/* TrendAI Brand - Dark Theme */
:root {
    --trendai-red: #d71920;
    --trendai-red-dark: #b81419;
    --trendai-amber: #ff9500;
    --trendai-signal: #2e0fe4;
    --bg: #000000;
    --card: #0a0a0a;
    --input-bg: #111111;
    --border: #1a1a1a;
    --input-border: #333333;
    --text-primary: #e5e5e5;
    --text-secondary: #888888;
    --text-muted: #666666;
    --error: #ff6b6f;
    --success: #22c55e;
}

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

body {
    font-family: 'Inter', 'Work Sans', system-ui, -apple-system, sans-serif;
    background: var(--bg);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.5;
}

/* Screen Management */
.screen { display: none; }
.screen.active { display: flex; flex-direction: column; min-height: 100vh; }

/* Top Bar */
.top-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 20px;
    border-bottom: 1px solid var(--border);
    background: var(--card);
}
.top-bar .logo { height: 28px; }
.top-bar .nav-right { display: flex; align-items: center; gap: 12px; }
.top-bar .user-info { color: var(--text-secondary); font-size: 13px; }
.top-bar .score-badge {
    background: var(--trendai-red);
    color: #fff;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 13px;
    font-weight: 600;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 24px;
    border: none;
    border-radius: 6px;
    font-family: 'Work Sans', sans-serif;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
}
.btn-primary {
    background: linear-gradient(135deg, var(--trendai-red) 0%, var(--trendai-amber) 100%);
    color: #fff;
}
.btn-primary:hover { opacity: 0.9; transform: translateY(-1px); }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; transform: none; }
.btn-outline {
    background: transparent;
    color: var(--text-primary);
    border: 1px solid var(--input-border);
}
.btn-outline:hover { border-color: var(--text-secondary); }
.btn-danger { background: var(--error); color: #fff; }
.btn-danger:hover { opacity: 0.9; }
.btn-sm { padding: 6px 14px; font-size: 12px; }
.btn-icon {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 6px;
    font-size: 18px;
}
.btn-icon:hover { color: var(--text-primary); }

/* Inputs */
input[type="text"], input[type="password"], input[type="email"],
input[type="datetime-local"], textarea, select {
    width: 100%;
    padding: 10px 14px;
    background: var(--input-bg);
    border: 1px solid var(--input-border);
    border-radius: 6px;
    color: var(--text-primary);
    font-family: 'Inter', sans-serif;
    font-size: 14px;
    transition: border-color 0.2s;
}
input:focus, textarea:focus, select:focus {
    outline: none;
    border-color: var(--trendai-red);
}
::placeholder { color: #444; }

label {
    display: block;
    font-size: 11px;
    font-weight: 700;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 6px;
}

/* Cards */
.card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 24px;
}

/* Login Screen */
.login-screen {
    align-items: center;
    justify-content: center;
    padding: 20px;
}
.login-box {
    width: 100%;
    max-width: 400px;
    text-align: center;
}
.login-box .logo-large { height: 48px; margin-bottom: 32px; }
.login-box h1 {
    font-family: 'Work Sans', sans-serif;
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--trendai-red);
}
.login-box .subtitle {
    color: var(--text-secondary);
    font-size: 14px;
    margin-bottom: 32px;
}
.form-group { margin-bottom: 16px; text-align: left; }
.form-group.error input { border-color: var(--error); }
.form-error { color: var(--error); font-size: 12px; margin-top: 4px; }
.login-btn { width: 100%; margin-top: 8px; }
.auth-toggle {
    margin-top: 16px;
    font-size: 13px;
    color: var(--text-secondary);
}
.auth-toggle a {
    color: var(--trendai-red);
    text-decoration: none;
    font-weight: 600;
}
.auth-toggle a:hover { text-decoration: underline; }

/* Admin spark icon */
.admin-spark { display: inline-flex; align-items: center; text-decoration: none; }
.admin-spark img { transition: opacity 0.2s; }
.admin-spark:hover img { opacity: 0.8 !important; }

/* Change Password Screen */
.change-pw-box {
    width: 100%;
    max-width: 400px;
    text-align: center;
}
.change-pw-box h2 { margin-bottom: 8px; color: var(--trendai-amber); }
.change-pw-box .notice {
    color: var(--text-secondary);
    font-size: 13px;
    margin-bottom: 24px;
}

/* Lobby Screen */
.lobby-screen { align-items: center; }
.lobby-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 40px 20px;
    text-align: center;
    max-width: 600px;
}
.lobby-content h1 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 12px;
}
.lobby-content .tagline {
    color: #ffffff;
    font-size: 16px;
    margin-bottom: 40px;
    line-height: 1.6;
}
.start-btn { font-size: 18px; padding: 16px 48px; }

/* Challenge Select Screen */
.select-screen { align-items: stretch; }
.select-header {
    text-align: center;
    padding: 24px 20px 8px;
}
.select-header h1 { font-size: 20px; font-weight: 700; }
.timer {
    color: var(--trendai-amber);
    font-size: 14px;
    font-family: 'Inter', monospace;
    margin-top: 4px;
}
.challenge-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 16px;
    padding: 20px;
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
}
.challenge-tile {
    background: var(--card);
    border: 2px solid var(--trendai-amber);
    border-radius: 10px;
    padding: 24px;
    cursor: pointer;
    transition: all 0.2s;
    position: relative;
    overflow: hidden;
}
.challenge-tile:hover {
    border-color: var(--trendai-red);
    transform: translateY(-2px);
    box-shadow: 0 4px 20px rgba(215, 25, 32, 0.15);
}
.challenge-tile.completed {
    border-color: var(--success);
}
.challenge-tile.completed:hover {
    border-color: var(--success);
    box-shadow: 0 4px 20px rgba(34, 197, 94, 0.15);
}
.challenge-tile.completed::after {
    content: '\2713';
    position: absolute;
    top: 12px;
    right: 12px;
    background: var(--success);
    color: #fff;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    font-weight: 700;
}
.challenge-tile.final-challenge {
    border-color: var(--trendai-amber);
    background: linear-gradient(135deg, rgba(215, 25, 32, 0.08) 0%, rgba(255, 149, 0, 0.08) 100%);
}
.challenge-tile.final-challenge.completed {
    border-color: var(--success);
}
.challenge-tile .tile-name {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}
.challenge-tile .tile-points {
    font-size: 13px;
    color: var(--trendai-amber);
    font-weight: 600;
}
.challenge-tile .tile-status {
    font-size: 12px;
    color: var(--text-muted);
    margin-top: 4px;
}

/* Challenge Detail Screen */
.detail-screen { align-items: stretch; }
.detail-content {
    flex: 1;
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
    padding: 24px 20px;
}
.detail-back {
    color: var(--text-secondary);
    font-size: 13px;
    cursor: pointer;
    margin-bottom: 16px;
    display: inline-flex;
    align-items: center;
    gap: 4px;
}
.detail-back:hover { color: var(--text-primary); }
.detail-title {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 4px;
}
.detail-points {
    color: var(--trendai-amber);
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 24px;
}
.detail-story {
    color: var(--text-primary);
    line-height: 1.8;
    margin-bottom: 24px;
    font-size: 15px;
    white-space: pre-wrap;
}
.detail-details {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 24px;
    line-height: 1.6;
}
.detail-details img {
    max-width: 100%;
    border-radius: 6px;
    margin: 12px 0;
}
.detail-details a {
    color: var(--trendai-red);
    text-decoration: none;
    font-weight: 600;
}
.detail-details a:hover { text-decoration: underline; }

/* Hints */
.hints-section { margin-bottom: 24px; }
.hint-btn {
    background: var(--input-bg);
    border: 1px solid var(--input-border);
    color: var(--text-secondary);
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
    margin-right: 8px;
    margin-bottom: 8px;
    transition: all 0.2s;
}
.hint-btn:hover { border-color: var(--trendai-amber); color: var(--trendai-amber); }
.hint-btn.revealed { border-color: var(--trendai-amber); color: var(--trendai-amber); }
.hint-content {
    background: rgba(255, 149, 0, 0.08);
    border: 1px solid rgba(255, 149, 0, 0.2);
    border-radius: 6px;
    padding: 12px 16px;
    margin-top: 8px;
    font-size: 14px;
    color: var(--text-primary);
    display: none;
}
.hint-content.visible { display: block; }
.hint-content a { color: var(--trendai-amber); }
.hint-penalty {
    font-size: 11px;
    color: var(--error);
    margin-top: 4px;
}

/* Answer Input */
.answer-section {
    display: flex;
    gap: 12px;
    align-items: flex-start;
}
.answer-section input { flex: 1; }
.answer-feedback {
    margin-top: 12px;
    padding: 10px 16px;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 600;
    display: none;
}
.answer-feedback.correct {
    display: block;
    background: rgba(34, 197, 94, 0.1);
    border: 1px solid rgba(34, 197, 94, 0.3);
    color: var(--success);
}
.answer-feedback.incorrect {
    display: block;
    background: rgba(255, 107, 111, 0.1);
    border: 1px solid rgba(255, 107, 111, 0.3);
    color: var(--error);
}

/* Scoreboard Screen */
.scoreboard-screen { align-items: center; }
.scoreboard-content {
    width: 100%;
    max-width: 900px;
    padding: 24px 20px;
}
.scoreboard-content h1 {
    text-align: center;
    font-size: 22px;
    margin-bottom: 20px;
}
.scoreboard-table {
    width: 100%;
    border-collapse: collapse;
}
.scoreboard-table th {
    text-align: left;
    padding: 10px 14px;
    font-size: 11px;
    font-weight: 700;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-bottom: 1px solid var(--border);
}
.scoreboard-table td {
    padding: 12px 14px;
    font-size: 14px;
    border-bottom: 1px solid var(--border);
}
.scoreboard-table tr.current-user td {
    background: rgba(215, 25, 32, 0.08);
    font-weight: 600;
}
.rank-1 td:first-child { color: #ffd700; }
.rank-2 td:first-child { color: #c0c0c0; }
.rank-3 td:first-child { color: #cd7f32; }

/* Footer Nav */
.footer-nav {
    display: flex;
    justify-content: center;
    gap: 16px;
    padding: 16px;
    border-top: 1px solid var(--border);
    background: var(--card);
}
.footer-nav .nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 13px;
    font-weight: 600;
    padding: 8px 16px;
    border-radius: 6px;
    transition: all 0.2s;
    cursor: pointer;
}
.footer-nav .nav-link:hover,
.footer-nav .nav-link.active {
    color: var(--text-primary);
    background: var(--input-bg);
}

/* Toast / Notifications */
.toast {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 12px 20px;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 500;
    z-index: 1000;
    animation: slideIn 0.3s ease;
}
.toast.success { background: var(--success); color: #fff; }
.toast.error { background: var(--error); color: #fff; }
@keyframes slideIn {
    from { transform: translateX(100%); opacity: 0; }
    to { transform: translateX(0); opacity: 1; }
}

/* Loading Spinner */
.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid var(--border);
    border-top-color: var(--trendai-red);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* Modal */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    padding: 20px;
}
.modal {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 32px;
    max-width: 500px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
}
.modal h2 { margin-bottom: 16px; font-size: 18px; }
.modal .form-group { margin-bottom: 16px; }
.modal .modal-actions {
    display: flex;
    gap: 12px;
    justify-content: flex-end;
    margin-top: 24px;
}

/* Responsive */
@media (max-width: 640px) {
    .challenge-grid { grid-template-columns: 1fr; padding: 12px; gap: 12px; }
    .top-bar { padding: 10px 14px; }
    .top-bar .logo { height: 22px; }
    .detail-content { padding: 16px 14px; }
    .detail-title { font-size: 20px; }
    .detail-story { font-size: 14px; }
    .answer-section { flex-direction: column; }
    .answer-section .btn { width: 100%; }
    .lobby-content { padding: 24px 14px; }
    .lobby-content h1 { font-size: 22px; }
    .scoreboard-table { font-size: 12px; }
    .scoreboard-table th, .scoreboard-table td { padding: 8px 6px; }
    .footer-nav { gap: 4px; }
    .footer-nav .nav-link { padding: 8px 10px; font-size: 12px; }
}

@media (max-width: 380px) {
    .login-box { padding: 0 8px; }
    .top-bar .nav-right { gap: 6px; }
    .top-bar .user-info { display: none; }
}