:root {
    --primary: #6366f1;
    --primary-hover: #4f46e5;
    --bg-gradient: linear-gradient(135deg, #0f172a 0%, #1e1b4b 100%);
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --success: #10b981;
    --danger: #ef4444;
}

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

body {
    font-family: 'Outfit', 'Noto Sans KR', sans-serif;
    background: var(--bg-gradient);
    background-attachment: fixed;
    color: var(--text-main);
    min-height: 100vh;
    line-height: 1.6;
}

.hidden {
    display: none !important;
}

/* Authentication Overlay */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    backdrop-filter: blur(10px);
}

.glass-card {
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 2rem;
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
}

.auth-card {
    width: 100%;
    max-width: 400px;
    text-align: center;
}

.auth-card h1 {
    margin-bottom: 0.5rem;
    font-weight: 600;
    background: linear-gradient(to right, #818cf8, #c084fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.auth-card p {
    color: var(--text-muted);
    margin-bottom: 2rem;
}

input[type="password"] {
    width: 100%;
    padding: 12px 20px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    color: white;
    margin-bottom: 1rem;
    outline: none;
}

button {
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
    border-radius: 12px;
    font-weight: 600;
}

#login-btn {
    width: 100%;
    padding: 12px;
    background: var(--primary);
    color: white;
}

#login-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
}

.error-msg {
    color: var(--danger);
    font-size: 0.875rem;
    margin-top: 1rem;
}

/* Main Layout */
header {
    padding: 1.5rem 2rem;
    border-bottom: 1px solid var(--glass-border);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(to right, #818cf8, #c084fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.nav-links button {
    background: transparent;
    color: var(--text-muted);
    padding: 8px 16px;
    margin-left: 1rem;
}

.nav-links button.active {
    color: var(--text-main);
    background: var(--glass-bg);
}

main {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 2rem;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.secondary-btn {
    background: var(--glass-bg);
    color: var(--text-main);
    padding: 10px 20px;
    border: 1px solid var(--glass-border);
}

/* Todo Grid */
.todo-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.todo-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 1.5rem;
    position: relative;
    overflow: hidden;
    transition: transform 0.3s ease;
}

.todo-card:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.08);
}

.part-tag {
    font-size: 0.75rem;
    text-transform: uppercase;
    color: var(--primary);
    letter-spacing: 0.05em;
    font-weight: 600;
}

.topic-title {
    font-size: 1.125rem;
    margin: 0.5rem 0 1rem 0;
    font-weight: 600;
}

.card-actions {
    display: flex;
    gap: 0.5rem;
}

.complete-btn {
    flex: 1;
    background: var(--success);
    color: white;
    padding: 8px;
    font-size: 0.875rem;
}

.cancel-btn {
    background: var(--danger);
    color: white;
    padding: 8px 12px;
    font-size: 0.875rem;
}

/* Stats Section */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.stat-item {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    padding: 1.5rem;
    text-align: center;
}

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

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
}

/* Table styling */
.log-container {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 1.5rem;
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
}

th {
    text-align: left;
    color: var(--text-muted);
    font-size: 0.875rem;
    padding: 12px;
    border-bottom: 1px solid var(--glass-border);
}

td {
    padding: 12px;
    border-bottom: 1px solid var(--glass-border);
}

@media (max-width: 640px) {
    .todo-grid {
        grid-template-columns: 1fr;
    }
}

.loading-msg,
.error-msg,
.info-msg {
    grid-column: 1 / -1;
    text-align: center;
    padding: 2rem;
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    color: var(--text-muted);
}

.error-msg {
    color: var(--danger);
    border-color: var(--danger);
}