:root {
    --bg-color: #0f172a;
    --primary-color: #3b82f6;
    --accent-color: #8b5cf6;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --glass-bg: rgba(30, 41, 59, 0.4);
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
    --font-family: 'Outfit', sans-serif;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-main);
    min-height: 100vh;
    overflow-x: hidden;
    position: relative;
}

/* Background Mesh Gradient */
.background-mesh {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    background: radial-gradient(circle at 15% 50%, rgba(59, 130, 246, 0.15), transparent 25%),
                radial-gradient(circle at 85% 30%, rgba(139, 92, 246, 0.15), transparent 25%);
    filter: blur(60px);
    animation: pulse 10s ease-in-out infinite alternate;
}

@keyframes pulse {
    0% { transform: scale(1); }
    100% { transform: scale(1.1); }
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 3rem 1.5rem;
}

/* Header */
.glass-header {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 2.5rem;
    text-align: center;
    margin-bottom: 3rem;
    box-shadow: var(--glass-shadow);
}

.glass-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    background: linear-gradient(to right, #60a5fa, #c084fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.glass-header p {
    color: var(--text-muted);
    font-size: 1.1rem;
}

/* Grid */
.assignments-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
}

/* Cards */
.assignment-card {
    text-decoration: none;
    color: inherit;
    display: block;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border-radius: 20px;
}

.assignment-card:hover:not(.placeholder) {
    transform: translateY(-5px);
}

.card-glass {
    background: var(--glass-bg);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 1.5rem;
    height: 100%;
    display: flex;
    flex-direction: column;
    transition: border-color 0.3s ease, background 0.3s ease;
}

.assignment-card:hover:not(.placeholder) .card-glass {
    border-color: rgba(96, 165, 250, 0.4);
    background: rgba(30, 41, 59, 0.6);
    box-shadow: 0 10px 40px -10px rgba(96, 165, 250, 0.2);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.day-badge {
    background: rgba(59, 130, 246, 0.2);
    color: #93c5fd;
    padding: 0.25rem 0.75rem;
    border-radius: 999px;
    font-size: 0.85rem;
    font-weight: 600;
    border: 1px solid rgba(59, 130, 246, 0.3);
}

.day-badge.locked {
    background: rgba(148, 163, 184, 0.1);
    color: var(--text-muted);
    border: 1px solid rgba(148, 163, 184, 0.2);
}

.date {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.topic {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.description {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.5;
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    border-top: 1px solid var(--glass-border);
}

.status {
    font-size: 0.8rem;
    font-weight: 600;
}

.status.completed {
    color: #4ade80;
}

.view-btn {
    font-size: 0.9rem;
    color: #60a5fa;
    font-weight: 600;
    transition: transform 0.2s ease;
}

.assignment-card:hover:not(.placeholder) .view-btn {
    transform: translateX(4px);
}

/* Placeholder card styles */
.assignment-card.placeholder {
    opacity: 0.5;
    cursor: default;
}

/* Back Button for Assignments */
.nav-bar {
    position: fixed;
    top: 2rem;
    left: 2rem;
    z-index: 100;
}

.btn-back {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--glass-bg);
    backdrop-filter: blur(8px);
    border: 1px solid var(--glass-border);
    color: var(--text-main);
    text-decoration: none;
    padding: 0.75rem 1.25rem;
    border-radius: 12px;
    font-weight: 600;
    font-size: 0.9rem;
    transition: all 0.2s ease;
}

.btn-back:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateX(-4px);
    border-color: rgba(255, 255, 255, 0.2);
}

/* Assignment Page Specific */
.assignment-content {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 3rem;
    margin-top: 5rem;
    box-shadow: var(--glass-shadow);
}

.assignment-content h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
    color: #fff;
    border-bottom: 1px solid var(--glass-border);
    padding-bottom: 1rem;
}

.assignment-content p {
    color: var(--text-muted);
    line-height: 1.6;
    margin-bottom: 1rem;
}

.assignment-box {
    background: rgba(0,0,0,0.2);
    border: 1px dashed var(--glass-border);
    border-radius: 12px;
    padding: 2rem;
    margin-top: 2rem;
    text-align: center;
}