:root {
    --bg-color: #f0f0f0;
    --text-color: #111;
    --primary: #ff3b30;
    --secondary: #1a1a1a;
    --accent: #ffd700;
    --border-width: 3px;
    --border-color: #111;
    --shadow-solid: 4px 4px 0px var(--border-color);
    --shadow-solid-hover: 2px 2px 0px var(--border-color);
    --font-mono: 'Space Mono', monospace;
    --font-sans: 'Work Sans', sans-serif;
}

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

body {
    font-family: var(--font-mono);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4 {
    font-family: var(--font-sans);
    text-transform: uppercase;
    font-weight: 900;
    letter-spacing: -0.02em;
}

/* Navbar */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    background-color: #fff;
    border-bottom: var(--border-width) solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    font-family: var(--font-sans);
    background-color: var(--accent);
    padding: 0.5rem 1rem;
    border: var(--border-width) solid var(--border-color);
    box-shadow: var(--shadow-solid);
    transform: rotate(-2deg);
    transition: transform 0.2s;
}

.logo:hover {
    transform: rotate(0deg);
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-links.show {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background-color: #fff;
    padding: 2rem;
    border-bottom: var(--border-width) solid var(--border-color);
    z-index: 99;
    box-shadow: 0 10px 0 var(--border-color);
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: bold;
    text-transform: uppercase;
    font-size: 0.9rem;
}

.nav-links a:hover {
    text-decoration: underline;
    text-underline-offset: 4px;
    text-decoration-thickness: 2px;
}

.btn-primary {
    background-color: var(--primary);
    color: #fff !important;
    padding: 0.5rem 1.5rem;
    border: var(--border-width) solid var(--border-color);
    box-shadow: var(--shadow-solid);
    font-family: var(--font-mono);
    text-transform: uppercase;
    font-weight: bold;
    cursor: pointer;
    text-decoration: none !important;
    transition: all 0.1s;
}

.btn-primary:active:not(:disabled) {
    box-shadow: 0 0 0 var(--border-color);
    transform: translate(4px, 4px);
}

.btn-primary.large {
    padding: 1rem 2rem;
    font-size: 1.2rem;
    margin-top: 2rem;
    display: inline-block;
}

.btn-primary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    background-color: #999;
    box-shadow: var(--shadow-solid);
    transform: none;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: var(--border-width) solid var(--border-color);
    padding: 0.5rem 0.75rem;
    font-size: 1.8rem;
    cursor: pointer;
    background-color: #fff;
    box-shadow: var(--shadow-solid);
    line-height: 1;
    z-index: 1001;
}

.mobile-menu-btn.active::before {
    content: "✕";
}

.mobile-menu-btn:not(.active)::before {
    content: "☰";
}

/* Layout */
.app-container {
    display: flex;
    min-height: calc(100vh - 80px); /* Approx navbar height */
}

/* Sidebar */
.sidebar {
    width: 300px;
    background-color: #fff;
    border-right: var(--border-width) solid var(--border-color);
    flex-shrink: 0;
    overflow-y: auto;
    height: calc(100vh - 80px);
    position: sticky;
    top: 80px;
}

.sidebar-header {
    padding: 1.5rem;
    border-bottom: var(--border-width) solid var(--border-color);
    background-color: var(--accent);
}

.topic-group {
    border-bottom: var(--border-width) solid var(--border-color);
}

.topic-header {
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    background-color: #fff;
    transition: background-color 0.2s;
}

.topic-header:hover {
    background-color: #f5f5f5;
}

.topic-header h3 {
    font-size: 1.1rem;
    margin: 0;
}

.topic-header .icon {
    font-size: 1.5rem;
    font-weight: bold;
}

.lesson-list {
    list-style: none;
    background-color: #fafafa;
    border-top: var(--border-width) solid var(--border-color);
}

.lesson-list.hidden {
    display: none;
}

.lesson-list li {
    border-bottom: var(--border-width) solid var(--border-color);
}

.lesson-list li:last-child {
    border-bottom: none;
}

.lesson-list a {
    display: block;
    padding: 0.75rem 1.5rem 0.75rem 2.5rem;
    text-decoration: none;
    color: var(--text-color);
    font-size: 0.9rem;
    transition: all 0.2s;
}

.lesson-list li.active a {
    background-color: var(--secondary);
    color: #fff;
    font-weight: bold;
}

.lesson-list a:hover:not(.active > a) {
    background-color: #eee;
    padding-left: 3rem;
}

/* Main Content */
.main-content {
    flex-grow: 1;
    padding: 3rem;
    background-color: var(--bg-color);
}

.lesson-article {
    max-width: 800px;
    margin: 0 auto;
    background-color: #fff;
    padding: 3rem;
    border: var(--border-width) solid var(--border-color);
    box-shadow: 8px 8px 0px var(--border-color);
}

.badge {
    display: inline-block;
    background-color: var(--accent);
    padding: 0.25rem 0.75rem;
    font-weight: bold;
    border: var(--border-width) solid var(--border-color);
    margin-bottom: 1rem;
    font-size: 0.8rem;
}

.lesson-title {
    font-size: 3rem;
    line-height: 1.1;
    margin-bottom: 1rem;
}

.lesson-meta {
    font-size: 0.9rem;
    color: #555;
    margin-bottom: 2rem;
    border-bottom: var(--border-width) solid var(--border-color);
    padding-bottom: 1rem;
}

.content-block h2 {
    font-size: 2rem;
    margin-top: 2.5rem;
    margin-bottom: 1rem;
}

.content-block p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
}

.callout {
    background-color: var(--accent);
    padding: 1.5rem;
    border: var(--border-width) solid var(--border-color);
    margin: 2rem 0;
    box-shadow: var(--shadow-solid);
}

/* Typing Area */
.typing-container {
    font-family: var(--font-mono);
    position: relative;
    cursor: text;
    outline: none;
    user-select: none;
    transition: all 0.2s;
    border: none;
    box-shadow: none;
    background: transparent;
}

.typing-container.block-mode {
    display: block;
    background-color: var(--secondary);
    color: #666; /* Greyed out text for untyped chars */
    border: var(--border-width) solid var(--border-color);
    box-shadow: var(--shadow-solid);
    padding: 2rem;
    margin: 2rem 0;
    font-size: 1.1rem;
    line-height: 1.8;
    white-space: pre-wrap;
    overflow-x: auto;
    width: 100%;
}

.typing-container.inline-mode {
    display: inline-block;
    padding: 0px 4px;
    margin: 0 2px;
    font-size: 0.95em;
    line-height: inherit;
    vertical-align: baseline;
    white-space: pre;
    background-color: #e8e8e8;
    color: #777;
    border-radius: 4px;
    border-bottom: 2px solid #ccc;
}

.typing-container.inline-mode:focus {
    background-color: var(--secondary);
    color: #666;
    border-bottom-color: var(--accent);
    box-shadow: 0 2px 0 var(--accent);
}

.typing-container.completed.inline-mode {
    background-color: #f0fdf4;
    border-color: #4CAF50;
    color: #4CAF50;
    border-bottom-width: 2px;
}

.typing-container.block-mode:focus {
    box-shadow: 8px 8px 0px var(--accent);
    border-color: var(--accent);
}

.typing-container.block-mode.completed {
    border-color: #4CAF50;
    box-shadow: 8px 8px 0px #4CAF50;
}

.typing-text {
    position: relative;
    word-break: break-all;
    white-space: pre-wrap;
}

.typing-container.inline-mode .typing-text {
    word-break: normal;
    white-space: pre;
}

.typing-text span {
    position: relative;
    border-radius: 2px;
    display: inline;
}

.typing-container.inline-mode .typing-text span {
    display: inline;
}

.typing-text .correct {
    color: #4CAF50; /* Softer green for better readability */
    font-weight: bold;
}

.typing-text .incorrect {
    color: #fff;
    background-color: var(--primary); /* High-contrast red background */
    font-weight: bold;
}

.typing-text .newline-char {
    opacity: 0.3;
    font-size: 0.8em;
    margin-left: 2px;
}

.typing-text .space-char {
    display: inline;
}

.typing-container.block-mode .typing-text .space-char {
    display: inline-block;
    min-width: 0.5ch;
}

/* Blinking cursor */
.typing-container:focus .typing-text .current::before {
    content: '';
    position: absolute;
    left: -1px;
    top: 50%;
    transform: translateY(-50%);
    width: 2px;
    height: 1.25em;
    background-color: var(--accent);
    animation: blink 1s step-end infinite;
    z-index: 10;
}

@keyframes blink {
    50% { opacity: 0; }
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}

.btn-primary.pulse {
    animation: pulse 1.5s infinite;
}

/* Forms */
.form-input {
    width: 100%;
    padding: 1rem;
    font-family: var(--font-mono);
    font-size: 1rem;
    border: var(--border-width) solid var(--border-color);
    background-color: #fff;
    margin-bottom: 1.5rem;
    box-shadow: 4px 4px 0px var(--border-color);
    outline: none;
}

.form-input:focus {
    box-shadow: 4px 4px 0px var(--primary);
    border-color: var(--primary);
}

.form-group label {
    display: block;
    font-family: var(--font-sans);
    text-transform: uppercase;
    font-weight: bold;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

/* Admin Controls */
.admin-controls {
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: var(--border-width) solid var(--border-color);
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn-admin {
    background-color: var(--accent);
    color: var(--text-color);
    padding: 0.5rem 1rem;
    border: var(--border-width) solid var(--border-color);
    box-shadow: 4px 4px 0px var(--border-color);
    font-family: var(--font-mono);
    text-transform: uppercase;
    font-weight: bold;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.1s;
    font-size: 0.8rem;
}

.btn-admin:hover {
    box-shadow: 2px 2px 0px var(--border-color);
    transform: translate(2px, 2px);
}


/* Responsive */
@media (max-width: 900px) {
    .navbar {
        padding: 1rem;
    }

    .nav-links {
        display: none;
    }

    .nav-links.show {
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100vh;
        background-color: rgba(255, 255, 255, 0.98);
        padding: 2rem;
        z-index: 1000;
        overflow-y: auto;
    }

    .nav-links a {
        font-size: 1.5rem;
        margin-bottom: 1.5rem;
    }
    
    .app-container {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        height: auto;
        position: static;
        border-right: none;
        border-bottom: var(--border-width) solid var(--border-color);
        display: none;
    }

    .sidebar.show {
        display: block;
    }
    
    .main-content {
        padding: 1.5rem;
    }
    
    .lesson-article {
        padding: 1.5rem;
        box-shadow: 4px 4px 0px var(--border-color);
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .lesson-title {
        font-size: 2.2rem;
    }

    h1 {
        font-size: 2.5rem !important;
    }

    .app-container > div > h1 {
        font-size: 3rem !important;
    }

    .app-container > div > p {
        font-size: 1.2rem !important;
    }

    .btn-primary.large {
        font-size: 1.2rem !important;
        padding: 1rem 1.5rem;
        width: 100%;
        margin-left: 0 !important;
        margin-top: 1rem !important;
        display: block;
        text-align: center;
    }

    .auth-container {
        margin: 2rem 1rem;
        max-width: calc(100% - 2rem);
    }
}

@media (max-width: 600px) {
    .lesson-title {
        font-size: 1.8rem;
    }

    .app-container > div > h1 {
        font-size: 2.2rem !important;
    }

    .logo {
        font-size: 1.2rem;
        padding: 0.3rem 0.6rem;
    }
}