$gray-medium-light: #eaeaea;

/* universal */

// #main_container {
//   padding-top: 60px;
// }

.container {
  max-width: 900px;
}

#main_container .alert {
  margin-top: 15px;
}

.center {
  text-align: center;
}
.jumbotron {
  h1 {
    font-size: 3.0em;
    margin-bottom: 30px;
  }
  h2 {
    font-size: 1.2em;
    letter-spacing: -1px;
    margin-bottom: 30px;
    text-align: center;
    font-weight: normal;
    color: $gray-light;
  }
}

/* Debug */

.debug_dump {
  clear: both;
  float: left;
  width: 100%;
  margin-top: 45px;
}

.screen_size {
  clear: both;
  float: left;
}

/* Error messages */

#error_explanation {
  color: red;
  ul {
    color: red;
    margin: 0 0 30px 0;
  }
}

.field_with_errors {
  @extend .has-error;
  .form-control {
    color: $state-danger-text;
  }
}

/* miscellaneous */

#author {
  margin-top: 10px;
  padding-top: 25px;
}

$gray-medium-light: #eaeaea;

/* universal */

// #main_container {
//   padding-top: 60px;
// }

.container {
  max-width: 940px;
}

#main_container .alert {
  margin-top: 15px;
}

.center {
  text-align: center;
}
.jumbotron {
  h1 {
    font-size: 3.0em;
    margin-bottom: 30px;
  }
  h2 {
    font-size: 1.2em;
    letter-spacing: -1px;
    margin-bottom: 30px;
    text-align: center;
    font-weight: normal;
    color: $gray-light;
  }
}

/* Debug */

.debug_dump {
  clear: both;
  float: left;
  width: 100%;
  margin-top: 45px;
}

.screen_size {
  clear: both;
  float: left;
}

/* Error messages */

#error_explanation {
  color: red;
  ul {
    color: red;
    margin: 0 0 30px 0;
  }
}

.field_with_errors {
  @extend .has-error;
  .form-control {
    color: $state-danger-text;
  }
}

/* miscellaneous */

#author {
  margin-top: 10px;
  padding-top: 25px;
}

Adjust container's max-width to make 3-col grid
Adjust container's max-width to make 3-col grid
