:root {
    --bg-color: #0b0f1a;
    --surface-color: #1a1f2e;
    --card-bg: rgba(26, 31, 46, 0.6);
    --card-border: rgba(255, 255, 255, 0.08);
    --text-primary: #ffffff;
    --text-secondary: #94a3b8;
    --accent-color: #38bdf8;
    --accent-glow: rgba(56, 189, 248, 0.3);
    --danger: #ef4444;
    --glass-blur: 16px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    --success: #10b981;
    --success-glow: rgba(16, 185, 129, 0.2);
}

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

body {
    background: var(--bg-color);
    color: var(--text-primary);
    font-family: 'Outfit', sans-serif;
    min-height: 100vh;
    padding: 60px 40px;
    background-image: 
        radial-gradient(at 100% 0%, hsla(210, 100%, 15%, 1) 0px, transparent 40%),
        radial-gradient(at 0% 100%, hsla(196, 100%, 10%, 1) 0px, transparent 40%),
        radial-gradient(circle at 50% 50%, #0f172a 0%, #0b0f1a 100%);
    background-attachment: fixed;
}

.app-container {
    max-width: 1300px;
    margin: 0 auto;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--card-bg);
    padding: 16px 32px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--card-border);
    backdrop-filter: blur(var(--glass-blur));
    margin-bottom: 48px;
    box-shadow: 0 20px 40px -15px rgba(0, 0, 0, 0.6);
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo h1 {
    font-size: 1.4rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    background: linear-gradient(to right, #fff, #94a3b8);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.month-selector {
    display: flex;
    align-items: center;
    gap: 12px;
    background: rgba(0, 0, 0, 0.2);
    padding: 6px;
    border-radius: 14px;
    border: 1px solid var(--card-border);
}

.month-display {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 0 16px;
    min-width: 200px;
    justify-content: center;
}

.month-display h2 {
    font-size: 1.1rem;
    font-weight: 600;
}

.month-display i {
    color: var(--accent-color);
    width: 20px;
}

.nav-prev, .nav-next {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: white;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 10px;
    cursor: pointer;
    transition: var(--transition);
}

.nav-prev:hover, .nav-next:hover {
    background: var(--accent-color);
    border-color: var(--accent-color);
    color: var(--bg-color);
    transform: translateY(-1px);
}

.btn-secondary {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.3);
    color: #f87171;
    padding: 10px 20px;
    border-radius: 12px;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.9rem;
    transition: var(--transition);
}

.btn-secondary:hover {
    background: #ef4444;
    color: white;
    box-shadow: 0 0 20px rgba(239, 68, 68, 0.3);
}

main {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 24px;
}

.week-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-lg);
    padding: 24px;
    backdrop-filter: blur(var(--glass-blur));
    display: flex;
    flex-direction: column;
    box-shadow: 0 10px 25px -10px rgba(0, 0, 0, 0.3);
    transition: var(--transition);
    min-height: 480px;
    height: auto;
}

.week-card:hover {
    border-color: rgba(56, 189, 248, 0.4);
    transform: translateY(-4px);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.week-header {
    margin-bottom: 24px;
}

.week-header h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 4px;
}

.week-dates {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.progress-container {
    width: 100%;
    height: 4px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 2px;
    margin-top: 12px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--accent-color), var(--success));
    transition: width 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 0 10px var(--accent-glow);
}

.task-list {
    list-style: none;
    flex-grow: 1;
    overflow-y: auto;
    margin-bottom: 16px;
    padding-right: 4px;
}

/* Scrollbar styling */
.task-list::-webkit-scrollbar {
    width: 4px;
}
.task-list::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 10px;
}

.day-section {
    margin-bottom: 20px;
}

.day-header {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-weight: 700;
    color: var(--accent-color);
    margin-bottom: 8px;
    padding-bottom: 4px;
    border-bottom: 1px solid rgba(56, 189, 248, 0.15);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.day-progress-container {
    width: 60px;
    height: 3px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 2px;
    overflow: hidden;
}

.day-progress-bar {
    height: 100%;
    width: 0%;
    background: var(--success);
    transition: width 0.3s ease;
    box-shadow: 0 0 5px var(--success-glow);
}

.day-task-list {
    list-style: none;
    margin-bottom: 8px;
}

.day-add-container {
    display: flex;
    align-items: center;
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 10px;
    padding: 2px;
    margin-top: 4px;
    transition: var(--transition);
}

.day-add-container:focus-within {
    border-color: var(--accent-color);
    background: rgba(255, 255, 255, 0.05);
}

.day-input {
    background: transparent;
    border: none;
    padding: 6px 10px;
    color: white;
    font-size: 0.8rem;
    flex-grow: 1;
    outline: none;
}

.day-add-btn {
    background: rgba(56, 189, 248, 0.1);
    color: var(--accent-color);
    border: none;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 6px;
    cursor: pointer;
    transition: var(--transition);
}

.day-add-btn:hover {
    background: var(--accent-color);
    color: #000;
}

.day-add-btn i {
    width: 14px;
    height: 14px;
}

.task-item {
    display: flex;
    align-items: center;
    padding: 10px 14px;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 12px;
    margin-bottom: 8px;
    animation: slideIn 0.3s ease-out;
    transition: var(--transition);
}

.task-item:hover {
    background: rgba(255, 255, 255, 0.06);
    border-color: rgba(255, 255, 255, 0.1);
}

.task-text {
    font-size: 0.9rem;
    flex-grow: 1;
    color: #e2e8f0;
    transition: var(--transition);
}

.task-item.completed .task-text {
    text-decoration: line-through;
    color: var(--text-secondary);
    opacity: 0.6;
}

/* Custom Checkbox Styles */
.checkbox-container {
    display: block;
    position: relative;
    padding-left: 30px;
    margin-right: 12px;
    cursor: pointer;
    user-select: none;
    height: 20px;
}

.checkbox-container input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    position: absolute;
    top: 0;
    left: 0;
    height: 20px;
    width: 20px;
    background-color: rgba(255, 255, 255, 0.05);
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: 6px;
    transition: var(--transition);
}

.checkbox-container:hover input ~ .checkmark {
    border-color: var(--accent-color);
    background-color: rgba(56, 189, 248, 0.1);
}

.checkbox-container input:checked ~ .checkmark {
    background-color: var(--success);
    border-color: var(--success);
    box-shadow: 0 0 10px var(--success-glow);
}

.checkmark:after {
    content: "";
    position: absolute;
    display: none;
}

.checkbox-container input:checked ~ .checkmark:after {
    display: block;
}

.checkbox-container .checkmark:after {
    left: 6px;
    top: 2px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

.delete-btn, .edit-btn {
    background: transparent;
    color: var(--text-secondary);
    border: none;
    padding: 6px;
    border-radius: 8px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.task-actions {
    display: flex;
    gap: 4px;
    opacity: 0;
    transition: var(--transition);
}

.task-item:hover .task-actions {
    opacity: 1;
}

.edit-btn:hover {
    background: rgba(56, 189, 248, 0.15);
    color: var(--accent-color);
}

.delete-btn:hover {
    background: rgba(239, 68, 68, 0.15);
    color: var(--danger);
}

.edit-btn i, .delete-btn i {
    width: 16px;
    height: 16px;
}

/* Clean Input Container */
.add-task-container {
    display: flex;
    align-items: center;
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--card-border);
    border-radius: 14px;
    padding: 4px;
    transition: var(--transition);
}

.add-task-container:focus-within {
    border-color: var(--accent-color);
    box-shadow: 0 0 0 2px var(--accent-glow);
}

.task-input {
    background: transparent;
    border: none;
    padding: 10px 12px;
    color: white;
    font-family: inherit;
    font-size: 0.9rem;
    flex-grow: 1;
    outline: none;
}

.task-input::placeholder {
    color: #64748b;
}

.add-btn {
    background: var(--accent-color);
    color: #000;
    border: none;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 10px;
    cursor: pointer;
    transition: var(--transition);
}

.add-btn:hover {
    background: #7dd3fc;
    transform: scale(1.05);
}

.add-btn i {
    width: 18px;
    height: 18px;
    stroke-width: 3px;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: scale(0.95) translateY(10px);
    }
    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

@media (max-width: 768px) {
    body { padding: 30px 20px; }
    header { flex-direction: column; gap: 24px; padding: 24px; }
    .month-selector { width: 100%; justify-content: space-between; }
}