .features {
        background: linear-gradient(135deg, #0052A3 0%, #003F87 100%);
    }
}

/* ========================================
   PRINT STYLES
   ======================================== */

@media print {
    header,
    footer,
    .hero__buttons {
        display: none;
    }

    section {
        page-break-inside: avoid;
    }

    body {
        font-size: 12px;
    }
}