/* ============================================================
   UCHIM.EU — Модерен дизайн (v3)
   Градиенти, стъклени карти, меки сенки, живи акценти.
   ВАЖНО: имена на класове са запазени идентични с v2 —
   само визията е сменена, HTML/PHP шаблоните не са пипани.
   ============================================================ */

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }

:root {
    --navy:      #150F2E;
    --blue:      #6D5AE6;
    --blue-d:    #5843D9;
    --blue-l:    #F1EEFE;
    --violet:    #8B5CF6;
    --cyan:      #22D3EE;
    --green:     #10B981;
    --red:       #EF4444;
    --yellow:    #F59E0B;
    --purple:    #8B5CF6;
    --gray:      #6B7280;
    --gray-l:    #F7F7FC;
    --gray-b:    #E7E5F5;
    --text:      #221C3D;
    --white:     #FFFFFF;

    --grad-main:  linear-gradient(135deg, #6D5AE6 0%, #8B5CF6 50%, #22D3EE 120%);
    --grad-soft:  linear-gradient(135deg, #F1EEFE 0%, #EAF9FF 100%);
    --grad-navy:  linear-gradient(160deg, #150F2E 0%, #2A1E5C 100%);

    --shadow:    0 4px 18px rgba(93, 68, 217, .08);
    --shadow-md: 0 14px 40px rgba(93, 68, 217, .16);
    --shadow-glow: 0 0 0 4px rgba(109, 90, 230, .12);
    --radius:    14px;
    --radius-lg: 22px;
    --transition: .22s cubic-bezier(.4,0,.2,1);
    --header-h:  76px;
}

body {
    font-family: 'Inter', 'Segoe UI', -apple-system, Arial, sans-serif;
    background: var(--white);
    color: var(--text);
    line-height: 1.65;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    -webkit-font-smoothing: antialiased;
}

a { color: var(--blue); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--blue-d); }
img { max-width: 100%; display: block; }
ul { list-style: none; }
button { cursor: pointer; font-family: inherit; }

.container { max-width: 1180px; margin: 0 auto; padding: 0 24px; }
@media (max-width: 768px) { .container { padding: 0 16px; } }

.main-content { flex: 1; padding: 40px 0 64px; }

/* ============================================================
   HEADER
   ============================================================ */
.site-header {
    background: rgba(255,255,255,.82);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 1px 0 rgba(231,229,245,.9);
    transition: box-shadow var(--transition);
}
.header-inner { display: flex; align-items: center; gap: 24px; height: var(--header-h); }

.logo { display: flex; align-items: center; gap: 8px; font-weight: 800; font-size: 21px; color: var(--navy); white-space: nowrap; letter-spacing: -.02em; }
.logo:hover { color: var(--blue); }
.logo-icon {
    font-size: 22px; width: 38px; height: 38px; display: flex; align-items: center; justify-content: center;
    background: var(--grad-main); border-radius: 12px; box-shadow: var(--shadow);
}

.main-nav { display: flex; align-items: center; gap: 4px; flex: 1; justify-content: center; }
@media (max-width: 1024px) { .main-nav { display: none; } }

.nav-link {
    padding: 9px 16px; color: var(--text); font-size: 14.5px; font-weight: 600;
    border-radius: 999px; transition: all var(--transition); white-space: nowrap;
}
.nav-link:hover { color: var(--blue); background: var(--blue-l); }
.nav-link.active { color: var(--white); font-weight: 700; background: var(--grad-main); box-shadow: var(--shadow); }

.header-right { display: flex; align-items: center; gap: 10px; margin-left: auto; }

.lang-switcher { display: flex; gap: 2px; font-size: 13px; font-weight: 700; color: var(--gray); }
.lang-switcher a { padding: 4px 7px; border-radius: 6px; }
.lang-switcher a.active { color: var(--blue); background: var(--blue-l); }

.user-menu { position: relative; }
.user-menu-btn {
    display: flex; align-items: center; gap: 8px; padding: 7px 14px 7px 7px; background: var(--gray-l);
    border: 1px solid var(--gray-b); border-radius: 999px; font-size: 13.5px; font-weight: 700; color: var(--text);
    transition: all var(--transition);
}
.user-menu-btn:hover { background: var(--blue-l); border-color: var(--blue); box-shadow: var(--shadow-glow); }
.user-dropdown {
    position: absolute; top: calc(100% + 10px); right: 0; min-width: 210px; background: var(--white);
    border: 1px solid var(--gray-b); border-radius: var(--radius); box-shadow: var(--shadow-md);
    display: none; flex-direction: column; padding: 8px; z-index: 200;
}
.user-dropdown.open { display: flex; }
.user-dropdown a { padding: 9px 12px; border-radius: 8px; font-size: 14px; color: var(--text); font-weight: 500; }
.user-dropdown a:hover { background: var(--blue-l); color: var(--blue-d); }
.user-dropdown hr { border: none; border-top: 1px solid var(--gray-b); margin: 6px 0; }
.logout-link { color: var(--red) !important; }

.plan-badge { color: #fff; font-size: 10.5px; font-weight: 800; padding: 3px 10px; border-radius: 999px; text-transform: uppercase; letter-spacing: .04em; }

.burger-btn { display: none; flex-direction: column; gap: 4px; width: 38px; height: 38px; align-items: center; justify-content: center; background: var(--gray-l); border-radius: 10px; border: none; }
.burger-btn span { width: 18px; height: 2px; background: var(--navy); border-radius: 2px; }
@media (max-width: 1024px) { .burger-btn { display: flex; } }

/* ============================================================
   BUTTONS
   ============================================================ */
.btn {
    display: inline-flex; align-items: center; justify-content: center; gap: 6px;
    padding: 11px 22px; border-radius: 999px; font-size: 14.5px; font-weight: 700;
    border: 1px solid transparent; transition: all var(--transition); cursor: pointer;
}
.btn-primary { background: var(--grad-main); color: #fff; box-shadow: var(--shadow); }
.btn-primary:hover { color: #fff; box-shadow: var(--shadow-md); transform: translateY(-2px); }
.btn-outline { background: var(--white); color: var(--navy); border-color: var(--gray-b); }
.btn-outline:hover { border-color: var(--blue); color: var(--blue); box-shadow: var(--shadow); transform: translateY(-2px); }
.btn-sm { padding: 8px 16px; font-size: 13px; }
.btn-lg { padding: 15px 30px; font-size: 16px; }
.btn-block { width: 100%; }

/* ============================================================
   HERO
   ============================================================ */
.hero {
    position: relative;
    display: grid; grid-template-columns: 1.1fr .9fr; gap: 48px; align-items: center;
    padding: 64px 0 80px;
    overflow: hidden;
}
.hero::before {
    content: '';
    position: absolute; top: -120px; right: -160px; width: 480px; height: 480px;
    background: var(--grad-main); opacity: .16; border-radius: 50%; filter: blur(40px);
    z-index: -1;
}
.hero::after {
    content: '';
    position: absolute; bottom: -100px; left: -140px; width: 340px; height: 340px;
    background: var(--cyan); opacity: .14; border-radius: 50%; filter: blur(50px);
    z-index: -1;
}
@media (max-width: 900px) { .hero { grid-template-columns: 1fr; } }

.hero-badge {
    display: inline-block; background: var(--blue-l); color: var(--blue-d); font-size: 13px;
    font-weight: 700; padding: 7px 16px; border-radius: 999px; margin-bottom: 20px;
    border: 1px solid rgba(109,90,230,.15);
}
.hero-title { font-size: 46px; line-height: 1.12; font-weight: 800; color: var(--navy); margin-bottom: 18px; letter-spacing: -.02em; }
.hero-title, .hero-badge + .hero-title { background: none; }
@media (max-width: 600px) { .hero-title { font-size: 32px; } }
.hero-sub { font-size: 17.5px; color: var(--gray); margin-bottom: 30px; max-width: 480px; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 40px; }
.guest-try-form {
    display: flex; align-items: center; gap: 8px; flex-wrap: wrap; margin: -18px 0 30px;
    font-size: 13px; color: var(--gray);
}
.guest-try-form select {
    padding: 7px 10px; border: 1.5px solid var(--gray-b); border-radius: 8px; font-size: 13px; background: var(--white);
}
.hero-stats { display: flex; gap: 36px; }
.hero-stat { display: flex; flex-direction: column; }
.stat-num { font-size: 24px; font-weight: 800; background: var(--grad-main); -webkit-background-clip: text; background-clip: text; color: transparent; }
.stat-label { font-size: 12.5px; color: var(--gray); font-weight: 600; }

.hero-demo-card {
    background: var(--white); border: 1px solid var(--gray-b); border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md); padding: 26px; max-width: 420px; margin-left: auto;
    position: relative;
}
.hero-demo-card::before {
    content: ''; position: absolute; inset: -1px; border-radius: var(--radius-lg);
    padding: 1px; background: var(--grad-main); opacity: .35;
    -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    -webkit-mask-composite: xor; mask-composite: exclude; pointer-events: none;
}
.demo-question { margin-bottom: 16px; }
.demo-label { font-size: 12px; font-weight: 800; color: var(--blue); text-transform: uppercase; letter-spacing: .05em; }
.demo-question p { margin-top: 8px; font-size: 15px; color: var(--text); }
.demo-formula { background: var(--grad-soft); border-radius: 10px; padding: 14px; margin-bottom: 14px; font-size: 15px; text-align: center; }
.demo-answer { padding: 11px 14px; border-radius: 10px; font-weight: 700; font-size: 14px; }
.demo-answer.correct { background: #ECFDF5; color: #047857; }

/* ============================================================
   FEATURES / SECTIONS
   ============================================================ */
.section-title { font-size: 30px; font-weight: 800; color: var(--navy); text-align: center; margin-bottom: 40px; letter-spacing: -.02em; }

.features { padding: 52px 0; }
.features-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
@media (max-width: 900px) { .features-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .features-grid { grid-template-columns: 1fr; } }

.feature-card {
    background: var(--white); border: 1px solid var(--gray-b); border-radius: var(--radius-lg);
    padding: 28px 24px; transition: all var(--transition);
}
.feature-card:hover { box-shadow: var(--shadow-md); transform: translateY(-5px); border-color: transparent; }
.feature-icon {
    font-size: 26px; margin-bottom: 14px; width: 52px; height: 52px; display: flex; align-items: center;
    justify-content: center; background: var(--grad-soft); border-radius: 14px;
}
.feature-card h3 { font-size: 16.5px; margin-bottom: 8px; color: var(--navy); font-weight: 700; }
.feature-card p { font-size: 13.5px; color: var(--gray); }

.how-it-works { padding: 60px 0; background: var(--grad-soft); border-radius: var(--radius-lg); margin: 28px 0; }
.steps { display: flex; align-items: flex-start; justify-content: center; gap: 8px; flex-wrap: wrap; padding: 0 20px; }
.step { max-width: 200px; text-align: center; }
.step-num {
    width: 40px; height: 40px; border-radius: 50%; background: var(--grad-main); color: #fff;
    display: flex; align-items: center; justify-content: center; font-weight: 800; margin: 0 auto 12px;
    box-shadow: var(--shadow);
}
.step h3 { font-size: 14.5px; margin-bottom: 6px; color: var(--navy); font-weight: 700; }
.step p { font-size: 12.5px; color: var(--gray); }
.step-arrow { font-size: 20px; color: #C9C3ED; margin-top: 10px; }
@media (max-width: 700px) { .step-arrow { display: none; } }

/* ============================================================
   PRICING
   ============================================================ */
.plans-preview-grid, .plans-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
@media (max-width: 900px) { .plans-preview-grid, .plans-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .plans-preview-grid, .plans-grid { grid-template-columns: 1fr; } }

.plan-card, .plan-preview-card {
    position: relative; background: var(--white); border: 1.5px solid var(--gray-b); border-radius: var(--radius-lg);
    padding: 30px 24px; transition: all var(--transition);
}
.plan-card:hover, .plan-preview-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.plan-card.featured, .plan-preview-card.featured {
    border-color: transparent; box-shadow: var(--shadow-md); background: var(--grad-navy); color: #fff; transform: scale(1.03);
}
.plan-card.featured .plan-name, .plan-preview-card.featured .plan-preview-name,
.plan-card.featured .plan-price, .plan-preview-card.featured .plan-preview-price { color: #fff; }
.plan-card.featured .plan-preview-desc, .plan-preview-card.featured .plan-preview-desc { color: #C9C3ED; }
.plan-card.featured .plan-features li, .plan-preview-card.featured .plan-features li { color: #E4E1FA; }
.plan-badge-top {
    position: absolute; top: -13px; left: 50%; transform: translateX(-50%);
    background: var(--grad-main); color: #fff; font-size: 11.5px; font-weight: 800; padding: 5px 14px; border-radius: 999px;
    box-shadow: var(--shadow);
}
.plan-icon { font-size: 28px; margin-bottom: 10px; }
.plan-preview-name, .plan-name { font-size: 15px; font-weight: 700; color: var(--navy); margin-bottom: 6px; }
.plan-preview-price, .plan-price { font-size: 32px; font-weight: 800; color: var(--navy); margin-bottom: 4px; letter-spacing: -.02em; }
.plan-preview-price strong, .plan-price strong { font-size: 32px; }
.plan-preview-desc { font-size: 13px; color: var(--gray); margin-bottom: 18px; }
.plan-features { list-style: none; margin: 18px 0; }
.plan-features li { font-size: 13.5px; padding: 7px 0; color: var(--text); display: flex; gap: 8px; }
.plan-features li.locked { color: #C4C9D2; text-decoration: line-through; }

/* ============================================================
   FORMS / AUTH
   ============================================================ */
.auth-wrap { max-width: 410px; margin: 40px auto; background: var(--white); border: 1px solid var(--gray-b);
    border-radius: var(--radius-lg); padding: 40px 34px; box-shadow: var(--shadow-md); }
.auth-wrap h1 { font-size: 23px; color: var(--navy); text-align: center; margin-bottom: 26px; font-weight: 800; }
.form-group { margin-bottom: 18px; }
.form-group label { display: block; font-size: 13px; font-weight: 700; color: var(--text); margin-bottom: 6px; }
.form-group input, .form-group select, .form-group textarea {
    width: 100%; padding: 12px 15px; border: 1.5px solid var(--gray-b); border-radius: 10px; font-size: 14.5px;
    transition: all var(--transition); background: var(--gray-l);
}
.form-group input:focus, .form-group select:focus, .form-group textarea:focus { outline: none; border-color: var(--blue); background: var(--white); box-shadow: var(--shadow-glow); }
.g-recaptcha { margin: 16px 0; display: flex; justify-content: center; }

/* ============================================================
   ALERTS
   ============================================================ */
.flash-container { max-width: 1180px; margin: 16px auto 0; padding: 0 24px; }
.alert { padding: 13px 18px; border-radius: 10px; font-size: 14px; margin-bottom: 16px; font-weight: 500; }
.alert-success { background: #ECFDF5; color: #047857; }
.alert-error   { background: #FEF2F2; color: #B91C1C; }
.alert-warning { background: #FFFBEB; color: #B45309; }
.alert-info    { background: var(--blue-l); color: var(--blue-d); }

/* ============================================================
   DASHBOARD
   ============================================================ */
.page-header { margin-bottom: 30px; }
.page-header h1 { font-size: 27px; color: var(--navy); margin-bottom: 6px; font-weight: 800; letter-spacing: -.02em; }
.page-header p { color: var(--gray); font-size: 14.5px; }

.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin-bottom: 30px; }
@media (max-width: 800px) { .stats-grid { grid-template-columns: repeat(2, 1fr); } }
.stat-card { display: flex; align-items: center; gap: 14px; background: var(--white); border: 1px solid var(--gray-b);
    border-radius: var(--radius); padding: 20px; transition: all var(--transition); }
.stat-card:hover { box-shadow: var(--shadow); transform: translateY(-2px); }
.stat-icon { font-size: 24px; width: 46px; height: 46px; display: flex; align-items: center; justify-content: center;
    background: var(--grad-soft); border-radius: 12px; }
.stat-value { font-size: 23px; font-weight: 800; color: var(--navy); }
.stat-label { font-size: 12px; color: var(--gray); font-weight: 600; }

.progress-bar { position: relative; background: var(--gray-b); border-radius: 999px; height: 22px; overflow: hidden; }
.progress-fill { height: 100%; border-radius: 999px; transition: width .4s ease; background: var(--grad-main); }
.progress-text { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; font-size: 11px; font-weight: 800; color: var(--navy); }

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer { background: var(--grad-navy); color: #CBD5E1; padding: 44px 0; margin-top: 52px; }
.footer-inner { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 16px; }
.footer-logo { font-weight: 800; color: #fff; font-size: 16px; }
.footer-logo p { font-size: 12.5px; color: #9891C4; margin-top: 4px; font-weight: 400; }
.footer-links { display: flex; gap: 22px; }
.footer-links a { color: #CBD5E1; font-size: 13.5px; font-weight: 500; }
.footer-links a:hover { color: #fff; }
.footer-copy { font-size: 12.5px; color: #7C74A8; }

/* ============================================================
   404
   ============================================================ */
.error-404 { text-align: center; padding: 90px 0; }
.error-404 .code { font-size: 88px; font-weight: 800; background: var(--grad-main); -webkit-background-clip: text; background-clip: text; color: transparent; }
.error-404 h1 { font-size: 23px; color: var(--navy); margin: 14px 0; font-weight: 800; }

/* ============================================================
   УРОЦИ / "УЧЕБНИК" — защитено четимо съдържание
   ============================================================ */
.lesson-content { line-height: 1.75; font-size: 15px; color: var(--text); }
.lesson-content h3 { font-size: 17px; color: var(--navy); margin: 22px 0 10px; font-weight: 800; }
.lesson-content h4 { font-size: 14.5px; color: var(--blue-d); margin: 16px 0 8px; font-weight: 700; text-transform: uppercase; letter-spacing: .03em; }
.lesson-content p { margin-bottom: 12px; }
.lesson-content ul, .lesson-content ol { margin: 0 0 14px 22px; }
.lesson-content li { margin-bottom: 6px; }
.lesson-content .rule-box {
    background: var(--blue-l); border-left: 4px solid var(--blue); border-radius: 8px;
    padding: 14px 16px; margin: 14px 0; font-weight: 600;
}
.lesson-content .example-box {
    background: var(--gray-l); border: 1px solid var(--gray-b); border-radius: 10px;
    padding: 14px 16px; margin: 14px 0;
}
.lesson-content .example-box strong { color: var(--blue-d); }
.olympiad-box .example-box { background: #FBF7FF; border-color: #E6D6FA; }

/* Пречи за копиране/маркиране на текста — не спира screenshot,
   но затруднява директно "селектирай + copy" на цели уроци */
.lesson-protected .lesson-content, .lesson-protected h2, .lesson-protected .feature-card {
    -webkit-user-select: none; -moz-user-select: none; user-select: none;
}

/* Воден знак — тих, диагонален, повтарящ се текст с потребителя.
   При изтичане на съдържание навън той е проследим до конкретния акаунт. */
.lesson-watermark {
    position: absolute; inset: 0; pointer-events: none; overflow: hidden;
    display: flex; flex-wrap: wrap; gap: 40px; transform: rotate(-22deg) scale(1.4);
    opacity: .05; z-index: 1;
}
.lesson-watermark span { font-size: 12px; font-weight: 700; color: var(--navy); white-space: nowrap; }
.lesson-protected > *:not(.lesson-watermark) { position: relative; z-index: 2; }

.print-blocked-msg { text-align: center; padding: 40px 0; font-weight: 700; color: var(--gray); }

/* Скрива урока изцяло при опит за печат на страницата */
@media print {
    .lesson-protected .lesson-content,
    .lesson-protected .lesson-watermark,
    .lesson-protected .feature-card { display: none !important; }
    .lesson-protected .print-blocked-msg { display: block !important; }
    .site-header, .site-footer, .practice-layout aside { display: none !important; }
}