:root {
    --bg-dark: #1a1a2e;
    --bg-card: #16213e;
    --accent: #e94560;
    --gold: #ffd700;
    --text: #eee;
    --text-dim: #888;
    --success: #4ade80;
    --code-bg: #0f0f1a;
    --border: #333;
}

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

body {
    font-family: 'Courier New', monospace;
    background: var(--bg-dark);
    color: var(--text);
    min-height: 100vh;
    line-height: 1.6;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 20px;
}

/* Language Switcher */
.lang-switcher {
    position: absolute;
    top: 10px;
    right: 20px;
    display: flex;
    gap: 8px;
    z-index: 100;
}

.lang-btn {
    background: var(--bg-card);
    border: 1px solid var(--border);
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1.2em;
    transition: all 0.2s;
    text-decoration: none;
}

.lang-btn:hover {
    border-color: var(--gold);
    transform: scale(1.1);
}

.lang-btn.active {
    border-color: var(--accent);
    background: rgba(233, 69, 96, 0.2);
}

/* Navigation */
.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
    border-bottom: 1px solid var(--border);
    margin-bottom: 30px;
}

.nav a {
    color: var(--text-dim);
    text-decoration: none;
    transition: color 0.2s;
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav a:hover {
    color: var(--gold);
}

.nav-center {
    color: var(--gold);
    font-weight: bold;
    text-align: center;
}

.nav-disabled {
    color: #444;
    cursor: not-allowed;
}

/* Chapter Header */
.chapter-header {
    text-align: center;
    margin-bottom: 30px;
}

.chapter-logo {
    width: 160px;
    height: 160px;
}

.chapter-number {
    color: var(--accent);
    font-size: 0.9em;
    text-transform: uppercase;
    letter-spacing: 3px;
    margin-bottom: 10px;
}

.chapter-title {
    font-size: 2em;
    color: var(--gold);
    text-shadow: 0 0 20px rgba(255, 215, 0, 0.3);
    margin-bottom: 15px;
}

/* Chapter Intro */
.chapter-intro {
    background: var(--code-bg);
    padding: 25px;
    border-radius: 8px;
    margin-bottom: 30px;
    border-left: 4px solid var(--accent);
    white-space: pre-wrap;
    font-size: 0.9em;
    overflow-x: auto;
}

/* Skills Badge */
.skills-section {
    background: var(--bg-card);
    padding: 15px 20px;
    border-radius: 8px;
    margin-bottom: 30px;
    display: flex;
    align-items: center;
    gap: 15px;
    flex-wrap: wrap;
}

.skills-label {
    color: var(--accent);
    font-weight: bold;
}

.skills-list {
    color: var(--text-dim);
}

/* Progress indicator */
.progress-bar {
    background: var(--bg-card);
    padding: 15px 20px;
    border-radius: 8px;
    margin-bottom: 30px;
    display: flex;
    align-items: center;
    gap: 15px;
}

.progress-bar-visual {
    flex: 1;
    height: 8px;
    background: var(--border);
    border-radius: 4px;
    overflow: hidden;
}

.progress-bar-fill {
    height: 100%;
    background: var(--success);
    transition: width 0.3s ease;
}

.progress-text {
    color: var(--text-dim);
    font-size: 0.9em;
    white-space: nowrap;
}

/* Level Cards */
.levels-container {
    display: flex;
    flex-direction: column;
    gap: 20px;
    margin-bottom: 30px;
}

.level-card {
    background: var(--bg-card);
    border-radius: 8px;
    border: 1px solid var(--border);
    overflow: hidden;
    transition: border-color 0.2s;
}

.level-card:hover {
    border-color: var(--accent);
}

.level-card.completed {
    border-color: var(--success);
}

.level-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    background: rgba(0, 0, 0, 0.2);
}

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

.level-number {
    background: var(--accent);
    color: white;
    padding: 4px 10px;
    border-radius: 4px;
    font-weight: bold;
    font-size: 0.85em;
}

.level-card.completed .level-number {
    background: var(--success);
}

.level-name {
    color: var(--gold);
    font-weight: bold;
}

.level-status {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.85em;
}

.status-completed {
    color: var(--success);
}

.status-pending {
    color: var(--text-dim);
}

.status-icon {
    width: 16px;
    height: 16px;
    border-radius: 50%;
    display: inline-block;
}

.status-icon.completed {
    background: var(--success);
}

.status-icon.pending {
    border: 2px solid var(--text-dim);
}

.level-body {
    padding: 20px;
}

.level-section {
    margin-bottom: 15px;
}

.level-section:last-child {
    margin-bottom: 0;
}

.section-label {
    color: var(--accent);
    font-size: 0.8em;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 8px;
}

.section-content {
    color: var(--text);
}

/* Curl Command Box */
.curl-box {
    background: var(--code-bg);
    border-radius: 6px;
    overflow: hidden;
}

.curl-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px 12px;
    background: rgba(255, 255, 255, 0.05);
    border-bottom: 1px solid var(--border);
}

.curl-label {
    color: var(--text-dim);
    font-size: 0.75em;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.copy-btn {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-dim);
    padding: 4px 10px;
    border-radius: 4px;
    cursor: pointer;
    font-family: inherit;
    font-size: 0.75em;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 5px;
}

.copy-btn:hover {
    border-color: var(--gold);
    color: var(--gold);
}

.copy-btn.copied {
    border-color: var(--success);
    color: var(--success);
}

.curl-code {
    padding: 15px;
    overflow-x: auto;
    white-space: pre;
}

.curl-code code {
    color: var(--success);
    font-size: 0.9em;
    display: block;
    line-height: 1.5;
}

/* Teaching Section */
.teaching {
    background: rgba(233, 69, 96, 0.1);
    border-left: 3px solid var(--accent);
    padding: 12px 15px;
    border-radius: 0 6px 6px 0;
    font-size: 0.9em;
}

/* Hint Section */
.hint-toggle {
    background: transparent;
    border: 1px dashed var(--text-dim);
    color: var(--text-dim);
    padding: 10px 15px;
    border-radius: 6px;
    cursor: pointer;
    font-family: inherit;
    font-size: 0.85em;
    width: 100%;
    text-align: left;
    transition: all 0.2s;
}

.hint-toggle:hover {
    border-color: var(--gold);
    color: var(--gold);
}

.hint-content {
    display: none;
    margin-top: 10px;
    padding: 12px 15px;
    background: rgba(255, 215, 0, 0.1);
    border-left: 3px solid var(--gold);
    border-radius: 0 6px 6px 0;
    font-size: 0.9em;
}

.hint-content.visible {
    display: block;
}

/* Links */
a {
    color: var(--gold);
    text-decoration: none;
    transition: color 0.2s;
}

a:hover {
    color: #ffed4a;
}

a:visited {
    color: var(--gold);
}

/* Footer */
footer {
    text-align: center;
    padding: 30px 0;
    margin-top: 30px;
    border-top: 1px solid var(--border);
    color: var(--text-dim);
}

footer a {
    color: var(--gold);
    text-decoration: none;
    padding: 5px 10px;
    border: 1px solid transparent;
    border-radius: 4px;
    transition: all 0.2s;
}

footer a:hover {
    border-color: var(--gold);
    background: rgba(255, 215, 0, 0.1);
}

/* Login prompt */
.login-prompt {
    background: var(--bg-card);
    padding: 15px 20px;
    border-radius: 8px;
    margin-bottom: 30px;
    border: 1px dashed var(--gold);
    text-align: center;
}

.login-prompt code {
    background: var(--code-bg);
    padding: 2px 8px;
    border-radius: 4px;
    color: var(--success);
}

/* Token input section */
.token-section {
    background: var(--bg-card);
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 30px;
    border: 1px dashed var(--gold);
}

.token-section > p:first-child {
    margin-bottom: 12px;
    color: var(--text);
}

.token-input-row {
    display: flex;
    gap: 10px;
    margin-bottom: 10px;
}

#token-input {
    flex: 1;
    background: var(--code-bg);
    border: 1px solid var(--border);
    color: var(--text);
    padding: 10px 15px;
    border-radius: 6px;
    font-family: inherit;
    font-size: 0.9em;
}

#token-input:focus {
    outline: none;
    border-color: var(--gold);
}

#token-input::placeholder {
    color: var(--text-dim);
}

#save-token-btn,
#clear-token-btn {
    background: var(--accent);
    border: none;
    color: white;
    padding: 10px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-family: inherit;
    font-size: 0.9em;
    transition: all 0.2s;
}

#save-token-btn:hover {
    background: #d63a52;
}

#clear-token-btn {
    background: transparent;
    border: 1px solid var(--text-dim);
    color: var(--text-dim);
}

#clear-token-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
}

#token-status {
    font-size: 0.85em;
    min-height: 1.2em;
}

#token-status.success {
    color: var(--success);
}

#token-status.error {
    color: var(--accent);
}

.login-hint {
    margin-top: 15px;
    color: var(--text-dim);
    font-size: 0.85em;
}

.login-hint code {
    background: var(--code-bg);
    padding: 2px 8px;
    border-radius: 4px;
    color: var(--success);
}

.token-section.has-token .login-hint {
    display: none;
}

/* Mobile responsive */
@media (max-width: 600px) {
    .container {
        padding: 15px;
    }

    .chapter-title {
        font-size: 1.5em;
    }

    .chapter-intro {
        font-size: 0.8em;
        padding: 15px;
    }

    .level-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }

    .level-status {
        align-self: flex-end;
    }

    .nav {
        flex-direction: column;
        gap: 15px;
    }

    .skills-section {
        flex-direction: column;
        align-items: flex-start;
    }

    .token-input-row {
        flex-direction: column;
    }

    #save-token-btn,
    #clear-token-btn {
        width: 100%;
    }

    .login-hint code {
        display: block;
        overflow-x: auto;
        white-space: pre;
        margin-top: 6px;
        padding: 8px;
    }
}