:root {
    --white: #fff;
    --light-grey: #f8f9fa;
    --dark-grey: #2d3748;
    --darker-grey: #1a202c;
    --primary: #4299e1;
    --primary-dark: #3182ce;
    --secondary: #48bb78;
    --danger: #f56565;
    --warning: #ed8936;
    --text: #2d3748;
    --text-light: #718096;
    --border: #e2e8f0;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

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

body {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

main {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 20px;
    min-height: 100vh;
}

h1 {
    color: var(--white);
    margin: 20px 0 40px 0;
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.todo-app {
    background-color: var(--white);
    width: 100%;
    max-width: 500px;
    min-height: 500px;
    border-radius: 20px;
    padding: 30px;
    box-shadow: var(--shadow-lg);
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.btn {
    cursor: pointer;
    padding: 12px 24px;
    border: none;
    border-radius: 10px;
    font-weight: 600;
    font-size: 0.9rem;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.large-btn {
    width: 100%;
    padding: 15px;
    font-size: 1.1rem;
}

#open-task-form-btn {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
}

#add-or-update-task-btn {
    background: linear-gradient(135deg, var(--secondary), #38a169);
    color: white;
}

.close-task-form-btn {
    background: none;
    border: none;
    cursor: pointer;
    padding: 5px;
    border-radius: 50%;
    transition: background-color 0.3s ease;
}

.close-task-form-btn:hover {
    background-color: var(--border);
}

.close-icon {
    width: 24px;
    height: 24px;
}

.task-form {
    display: flex;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background-color: var(--white);
    border-radius: 20px;
    padding: 25px;
    width: 90%;
    max-width: 450px;
    min-height: 500px;
    flex-direction: column;
    justify-content: space-between;
    overflow: auto;
    box-shadow: var(--shadow-lg);
    z-index: 1000;
}

.task-form-header {
    display: flex;
    justify-content: flex-end;
}

.task-form-body {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.task-form-footer {
    display: flex;
    justify-content: center;
    margin-top: 20px;
}

.task-form-label {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 8px;
    display: block;
}

#title-input,
#date-input,
#description-input {
    width: 100%;
    padding: 12px;
    border: 2px solid var(--border);
    border-radius: 10px;
    font-size: 1rem;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

#title-input:focus,
#date-input:focus,
#description-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(66, 153, 225, 0.1);
}

#description-input {
    resize: vertical;
    min-height: 100px;
    font-family: inherit;
}

#confirm-close-dialog {
    padding: 30px;
    margin: 10px auto;
    border-radius: 20px;
    border: none;
    box-shadow: var(--shadow-lg);
    max-width: 400px;
}

.confirm-close-dialog-btn-container {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 20px;
}

#cancel-btn {
    background-color: var(--light-grey);
    color: var(--text);
}

#discard-btn {
    background-color: var(--danger);
    color: white;
}

.discard-message-text {
    font-weight: 600;
    font-size: 1.3rem;
    text-align: center;
    color: var(--text);
}

#tasks-container {
    height: 400px;
    overflow-y: auto;
    padding: 10px;
    border: 2px solid var(--border);
    border-radius: 15px;
    background-color: var(--light-grey);
}

.task {
    background: white;
    padding: 20px;
    margin: 10px 0;
    border-radius: 15px;
    box-shadow: var(--shadow);
    border-left: 5px solid var(--primary);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.task:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.task p {
    margin: 8px 0;
    color: var(--text);
}

.task strong {
    color: var(--dark-grey);
}

.task button {
    margin: 5px 5px 0 0;
    padding: 8px 16px;
    font-size: 0.8rem;
}

.task button:first-of-type {
    background: linear-gradient(135deg, var(--warning), #dd6b20);
    color: white;
}

.task button:last-of-type {
    background: linear-gradient(135deg, var(--danger), #e53e3e);
    color: white;
}

.hidden {
    display: none;
}

/* Scrollbar styling */
#tasks-container::-webkit-scrollbar {
    width: 8px;
}

#tasks-container::-webkit-scrollbar-track {
    background: var(--border);
    border-radius: 10px;
}

#tasks-container::-webkit-scrollbar-thumb {
    background: var(--primary);
    border-radius: 10px;
}

#tasks-container::-webkit-scrollbar-thumb:hover {
    background: var(--primary-dark);
}

/* Responsive design */
@media (max-width: 768px) {
    main {
        padding: 10px;
    }

    h1 {
        font-size: 2rem;
        margin: 10px 0 30px 0;
    }

    .todo-app {
        padding: 20px;
        min-height: 400px;
    }

    .task-form {
        width: 95%;
        padding: 20px;
    }

    #tasks-container {
        height: 300px;
    }
}

@media (max-width: 480px) {
    .confirm-close-dialog-btn-container {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        margin: 5px 0;
    }

    .task button {
        width: 100%;
        margin: 5px 0;
    }
}