:root {
    --osdl-font: 'Jupiter Sans', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --osdl-icons: 'Jupiter Symbols Outlined', 'Jupiter Sans', sans-serif;

    /* Google-ish palette */
    --bg: #f8f9fa;
    --surface: #ffffff;
    --text-primary: #202124;
    --text-secondary: #5f6368;
    --primary: #1a73e8;
    --primary-hover: #1558c0;
    --border: #e0e0e0;
    --radius: 12px;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.12);
}

* {
    box-sizing: border-box;
}

body {
    font-family: var(--osdl-font);
    margin: 0;
    padding: 0;
    background-color: var(--bg);
    color: var(--text-primary);
}

/* ---------- Header ---------- */

header {
    background-color: var(--surface);
    color: var(--text-primary);
    text-align: center;
    padding: 2rem 1rem;
    box-shadow: var(--shadow-sm);
}

header h1 {
    margin: 0;
    font-weight: 600;
    font-size: 2rem;
}

header p {
    margin-top: 0.5rem;
    color: var(--text-secondary);
}

/* ---------- Layout ---------- */

main {
    max-width: 1100px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

h2 {
    font-weight: 600;
    margin-bottom: 1rem;
}

/* ---------- Search ---------- */

#search-section {
    text-align: center;
    margin-bottom: 2.5rem;
}

#search-form {
    display: flex;
    gap: 0.75rem;
    justify-content: center;
    flex-wrap: wrap;
}

#search-form input,
#search-form select {
    font-family: var(--osdl-font);
    padding: 0.75em 1em;
    font-size: 1rem;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    background-color: var(--surface);
    min-width: 160px;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

#search-form input {
    flex: 1;
    min-width: 260px;
}

#search-form input:focus,
#search-form select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(26, 115, 232, 0.15);
}

#search-form button {
    font-family: var(--osdl-font);
    padding: 0.75em 1.5em;
    font-size: 1rem;
    border-radius: var(--radius);
    border: none;
    background-color: var(--primary);
    color: #fff;
    cursor: pointer;
    transition: background-color 0.2s ease, box-shadow 0.2s ease, transform 0.1s ease;
}

#search-form button:hover {
    background-color: var(--primary-hover);
    box-shadow: var(--shadow-sm);
}

#search-form button:active {
    transform: translateY(1px);
}

/* ---------- Results ---------- */

#results-section {
    background-color: var(--surface);
    padding: 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
}

.result-item {
    padding: 1.25rem 0;
    border-bottom: 1px solid var(--border);
}

.result-item:last-child {
    border-bottom: none;
}

.result-title {
    font-weight: 500;
    font-size: 1.1rem;
    margin: 0 0 0.4rem;
}

.result-title a {
    text-decoration: none;
    color: var(--primary);
}

.result-title a:hover {
    text-decoration: underline;
}

.result-authors,
.result-date {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* ---------- Load More ---------- */

#load-more {
    display: block;
    margin: 2.5rem auto 0;
    padding: 0.75em 2.5em;
    font-size: 1rem;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    background-color: var(--surface);
    color: var(--primary);
    cursor: pointer;
    transition: background-color 0.2s ease, box-shadow 0.2s ease;
}

#load-more:hover {
    background-color: #f1f3f4;
    box-shadow: var(--shadow-sm);
}