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

:root {
    --bg: #F7F6F3;
    --surface: #FFFFFF;
    --text: #3A3A3A;
    --text-secondary: #8C8C8C;
    --border: #E8E6E1;
    --primary: #5B9A8B;
    --primary-hover: #4A8578;
    --primary-light: #EDF5F3;
    --danger: #D46A5A;
    --danger-light: #FDF0EE;
    --header-bg: #FFFFFF;
    --header-text: #3A3A3A;
    --accent-warm: #E8C87A;
    --shimmer-bg: #EDECEA;
    --shimmer-shine: #F5F4F1;
}

body {
    font-family: 'Source Sans Pro', 'Segoe UI', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.65;
    -webkit-font-smoothing: antialiased;
}

/* === Buttons === */
.btn {
    padding: 12px 28px;
    border: 2px solid var(--border);
    border-radius: 8px;
    background: var(--surface);
    color: var(--text);
    cursor: pointer;
    font-size: 15px;
    font-weight: 600;
    letter-spacing: 0.02em;
    transition: all 0.2s ease;
    white-space: nowrap;
}
.btn:hover {
    background: var(--bg);
    border-color: #D4D2CD;
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}
.btn:active { transform: translateY(0); }
.btn-sm { padding: 8px 20px; font-size: 14px; }
.btn-primary {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}
.btn-primary:hover {
    background: var(--primary-hover);
    border-color: var(--primary-hover);
}
.btn-secondary { background: transparent; }
.btn-danger {
    color: var(--danger);
    border-color: var(--danger);
}
.btn-danger:hover {
    background: var(--danger-light);
    border-color: var(--danger);
}

/* === Login Page === */
.login-page {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background: var(--bg);
}
.login-container {
    text-align: center;
    padding: 64px 56px;
    background: var(--surface);
    border-radius: 16px;
    box-shadow: 0 4px 24px rgba(0,0,0,0.06);
    border: 1px solid var(--border);
    max-width: 440px;
    width: 100%;
}
.login-title {
    font-size: 42px;
    color: var(--primary);
    margin-bottom: 6px;
    font-weight: 700;
    letter-spacing: -0.01em;
}
.login-subtitle {
    color: var(--text-secondary);
    margin-bottom: 48px;
    font-size: 17px;
    font-weight: 400;
}
.login-form { width: 100%; text-align: left; }
.form-group { margin-bottom: 24px; }
.form-group label {
    display: block;
    margin-bottom: 8px;
    font-size: 14px;
    font-weight: 600;
    color: var(--text);
    letter-spacing: 0.03em;
    text-transform: uppercase;
}
.form-group input {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid var(--border);
    border-radius: 10px;
    background: var(--bg);
    color: var(--text);
    font-size: 16px;
    box-sizing: border-box;
    transition: border-color 0.2s, box-shadow 0.2s;
}
.form-group input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(91, 154, 139, 0.15);
}
.login-btn {
    width: 100%;
    padding: 16px;
    border: none;
    border-radius: 10px;
    background: var(--primary);
    color: #fff;
    font-size: 17px;
    font-weight: 700;
    cursor: pointer;
    margin-top: 8px;
    transition: all 0.2s ease;
    letter-spacing: 0.02em;
}
.login-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 16px rgba(91, 154, 139, 0.3);
}
.login-btn:active { transform: translateY(0); }
.error-msg { margin-top: 20px; color: var(--danger); font-size: 14px; font-weight: 500; }

/* === App Header === */
.app-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 40px;
    background: var(--header-bg);
    color: var(--header-text);
    border-bottom: 1px solid var(--border);
}
.app-title {
    font-size: 24px;
    font-weight: 700;
    color: var(--primary);
}
.header-center { flex: 1; max-width: 520px; margin: 0 40px; }
.header-right { display: flex; align-items: center; gap: 16px; }
.user-email { font-size: 14px; color: var(--text-secondary); }
.admin-link {
    color: var(--primary);
    font-size: 14px;
    font-weight: 600;
    text-decoration: none;
}
.admin-link:hover { color: var(--primary-hover); }

.search-input {
    width: 100%;
    padding: 12px 20px;
    border: 2px solid var(--border);
    border-radius: 10px;
    font-size: 15px;
    background: var(--bg);
    color: var(--text);
    transition: border-color 0.2s, box-shadow 0.2s;
}
.search-input::placeholder { color: var(--text-secondary); }
.search-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(91, 154, 139, 0.15);
    background: var(--surface);
}

/* === Library === */
.library-container { max-width: 1100px; margin: 0 auto; padding: 40px 32px; }

.filters-bar {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 32px;
}
.filter-select {
    padding: 10px 16px;
    border: 2px solid var(--border);
    border-radius: 8px;
    font-size: 15px;
    background: var(--surface);
    color: var(--text);
    cursor: pointer;
    transition: border-color 0.2s;
}
.filter-select:focus {
    outline: none;
    border-color: var(--primary);
}
.isbn-filter-label {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 14px;
    color: var(--text-secondary);
    cursor: pointer;
    user-select: none;
}
.results-count { margin-left: auto; font-size: 14px; color: var(--text-secondary); }

/* Recently Read */
.recently-read { margin-bottom: 36px; }
.recently-read h3 {
    font-size: 16px;
    margin-bottom: 14px;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    font-weight: 600;
}
.recently-read-list { display: flex; gap: 14px; flex-wrap: wrap; }
.recently-read-item {
    padding: 14px 24px;
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 10px;
    font-size: 14px;
    cursor: pointer;
    transition: all 0.2s ease;
}
.recently-read-item:hover {
    border-color: var(--primary);
    background: var(--primary-light);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.06);
}
.recently-read-item .rr-title { font-weight: 600; }
.recently-read-item .rr-page { color: var(--text-secondary); margin-left: 10px; }

/* Book Table */
.book-table-container {
    background: var(--surface);
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid var(--border);
    box-shadow: 0 2px 12px rgba(0,0,0,0.04);
}
.book-table { width: 100%; border-collapse: collapse; }
.book-table th {
    text-align: left;
    padding: 16px 24px;
    font-size: 12px;
    font-weight: 700;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    border-bottom: 2px solid var(--border);
    background: var(--bg);
}
.book-table td {
    padding: 16px 24px;
    font-size: 15px;
    border-bottom: 1px solid var(--border);
}
.book-table tbody tr { cursor: pointer; transition: background 0.15s; }
.book-table tbody tr:hover { background: var(--primary-light); }
.book-table tbody tr:last-child td { border-bottom: none; }

/* Pagination */
.pagination {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    margin-top: 32px;
}
.pagination button {
    padding: 10px 20px;
    border: 2px solid var(--border);
    border-radius: 8px;
    background: var(--surface);
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.2s ease;
}
.pagination button:hover:not(:disabled) {
    border-color: var(--primary);
    color: var(--primary);
}
.pagination button:disabled { opacity: 0.35; cursor: default; }
.pagination .page-info { font-size: 14px; color: var(--text-secondary); }

/* === Reader === */
.reader-body {
    display: flex;
    flex-direction: column;
    height: 100vh;
    overflow: hidden;
    background: #E8E6E1;
}
.reader-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 28px;
    background: var(--surface);
    color: var(--text);
    flex-shrink: 0;
    border-bottom: 1px solid var(--border);
}
.back-link {
    color: var(--primary);
    text-decoration: none;
    font-size: 15px;
    font-weight: 600;
}
.back-link:hover { color: var(--primary-hover); }
.book-title-header { font-size: 15px; font-weight: 600; color: var(--text); }
.page-indicator {
    font-size: 14px;
    cursor: pointer;
    padding: 6px 14px;
    border-radius: 8px;
    color: var(--text-secondary);
    font-weight: 500;
    transition: background 0.15s;
}
.page-indicator:hover { background: var(--bg); }

.reader-viewport {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    padding: 24px;
}
.page-container {
    display: flex;
    gap: 6px;
    max-height: 100%;
    align-items: center;
    justify-content: center;
}
.page-container.single-page .page-slot:last-child { display: none; }

.page-slot {
    display: flex;
    align-items: center;
    justify-content: center;
    background: white;
    box-shadow: 0 2px 20px rgba(0,0,0,0.12), 0 0 1px rgba(0,0,0,0.08);
    position: relative;
    overflow: hidden;
    min-width: 100px;
    min-height: 200px;
    border-radius: 2px;
}
.page-slot img {
    display: block;
    max-height: 100%;
    width: auto;
    user-select: none;
    -webkit-user-drag: none;
}

/* Shimmer loading animation */
.page-shimmer {
    width: 350px;
    height: 500px;
    background: linear-gradient(
        110deg,
        var(--shimmer-bg) 8%,
        var(--shimmer-shine) 18%,
        var(--shimmer-bg) 33%
    );
    background-size: 200% 100%;
    animation: shimmer 1.5s linear infinite;
}
@keyframes shimmer {
    to { background-position: -200% 0; }
}

/* Reader nav */
.reader-nav {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 14px 28px;
    background: var(--surface);
    flex-shrink: 0;
    border-top: 1px solid var(--border);
}
.nav-btn {
    width: 48px;
    height: 48px;
    border: 2px solid var(--border);
    border-radius: 50%;
    background: var(--surface);
    color: var(--text);
    font-size: 26px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
}
.nav-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-light);
}
.nav-btn:disabled { opacity: 0.25; cursor: default; }
.nav-btn:disabled:hover { border-color: var(--border); color: var(--text); background: var(--surface); }

.scrubber-container { flex: 1; }
.page-scrubber {
    width: 100%;
    cursor: pointer;
    accent-color: var(--primary);
}

/* Reader toolbar */
.reader-toolbar {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 32px;
    padding: 10px 28px;
    background: var(--bg);
    flex-shrink: 0;
    border-top: 1px solid var(--border);
}
.reader-toolbar .btn {
    background: var(--surface);
    color: var(--text);
    border-color: var(--border);
}
.reader-toolbar .btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}
.zoom-controls, .fit-controls, .fullscreen-control { display: flex; align-items: center; gap: 8px; }
.zoom-level { color: var(--text-secondary); font-size: 14px; min-width: 48px; text-align: center; font-weight: 600; }

/* === Modals === */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.3);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}
.modal-dialog {
    background: var(--surface);
    padding: 36px;
    border-radius: 16px;
    box-shadow: 0 8px 40px rgba(0,0,0,0.12);
    min-width: 320px;
    border: 1px solid var(--border);
}
.modal-dialog h3 { margin-bottom: 20px; font-size: 20px; }
.jump-input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: 10px;
    font-size: 16px;
    margin-bottom: 20px;
    transition: border-color 0.2s;
}
.jump-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(91, 154, 139, 0.15);
}
.modal-actions { display: flex; gap: 12px; justify-content: flex-end; }

/* === Admin === */
.admin-container { max-width: 1000px; margin: 0 auto; padding: 40px 32px; }
.tab-bar { display: flex; gap: 6px; margin-bottom: 36px; }
.tab-btn {
    padding: 12px 28px;
    border: 2px solid var(--border);
    border-radius: 10px 10px 0 0;
    background: var(--bg);
    cursor: pointer;
    font-size: 15px;
    font-weight: 600;
    color: var(--text-secondary);
    transition: all 0.15s;
}
.tab-btn.active {
    background: var(--surface);
    border-bottom-color: var(--surface);
    color: var(--primary);
}
.tab-btn:hover:not(.active) { color: var(--text); }

.section-header { margin-bottom: 24px; }
.section-header h2 { font-size: 24px; font-weight: 700; }
.add-user-form { display: flex; gap: 12px; margin-bottom: 28px; align-items: center; flex-wrap: wrap; }
.form-input {
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: 8px;
    font-size: 15px;
    transition: border-color 0.2s;
}
.form-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(91, 154, 139, 0.15);
}

.import-section {
    background: var(--surface);
    padding: 28px;
    border-radius: 12px;
    border: 1px solid var(--border);
    box-shadow: 0 2px 12px rgba(0,0,0,0.04);
}
.import-form { display: flex; gap: 16px; align-items: center; margin-bottom: 16px; }
.file-label { font-size: 15px; cursor: pointer; font-weight: 500; }
.file-input { margin-left: 8px; }
.csv-format-hint { font-size: 14px; color: var(--text-secondary); margin-bottom: 20px; }
.csv-format-hint code {
    background: var(--bg);
    padding: 3px 8px;
    border-radius: 6px;
    font-size: 13px;
    border: 1px solid var(--border);
}
.import-status { font-size: 14px; color: var(--text-secondary); margin-bottom: 12px; }
.import-result { padding: 16px; background: var(--bg); border-radius: 8px; font-size: 14px; }
.import-result.success { border-left: 4px solid var(--primary); }
.import-result.has-errors { border-left: 4px solid var(--accent-warm); }

/* === Labels === */
.label-on-demand {
    display: inline-block;
    font-size: 11px;
    padding: 2px 8px;
    border-radius: 6px;
    background: var(--primary-light);
    color: var(--primary);
    border: 1px solid rgba(91, 154, 139, 0.3);
    vertical-align: middle;
    margin-left: 6px;
    font-weight: 600;
}

/* === Settings === */
.setting-row {
    display: flex;
    align-items: center;
    gap: 24px;
    padding: 24px 28px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    box-shadow: 0 2px 12px rgba(0,0,0,0.04);
}
.setting-info { flex: 1; }
.setting-label { display: block; font-weight: 700; font-size: 16px; margin-bottom: 4px; }
.setting-description { font-size: 14px; color: var(--text-secondary); line-height: 1.5; }
.toggle-switch { position: relative; display: inline-block; width: 52px; height: 28px; flex-shrink: 0; }
.toggle-switch input { opacity: 0; width: 0; height: 0; }
.toggle-slider {
    position: absolute;
    cursor: pointer;
    inset: 0;
    background: var(--border);
    border-radius: 28px;
    transition: 0.25s;
}
.toggle-slider:before {
    content: "";
    position: absolute;
    height: 22px;
    width: 22px;
    left: 3px;
    bottom: 3px;
    background: white;
    border-radius: 50%;
    transition: 0.25s;
    box-shadow: 0 1px 4px rgba(0,0,0,0.15);
}
.toggle-switch input:checked + .toggle-slider { background: var(--primary); }
.toggle-switch input:checked + .toggle-slider:before { transform: translateX(24px); }

/* === Utility === */
.hidden { display: none !important; }