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

:root {
    /* Primary Blue/Indigo Colors */
    --primary-50: #eef7ff;
    --primary-100: #dbebff;
    --primary-200: #b6d3f5;
    --primary-300: #84bdf0;
    --primary-400: #539de3;
    --primary-500: #3a7bd5; /* Primary color */
    --primary-600: #2a5fb8;
    --primary-700: #1f4aa3;
    --primary-800: #183a82;
    --primary-900: #142f6b;
    
    /* Accent Colors */
    --accent-50: #f0f9ff;
    --accent-100: #d1e9ff;
    --accent-200: #b3d7ff;
    --accent-300: #7fb8ff;
    --accent-400: #4a9eff;
    --accent-500: #007bff; /* Accent color */
    --accent-600: #0069d9;
    --accent-700: #005cbf;
    --accent-800: #004a9e;
    --accent-900: #003d82;
    
    /* Neutral Colors */
    --neutral-50: #f8f9fa;
    --neutral-100: #f1f3f5;
    --neutral-200: #e9ecef;
    --neutral-300: #dee2e6;
    --neutral-400: #ced4da;
    --neutral-500: #adb5bd;
    --neutral-600: #868e96;
    --neutral-700: #495057;
    --neutral-800: #343a40;
    --neutral-900: #212529;
    
    /* Success, Warning, Error */
    --success: #28a745;
    --warning: #ffc107;
    --danger: #dc3545;
    --info: #17a2b8;
    
    /* Backgrounds */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --bg-card: #ffffff;
    --bg-modal: rgba(0, 0, 0, 0.5);
    
    /* Text Colors */
    --text-primary: #212529;
    --text-secondary: #495057;
    --text-muted: #6c757d;
    --text-light: #f8f9fa;
    --text-white: #ffffff;
    
    /* Borders */
    --border-color: #dee2e6;
    --border-light: #e9ecef;
    --border-dark: #adb5bd;
    
    /* Shadows */
    --shadow-sm: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.075);
    --shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.175);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--primary-900) 0%, var(--primary-800) 50%, var(--primary-700) 100%);
    color: var(--text-light);
    min-height: 100vh;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

.header {
    text-align: center;
    margin-bottom: 40px;
    animation: fadeInDown 1s ease-out;
}

.logo {
    font-size: 3rem;
    font-weight: 700;
    background: linear-gradient(45deg, var(--primary-500), var(--accent-500));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 10px;
}

.subtitle {
    font-size: 1.2rem;
    color: var(--text-muted);
    opacity: 0;
    animation: fadeIn 1s ease-out 0.5s forwards;
}

.add-task-section {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(58, 123, 213, 0.485);
    border-radius: 16px;
    padding: 30px;
    margin-bottom: 40px;
    animation: slideUp 0.8s ease-out;
}

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

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--primary-500);
}

input[type="text"], input[type="datetime-local"] {
    width: 100%;
    padding: 15px;
    border: 2px solid rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    background: rgba(255, 255, 255, 0.05);
    color: white;
    font-size: 1rem;
    transition: all 0.3s ease;
}

input[type="text"]:focus, input[type="datetime-local"]:focus {
    outline: none;
    border-color: var(--primary-500);
    box-shadow: 0 0 20px rgba(58, 123, 213, 0.3);
    transform: translateY(-2px);
}

.add-btn {
    background: linear-gradient(45deg, var(--primary-500), var(--accent-500));
    border: none;
    padding: 15px 30px;
    border-radius: 8px;
    color: white;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(58, 123, 213, 0.3);
}

.add-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(58, 123, 213, 0.4);
}

.add-btn:active {
    transform: translateY(-1px);
}

.tasks-section {
    animation: fadeIn 1s ease-out 0.3s both;
}

.section-title {
    font-size: 2rem;
    margin-bottom: 20px;
    text-align: center;
    color: #ffffff;
}

.tasks-list {
    display: grid;
    gap: 15px;
}

.task-item {
    background: rgba(0, 0, 0, 0.3);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 12px;
    padding: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all 0.3s ease;
    animation: slideInLeft 0.5s ease-out;
    position: relative;
    overflow: hidden;
}

.task-item:hover {
    transform: translateX(10px);
    border-color: rgba(58, 123, 213, 0.5);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.3);
}

.task-item.urgent {
    border-left: 4px solid var(--danger);
    background: linear-gradient(90deg, rgba(220, 53, 69, 0.1) 0%, rgba(0, 0, 0, 0.3) 100%);
    animation: pulse 2s infinite;
}

.task-content {
    flex-grow: 1;
}

.task-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 5px;
}

.task-time {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.task-countdown {
    color: var(--danger);
    font-weight: 600;
    font-size: 0.85rem;
    margin-top: 5px;
}

.delete-btn {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: white;
    padding: 8px 12px;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.delete-btn:hover {
    background: rgba(220, 53, 69, 0.8);
    transform: scale(1.1);
}

.notification {
    position: fixed;
    top: 20px;
    right: 20px;
    background: linear-gradient(45deg, var(--primary-500), var(--accent-500));
    color: white;
    padding: 15px 20px;
    border-radius: 8px;
    box-shadow: 0 4px 20px rgba(58, 123, 213, 0.3);
    z-index: 1000;
    transform: translateX(400px);
    transition: transform 0.3s ease;
    max-width: 300px;
}

.notification.show {
    transform: translateX(0);
}

.alarm-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0, 0, 0, 0.9);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 2000;
    animation: fadeIn 0.3s ease-out;
}

.alarm-content {
    background: linear-gradient(45deg, var(--primary-500), var(--accent-500));
    padding: 40px;
    border-radius: 16px;
    text-align: center;
    max-width: 400px;
    animation: bounceIn 0.5s ease-out;
}

.alarm-title {
    font-size: 2rem;
    margin-bottom: 20px;
    animation: pulse 1s infinite;
}

.snooze-btn, .dismiss-btn {
    padding: 10px 20px;
    margin: 10px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
}

.snooze-btn {
    background: rgba(255, 255, 255, 0.2);
    color: white;
}

.dismiss-btn {
    background: white;
    color: var(--danger);
}

.snooze-btn:hover, .dismiss-btn:hover {
    transform: scale(1.1);
}

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

.empty-icon {
    font-size: 4rem;
    margin-bottom: 20px;
    opacity: 0.5;
}

@keyframes fadeInDown {
    from { opacity: 0; transform: translateY(-30px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideUp {
    from { opacity: 0; transform: translateY(30px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes slideInLeft {
    from { opacity: 0; transform: translateX(-30px); }
    to { opacity: 1; transform: translateX(0); }
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

@keyframes bounceIn {
    0% { transform: scale(0.3); opacity: 0; }
    50% { transform: scale(1.05); }
    70% { transform: scale(0.9); }
    100% { transform: scale(1); opacity: 1; }
}

@media (max-width: 768px) {
    .container { padding: 15px; }
    .logo { font-size: 2rem; }
    .add-task-section { padding: 20px; }
    .task-item { flex-direction: column; align-items: flex-start; gap: 10px; }
    .delete-btn { align-self: flex-end; }
}
/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--gradient);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.2rem;
    cursor: pointer;
    transition: all 0.3s ease;
    opacity: 0;
    visibility: hidden;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
}
.back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(58, 123, 213, 0.4);
}
/* Footer */
.footer {
    background: rgba(255, 255, 255, 0.05);
    border-top: 1px solid rgba(58, 123, 213, 0.2);
    padding: 2rem;
    text-align: center;
    color: var(--text-muted);
}
.footer-content {
    padding: 2rem 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}