:root {
    --primary: #0f9d58;
    --primary-dark: #0d8549;
    --secondary: #4285f4;
    --danger: #db4437;
    --background: #1a1a1a;
    --surface: #2d2d2d;
    --surface-light: #3a3a3a;
    --text: #e8eaed;
    --text-secondary: #9aa0a6;
    --border: #444;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--background);
    color: var(--text);
    line-height: 1.6;
}

.screen {
    min-height: 100vh;
}

.hidden {
    display: none !important;
}

/* Auth Screen */
.auth-container {
    max-width: 400px;
    margin: 0 auto;
    padding: 100px 20px;
    text-align: center;
}

.auth-container h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
}

.auth-container p {
    color: var(--text-secondary);
    margin-bottom: 30px;
}

#auth-form {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

input[type="text"],
input[type="password"],
textarea,
select {
    padding: 12px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 6px;
    color: var(--text);
    font-size: 16px;
    font-family: inherit;
}

input:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--primary);
}

button {
    padding: 12px 24px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.2s;
}

button:hover {
    background: var(--primary-dark);
}

.btn-secondary {
    background: var(--surface-light);
}

.btn-secondary:hover {
    background: var(--border);
}

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

.error {
    color: var(--danger);
    font-size: 14px;
    margin-top: 10px;
}

.success {
    color: var(--primary);
    font-size: 14px;
    margin-top: 10px;
}

/* Navbar */
.navbar {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 15px 0;
}

.nav-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-content h1 {
    font-size: 1.5rem;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 15px;
}

#current-user {
    color: var(--text-secondary);
}

/* Container */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

/* Day Selector */
.day-selector {
    margin-bottom: 30px;
}

.day-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(80px, 1fr));
    gap: 10px;
}

.day-btn {
    padding: 20px;
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 8px;
    color: var(--text);
    font-size: 18px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.day-btn:hover {
    border-color: var(--primary);
    transform: translateY(-2px);
}

.day-btn.active {
    background: var(--primary);
    border-color: var(--primary);
}

/* Content */
.content {
    background: var(--surface);
    border-radius: 12px;
    padding: 30px;
}

/* View Toggle */
.view-toggle {
    display: flex;
    gap: 10px;
    margin-bottom: 30px;
    border-bottom: 2px solid var(--border);
    padding-bottom: 15px;
}

.view-btn {
    background: transparent;
    color: var(--text-secondary);
    padding: 10px 20px;
    border-radius: 6px 6px 0 0;
}

.view-btn:hover {
    background: var(--surface-light);
    color: var(--text);
}

.view-btn.active {
    background: var(--surface-light);
    color: var(--text);
    border-bottom: 2px solid var(--primary);
}

.view {
    display: none;
}

.view.active {
    display: block;
}

/* Part Selector */
.part-selector {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.part-btn {
    padding: 10px 20px;
    background: var(--surface-light);
    border-radius: 6px;
}

.part-btn.active {
    background: var(--primary);
}

/* Leaderboard */
.leaderboard-table {
    width: 100%;
    border-collapse: collapse;
}

.leaderboard-table th,
.leaderboard-table td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

.leaderboard-table th {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 14px;
}

.rank-badge {
    display: inline-block;
    width: 30px;
    height: 30px;
    line-height: 30px;
    text-align: center;
    border-radius: 50%;
    background: var(--surface-light);
    font-weight: 600;
}

.rank-badge.gold {
    background: #ffd700;
    color: #000;
}

.rank-badge.silver {
    background: #c0c0c0;
    color: #000;
}

.rank-badge.bronze {
    background: #cd7f32;
    color: #000;
}

/* Solutions */
.solution-card {
    background: var(--surface-light);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 15px;
}

.solution-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.solution-meta {
    display: flex;
    gap: 15px;
    font-size: 14px;
    color: var(--text-secondary);
}

.solution-code {
    background: #1e1e1e;
    border-radius: 6px;
    padding: 15px;
    overflow-x: auto;
    margin-top: 10px;
}

.solution-code pre {
    margin: 0;
}

.solution-code code {
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 14px;
    line-height: 1.5;
}

/* Submit Form */
.submit-form-container {
    max-width: 800px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}

textarea {
    width: 100%;
    resize: vertical;
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
}

/* My Solutions */
.solutions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 15px;
}

.my-solution-card {
    background: var(--surface-light);
    border-radius: 8px;
    padding: 20px;
    cursor: pointer;
    transition: transform 0.2s;
}

.my-solution-card:hover {
    transform: translateY(-2px);
}

.my-solution-title {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 10px;
}

.my-solution-meta {
    font-size: 14px;
    color: var(--text-secondary);
}

.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.empty-state h3 {
    margin-bottom: 10px;
    color: var(--text);
}

/* Responsive */
@media (max-width: 768px) {
    .day-grid {
        grid-template-columns: repeat(auto-fill, minmax(60px, 1fr));
    }
    
    .day-btn {
        padding: 15px;
        font-size: 16px;
    }
    
    .view-toggle {
        overflow-x: auto;
    }
    
    .solutions-grid {
        grid-template-columns: 1fr;
    }
}