:root{--primary:#667eea;--secondary:#764ba2;--accent:#4CAF50;--light:#f8f9fa;--dark:#333;--success:#28a745;--warning:#ffc107;--danger:#dc3545;--gray:#6c757d}
*{margin:0;padding:0;box-sizing:border-box}
body{font-family:'Segoe UI',Tahoma,Geneva,Verdana,sans-serif;line-height:1.6;color:var(--dark);background:linear-gradient(135deg,var(--primary) 0%,var(--secondary) 100%);min-height:100vh}
.container{max-width:1400px;margin:0 auto;padding:20px}
header{text-align:center;padding:40px 0;color:white;display:flex;align-items:center;justify-content:center;gap:15px}
header .logo{height:50px;width:auto;border-radius:8px;vertical-align:middle;animation:logoFloat 3s ease-in-out infinite}
@keyframes logoFloat{0%,100%{transform:translateY(0)}50%{transform:translateY(-8px)}}
header h1{font-size:3em;margin-bottom:0;text-shadow:2px 2px 4px rgba(0,0,0,0.3);display:flex;align-items:center;gap:15px;margin:0}
.nav{background:rgba(255,255,255,0.95);padding:12px 20px;border-radius:10px;margin:20px 0;box-shadow:0 4px 15px rgba(0,0,0,0.1);display:flex;align-items:center}
.nav .logo-link{display:flex;align-items:center;gap:8px;text-decoration:none;margin-right:auto;height:50px}
.nav .logo-link img{height:40px;width:auto;border-radius:6px}
.nav .logo-link span{font-weight:bold;color:var(--primary);font-size:1.1em;white-space:nowrap}
.nav ul{display:flex;justify-content:center;list-style:none;flex-wrap:wrap;gap:15px}
.nav a{text-decoration:none;color:var(--primary);font-weight:bold;padding:10px 20px;border-radius:25px;transition:all .3s}
.nav a:hover,.nav a.active{background:var(--primary);color:white}
.main-content{display:grid;grid-template-columns:2fr 1fr;gap:30px;margin:30px 0}
.content-section{background:white;padding:30px;border-radius:15px;box-shadow:0 4px 15px rgba(0,0,0,0.1);min-height:500px}
.sidebar{background:white;padding:25px;border-radius:15px;box-shadow:0 4px 15px rgba(0,0,0,0.1)}
h2{color:var(--primary);margin-bottom:20px;border-bottom:3px solid var(--primary);padding-bottom:10px}
h3{color:var(--secondary);margin:15px 0 10px 0}
.code-block{background:#f8f9fa;border:1px solid #e9ecef;border-radius:8px;padding:20px;margin:15px 0;overflow-x:auto;font-family:Consolas,Monaco,monospace;position:relative}
.code-block pre{margin:0}
.copy-btn{position:absolute;top:5px;right:5px;background:var(--primary);color:white;border:none;padding:5px 10px;border-radius:4px;cursor:pointer;font-size:12px}
.feature-list{list-style:none;margin:20px 0}
.feature-list li{padding:10px;margin:8px 0;background:#f8f9fa;border-left:4px solid var(--primary);border-radius:4px;cursor:pointer;transition:all .2s}
.feature-list li:hover{background:#e9ecef;transform:translateX(5px)}
.example-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(300px,1fr));gap:20px;margin:20px 0}
.example-card{background:#f8f9fa;padding:20px;border-radius:10px;border:1px solid #e9ecef;transition:transform .3s}
.example-card:hover{transform:translateY(-5px);box-shadow:0 5px 15px rgba(0,0,0,0.1)}
footer{text-align:center;color:white;padding:30px 0;margin-top:50px}
.ide-container{background:#1e1e1e;border-radius:10px;overflow:hidden;margin:20px 0;box-shadow:0 4px 15px rgba(0,0,0,0.2)}
.ide-header{background:#2d2d30;padding:10px 15px;color:#ccc;display:flex;justify-content:space-between;align-items:center}
.ide-controls button{background:#007acc;color:white;border:none;padding:5px 15px;border-radius:4px;cursor:pointer}
.ide-content{display:flex;height:400px}
.ide-editor{flex:3;background:#1e1e1e;overflow:auto}
.ide-output{flex:2;background:#0e0e0e;color:#ccc;padding:15px;overflow-y:auto;border-left:1px solid #333;font-family:Consolas,monospace}
.code-editor{width:100%;height:100%;background:#1e1e1e;color:#d4d4d4;border:none;padding:15px;font-family:Consolas,monospace;font-size:14px;outline:none;resize:none}
.ai-assistant{background:white;border-radius:10px;padding:20px;margin:20px 0;box-shadow:0 4px 15px rgba(0,0,0,0.1);border-left:5px solid var(--accent)}
.ai-icon{background:var(--accent);color:white;width:40px;height:40px;border-radius:50%;display:flex;align-items:center;justify-content:center;margin-right:10px;font-weight:bold}
.ai-hint,.ai-suggestion{background:#e8f5e9;padding:15px;border-radius:8px;margin:10px 0;border-left:4px solid var(--accent)}
.ai-suggestion{background:#e3f2fd;border-left-color:var(--primary)}
.ai-input{display:flex;margin-top:15px}
.ai-input input{flex:1;padding:10px;border:1px solid #ddd;border-radius:4px 0 0 4px;outline:none}
.ai-input button{background:var(--accent);color:white;border:none;padding:10px 15px;border-radius:0 4px 4px 0;cursor:pointer}
.page-navigation{display:flex;justify-content:space-between;margin-top:30px;padding-top:20px;border-top:1px solid #eee}
.page-btn{background:var(--primary);color:white;border:none;padding:10px 20px;border-radius:4px;text-decoration:none;display:inline-block}
.page-btn:hover{background:var(--secondary)}
.progress-container{background:#e9ecef;border-radius:10px;height:10px;margin:20px 0;overflow:hidden}
.progress-bar{background:var(--accent);height:100%;width:0;transition:width .3s}
@media(max-width:1024px){.main-content{grid-template-columns:1fr}.ide-content{flex-direction:column;height:600px}.ide-output{border-left:none;border-top:1px solid #333}}
@media(max-width:768px){header h1{font-size:2em}.nav ul{flex-direction:column;align-items:center}.example-grid{grid-template-columns:1fr}}

/* Login Button Style */
.login-btn {
    background: linear-gradient(135deg, #ff6b6b 0%, #ee5253 100%); /* 鮮豔的橙紅色，與你的藍紫色主題形成對比 */
    color: white !important; /* 強制字體白色 */
    padding: 10px 25px !important;
    border-radius: 30px;
    font-weight: bold;
    box-shadow: 0 4px 15px rgba(238, 82, 83, 0.4); /* 柔和的陰影 */
    transition: all 0.3s ease;
    border: 2px solid transparent;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.login-btn:hover {
    transform: translateY(-2px); /* 鼠標懸停時微微上浮 */
    box-shadow: 0 6px 20px rgba(238, 82, 83, 0.6);
    background: linear-gradient(135deg, #ee5253 0%, #ff6b6b 100%); /* 漸變反轉 */
}

/* 確保導航欄在大螢幕上可以把 Login 按鈕推到最右邊 */
.nav ul {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    /* justify-content: center;  <-- 刪除這行，改用下面的 gap */
    gap: 15px;
    padding: 0 20px; /* 給左右一點空間 */
}

/* ===== INTERACTIVE IDE MODULE ===== */

/* Try in IDE Button */
.try-ide-btn {
    background: var(--accent);
    color: white;
    border: none;
    padding: 6px 12px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 12px;
    margin-left: 8px;
    transition: all 0.2s;
    font-weight: bold;
}

.try-ide-btn:hover {
    background: #3d943a;
    box-shadow: 0 3px 10px rgba(76, 175, 80, 0.3);
    transform: translateY(-1px);
}

.try-ide-btn:active {
    transform: translateY(0);
}

/* Code Block Actions Container */
.code-actions {
    display: flex;
    gap: 8px;
    align-items: center;
    position: absolute;
    top: 5px;
    right: 5px;
}

.code-actions .copy-btn {
    position: static;
    margin: 0;
}

/* IDE Modal/Drawer - Desktop (Side Panel) */
#ide-panel {
    position: fixed;
    right: 0;
    top: 0;
    width: 45%;
    height: 100vh;
    background: white;
    box-shadow: -4px 0 20px rgba(0, 0, 0, 0.15);
    border-left: 3px solid var(--primary);
    border-radius: 0;
    z-index: 1000;
    display: none;
    flex-direction: column;
    overflow: hidden;
    transition: all 0.3s ease;
}

#ide-panel.active {
    display: flex;
}

/* IDE Header */
.ide-panel-header {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    padding: 15px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-shrink: 0;
}

.ide-panel-header h3 {
    margin: 0;
    color: white;
    font-size: 1.2em;
}

.ide-close-btn {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: white;
    cursor: pointer;
    font-size: 1.5em;
    width: 40px;
    height: 40px;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.ide-close-btn:hover {
    background: rgba(255, 255, 255, 0.3);
}

/* IDE Editor Area */
.ide-editor-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    padding: 15px;
    gap: 15px;
}

.ide-code-input {
    flex: 1;
    background: #f5f5f5;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    padding: 15px;
    font-family: 'Courier New', monospace;
    font-size: 14px;
    resize: none;
    outline: none;
    transition: all 0.2s;
}

.ide-code-input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.ide-controls {
    display: flex;
    gap: 10px;
}

.ide-run-btn {
    flex: 1;
    background: linear-gradient(135deg, var(--accent) 0%, #45a049 100%);
    color: white;
    border: none;
    padding: 12px 20px;
    border-radius: 6px;
    font-weight: bold;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.ide-run-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(76, 175, 80, 0.3);
}

.ide-run-btn:active {
    transform: translateY(0);
}

.ide-clear-btn {
    background: #6c757d;
    color: white;
    border: none;
    padding: 12px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.2s;
}

.ide-clear-btn:hover {
    background: #5a6268;
}

/* IDE Output Area */
.ide-output-area {
    background: #1e1e1e;
    color: #d4d4d4;
    padding: 15px;
    border-radius: 8px;
    font-family: 'Courier New', monospace;
    font-size: 13px;
    max-height: 200px;
    overflow-y: auto;
    border: 1px solid #333;
    white-space: pre-wrap;
    word-wrap: break-word;
    flex-shrink: 0;
}

.ide-output-area.has-error {
    color: #ff6b6b;
    background: #2b1b1b;
}

.ide-output-area.has-success {
    color: #51cf66;
}

.ide-output-empty {
    color: #999;
    font-style: italic;
}

/* ===== RESPONSIVE LAYOUT ===== */

/* Desktop Layout: Content + IDE Side-by-Side */
body.ide-active .main-content {
    grid-template-columns: 55% 45%;
    gap: 0;
}

body.ide-active .content-section {
    border-radius: 15px 0 0 15px;
    margin-right: 0;
}

/* Mobile Layout: IDE as Full-Screen Modal/Drawer */
@media (max-width: 1024px) {
    #ide-panel {
        width: 100%;
        height: 100%;
        border-left: none;
        border-radius: 0;
    }

    #ide-panel.active {
        animation: slideUp 0.3s ease;
    }

    @keyframes slideUp {
        from {
            transform: translateY(100%);
        }
        to {
            transform: translateY(0);
        }
    }

    body.ide-active .main-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    #ide-panel {
        width: 100%;
        height: 90vh;
        bottom: 0;
        top: auto;
    }

    .ide-code-input {
        font-size: 16px;
    }

    .code-actions {
        flex-wrap: wrap;
        top: 10px;
        right: 10px;
    }
}

/* ===== TEACHER / DASHBOARD SHARED COMPONENTS ===== */

/* Teacher Dashboard Header */
.dashboard-header {
    background: linear-gradient(135deg, rgba(82,84,242,0.95) 0%, rgba(118,75,162,0.95) 100%);
    color: white;
    padding: 25px 20px;
    border-radius: 15px;
    margin-bottom: 25px;
    box-shadow: 0 10px 30px rgba(82,84,242,0.2);
}
.dashboard-header h2 { font-size: 2em; margin: 0 0 8px 0; color: white; }
.dashboard-header p { margin: 4px 0; opacity: 0.95; }

/* Teacher Sub-Navigation */
.teacher-subnav {
    display: flex;
    gap: 8px;
    margin-bottom: 28px;
    flex-wrap: wrap;
    background: #f8fafc;
    padding: 12px;
    border-radius: 12px;
    border: 1px solid #e2e8f0;
}
.subnav-btn {
    background: white;
    border: 2px solid #cbd5e1;
    padding: 9px 16px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9em;
    font-weight: 600;
    color: #475569;
    text-decoration: none;
    transition: all 0.2s;
}
.subnav-btn:hover { border-color: #5254f2; color: #5254f2; background: #f0f0ff; }
.subnav-btn.active { background: #5254f2; color: white; border-color: #5254f2; }

/* Section Cards */
.section-card {
    background: white;
    padding: 25px;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.08);
    margin-bottom: 25px;
}
.section-card h3 {
    color: #5254f2;
    border-bottom: 3px solid #10b981;
    padding-bottom: 12px;
    margin-bottom: 20px;
    font-size: 1.4em;
}

/* Form Groups (Teacher Forms) */
.form-group { margin-bottom: 18px; }
.form-group label { display: block; margin-bottom: 8px; font-weight: 600; color: #334155; }
.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 12px;
    border: 1.5px solid #cbd5e1;
    border-radius: 8px;
    font-size: 1em;
    background: #f8fafc;
    font-family: inherit;
}
.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: #5254f2;
    box-shadow: 0 0 0 4px rgba(82,84,242,0.1);
    background: white;
}

/* Submit Button */
.submit-btn {
    background: linear-gradient(135deg, #5254f2 0%, #764ba2 100%);
    color: white;
    padding: 13px 28px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1em;
    font-weight: 600;
    transition: all 0.2s;
    box-shadow: 0 4px 12px rgba(82,84,242,0.3);
}
.submit-btn:hover { transform: translateY(-2px); box-shadow: 0 6px 18px rgba(82,84,242,0.4); }
.submit-btn:active { transform: translateY(0); }

/* Stats Grid (Teacher Dashboard) */
.stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 20px; }
.stat-box { padding: 22px; border-radius: 10px; color: white; text-align: center; }
.stat-box .stat-number { font-size: 2.2em; font-weight: bold; }
.stat-box .stat-label { opacity: 0.92; font-size: 0.95em; margin-top: 4px; }

/* Actions Grid (Teacher Dashboard) */
.actions-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 20px; }
.action-card {
    background: white;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    padding: 24px 20px;
    text-align: center;
    text-decoration: none;
    color: #334155;
    transition: all 0.25s;
    display: block;
}
.action-card:hover {
    border-color: #5254f2;
    box-shadow: 0 6px 20px rgba(82,84,242,0.15);
    transform: translateY(-3px);
    color: #5254f2;
}
.action-card .action-icon { font-size: 2.4em; margin-bottom: 10px; }
.action-card .action-title { font-size: 1.1em; font-weight: 700; margin-bottom: 6px; }
.action-card .action-desc { font-size: 0.85em; color: #64748b; line-height: 1.4; }

/* Info Box */
.info-box {
    background: #dbeafe;
    border-left: 4px solid #5254f2;
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 20px;
    color: #1e40af;
}
.info-box strong { display: block; margin-bottom: 5px; }

/* Responsive overrides for teacher/dashboard pages */
@media (max-width: 768px) {
    .teacher-subnav { flex-direction: column; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); }
    .actions-grid { grid-template-columns: 1fr; }
}

/* ===== DASHBOARD LAYOUT (student-dashboard, teacher-grading) ===== */
body.dashboard-layout {
    background: #f0f4f8;
    margin: 0;
    padding: 0;
}
body.dashboard-layout .nav {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 15px 30px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    border-radius: 0;
    margin: 0;
}
body.dashboard-layout .nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    gap: 0;
    align-items: center;
}
body.dashboard-layout .nav a {
    color: white;
    text-decoration: none;
    padding: 10px 20px;
    border-radius: 8px;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    gap: 5px;
    font-weight: normal;
    background: none;
}
body.dashboard-layout .nav a:hover {
    background: rgba(255,255,255,0.2);
}
body.dashboard-layout .nav a.active {
    background: rgba(255,255,255,0.3);
    font-weight: 600;
}
.main-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 30px 20px;
}