:root {
    --primary: #FF6A13;
    --primary-hover: #e55a00;
    --text: #1a1a1a;
    --text-muted: #6b7280;
    --bg: #fafafa;
    --bg-dark: #1e1e1e;
    --font: 'Outfit', 'Helvetica Neue', Arial, sans-serif;
    --nav-height: 72px;
    --radius: 12px;
    --transition: 0.28s ease;
}

/* === Base === */
*, *::before, *::after { box-sizing: border-box; }

html, body { width: 100%; }

body {
    font-family: var(--font);
    font-size: 16px;
    line-height: 1.6;
    color: var(--text);
    background-color: var(--bg);
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font);
    font-weight: 700;
    line-height: 1.2;
    color: var(--text);
}

p {
    margin-bottom: 1rem;
    line-height: 1.7;
    color: var(--text-muted);
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover { color: var(--primary-hover); }

hr {
    max-width: 48px;
    border: 0;
    border-top: 3px solid var(--primary);
    opacity: 1;
    margin: 1.5rem auto;
}

hr.hr-light { border-top-color: rgba(255, 255, 255, 0.55); }

/* === Utilities === */
.text-primary { color: var(--primary) !important; }
.text-faded   { color: rgba(255, 255, 255, 0.82); }
.bg-primary   { background-color: var(--primary) !important; }
.uppercase    { text-transform: uppercase; }

.section-heading {
    margin-top: 0;
    font-size: clamp(1.6rem, 3vw, 2.2rem);
    letter-spacing: -0.025em;
    font-weight: 700;
}

/* === Navbar === */
#mainNav {
    font-family: var(--font);
    background-color: var(--primary);
    border: none;
    padding: 0.75rem 0;
    transition: background-color var(--transition), box-shadow var(--transition);
}

#mainNav .navbar-brand {
    font-weight: 800;
    font-size: 1.2rem;
    letter-spacing: 0.07em;
    text-transform: uppercase;
    color: rgba(255, 255, 255, 0.95);
    transition: color var(--transition);
}

#mainNav .navbar-brand:hover { color: #fff; }

#mainNav .nav-link {
    font-size: 0.78rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: rgba(255, 255, 255, 0.85);
    padding: 0.5rem 0.85rem;
    transition: color var(--transition);
}

#mainNav .nav-link:hover { color: #fff; }

#mainNav.scrolled {
    background-color: rgba(255, 255, 255, 0.97);
    backdrop-filter: blur(8px);
    box-shadow: 0 1px 16px rgba(0, 0, 0, 0.07);
}

#mainNav.scrolled .navbar-brand { color: var(--primary); }
#mainNav.scrolled .navbar-brand:hover { color: var(--primary-hover); }
#mainNav.scrolled .nav-link { color: #374151; }
#mainNav.scrolled .nav-link:hover { color: var(--primary); }

.navbar-toggler {
    border-color: rgba(255, 255, 255, 0.4);
    padding: 0.35rem 0.6rem;
}

.navbar-toggler-icon {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(255,255,255,0.9)' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2.5' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
}

#mainNav.scrolled .navbar-toggler {
    border-color: rgba(0, 0, 0, 0.15);
}

#mainNav.scrolled .navbar-toggler-icon {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba(0,0,0,0.65)' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2.5' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
}

.lang-sep { margin-left: 0.5rem; }

@media (min-width: 992px) {
    .lang-sep .nav-link {
        border-left: 1px solid rgba(255, 255, 255, 0.3);
        padding-left: 1.1rem;
    }
    #mainNav.scrolled .lang-sep .nav-link {
        border-left-color: rgba(0, 0, 0, 0.12);
    }
}

/* === Hero === */
header {
    min-height: 100dvh;
    display: flex;
    align-items: center;
    padding-top: var(--nav-height);
    padding-bottom: 3rem;
    background-color: var(--bg);
}

header h1 {
    font-size: clamp(2rem, 4.5vw, 3.4rem);
    font-weight: 700;
    letter-spacing: -0.03em;
    color: var(--text);
    text-wrap: balance;
    margin-bottom: 0.5rem;
}

header p {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-muted);
}

.logo-hero {
    max-width: 200px;
    margin-top: 2rem;
}

@media (min-width: 768px) {
    .logo-hero {
        margin-top: 0;
        max-width: 240px;
    }
}

/* === Sections === */
section { padding: 4.5rem 0; }

section#about { padding: 5rem 0; }

#about h2 { color: #fff; }
#about p  { color: rgba(255, 255, 255, 0.85); }
#about hr { border-top-color: rgba(255, 255, 255, 0.45); }

/* === Services === */
.service-box {
    padding: 2rem 1.5rem;
    border-radius: var(--radius);
    margin-bottom: 1rem;
    transition: transform var(--transition), box-shadow var(--transition);
}

.service-box:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 32px rgba(255, 106, 19, 0.12);
}

.service-box i.text-primary {
    font-size: 2.5rem;
    margin-bottom: 1.25rem;
    display: block;
}

.service-box h3 {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 0.6rem;
}

.service-box p {
    margin-bottom: 0;
    font-size: 0.95rem;
    line-height: 1.7;
    text-align: left;
}

/* === Preview section === */
#preview { padding-bottom: 3rem; }

#preview .nav-tabs {
    border-bottom: 2px solid #e5e7eb;
    gap: 0.25rem;
    margin-bottom: 2rem;
}

#preview .nav-tabs .nav-link {
    font-weight: 600;
    font-size: 0.82rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--text-muted);
    border: none;
    border-bottom: 2px solid transparent;
    border-radius: 0;
    margin-bottom: -2px;
    padding: 0.75rem 1.25rem;
    background: transparent;
    transition: color var(--transition), border-color var(--transition);
}

#preview .nav-tabs .nav-link:hover { color: var(--primary); }

#preview .nav-tabs .nav-link.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
    background: transparent;
}

#smartphone {
    background: url(../img/iphone_6_t.png) center top no-repeat;
    height: 600px;
    position: relative;
}

.app-frame {
    position: absolute;
    left: 50%;
    top: 106px;
    transform: translateX(-50%);
    width: 218px;
    height: 387px;
    overflow: hidden;
}

.app-frame img {
    width: 218px;
    height: 387px;
    object-fit: cover;
    display: none;
}

.app-frame img.active { display: block; }

#slider-pager-learners,
#slider-pager-teachers {
    display: flex;
    flex-wrap: wrap;
    margin-top: 2rem;
}

.pager-item {
    margin: 0 1rem 0 0;
    padding: 0;
}

.pager-item a {
    display: block;
    text-align: center;
    color: #d1d5db;
    transition: color var(--transition);
    outline: none;
}

.pager-item a i { font-size: 1.75rem; }

.pager-item a:hover  { color: #9ca3af; }
.pager-item a.active { color: var(--primary); }

.tab-title {
    display: block;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: #9ca3af;
    margin-top: 0.5rem;
    line-height: 1.3;
}

.pager-item a.active .tab-title { color: var(--primary); }

.slide-descriptions p {
    display: none;
    font-size: 1.1rem;
    line-height: 1.8;
    font-weight: 300;
    margin-top: 1.5rem;
}

.slide-descriptions p.active { display: block; }

/* === FAQ === */
#faq { padding-top: 3rem; }

#faq .section-heading { margin-bottom: 2.5rem; }

.accordion-item {
    border: none;
    border-bottom: 1px solid #e5e7eb;
    background-color: transparent;
}

.accordion-item:first-of-type {
    border-top: 1px solid #e5e7eb;
    border-radius: 0;
}

.accordion-item:last-of-type { border-radius: 0; }

.accordion-button {
    font-family: var(--font);
    font-weight: 500;
    font-size: 1rem;
    color: var(--text);
    background-color: transparent;
    padding: 1.25rem 2rem 1.25rem 0;
    box-shadow: none;
}

.accordion-button:not(.collapsed) {
    color: var(--primary);
    background-color: transparent;
    box-shadow: none;
}

.accordion-button:focus { box-shadow: none; }

.accordion-button::after {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='%236b7280'%3e%3cpath fill-rule='evenodd' d='M1.646 4.646a.5.5 0 0 1 .708 0L8 10.293l5.646-5.647a.5.5 0 0 1 .708.708l-6 6a.5.5 0 0 1-.708 0l-6-6a.5.5 0 0 1 0-.708z'/%3e%3c/svg%3e");
    flex-shrink: 0;
    margin-left: auto;
}

.accordion-button:not(.collapsed)::after {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='%23FF6A13'%3e%3cpath fill-rule='evenodd' d='M1.646 4.646a.5.5 0 0 1 .708 0L8 10.293l5.646-5.647a.5.5 0 0 1 .708.708l-6 6a.5.5 0 0 1-.708 0l-6-6a.5.5 0 0 1 0-.708z'/%3e%3c/svg%3e");
}

.accordion-body {
    padding: 0 2rem 1.25rem 0;
    font-size: 0.95rem;
    line-height: 1.75;
}

/* === Team === */
#team { padding-top: 2rem; }

.team-img {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    object-fit: cover;
    filter: grayscale(100%);
    transition: filter 0.4s ease, transform 0.4s ease;
    margin: 0 auto 1rem;
    display: block;
}

.team-card {
    display: block;
    text-decoration: none;
    color: inherit;
}

.team-card:hover .team-img {
    filter: grayscale(0%);
    transform: scale(1.05);
}

.team-card h3 {
    color: var(--primary);
    font-size: 1.05rem;
    font-weight: 600;
    margin-bottom: 0.2rem;
}

.team-card p {
    font-size: 0.9rem;
    margin-bottom: 0;
    text-align: center;
}

/* === Footer === */
footer {
    background-color: var(--bg-dark);
    padding: 5rem 0;
}

footer .section-heading { color: #fff; }

footer hr { border-top-color: var(--primary); }

footer p { color: rgba(255, 255, 255, 0.55); }

.social-links {
    display: flex;
    gap: 2rem;
    justify-content: center;
    margin: 2rem 0;
}

.social-links a {
    color: rgba(255, 255, 255, 0.45);
    font-size: 1.5rem;
    transition: color var(--transition), transform var(--transition);
}

.social-links a:hover {
    color: var(--primary);
    transform: translateY(-3px);
}

.copyright {
    font-size: 0.8rem;
    margin-top: 2rem;
    color: rgba(255, 255, 255, 0.35) !important;
}

/* === Error pages === */
.error-404, .error-500 { text-align: center; color: #e5e7eb; }
p.error-404, p.error-500 { font-size: 4vw; }
h1.error-404, h1.error-500 { font-size: 10vw; }

section.generic {
    padding-top: var(--nav-height);
    min-height: 100dvh;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
}

/* === Mini breakpoint <=450px === */
@media (max-width: 450px) {
    .col-mi-12 { width: 100%; }
    .col-mi-8  { width: 66.667%; }
}