/* ============================================
   Base Styles - Typography, Containers, Buttons
   ============================================ */

/* ===== Body & Document ===== */
body {
    font-family: var(--font-family-base);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-normal);
    color: var(--color-text-primary);
    background-color: var(--color-bg-light);
    line-height: var(--line-height-normal);
}

/* ===== Headings ===== */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-family-heading);
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    letter-spacing: -0.02em;
    color: var(--color-text-primary);
}

/* ===== Container ===== */
.container {
    width: 100%;
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding-left: var(--container-padding);
    padding-right: var(--container-padding);
}

/* ===== Sections ===== */
section {
    padding: var(--spacing-6) 0;
}

.section__title {
    font-family: var(--font-family-heading);
    font-size: var(--font-size-3xl);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    text-align: center;
    margin-bottom: var(--spacing-4);
    line-height: var(--line-height-tight);
    letter-spacing: -0.02em;
    position: relative;
    display: block;
}

/* Декоративная линия под заголовком */
.section__title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg,
        var(--color-primary) 0%,
        var(--color-primary-dark) 100%);
    margin: var(--spacing-2) auto 0;
    border-radius: var(--radius-full);
    box-shadow: 0 2px 8px rgba(0, 91, 255, 0.3);
}

.section__subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    text-align: center;
    margin-bottom: var(--spacing-2);
    line-height: var(--line-height-normal);
    font-weight: var(--font-weight-normal);
}

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    font-family: var(--font-family-base);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    letter-spacing: -0.01em;
    border-radius: var(--radius-md);
    transition: all var(--transition-normal);
    cursor: pointer;
    border: none;
    text-align: center;
    line-height: 1;
    white-space: nowrap;
    user-select: none;
}

.btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

/* Primary Button */
.btn--primary {
    background-color: var(--color-primary);
    color: white;
}

.btn--primary:hover:not(:disabled) {
    background-color: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn--primary:active:not(:disabled) {
    transform: translateY(0);
}

/* Secondary Button */
.btn--secondary {
    background-color: white;
    color: var(--color-primary);
    border: 2px solid var(--color-primary);
}

.btn--secondary:hover:not(:disabled) {
    background-color: var(--color-primary-light);
    transform: translateY(-1px);
}

.btn--secondary:active:not(:disabled) {
    transform: translateY(0);
}

/* Add to Cart Button */
.btn--add-to-cart {
    background-color: var(--color-secondary);
    color: white;
    font-weight: var(--font-weight-semibold);
    min-width: auto;
    padding: 10px 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
}

/* Icon-only variant for compact cards */
.course-card .btn--add-to-cart {
    padding: 8px;
    width: auto;
    min-width: auto;
}

.course-card .btn--add-to-cart svg {
    flex-shrink: 0;
}

.btn--add-to-cart:hover:not(:disabled) {
    background-color: #E55A2B;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn--add-to-cart:active:not(:disabled) {
    transform: translateY(0);
}

.btn--add-to-cart.loading {
    opacity: 0.8;
    cursor: wait;
}

.btn--add-to-cart.added {
    background-color: var(--color-success);
}

/* Preview Button */
.btn--preview {
    background-color: white;
    color: var(--color-primary);
    padding: 10px 20px;
    font-weight: var(--font-weight-semibold);
}

.btn--preview:hover {
    background-color: var(--color-primary-light);
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-family-heading);
    font-weight: var(--font-weight-bold);
    line-height: var(--line-height-tight);
    color: var(--color-text-primary);
}

h1 {
    font-size: var(--font-size-4xl);
}

h2 {
    font-size: var(--font-size-3xl);
}

h3 {
    font-size: var(--font-size-2xl);
}

h4 {
    font-size: var(--font-size-xl);
}

h5 {
    font-size: var(--font-size-lg);
}

h6 {
    font-size: var(--font-size-base);
}

p {
    line-height: var(--line-height-normal);
}

/* Links */
a {
    color: var(--color-primary);
    transition: color var(--transition-fast);
}

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

/* Сохраняем цвет текста для кнопок-ссылок при наведении */
a[class*="btn"]:hover,
a.authors-intro__cta:hover,
a.final-cta__btn:hover {
    color: white;
}

/* ===== Utility Classes ===== */

/* Text Alignment */
.text-left {
    text-align: left;
}

.text-center {
    text-align: center;
}

.text-right {
    text-align: right;
}

/* Font Weights */
.font-normal {
    font-weight: var(--font-weight-normal);
}

.font-medium {
    font-weight: var(--font-weight-medium);
}

.font-semibold {
    font-weight: var(--font-weight-semibold);
}

.font-bold {
    font-weight: var(--font-weight-bold);
}

/* Text Colors */
.text-primary {
    color: var(--color-text-primary);
}

.text-secondary {
    color: var(--color-text-secondary);
}

.text-light {
    color: var(--color-text-light);
}

/* Margins */
.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-1); }
.mt-2 { margin-top: var(--spacing-2); }
.mt-3 { margin-top: var(--spacing-3); }
.mt-4 { margin-top: var(--spacing-4); }
.mt-5 { margin-top: var(--spacing-5); }
.mt-6 { margin-top: var(--spacing-6); }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-1); }
.mb-2 { margin-bottom: var(--spacing-2); }
.mb-3 { margin-bottom: var(--spacing-3); }
.mb-4 { margin-bottom: var(--spacing-4); }
.mb-5 { margin-bottom: var(--spacing-5); }
.mb-6 { margin-bottom: var(--spacing-6); }

/* Paddings */
.pt-0 { padding-top: 0; }
.pt-1 { padding-top: var(--spacing-1); }
.pt-2 { padding-top: var(--spacing-2); }
.pt-3 { padding-top: var(--spacing-3); }
.pt-4 { padding-top: var(--spacing-4); }

.pb-0 { padding-bottom: 0; }
.pb-1 { padding-bottom: var(--spacing-1); }
.pb-2 { padding-bottom: var(--spacing-2); }
.pb-3 { padding-bottom: var(--spacing-3); }
.pb-4 { padding-bottom: var(--spacing-4); }

/* Display */
.hidden {
    display: none;
}

.block {
    display: block;
}

.inline-block {
    display: inline-block;
}

.flex {
    display: flex;
}

.inline-flex {
    display: inline-flex;
}

/* Flexbox Utilities */
.items-center {
    align-items: center;
}

.items-start {
    align-items: flex-start;
}

.items-end {
    align-items: flex-end;
}

.justify-center {
    justify-content: center;
}

.justify-between {
    justify-content: space-between;
}

.justify-around {
    justify-content: space-around;
}

.gap-1 { gap: var(--spacing-1); }
.gap-2 { gap: var(--spacing-2); }
.gap-3 { gap: var(--spacing-3); }
.gap-4 { gap: var(--spacing-4); }

/* Overflow */
.overflow-hidden {
    overflow: hidden;
}

/* Visibility */
.visible {
    visibility: visible;
}

.invisible {
    visibility: hidden;
}

/* Opacity */
.opacity-0 { opacity: 0; }
.opacity-50 { opacity: 0.5; }
.opacity-100 { opacity: 1; }

/* Cursor */
.cursor-pointer {
    cursor: pointer;
}

.cursor-not-allowed {
    cursor: not-allowed;
}

/* User Select */
.select-none {
    user-select: none;
}

/* ===== Footer ===== */
.footer {
    background: linear-gradient(180deg, #1F2937 0%, #111827 100%);
    color: white;
    padding: var(--spacing-8) 0 var(--spacing-4);
    margin-top: auto;
}

.footer__top {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: var(--spacing-6);
    padding-bottom: var(--spacing-6);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    margin-bottom: var(--spacing-4);
}

.footer__column:first-child {
    grid-column: span 1;
}

.footer__title {
    font-family: var(--font-family-heading);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
    color: white;
    margin-bottom: var(--spacing-3);
    letter-spacing: -0.01em;
}

.footer__description {
    font-size: var(--font-size-sm);
    line-height: var(--line-height-normal);
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: var(--spacing-3);
}

.footer__social {
    display: flex;
    gap: var(--spacing-2);
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    color: rgba(255, 255, 255, 0.7);
    transition: all var(--transition-fast);
}

.social-link:hover {
    background: var(--color-primary);
    color: white;
    transform: translateY(-2px);
}

.footer__links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-1-5);
}

.footer__links a {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.7);
    transition: all var(--transition-fast);
    display: inline-block;
}

.footer__links a:hover {
    color: white;
    transform: translateX(4px);
}

.footer__contacts {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-2);
}

.footer__contacts li {
    display: flex;
    align-items: center;
    gap: var(--spacing-1-5);
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.7);
}

.footer__contacts svg {
    color: var(--color-primary);
    flex-shrink: 0;
}

.footer__bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: var(--spacing-4);
}

.footer__copyright p {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.6);
}

.footer__legal {
    display: flex;
    gap: var(--spacing-4);
}

.footer__legal a {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.6);
    transition: all var(--transition-fast);
}

.footer__legal a:hover {
    color: white;
}

/* Footer responsive */
@media (max-width: 1024px) {
    .footer__top {
        grid-template-columns: 1fr 1fr;
    }

    .footer__column:first-child {
        grid-column: span 2;
    }
}

@media (max-width: 768px) {
    .footer__top {
        grid-template-columns: 1fr;
        gap: var(--spacing-4);
    }

    .footer__column:first-child {
        grid-column: span 1;
    }

    .footer__bottom {
        flex-direction: column;
        gap: var(--spacing-3);
        text-align: center;
    }

    .footer__legal {
        flex-direction: column;
        gap: var(--spacing-2);
    }
}