/* The Paperboy - Minimalist Design System */

:root {
    /* Color Palette */
    --primary-blue: #1e5a8e;
    --pure-white: #ffffff;
    --paper-cream: #f9f7f4;
    --text-charcoal: #2d3748;
    --text-muted: #64748b;
    
    /* Semantic Colors */
    --success-color: #059669;
    --error-color: #dc2626;
    --border-color: #e2e8f0;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 3rem;
    --spacing-xl: 4rem;
}

/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--paper-cream);
    color: var(--text-charcoal);
    line-height: 1.7;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-sm);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    line-height: 1.3;
    font-weight: 600;
}

h1 { font-size: 3rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }

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

a:hover {
    text-decoration: underline;
}

/* Navigation */
.navbar {
    background-color: var(--pure-white);
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-sm) 0;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.navbar-brand img {
    width: 32px;
    height: 32px;
}

.navbar-brand a {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-blue);
    text-decoration: none;
}

.navbar-brand a:hover {
    text-decoration: none;
    opacity: 0.8;
}

.navbar-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.navbar-menu a:not(.btn) {
    color: var(--text-charcoal);
    text-decoration: none;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 4px;
    transition: background-color 0.2s;
}

.navbar-menu a:not(.btn):hover {
    background-color: var(--paper-cream);
    text-decoration: none;
}

.user-info {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Main Content */
main {
    padding: var(--spacing-md) 0;
    min-height: calc(100vh - 200px);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 500;
    text-align: center;
    border: 2px solid transparent;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
}

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

.btn-primary:hover {
    background-color: #174570;
    border-color: #174570;
    text-decoration: none;
    transform: translateY(-2px);
}

.btn-secondary {
    background-color: var(--pure-white);
    color: var(--primary-blue);
    border-color: var(--primary-blue);
}

.btn-secondary:hover {
    background-color: var(--primary-blue);
    color: var(--pure-white);
    text-decoration: none;
}

.btn-lg {
    padding: 1rem 2rem;
    font-size: 1.125rem;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-full {
    width: 100%;
}

.btn-action {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    border: 1px solid var(--border-color);
    background-color: var(--pure-white);
    color: var(--text-charcoal);
}

.btn-action:hover {
    background-color: var(--paper-cream);
    text-decoration: none;
}

.btn-like.liked {
    background-color: #fee2e2;
    color: var(--error-color);
    border-color: var(--error-color);
}

/* Cards */
.card {
    background-color: var(--pure-white);
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

/* Digest List Page */
.page-header {
    text-align: center;
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.page-header h1 {
    margin-bottom: var(--spacing-xs);
}

.page-header p {
    color: var(--text-muted);
    font-size: 1.125rem;
}

.digests-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-md);
}

.digest-card-link {
    text-decoration: none;
    color: inherit;
}

.digest-card {
    background-color: var(--pure-white);
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    transition: transform 0.2s, border-color 0.2s;
}

.digest-card:hover {
    transform: translateY(-2px);
    border-color: var(--primary-blue);
}

.digest-card-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: var(--spacing-sm);
}

.digest-card-header h3 {
    font-size: 1.25rem;
    flex: 1;
}

.digest-date {
    font-size: 0.875rem;
    color: var(--text-muted);
    white-space: nowrap;
    margin-left: var(--spacing-sm);
}

.digest-stats {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
    font-size: 0.875rem;
    color: var(--text-muted);
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.digest-preview {
    margin-bottom: var(--spacing-sm);
}

.top-paper-title {
    font-size: 0.875rem;
    color: var(--text-muted);
    line-height: 1.6;
}

.digest-footer {
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* Digest Detail Page */
.digest-header {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.digest-header h1 {
    margin-bottom: var(--spacing-xs);
}

.digest-meta {
    color: var(--text-muted);
    font-size: 1.125rem;
}

.word-cloud-section {
    background-color: var(--pure-white);
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    margin-bottom: var(--spacing-md);
    text-align: center;
}

.word-cloud-image {
    max-width: 100%;
    height: auto;
    border-radius: 4px;
}

.stats-dashboard {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.stat-card {
    background-color: var(--pure-white);
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    text-align: center;
}

.stat-value {
    font-size: 2rem;
    font-weight: 600;
    color: var(--primary-blue);
}

.stat-label {
    color: var(--text-muted);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.controls {
    background-color: var(--pure-white);
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    margin-bottom: var(--spacing-md);
}

.search-box {
    margin-bottom: var(--spacing-sm);
}

.search-input {
    width: 100%;
    padding: 0.75rem;
    font-size: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.search-input:focus {
    outline: none;
    border-color: var(--primary-blue);
}

.filters {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.filter-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 0.25rem;
    color: var(--text-muted);
}

.filter-select {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--pure-white);
}

.filter-select:focus {
    outline: none;
    border-color: var(--primary-blue);
}

.results-count {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
}

/* Papers List */
.papers-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.paper-card {
    background-color: var(--pure-white);
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    transition: border-color 0.2s;
}

.paper-card:hover {
    border-color: var(--primary-blue);
}

.paper-title {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-xs);
}

.paper-title a {
    color: var(--text-charcoal);
    text-decoration: none;
}

.paper-title a:hover {
    color: var(--primary-blue);
}

.paper-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-xs);
}

.paper-authors {
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-xs);
}

.authors-more {
    color: var(--primary-blue);
}

.paper-conclusion {
    margin: var(--spacing-sm) 0;
    padding: var(--spacing-sm);
    background-color: var(--paper-cream);
    border-left: 3px solid var(--primary-blue);
    font-style: italic;
}

.paper-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin: var(--spacing-sm) 0;
}

.tag {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    font-size: 0.75rem;
    border-radius: 12px;
    background-color: var(--paper-cream);
    color: var(--text-charcoal);
    border: 1px solid var(--border-color);
}

.tag-theme {
    background-color: #e0f2fe;
    color: #0c4a6e;
    border-color: #7dd3fc;
}

.tag-country {
    background-color: #fef3c7;
    color: #92400e;
    border-color: #fcd34d;
}

.tag-methodology {
    background-color: #d1fae5;
    color: #065f46;
    border-color: #6ee7b7;
}

.paper-actions {
    display: flex;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
}

/* Authors Section */
.authors-section {
    margin-top: var(--spacing-lg);
    background-color: var(--pure-white);
    padding: var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.authors-section h2 {
    margin-bottom: var(--spacing-sm);
}

.authors-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: var(--spacing-xs);
    max-height: 400px;
    overflow: hidden;
    transition: max-height 0.3s;
}

.authors-grid.show-all {
    max-height: none;
}

.author-card {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-xs);
    background-color: var(--paper-cream);
    border-radius: 4px;
}

.author-name {
    font-weight: 500;
}

.author-count {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Login Page */
.login-page {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 60vh;
}

.login-card {
    background-color: var(--pure-white);
    padding: var(--spacing-lg);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    max-width: 500px;
    width: 100%;
}

.login-card h1 {
    text-align: center;
    margin-bottom: var(--spacing-sm);
}

.login-description {
    text-align: center;
    color: var(--text-muted);
    margin-bottom: var(--spacing-md);
}

.form-group {
    margin-bottom: var(--spacing-md);
}

.form-group label {
    display: block;
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
}

.form-input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 1rem;
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-blue);
}

.message {
    padding: var(--spacing-sm);
    border-radius: 4px;
    margin-top: var(--spacing-sm);
}

.message-success {
    background-color: #d1fae5;
    color: #065f46;
    border: 1px solid var(--success-color);
}

.message-error {
    background-color: #fee2e2;
    color: #991b1b;
    border: 1px solid var(--error-color);
}

.login-help {
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* Error Page */
.error-page {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 60vh;
}

.error-card {
    text-align: center;
    background-color: var(--pure-white);
    padding: var(--spacing-xl);
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.error-code {
    font-size: 4rem;
    color: var(--error-color);
    margin-bottom: var(--spacing-sm);
}

.error-message {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
}

.error-details {
    color: var(--text-muted);
    margin-bottom: var(--spacing-md);
}

.error-actions {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
}

/* Account Dropdown */
.account-dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-toggle {
    cursor: pointer;
    user-select: none;
}

.dropdown-menu {
    display: none;
    position: absolute;
    top: calc(100% + 0.5rem);
    right: 0;
    background-color: var(--pure-white);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    min-width: 220px;
    z-index: 1000;
    padding: 0.5rem 0;
}

.dropdown-menu.show {
    display: block;
}

.dropdown-header {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 500;
    word-break: break-word;
}

.dropdown-item {
    display: block;
    padding: 0.5rem 1rem;
    color: var(--text-charcoal);
    text-decoration: none;
    transition: background-color 0.2s;
    cursor: pointer;
}

.dropdown-item:hover {
    background-color: var(--paper-cream);
    text-decoration: none;
}

.dropdown-divider {
    height: 1px;
    background-color: var(--border-color);
    margin: 0.5rem 0;
}

/* Footer */
.footer {
    background-color: var(--pure-white);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-md) 0;
    margin-top: var(--spacing-xl);
    text-align: center;
}

.footer p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    h1 { font-size: 2rem; }
    h2 { font-size: 1.5rem; }
    h3 { font-size: 1.25rem; }
    
    .navbar .container {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .navbar-menu {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .digests-grid {
        grid-template-columns: 1fr;
    }
    
    .stats-dashboard {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .filters {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .btn-lg {
        padding: 0.75rem 1.5rem;
        font-size: 1rem;
    }
    
    .stats-dashboard {
        grid-template-columns: 1fr;
    }
}