/* --- Global Styles & Variables --- */
:root {
    --bg-color-dark: #1a1c2c;
    --primary-color-dark: #24273a;
    --secondary-color-dark: #363a4f;
    --font-color-dark: #cad3f5;
    --accent-color-1: #8aadf4; /* Blue */
    --accent-color-2: #eed49f; /* Yellow */
    --green-color: #a6da95;
    --pink-color: #f5bde6;
    --border-color-dark: #494d64;

    --bg-color-light: #eff1f5;
    --primary-color-light: #ffffff;
    --secondary-color-light: #e6e9ef;
    --font-color-light: #4c4f69;
    --border-color-light: #dce0e8;
}

/* --- Animations --- */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes pop {
    0% { transform: scale(1); }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); }
}


body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--bg-color-dark);
    color: var(--font-color-dark);
    margin: 0;
    padding: 2rem;
    display: flex;
    justify-content: center;
    align-items: flex-start; /* Align to top for longer content */
    min-height: 100vh;
    transition: background-color 0.3s, color 0.3s;
}

body.light-mode {
    background-color: var(--bg-color-light);
    color: var(--font-color-light);
}

/* --- Main Container & Header --- */
.container {
    width: 100%;
    max-width: 800px;
    background-color: var(--primary-color-dark);
    border-radius: 16px;
    padding: 2rem;
    border: 1px solid var(--border-color-dark);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    transition: background-color 0.3s, border-color 0.3s;
}

body.light-mode .container {
    background-color: var(--primary-color-light);
    border-color: var(--border-color-light);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    text-align: left;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color-dark);
    padding-bottom: 1.5rem;
    transition: border-color 0.3s;
}

body.light-mode header {
    border-color: var(--border-color-light);
}

header h1 {
    margin: 0;
    font-size: 2rem;
    font-weight: 700;
    color: var(--font-color-dark);
}

body.light-mode header h1 {
    color: var(--font-color-light);
}

header p {
    font-size: 1rem;
    color: #a0a0a0;
}

body.light-mode header p {
    color: #666;
}

/* --- Theme Switcher --- */
.theme-switcher button {
    background: var(--secondary-color-dark);
    border: 1px solid var(--border-color-dark);
    border-radius: 50%;
    cursor: pointer;
    padding: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    transition: background-color 0.3s, transform 0.2s ease;
}

.theme-switcher button:hover {
    transform: scale(1.1);
}

body.light-mode .theme-switcher button {
    background: var(--secondary-color-light);
    border: 1px solid var(--border-color-light);
}

.theme-switcher .dark-icon,
.theme-switcher .light-icon {
    font-size: 1.5rem;
}

.theme-switcher .dark-icon {
    display: none;
}

body.light-mode .theme-switcher .dark-icon {
    display: block;
}

body.light-mode .theme-switcher .light-icon {
    display: none;
}

/* --- Coding Tip Section --- */
.coding-tip {
    background-color: var(--secondary-color-dark);
    border-radius: 12px;
    padding: 1rem 1.5rem;
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    border-left: 4px solid var(--accent-color-2);
    transition: background-color 0.3s, border-color 0.3s;
}

body.light-mode .coding-tip {
    background-color: var(--secondary-color-light);
}

.coding-tip .tip-icon {
    font-size: 1.5rem;
    margin-right: 1rem;
}

.coding-tip p {
    margin: 0;
    font-style: italic;
    color: var(--accent-color-2);
}

body.light-mode .coding-tip p {
    color: #6c584c; /* A darker yellow/brown for light mode */
}


/* --- Progress Bar --- */
.progress-container {
    margin-bottom: 2rem;
}

.progress-bar-label {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.progress-bar {
    width: 100%;
    height: 12px;
    background-color: var(--secondary-color-dark);
    border-radius: 6px;
    overflow: hidden;
}

body.light-mode .progress-bar {
    background-color: var(--secondary-color-light);
}

.progress-bar-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--accent-color-1), var(--pink-color));
    border-radius: 6px;
    transition: width 0.5s cubic-bezier(0.25, 1, 0.5, 1);
}

/* --- Phase Sections (Accordion) --- */
.phase {
    background-color: transparent;
    border-radius: 12px;
    margin-bottom: 1.5rem;
    overflow: hidden;
    border: 1px solid var(--border-color-dark);
    transition: background-color 0.3s, border-color 0.3s;
}

body.light-mode .phase {
    border-color: var(--border-color-light);
}

.phase-header {
    padding: 1rem 1.5rem;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--secondary-color-dark);
    transition: background-color 0.2s ease;
}

.phase-header:hover {
    background-color: #494d64;
}

body.light-mode .phase-header {
    background-color: var(--secondary-color-light);
}

body.light-mode .phase-header:hover {
    background-color: #dce0e8;
}

.phase-header h2 {
    margin: 0;
    font-size: 1.25rem;
    font-weight: 600;
}

.phase-header .arrow {
    font-size: 1.5rem;
    transition: transform 0.3s ease;
}

.phase-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.5s ease-in-out, padding 0.5s ease-in-out;
    padding: 0 1.5rem;
    background-color: var(--primary-color-dark);
}

body.light-mode .phase-content {
    background-color: var(--primary-color-light);
}

.phase.open .phase-content {
    padding: 1rem 1.5rem;
}

.phase.open .arrow {
    transform: rotate(90deg);
}

/* --- Topic Items --- */
.topic-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.topic-header {
    padding: 1rem 0 0.5rem 0;
    border-bottom: 1px solid var(--border-color-dark);
    margin-bottom: 0.5rem;
    transition: border-color 0.3s;
}
body.light-mode .topic-header {
    border-color: var(--border-color-light);
}
.topic-header h3 {
    margin: 0 0 0.25rem 0;
    color: var(--green-color);
    font-size: 1.1rem;
}
.topic-header p {
    margin: 0;
    font-size: 0.9rem;
    color: #a0a0a0;
    font-style: italic;
}
body.light-mode .topic-header p {
    color: #666;
}

.topic-item {
    display: flex;
    align-items: center;
    padding: 0.75rem 0.5rem;
    border-bottom: 1px solid var(--border-color-dark);
    animation: fadeIn 0.5s ease-out forwards;
    opacity: 0;
    padding-left: 1rem;
}

.phase.open .topic-item {
    animation-delay: calc(var(--i, 0) * 50ms);
}

body.light-mode .topic-item {
    border-color: var(--border-color-light);
}

.topic-item:last-child {
    border-bottom: none;
}

.topic-item label {
    display: flex;
    align-items: center;
    cursor: pointer;
    flex-grow: 1;
}

.topic-item input[type="checkbox"] {
    display: none;
}

.custom-checkbox {
    width: 20px;
    height: 20px;
    border: 2px solid var(--font-color-dark);
    border-radius: 6px;
    margin-right: 1rem;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all 0.2s ease;
}

.topic-item.checked-animation .custom-checkbox {
    animation: pop 0.3s ease;
}

body.light-mode .custom-checkbox {
    border-color: var(--font-color-light);
}

.custom-checkbox .checkmark {
    display: none;
    color: var(--primary-color-dark);
    font-weight: bold;
}

.topic-item input[type="checkbox"]:checked + .custom-checkbox {
    background-color: var(--green-color);
    border-color: var(--green-color);
}

.topic-item input[type="checkbox"]:checked + .custom-checkbox .checkmark {
    display: block;
}

.topic-name {
    flex-grow: 1;
    transition: color 0.2s ease;
}

.topic-item input[type="checkbox"]:checked ~ .topic-name {
    text-decoration: line-through;
    color: #888;
}

.topic-link {
    text-decoration: none;
    color: var(--accent-color-1);
    font-weight: 500;
    padding: 0.25rem 0.5rem;
    border-radius: 6px;
    transition: background-color 0.2s ease;
}

.topic-link:hover {
    background-color: rgba(138, 173, 244, 0.2);
}