/* HESCON Kongre Kitapları — kurumsal statik arşiv */

:root {
    --color-primary: #1a5276;
    --color-primary-dark: #0e3450;
    --color-accent: #78d5ef;
    --color-accent-dark: #4db8d9;
    --color-text: #2c3e50;
    --color-text-muted: #5d6d7e;
    --color-bg: #f4f7f9;
    --color-white: #ffffff;
    --color-border: #dde4ea;
    --color-shadow: rgba(26, 82, 118, 0.08);
    --font-family: "Work Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --radius: 10px;
    --radius-lg: 16px;
    --transition: 0.2s ease;
    --container-width: 1140px;
    --header-height: 88px;
}

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

html {
    scroll-behavior: smooth;
    overflow-x: hidden;
}

body {
    margin: 0;
    font-family: var(--font-family);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    overflow-x: hidden;
    width: 100%;
    max-width: 100%;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

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

.container {
    width: 100%;
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* Header */

.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--color-white);
    border-bottom: 1px solid var(--color-border);
    box-shadow: 0 2px 12px var(--color-shadow);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    min-height: 88px;
}

.logo-link {
    flex-shrink: 0;
}

.logo {
    height: 56px;
    width: auto;
}

.header-nav {
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-link {
    padding: 10px 16px;
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text);
    border-radius: var(--radius);
    transition: background var(--transition), color var(--transition);
}

.nav-link:hover {
    background: var(--color-bg);
    color: var(--color-primary);
}

.nav-link--active {
    background: var(--color-primary);
    color: var(--color-white);
}

.nav-link--active:hover {
    background: var(--color-primary-dark);
    color: var(--color-white);
}

.menu-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 40px;
    height: 40px;
    padding: 0;
    border: none;
    background: transparent;
    cursor: pointer;
}

.menu-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--color-primary);
    border-radius: 2px;
    transition: transform var(--transition), opacity var(--transition);
}

.menu-toggle.is-open span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.menu-toggle.is-open span:nth-child(2) {
    opacity: 0;
}

.menu-toggle.is-open span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* Hero slider */

.hero-slider {
    width: 100%;
    max-width: 100%;
    background: #ffffff;
    overflow: hidden;
}

.hero-slider__track {
    width: 100%;
    overflow: hidden;
    line-height: 0;
}

.hero-slider__slide {
    width: 100%;
}

.hero-slider__image {
    display: block;
    width: 100%;
    max-width: 1920px;
    height: auto;
    margin: 0 auto;
    aspect-ratio: 16 / 9;
}

.section-icon {
    display: block;
    margin: 0 auto 16px;
    opacity: 0.9;
}

/* Sections */

.section {
    padding: 72px 0;
}

.section-header {
    margin-bottom: 40px;
    text-align: center;
}

.section-header h2 {
    margin: 0 0 10px;
    font-size: 1.875rem;
    font-weight: 700;
    color: var(--color-primary-dark);
}

.section-header p {
    margin: 0;
    color: var(--color-text-muted);
}

/* Filter */

.filter-bar {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    margin-bottom: 36px;
}

.filter-label {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text-muted);
}

.filter-select {
    min-width: 160px;
    padding: 10px 14px;
    font-family: var(--font-family);
    font-size: 0.9375rem;
    color: var(--color-text);
    background: var(--color-white);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    cursor: pointer;
    transition: border-color var(--transition), box-shadow var(--transition);
}

.filter-select:focus {
    outline: none;
    border-color: var(--color-accent-dark);
    box-shadow: 0 0 0 3px rgba(120, 213, 239, 0.25);
}

/* Book grid */

.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 28px;
}

.book-card {
    display: flex;
    flex-direction: column;
    background: var(--color-white);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: 0 4px 20px var(--color-shadow);
    transition: transform var(--transition), box-shadow var(--transition);
}

.book-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 32px rgba(26, 82, 118, 0.12);
}

.book-card.is-hidden {
    display: none;
}

.book-cover {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 8px;
    min-height: 160px;
    background: linear-gradient(160deg, var(--color-primary) 0%, #2471a3 100%);
    color: var(--color-white);
}

.book-cover--alt {
    background: linear-gradient(160deg, #154360 0%, var(--color-primary-dark) 100%);
}

.book-year {
    font-size: 2.5rem;
    font-weight: 700;
    line-height: 1;
    letter-spacing: -0.02em;
}

.book-label {
    font-size: 0.8125rem;
    font-weight: 500;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    opacity: 0.85;
}

.book-body {
    display: flex;
    flex-direction: column;
    flex: 1;
    padding: 24px;
}

.book-title {
    margin: 0 0 8px;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-primary-dark);
    line-height: 1.35;
}

.book-meta {
    margin: 0 0 12px;
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--color-accent-dark);
}

.book-desc {
    margin: 0 0 20px;
    flex: 1;
    font-size: 0.9375rem;
    color: var(--color-text-muted);
}

.book-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

/* Buttons */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 18px;
    font-family: var(--font-family);
    font-size: 0.875rem;
    font-weight: 600;
    border-radius: var(--radius);
    border: 2px solid transparent;
    cursor: pointer;
    transition: background var(--transition), color var(--transition), border-color var(--transition);
}

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

.btn-primary:hover {
    background: var(--color-primary-dark);
    color: var(--color-white);
}

.btn-outline {
    background: transparent;
    color: var(--color-primary);
    border-color: var(--color-border);
}

.btn-outline:hover {
    border-color: var(--color-primary);
    background: var(--color-bg);
    color: var(--color-primary-dark);
}

.empty-state {
    margin: 32px 0 0;
    padding: 32px;
    text-align: center;
    font-size: 1rem;
    color: var(--color-text-muted);
    background: var(--color-white);
    border: 1px dashed var(--color-border);
    border-radius: var(--radius-lg);
}

/* About */

.about-section {
    background: var(--color-white);
    border-top: 1px solid var(--color-border);
}

.about-grid {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 48px;
    align-items: start;
}

.about-content {
    padding-left: 24px;
    border-left: 4px solid var(--color-primary);
}

.about-label {
    margin: 0 0 10px;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-accent-dark);
}

.about-content h2 {
    margin: 0 0 20px;
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--color-primary-dark);
}

.about-content p {
    margin: 0 0 16px;
    color: var(--color-text-muted);
    line-height: 1.75;
}

.about-content p:last-child {
    margin-bottom: 0;
}

.about-card {
    padding: 32px;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
}

.about-card h3 {
    margin: 0 0 20px;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-primary-dark);
}

.info-list {
    list-style: none;
    margin: 0;
    padding: 0;
}

.info-list li {
    display: flex;
    flex-direction: column;
    gap: 4px;
    padding: 14px 0;
    border-bottom: 1px solid var(--color-border);
}

.info-list li:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.info-list li:first-child {
    padding-top: 0;
}

.info-label {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--color-text-muted);
}

.info-value {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text);
}

/* Footer */

.site-footer {
    padding: 28px 0;
    background: var(--color-primary-dark);
    color: rgba(255, 255, 255, 0.75);
    text-align: center;
}

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

.footer-inner p {
    margin: 0 auto;
    width: 100%;
    text-align: center;
    font-size: 0.875rem;
}

/* Responsive */

@media (max-width: 768px) {
    :root {
        --header-height: 72px;
    }

    .header-inner {
        min-height: 72px;
    }

    .logo {
        height: 44px;
    }

    .menu-toggle {
        display: flex;
    }

    .header-nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        padding: 16px 24px 24px;
        background: var(--color-white);
        border-bottom: 1px solid var(--color-border);
        box-shadow: 0 8px 24px var(--color-shadow);
    }

    .header-nav.is-open {
        display: flex;
    }

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

    .site-header .container {
        position: relative;
    }

    .section {
        padding: 56px 0;
    }

    .about-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .about-content {
        padding-left: 20px;
    }

    .filter-bar {
        flex-direction: column;
    }

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

@media (max-width: 480px) {
    .book-actions {
        flex-direction: column;
    }

    .book-actions .btn {
        width: 100%;
    }
}