/* === Reset & Base === */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --color-primary: #1a1a2e;
    --color-accent: #e94560;
    --color-accent-hover: #d63350;
    --color-bg: #f8f9fa;
    --color-surface: #ffffff;
    --color-text: #2d2d2d;
    --color-text-muted: #6c757d;
    --color-border: #e0e0e0;
    --color-success: #28a745;
    --color-warning: #ffc107;
    --color-danger: #dc3545;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --radius: 8px;
    --radius-lg: 12px;
    --shadow: 0 2px 8px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);
    --container: 1200px;
    --container-wide: 1400px;
}

html { scroll-behavior: smooth; }

body {
    font-family: var(--font-family);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text);
    background: var(--color-bg);
    -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--color-accent); text-decoration: none; }
a:hover { color: var(--color-accent-hover); }

.container {
    max-width: var(--container);
    margin: 0 auto;
    padding: 0 20px;
}
.container--wide { max-width: var(--container-wide); }

/* === Buttons === */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 24px;
    border-radius: var(--radius);
    font-family: var(--font-family);
    font-size: 15px;
    font-weight: 600;
    border: 2px solid transparent;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
    line-height: 1.4;
}
.btn--primary {
    background: var(--color-accent);
    color: #fff;
    border-color: var(--color-accent);
}
.btn--primary:hover {
    background: var(--color-accent-hover);
    border-color: var(--color-accent-hover);
    color: #fff;
}
.btn--outline {
    background: transparent;
    color: var(--color-accent);
    border-color: var(--color-accent);
}
.btn--outline:hover {
    background: var(--color-accent);
    color: #fff;
}
.btn--ghost {
    background: transparent;
    color: var(--color-text);
    border-color: transparent;
}
.btn--ghost:hover { background: rgba(0,0,0,0.05); }
.btn--sm { padding: 6px 16px; font-size: 14px; }
.btn--lg { padding: 14px 32px; font-size: 17px; }
.btn--full { width: 100%; }

/* === Header === */
.site-header {
    background: var(--color-primary);
    color: #fff;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow);
}
.site-header__inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
    gap: 24px;
}
.site-logo__text {
    font-size: 20px;
    font-weight: 800;
    color: #fff;
    text-decoration: none;
    letter-spacing: -0.5px;
}
.site-logo a { text-decoration: none; }
.site-logo .custom-logo { height: 40px; width: auto; }
.nav-list {
    display: flex;
    list-style: none;
    gap: 8px;
}
.nav-list a {
    color: rgba(255,255,255,0.8);
    padding: 8px 16px;
    border-radius: var(--radius);
    font-weight: 500;
    font-size: 15px;
    transition: all 0.2s;
}
.nav-list a:hover { color: #fff; background: rgba(255,255,255,0.1); }
.site-header__actions { display: flex; gap: 8px; }
.site-header__actions .btn--outline {
    color: #fff;
    border-color: rgba(255,255,255,0.3);
}
.site-header__actions .btn--outline:hover {
    background: rgba(255,255,255,0.1);
    border-color: #fff;
    color: #fff;
}
.site-header__actions .btn--ghost { color: rgba(255,255,255,0.8); }
.site-header__actions .btn--ghost:hover { color: #fff; }

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}
.mobile-menu-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: #fff;
    transition: 0.2s;
}

/* === Hero === */
.hero {
    background: var(--color-primary);
    color: #fff;
    padding: 80px 0 100px;
    text-align: center;
}
.hero__title {
    font-size: clamp(32px, 5vw, 56px);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 20px;
    letter-spacing: -1px;
}
.hero__subtitle {
    font-size: 18px;
    color: rgba(255,255,255,0.7);
    max-width: 600px;
    margin: 0 auto 32px;
}
.hero__cta { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.hero .btn--outline { color: #fff; border-color: rgba(255,255,255,0.3); }
.hero .btn--outline:hover { background: rgba(255,255,255,0.1); border-color: #fff; color: #fff; }

/* === Sections === */
.section { padding: 60px 0; }
.section__title {
    font-size: 32px;
    font-weight: 700;
    text-align: center;
    margin-bottom: 8px;
}
.section__subtitle {
    text-align: center;
    color: var(--color-text-muted);
    margin-bottom: 40px;
    font-size: 17px;
}
.section__action { text-align: center; margin-top: 40px; }

/* === Page Header === */
.page-header {
    background: var(--color-primary);
    color: #fff;
    padding: 40px 0;
    text-align: center;
}
.page-header--sm { padding: 30px 0; }
.page-header__title { font-size: 36px; font-weight: 700; }
.page-header__subtitle { color: rgba(255,255,255,0.7); margin-top: 8px; }

/* === Course Grid === */
.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 24px;
}
.course-card {
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.2s, box-shadow 0.2s;
}
.course-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.course-card__image { aspect-ratio: 4/3; overflow: hidden; }
.course-card__image img { width: 100%; height: 100%; object-fit: cover; }
.course-card__image--placeholder {
    background: var(--color-primary);
    display: flex;
    align-items: center;
    justify-content: center;
}
.course-card__image--placeholder span {
    font-size: 48px;
    font-weight: 800;
    color: rgba(255,255,255,0.3);
}
.course-card__body { padding: 20px; }
.course-card__level {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}
.level-basic { background: #d4edda; color: #155724; }
.level-intermediate { background: #cce5ff; color: #004085; }
.level-advanced { background: #fff3cd; color: #856404; }
.level-master { background: #f8d7da; color: #721c24; }
.course-card__title {
    font-size: 18px;
    margin: 10px 0 8px;
    font-weight: 600;
}
.course-card__title a { color: var(--color-text); }
.course-card__title a:hover { color: var(--color-accent); }
.course-card__excerpt {
    color: var(--color-text-muted);
    font-size: 14px;
    margin-bottom: 16px;
}
.course-card__meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 14px;
    color: var(--color-text-muted);
    border-top: 1px solid var(--color-border);
    padding-top: 12px;
}
.course-card__price { font-weight: 700; color: var(--color-accent); }

/* === Course Filter === */
.courses-filter {
    display: flex;
    gap: 8px;
    justify-content: center;
    margin-bottom: 30px;
    flex-wrap: wrap;
}
.filter-btn {
    padding: 8px 20px;
    border-radius: 20px;
    border: 1px solid var(--color-border);
    background: var(--color-surface);
    font-family: var(--font-family);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
}
.filter-btn:hover, .filter-btn.active {
    background: var(--color-accent);
    color: #fff;
    border-color: var(--color-accent);
}

/* === Features Grid === */
.features__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 24px;
}
.feature-card {
    background: var(--color-surface);
    padding: 32px;
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: var(--shadow);
}
.feature-card__icon { font-size: 36px; margin-bottom: 16px; }
.feature-card h3 { font-size: 18px; margin-bottom: 8px; }
.feature-card p { color: var(--color-text-muted); font-size: 14px; }

/* === Single Course === */
.course-hero { background: var(--color-primary); color: #fff; padding: 60px 0; }
.course-hero__grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: center; }
.course-hero__content .course-card__level { margin-bottom: 12px; }
.course-hero__content h1 { font-size: 36px; font-weight: 700; margin-bottom: 16px; }
.course-hero__excerpt { color: rgba(255,255,255,0.7); margin-bottom: 16px; }
.course-hero__meta { display: flex; gap: 20px; margin-bottom: 24px; color: rgba(255,255,255,0.6); font-size: 15px; }
.course-hero__image img { border-radius: var(--radius-lg); }
.course-hero__enrolled { margin-top: 20px; }

.course-content__grid { display: grid; grid-template-columns: 2fr 1fr; gap: 40px; }
.course-description { line-height: 1.8; }

/* === Progress Bar === */
.progress-bar {
    height: 8px;
    background: rgba(255,255,255,0.2);
    border-radius: 4px;
    overflow: hidden;
}
.progress-bar__fill {
    height: 100%;
    background: var(--color-success);
    border-radius: 4px;
    transition: width 0.3s;
}
.progress-bar__label { font-size: 13px; margin-top: 4px; display: block; }
.dashboard .progress-bar { background: var(--color-border); }

/* === Lesson List === */
.lesson-list {
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow);
}
.lesson-list h3 { font-size: 18px; margin-bottom: 16px; }
.lesson-list__items { list-style: none; counter-reset: none; }
.lesson-list__item { border-bottom: 1px solid var(--color-border); }
.lesson-list__item:last-child { border-bottom: none; }
.lesson-list__item a,
.lesson-list__item .lesson-list__locked {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 8px;
    color: var(--color-text);
    transition: background 0.2s;
}
.lesson-list__item a:hover { background: var(--color-bg); border-radius: var(--radius); }
.lesson-list__item.current a { background: #ffe8ec; border-radius: var(--radius); font-weight: 600; }
.lesson-list__item.completed a { color: var(--color-success); }
.lesson-list__number {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--color-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 13px;
    font-weight: 600;
    flex-shrink: 0;
}
.lesson-list__title { flex: 1; font-size: 14px; }
.lesson-list__check { color: var(--color-success); font-weight: 700; }
.lesson-list__lock { color: var(--color-text-muted); font-size: 14px; }
.lesson-list__locked { color: var(--color-text-muted); }

/* === Single Lesson === */
.lesson-breadcrumb {
    background: var(--color-primary);
    padding: 12px 0;
}
.lesson-breadcrumb .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.lesson-breadcrumb a { color: rgba(255,255,255,0.7); font-size: 14px; }
.lesson-breadcrumb a:hover { color: #fff; }
.lesson-breadcrumb span { color: rgba(255,255,255,0.5); font-size: 14px; }

.lesson-content__grid { display: grid; grid-template-columns: 2fr 1fr; gap: 40px; }
.lesson-content__main h1 { font-size: 28px; margin-bottom: 20px; }
.lesson-description { line-height: 1.8; }
.lesson-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 40px;
    padding-top: 24px;
    border-top: 1px solid var(--color-border);
}

/* === Video Player === */
.video-wrapper {
    position: relative;
    background: #000;
    border-radius: var(--radius-lg);
    overflow: hidden;
    aspect-ratio: 16/9;
    user-select: none;
    -webkit-user-select: none;
}
.video-wrapper video { width: 100%; height: 100%; object-fit: contain; }
.video-watermark {
    position: absolute;
    top: 10px;
    right: 10px;
    color: rgba(255,255,255,0.15);
    font-size: 14px;
    font-weight: 600;
    pointer-events: none;
    user-select: none;
    z-index: 10;
}
.video-controls {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(transparent, rgba(0,0,0,0.8));
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 20px 16px 12px;
    opacity: 0;
    transition: opacity 0.3s;
}
.video-wrapper:hover .video-controls { opacity: 1; }
.vc-btn {
    background: none;
    border: none;
    color: #fff;
    cursor: pointer;
    font-size: 18px;
    padding: 4px 8px;
    transition: opacity 0.2s;
}
.vc-btn:hover { opacity: 0.8; }
.vc-progress { flex: 1; cursor: pointer; }
.vc-progress__bar {
    height: 4px;
    background: rgba(255,255,255,0.3);
    border-radius: 2px;
    position: relative;
}
.vc-progress__fill {
    height: 100%;
    background: var(--color-accent);
    border-radius: 2px;
    width: 0%;
    transition: width 0.1s;
}
.vc-time { color: rgba(255,255,255,0.7); font-size: 13px; font-variant-numeric: tabular-nums; }

/* === Auth Pages === */
.auth-page { display: flex; align-items: center; min-height: calc(100vh - 200px); }
.auth-form-wrapper {
    max-width: 440px;
    margin: 0 auto;
    background: var(--color-surface);
    padding: 40px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    width: 100%;
}
.auth-form-wrapper h1 { font-size: 24px; margin-bottom: 8px; }
.auth-form__intro { color: var(--color-text-muted); margin-bottom: 24px; }
.auth-form__footer { text-align: center; margin-top: 20px; font-size: 14px; color: var(--color-text-muted); }

.form-group { margin-bottom: 20px; }
.form-group label { display: block; font-size: 14px; font-weight: 600; margin-bottom: 6px; }
.form-group input {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    font-family: var(--font-family);
    font-size: 15px;
    transition: border-color 0.2s;
}
.form-group input:focus { outline: none; border-color: var(--color-accent); }
.form-hint { font-size: 12px; color: var(--color-text-muted); margin-top: 4px; display: block; }

/* === Dashboard === */
.dashboard__grid { display: grid; grid-template-columns: 2fr 1fr; gap: 30px; }
.dashboard__main h2 { font-size: 22px; margin-bottom: 20px; }

.dashboard-course-card {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: var(--color-surface);
    padding: 20px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 12px;
}
.dashboard-course-card__info { flex: 1; margin-right: 16px; }
.dashboard-course-card__info h3 { font-size: 16px; margin-bottom: 8px; }
.dashboard-course-card__info h3 a { color: var(--color-text); }
.dashboard-course-card__info h3 a:hover { color: var(--color-accent); }

.dashboard-empty {
    background: var(--color-surface);
    padding: 40px;
    text-align: center;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
}
.dashboard-empty p { margin-bottom: 16px; color: var(--color-text-muted); }

.dashboard-card {
    background: var(--color-surface);
    padding: 24px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 16px;
}
.dashboard-card h3 { font-size: 16px; margin-bottom: 12px; }
.dashboard-card__status { font-weight: 600; }
.status--active { color: var(--color-success); }
.status--none { color: var(--color-text-muted); }
.dashboard-card__detail { font-size: 14px; color: var(--color-text-muted); margin-top: 4px; }

.dashboard-activity { background: var(--color-surface); border-radius: var(--radius); box-shadow: var(--shadow); overflow: hidden; }
.activity-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    border-bottom: 1px solid var(--color-border);
}
.activity-item:last-child { border-bottom: none; }
.activity-item__status {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--color-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    flex-shrink: 0;
}
.activity-item__status.completed { background: #d4edda; color: var(--color-success); }
.activity-item__info { flex: 1; }
.activity-item__info a { color: var(--color-text); font-size: 14px; font-weight: 500; }
.activity-item__info a:hover { color: var(--color-accent); }
.activity-item__time { display: block; font-size: 12px; color: var(--color-text-muted); }
.activity-item__percent { font-size: 14px; font-weight: 600; color: var(--color-text-muted); }

/* === Pricing === */
.pricing__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 24px;
    align-items: start;
}
.pricing-card {
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    overflow: hidden;
}
.pricing-card--featured {
    box-shadow: var(--shadow-lg);
    border: 2px solid var(--color-accent);
    transform: scale(1.05);
}
.pricing-card__header {
    padding: 32px 24px;
    text-align: center;
    border-bottom: 1px solid var(--color-border);
}
.pricing-card__header h3 { font-size: 20px; margin-bottom: 8px; }
.pricing-card__amount { font-size: 36px; font-weight: 800; }
.pricing-card__period { font-size: 16px; color: var(--color-text-muted); }
.pricing-card__body { padding: 24px; }
.pricing-card__features { list-style: none; }
.pricing-card__features li { padding: 8px 0; font-size: 14px; color: var(--color-text); }
.pricing-card__footer { padding: 0 24px 24px; }

/* === Footer === */
.site-footer {
    background: var(--color-primary);
    color: rgba(255,255,255,0.7);
    padding: 40px 0 0;
}
.site-footer__inner { display: flex; justify-content: space-between; align-items: flex-start; gap: 40px; }
.site-footer__brand .site-logo__text { color: #fff; display: block; margin-bottom: 8px; }
.site-footer__brand p { font-size: 14px; }
.footer-nav-list { list-style: none; display: flex; gap: 20px; }
.footer-nav-list a { color: rgba(255,255,255,0.6); font-size: 14px; }
.footer-nav-list a:hover { color: #fff; }
.site-footer__bottom {
    margin-top: 30px;
    padding: 16px 0;
    border-top: 1px solid rgba(255,255,255,0.1);
    font-size: 13px;
}

/* === Responsive === */
@media (max-width: 768px) {
    .site-nav, .site-header__actions { display: none; }
    .mobile-menu-toggle { display: flex; }
    .site-header.menu-open .site-nav,
    .site-header.menu-open .site-header__actions {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: var(--color-primary);
        padding: 16px 20px;
        border-top: 1px solid rgba(255,255,255,0.1);
    }
    .site-header.menu-open .nav-list { flex-direction: column; }

    .course-grid { grid-template-columns: 1fr; }
    .course-hero__grid { grid-template-columns: 1fr; }
    .course-hero__image { display: none; }
    .course-content__grid { grid-template-columns: 1fr; }
    .lesson-content__grid { grid-template-columns: 1fr; }
    .dashboard__grid { grid-template-columns: 1fr; }
    .pricing-card--featured { transform: none; }
    .pricing__grid { grid-template-columns: 1fr; }
    .site-footer__inner { flex-direction: column; }
    .footer-nav-list { flex-direction: column; gap: 8px; }
    .hero { padding: 50px 0 60px; }
}

/* === No results === */
.no-results {
    grid-column: 1 / -1;
    text-align: center;
    padding: 60px 20px;
    color: var(--color-text-muted);
}