* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

body {
    background-color: #f7f9fa;
    color: #0f1419;
    line-height: 1.4;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    background-color: #fff;
    min-height: 100vh;
    border-left: 1px solid #ebeef0;
    border-right: 1px solid #ebeef0;
    position: relative;
    padding-bottom: 60px; /* Space for bottom nav */
}

/* Header */
.main-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px;
    border-bottom: 1px solid #ebeef0;
    position: sticky;
    top: 0;
    background-color: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(5px);
    z-index: 10;
}

.main-header h1 {
    font-size: 20px;
    font-weight: 700;
}

.sign-in-btn {
    background-color: #1da1f2;
    color: white;
    border: none;
    border-radius: 20px;
    padding: 8px 16px;
    font-weight: bold;
    cursor: pointer;
}

/* Tabs */
.tabs {
    display: flex;
    border-bottom: 1px solid #ebeef0;
}

.tab {
    flex: 1;
    text-align: center;
    padding: 15px 0;
    font-weight: bold;
    color: #536471;
    cursor: pointer;
    position: relative;
}

.tab.active {
    color: #0f1419;
}

.tab.active::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 50px;
    height: 4px;
    background-color: #1da1f2;
    border-radius: 4px;
}

/* Compose Tweet */
.compose-tweet {
    display: flex;
    padding: 15px;
    border-bottom: 1px solid #ebeef0;
}

.avatar img {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    object-fit: cover;
}

.compose-input {
    flex: 1;
    margin-left: 15px;
}

.compose-input input {
    width: 100%;
    border: none;
    font-size: 18px;
    padding: 10px 0;
    outline: none;
}

.tweet-btn {
    background-color: #1da1f2;
    color: white;
    border: none;
    border-radius: 20px;
    padding: 8px 16px;
    font-weight: bold;
    margin-top: 10px;
    float: right;
    cursor: pointer;
}

/* Tweet Feed */
.tweet-feed {
    border-top: 10px solid #f7f9fa;
}

.tweet {
    display: flex;
    padding: 15px;
    border-bottom: 1px solid #ebeef0;
    transition: background-color 0.2s;
}

.tweet:hover {
    background-color: rgba(0, 0, 0, 0.03);
}

.tweet-avatar img {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    object-fit: cover;
}

.tweet-content {
    flex: 1;
    margin-left: 15px;
}

.tweet-header {
    margin-bottom: 5px;
}

.name {
    font-weight: bold;
}

.handle, .dot, .time {
    color: #536471;
    font-size: 14px;
}

.tweet-text {
    margin-bottom: 10px;
    word-wrap: break-word;
}

.tweet-actions {
    display: flex;
    justify-content: space-between;
    max-width: 425px;
    margin-top: 10px;
}

.action {
    display: flex;
    align-items: center;
    color: #536471;
    font-size: 14px;
}

.action i {
    margin-right: 5px;
}

.action:nth-child(1):hover {
    color: #1da1f2;
}

.action:nth-child(2):hover {
    color: #17bf63;
}

.action:nth-child(3):hover {
    color: #e0245e;
}

.action:nth-child(4):hover {
    color: #1da1f2;
}

/* Bottom Navigation */
.bottom-nav {
    display: flex;
    justify-content: space-around;
    align-items: center;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background-color: white;
    border-top: 1px solid #ebeef0;
    padding: 10px 0;
    max-width: 600px;
    margin: 0 auto;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    color: #536471;
    text-decoration: none;
    font-size: 12px;
}

.nav-item i {
    font-size: 20px;
    margin-bottom: 4px;
}

.nav-item.active {
    color: #1da1f2;
}

/* Responsive Design */
@media (max-width: 600px) {
    .container {
        width: 100%;
        border: none;
    }
    
    .tweet-actions {
        max-width: 100%;
    }
}

@media (max-width: 480px) {
    .action span {
        display: none;
    }
    
    .action i {
        margin-right: 0;
    }
    
    .nav-item span {
        display: none;
    }
}